Karyopharm Therapeutics Inc.

1. Organization and Operations

We are a commercial-stage pharmaceutical company pioneering novel cancer therapies and dedicated to the discovery, development and commercialization of first-in-class drugs directed against nuclear export for the treatment of cancer. Our scientific expertise is based upon an understanding of the regulation of intracellular communication between the nucleus and the cytoplasm. We have discovered and are developing and commercializing novel, small molecule XPO1 inhibitor compounds that inhibit the nuclear export protein exportin 1. Our primary focus is on marketing XPOVIO® (selinexor) in its currently approved indications, as well as developing and seeking the regulatory approval of selinexor as an oral agent targeting multiple high unmet cancer indications, including our lead clinical programs in myelofibrosis and endometrial cancer and our other late-stage clinical program in multiple myeloma. We were incorporated in Delaware on December 22, 2008 and have a principal place of business in Newton, Massachusetts.

Our lead asset, XPOVIO, received its initial U.S. approval from the U.S. Food and Drug Administration (the “FDA”) in July 2019 and is currently approved and marketed for the following indications: (i) in combination with bortezomib and dexamethasone for the treatment of adult patients with multiple myeloma who have received at least one prior therapy; (ii) in combination with dexamethasone for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, at least two immunomodulatory agents, and an anti-CD38 monoclonal antibody; and (iii) for the treatment of adult patients with relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”), not otherwise specified, including DLBCL arising from follicular lymphoma, after at least two lines of systemic therapy. The commercialization of XPOVIO and NEXPOVIO®(selinexor) (the brand name for selinexor in Europe and the United Kingdom) outside of the U.S. is managed by our partners in their respective territories. XPOVIO/NEXPOVIO has received regulatory approval in various indications in 50 territories and countries outside the U.S. and is commercially available in a growing number of countries as our partners continue to secure reimbursement approvals.

We have historically financed our operations primarily through a combination of proceeds from (i) product revenue sales; (ii) public and private placements of equity securities; (iii) the issuance of convertible debt; (iv) a term loan; (v) our deferred royalty obligation; (vi) at the market offerings; and (vii) business development activities. As of December 31, 2025, we had $63.7 million of cash, cash equivalents and investments and an accumulated deficit of $1.8 billion. We have incurred significant operating losses since our inception and we anticipate that we will continue to incur significant operating losses to maintain our research and development programs, including as we continue to develop and seek regulatory approval of selinexor for multiple cancer indications, and to support our continued operations. As a result, our continued operations are dependent on our ability to raise additional funding or enter in other strategic alternatives and marketing XPOVIO in its currently approved indications. Based on our current business plan and current capital resources, given the uncertainty regarding the availability of additional funding or other strategic alternatives and considering our debt service obligations and financial covenant to maintain minimum liquidity, we have concluded that there is substantial doubt regarding our ability to continue as a going concern within one year after the date the accompanying consolidated financial statements are issued. We plan to address the conditions that raise substantial doubt regarding our ability to continue as a going concern by, among other things, obtaining additional funding through equity offerings, debt financings and refinancings, collaborations, strategic alliances and/or licensing arrangements. However, there is no assurance that these efforts will result in additional funding, strategic alliances or licensing arrangements or sufficiently address the Company’s ability to continue as a going concern.

If we utilize our capital resources more quickly than anticipated or are unable to obtain additional funding or engage in strategic alternatives, we may have to significantly curtail, delay, reduce or eliminate one or more of our research and development programs or any current or future commercialization efforts for one or more of our products or product candidates, which could materially adversely affect our business, financial condition, and results of operations. We may determine to take additional actions to reduce our spending in the near term. As we announced in July 2025, we reduced our workforce by approximately 20% as part of our ongoing careful management of operating expenses. If we are unable to continue as a going concern, we may have to liquidate assets and may receive less than the value at which those assets are carried on our financial statements. We may also determine to cease operations or file for bankruptcy protection. In any of these circumstances, it is likely that investors will lose all or part of their investment. If there remains substantial doubt about our ability to continue as a going concern, investors or other financing sources may be unwilling to provide funding to us on commercially reasonable terms, if at all. The accompanying consolidated financial statements do not include any adjustments to the carrying amounts and classification of assets and liabilities that may be necessary if we were unable to continue as a going concern.

2. Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the accounts of (i) Karyopharm Therapeutics Inc., (ii) Karyopharm Securities Corp. (“KSC”), our wholly-owned Massachusetts corporation incorporated in December 2013 and dissolved in October 2024, (iii) Karyopharm Europe GmbH, our wholly-owned German limited liability company, incorporated in September 2014, and (iv) Karyopharm Israel Ltd., our wholly-owned Israeli subsidiary formed in June 2018. All intercompany balances and transactions have been eliminated in consolidation.

On February 25, 2025, we effected a 1-for-15 reverse stock split of our common stock (the “Reverse Stock Split”). All share and per share amounts in these consolidated financial statements and notes thereto, including the conversion rates of convertible debt and the exercise price of common stock warrants, have been adjusted retroactively to reflect the Reverse Stock Split for all periods presented.

Recent Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board issued Accounting Standards Update 2023-09, Improvements to Income Tax Disclosures, which requires entities to disclose additional information about their effective tax rate reconciliation. We adopted this standard on a prospective basis beginning with the year ended December 31, 2025. The adoption of this standard had no material impact on our financial statements and resulted only in expanded income tax disclosure requirements.

In November 2024, the Financial Accounting Standards Board issued Accounting Standards Update 2024-03, Reporting Comprehensive Income - Expense Disaggregation Disclosures. This standard requires disclosure of specified information about certain costs and expenses including purchases of inventory and employee compensation. This standard also requires disclosure of the total amount of selling expenses, and, in annual reporting periods, the Company’s definition of selling expenses. This standard is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. We are evaluating the impact of this standard and expect its effect to be limited to enhanced disclosures in the notes to the consolidated financial statements.

Segment Information

Operating segments are defined as components of an enterprise whose operating results are regularly reviewed by the Chief Operating Decision Maker (“CODM”) to allocate resources and assess performance. We view our operations and manage our business as a single operating segment, which is the business of discovering, developing and commercializing drugs to treat cancer. All our revenue and all our long-lived assets are attributable to our single operating segment and to Karyopharm Therapeutics Inc., which is domiciled in the United States.

Our CODM is our Chief Executive Officer who usesnet loss as reported on the consolidated statements of operations to monitor budget versus actual results and to ensure we have sufficient capital resources to develop and seek regulatory approval of our product candidates. The following table presents the significant revenue and expense categories (in thousands) in our single operating segment:

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period.

On an ongoing basis, we evaluate our estimates, including estimates related to our net product revenue, license and other revenue, clinical trial accruals, stock-based compensation expense, interest expense on our deferred royalty obligation, embedded derivative liabilities, liability-classified common stock warrants, valuation allowances, and other reported amounts of expenses during the reported period. We base our estimates on historical experience and other market-specific or relevant assumptions that we believe to be reasonable under the circumstances. Although we regularly assess these estimates, actual results could differ from those estimates. Changes in estimates are recorded in the period in which they become known.

Concentrations of Credit Risk and Off-Balance Sheet Risk

Financial instruments which potentially subject us to credit risk consist primarily of cash, cash equivalents and investments. We hold these investments in highly rated financial institutions, and, by policy, limit the amounts of credit exposure to any one financial institution. These amounts at times may exceed federally insured limits. We have not experienced any credit losses in such accounts and do not believe we are exposed to any significant credit risk on these funds. We have no off-balance sheet concentrations of credit risk.

The following table summarizes customers that represent 10% or greater of our consolidated total revenue:

The following table summarizes customers with amounts due that represent 10% or greater of our consolidated accounts receivable, net balance:

Fair Value Measurements

Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value and is not a measure of credit quality. The hierarchy defines three levels of valuation inputs:

Level 1 inputs: Quoted prices in active markets for identical assets or liabilities

Level 2 inputs: Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly

Level 3 inputs: Unobservable inputs that reflect our own assumptions about the assumptions market participants would use in pricing the asset or liability.

Cash and Cash Equivalents

Cashand cash equivalents consist primarily of demand deposit accounts and deposits in short-term money market funds. Cash equivalents are stated at cost, which approximates fair value. We consider all highly liquid investments with maturities of three monthsor less from the date of purchase to be cash equivalents. We do not hold any money market funds with significant liquidity restrictions that would be required to be excluded from cash equivalents.

Investments

We determine the appropriate classification of our investments at the time of purchase. All of our investments are reported as short-term as they are available for use during the normal cycle of business. We review any investment when its fair value is less than its amortized cost and when evidence indicates that the investment’s carrying amount is not recoverable within a reasonable period. We evaluate whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, we consider the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists and if the present value of cash flows expected to be collected is less than the amortized cost basis, an allowance is recorded on our consolidated balance sheet, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that is not related to a credit loss is recognized in other comprehensive (loss) income.

Changes in the allowance for credit losses are recorded as a provision for (or reversal of) credit loss expense. Losses are charged against the allowance when we believe the uncollectability of an investment is confirmed or when either of the criteria regarding intent or requirement to sell is met.

Accounts Receivable

Amounts are recorded as accounts receivable when our right to consideration is unconditional other than the passage of time. Accounts receivable consists of amounts due from customers, net of customer allowances for cash discounts and chargebacks. Our contracts with customers have standard payment terms that generally require payment within 30 to 68 days. We analyze accounts for collectability and periodically evaluate the creditworthiness of our customers. We determined an allowance for credit losses wasnot material as of December 31, 2025 and 2024 as we have hadno bad debt write-offs to date and we did not have credit issues with any customers as of December 31, 2025.

Accrued Research and Development Costs

We estimate our accrued research and development costs by reviewing quotes and contracts, identifying services that have been performed on our behalf, and estimating the associated cost incurred for services performed when we have not yet been invoiced or otherwise notified of the actual cost. Most of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued research and development costs at each balance sheet date in our financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with the service providers and make adjustments if necessary. The significant estimates in our accrued research and development costs include fees incurred with contract research organizations (“CROs”) in connection with research and development activities as well as fees to be paid to investigative sites in connection with clinical studies, for which we have not yet been invoiced.

We base our expenses related to CROs on our estimates of the services performed and efforts expended pursuant to quotes and contracts with CROs that conduct research and development activities on our behalf. The payment terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our service providers will exceed the level of services performed and result in a prepayment. In accruing service fees, we estimate the time period over which the services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimates, we adjust the accrual or prepayment accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, it could result in us reporting amounts that are too high or too low in any particular period. To date, our estimates have not been materially different than amounts actually incurred.

Deferred Royalty Obligation

The deferred royalty obligation, as discussed further in Note 10, “Long-Term Obligations”, is amortized using the effective interest rate method over the estimated life of the revenue streams. We recognize interest expense thereon using the effective rate, which is based on our current estimates of future revenues over the life of the arrangement. We periodically assess our expected revenues using internal projections, impute interest on the carrying value of the deferred royalty obligation, and record interest expense using the imputed effective interest rate. To the extent our estimates of future revenues are greater or less than previous estimates or the estimated timing of such payments is materially different than previous estimates, we will account for any such changesby adjusting the effective interest rate on a prospective basis, which will adjust future interest expense with a corresponding impact to the classification of our deferred royalty obligation. The assumptions used in determining the expected repayment term of the deferred royalty obligation and amortization period of the issuance costs requires that we make estimates that could impact the short-term and long-term classification of such costs, as well as the period over which such costs will be amortized.

Embedded Derivatives

Embedded derivatives that require bifurcation are separated from the host debt instrument and are measured at fair value at the end of each reporting period. See Note 6, “Fair Value Measurements”, for additional detail on the valuation methodology. Changes in fair value are recognized as a component of other income (expense), net on our consolidated statements of operations. Embedded derivatives are reported in the same line as the host debt instrument on the consolidated balance sheets.

Common Stock Warrants

We classify our common stock warrants, including pre-funded warrants, in stockholder’s deficit if they allow for settlement only in shares of our common stock, are indexed to our common stock, and meet the criteria for equity classification. Common stock warrants that do not meet the criteria for equity classification are classified as liabilities and are measured at fair value at the end of each reporting period. See Note 6, “Fair Value Measurements”, for additional detail on the valuation methodology.

Revenue Recognition

To determine revenue recognition, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy a performance obligation. At contract inception, we assess whether the goods or services promised within a contract with a customer are distinct and, therefore, represent a separate performance obligation. Goods or services that are determined not to be distinct are combined with other promised goods and services until a distinct bundle is identified. We then determine the transaction price, which is the total amount of consideration we expect to receive from a customer in exchange for the promised goods or services and includes an estimate of any variable consideration in the contract. We then allocate the transaction price to each performance obligation and recognize the associated revenue when (or as) our customer obtains control of the goods or services within the performance obligation.

Incremental costs of obtaining a contract with a customer are capitalized and amortized consistent with the pattern of transferring the goods or services to which the cost relates when the expected amortization period of the asset is greater than one year. Incremental costs are expensed as incurred if the expected amortization period of the asset that we would have recognized is one year or less.

Product Revenue Recognition

We ship XPOVIO in the U.S. to specialty pharmacies and specialty distributors, collectively referred to as our customers, under a limited number of distribution arrangements with such third parties. Our specialty pharmacy customers resell XPOVIO directly to patients, while our specialty distributor customers resell XPOVIO to healthcare entities, who then resell XPOVIO to patients. We also enter into certain arrangements with group purchasing organizations and/or other payors that provide for government mandated and/or privately negotiated rebates, chargebacks, and discounts with respect to the purchase of our products.

Each unit of XPOVIO that is ordered by our customers represents a distinct performance obligation that is completed when control of the product is transferred to the customer. Accordingly, we recognize product revenue when the customer obtains control of our product, which occurs at a point in time, upon delivery pursuant to our agreements with our customers. If taxes are collected from customers relating to product sales and remitted to governmental authorities, they are excluded from revenue.

Revenue from product sales is recorded at the net sales price, which includes estimates of variable consideration for which reserves are reported. These reserves, as detailed below, are based on the amounts earned, or to be claimed on the related sales, and are generally classified as reductions of accounts receivable (if the amount is payable to the customer) or a current liability (if the amount is payable to a party other than a customer). Certain amounts are known at the time of sale based on contractual terms and are recorded pursuant to the most likely amount method, which is the single most likely amount in a range of possible considerations.

The following are the components of variable consideration related to product revenue:

Cash discounts and distributor fees: We provide customary discounts on XPOVIO sales to our customers for prompt payment, the terms of which are explicitly stated in our contracts with such customers. We also pay fees to our customers for sales order management, data, and distribution services, the terms of which are also explicitly stated in our contracts with such customers. Such fees are not for a distinct good or service and, accordingly, are recorded as a reduction of revenue, as well as a reduction to accounts receivable (cash discounts) or as a component of accrued expenses (distributor fees).

Product returns: Consistent with industry practice, we offer our customers and other indirect purchasers a limited right of return for purchased units of XPOVIO for damage, defect, recall, and/or product expiry (beginning three months prior to the product’s expiration date and ending six to twelve months after the product’s expiration date). We estimate the amount of product sales that will be returned using quantitative and qualitative considerations, such as visibility into the inventory remaining in the distribution channel and historical returns data. Reserves for estimated returns are recorded as a reduction of revenue in the period that the related revenue is recognized, as well as a component of accrued expenses. We update our estimated return liability each reporting period based on actual shipments of XPOVIO subject to contractual return rights, changes in expectations about the amount of estimated and/or actual returns, and other qualitative considerations.

Chargebacks: Chargebacks for fees and discounts represent the estimated obligations resulting from our contractual commitments to provide products to qualified healthcare entities at prices lower than the list prices charged to our customers who purchase XPOVIO directly from us. Our customers charge us for the discount provided to the healthcare entities. Chargebacks are generally determined at the time of resale to the qualified healthcare provider by our customers. Accordingly, reserves for chargebacks consist of credits that we expect to issue for units that remain in the distribution channel inventory at the end of the reporting period that we expect will be sold to qualified healthcare entities, as well as chargebacks that customers have claimed, but for which we have not yet issued a credit. We record reserves for chargebacks based on contractual terms in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. We generally issue credits to the customer for such amounts within a few weeks after the customer notifies us of the resale to a discount-eligible healthcare entity.

Government rebates: We are subject to discount obligations under state Medicaid programs, Medicare, the Department of Veterans Affairs, the Department of Defense, and others. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current or long-term liability. Current liabilities are included as a component of accrued expenses and long-term liabilities are included as a component of other liabilities on the consolidated balance sheets. For Medicare, we estimate the number of patients in the prescription drug coverage gap for whom we will owe an additional liability under Medicare Part D. Our liability for these rebates consists of invoices received for claims from prior and current quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimated future claims that will be made for product that has been recognized as revenue, but which remains in distribution channel inventories at the end of the reporting period.

Other incentives: Other incentives offered by us include co-payment assistance, which we provide as financial assistance to patients with commercial insurance that requires prescription drug co-payments by the patient. We calculate the accrual for co-payment assistance based on estimates of claims and the average co-payment assistance amounts per claim that we expect to receive associated with sales of XPOVIO that have been recognized as revenue but remain in distribution channel inventories at the end of the reporting period. Such estimates are based on industry experience with similar products, as well as actual amounts from our product sales to date. Any adjustments to such estimated liabilities on units in the distribution channel at period end, as well as actual amounts incurred on units sold through the distribution channel during the period, are recorded in the same period that the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability, which is included as a component of accrued expenses.

Product revenue reserves and allowances: As noted above, cash discounts and chargebacks are recorded as reductions of accounts receivable and product returns, distributor fees, government rebates, and other incentives are recorded as a component of accrued expenses. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we will adjust these estimates, which would affect product revenue, net and earnings in the period in which such variances become known.

License Agreements

We generate revenue from license or similar agreements with pharmaceutical companies for the development and commercialization of certain of our products and product candidates. Such agreements may include the transfer of intellectual property rights in the form of licenses, transfer of technological know-how, delivery of drug substances, research and development services, and participation on certain committees with the counterparty. Payments made by the customer may include non-refundable upfront fees, payments upon the exercise of options, payments based upon the achievement of defined milestones, and royalties on sales of products and product candidates if they are approved and commercialized. Our license agreements are detailed in Note 5, “License Agreements”.

At contract inception, we evaluate all goods or services in the agreement to determine if they are distinct. If they are not distinct, they are combined with other promised goods or services to create a bundle of promised goods or services that are distinct. Distinct goods or services and distinct bundles of goods or services are considered performance obligations. Optional future services where any additional consideration paid to us reflects their standalone selling prices do not provide the customer with a material right and, therefore, are not considered performance obligations. Optional future services that are priced in a manner which provides the customer with a significant or incremental discount are considered performance obligations because they provide the customer with a material right.

We utilize judgment to estimate the transaction price at contract inception. We evaluate contingent milestones to determine if they should be included in the transaction price using the most likely amount method. Milestone payments that are not within our control, such as regulatory approvals, are not considered likely of being achieved until those approvals are received and are excluded from the transaction price using the most likely amount method. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which we recognize revenue as or when the performance obligations are satisfied. At the end of each reporting period, we re-evaluate our estimate of the transaction price, including the probability of achieving milestone payments that may not be subject to a material reversal, and adjust the transaction price if necessary. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license and other revenue in the period of adjustment.

We then determine whether the performance obligations are satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. We evaluate the measure of progress, as applicable, for each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded within deferred revenue. Contract liabilities within deferred revenue are recognized as revenue after control of the goods or services is transferred to the customer and all revenue recognition criteria have been met.

For arrangements that include a license of intellectual property and sales-based royalties, including sales-based milestone payments, we recognize revenue when the related sales occur because the license of intellectual property is deemed to be the predominant item to which the royalties relate.

Research and Development Expenses

Research and development costs are charged to expense as incurred and include, but are not limited to:

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employee-related expenses, including salaries, benefits, travel and stock-based compensation expense;

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expenses incurred under agreements with CROs, CMOs and consultants that help conduct clinical trials and preclinical studies;

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the cost of acquiring, developing and manufacturing clinical trial materials, including comparator products;

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facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and other supplies; and

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costs associated with preclinical activities and regulatory operations.

Costs for certain research and development activities, such as clinical trials, are recognized based on various inputs, including an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, and other information provided to us by our vendors based on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are accordingly reflected in our financial statements as prepaid or accrued research and development costs.

Selling, General and Administrative Expenses

Selling, general and administrative costs are charged to expense as incurred and consist primarily of salaries, benefits, travel, and other related costs, including stock-based compensation, for personnel in executive, finance, commercial and administrative functions. Other significant costs include facility costs not otherwise included in research and development expenses, legal fees relating to patent and corporate matters and fees for accounting and consulting services.

Accounting for Stock-Based Compensation

We grant stock-based awards to employees and non-employees, including stock options, restricted stock units (“RSUs”), performance-based restricted stock units (“PSUs”) and shares issued under our employee stock purchase plan (“ESPP”). We account for all stock-based awards at their fair value as of the grant date and recognize compensation expense on the consolidated statements of operations on a straight-line basis over the vesting period of the award. We use the Black-Scholes option pricing model to determine the fair value of stock options as of the grant date. The fair value of RSUs is the quoted closing market price per share of our common stock on the Nasdaq Global Select Market on the grant date. Forfeitures are recognized as they occur.

PSUs are awards which will vest if certain performance goals are achieved over a certain performance period. Certain portions of certain PSU awards vest based on continuous service to the Company throughout the performance period even if the performance goal is not achieved. Stock-based compensation expense for PSUs is determined using the grant date fair value, which is the quoted closing market price per share of our common stock on the Nasdaq Global Select Market on the grant date. The grant date fair value of PSUs with a market condition also includes a discount that represents the likelihood that the related performance goals will not be achieved. Stock-based compensation expense for PSUs with a market condition is recognized on a straight-line basis over the service period. Market conditions include goals related to the performance of our common stock. Stock-based compensation expense for PSUs without a market condition is not recognized until the achievement of the performance goal is deemed probable (the “Probable Date”). At the Probable Date, we record a cumulative catch-up expense for the portion of the grant date fair value attributable to the period from the grant date to the Probable Date. The remaining expense is recognized over the remaining service period on a straight-line basis.

Foreign Currency Transactions

The functional currency of our subsidiaries in Germany and Israel are the Euro and Shekel, respectively. Foreign currency transaction gains and losses are recorded on the consolidated statements of operations and were immaterial for the years ended December 31, 2025, 2024 and 2023.

Income Taxes

We use the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial reporting and the tax reporting basis of assets and liabilities and are measured using the enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. We provide a valuation allowance against deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized. We have evaluated available evidence and concluded that we may not realize the benefit of our deferred tax assets; therefore, a valuation allowance has been established for the full amount of the net deferred tax assets. We recognize interest and/or penalties related to income tax matters in income tax expense. Our state tax provision pertains to income generated by our KSC entity. Our foreign tax provision pertains to foreign income taxes due by our German and Israel subsidiaries, both of which operate on a cost-plus profit margin basis.

Net Loss Per Share

Basic net loss per common share is calculated using the two-class method by dividing the net loss allocated to common shares by the weighted-average number of common shares outstanding for the period, which includes the common shares deliverable upon the exercise of outstanding pre-funded warrants. Diluted net loss per common share is calculated by adjusting net loss to remove the effects from potential dilutive common shares and dividing this adjusted amount by the weighted average number of common shares and potential dilutive common shares outstanding for the period. Potential dilutive common shares are not included if their effect is anti-dilutive.

As discussed further in Note 10, “Long-Term Obligations”, the conversion obligation for our 3.00%unsecured convertible senior notes due 2025 (the “2025 Notes”) could have been settled in common shares. The 2025 Notes did not impact the calculation of dilutive loss per common share during the year ended December 31, 2023 because they were anti-dilutive in that period. The table below describes the impact of the 2025 Notes on the calculation of dilutive loss per common share during the year ended December

31,2024. No 2025 Notes were outstanding as of December 31, 2025.

As discussed further in Note 10, “Long-Term Obligations”, the conversion obligations for our: (i)6.00% senior secured convertible notes due 2029 (the “2029 Notes”), (ii)9.00% senior secured convertible notes due 2029 (the “New 2029 Notes”), and (iii)9.00% senior secured convertible notes due 2028 (the “2028 Notes”) can potentially be settled in common shares. The 2029 Notes, New 2029 Notes, and 2028 Notes did not impact the calculation of dilutive loss per common share during the years ended December 31,2025, 2024, and 2023 because they either did not exist or were anti-dilutive during these periods.

As discussed further in Note 11, “Common Share Warrants”, warrants to purchase common shares were outstanding as of December 31, 2025, 2024 and 2023. All outstanding warrants, except pre-funded warrants, are not included in the calculation of basic net loss per share because the warrant holders do not have an obligation to share in our losses, and these warrants did not impact the calculation of dilutive loss per common share during the years ended December 31, 2025, 2024 and 2023 because they either did not exist or were anti-dilutive during these periods. Pre-funded warrants are included in the calculation of basic and diluted net loss per share due to their de-minimus exercise price.

Diluted net loss per common share was equal to basic net loss per common share for the years ended December 31, 2025 and 2023. The following is a reconciliation of the numerator and denominator used to calculate diluted net loss per common share for the year ended December 31, 2024 (in thousands except per share amounts):

The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect (in thousands):

Comprehensive Loss

Comprehensive loss consists of net loss and certain changes in stockholders’ deficit that are excluded from net loss, which currently consists of unrealized gains and losses on investments and foreign currency translation adjustments.

3. Product Revenue

To date, our only source of product revenue has been from the U.S. sales of XPOVIO. The following table summarizes activity in each of the product revenue allowance and reserve categories (in thousands):

Discounts and chargebacks are recorded as reductions of accounts receivable, and returns, fees, rebates, and other incentives are recorded as a component of accrued expenses and other liabilities.

As of December 31, 2025 and 2024, net product revenue of $22.7 million and $27.8 million, respectively, was included in accounts receivable, net.

4. Inventory

Prior to regulatory approval, we expense costs relating to the production of inventory as research and development expenses in the period incurred. We capitalize the costs incurred to manufacture our products after regulatory approval when, based on our judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. We value our inventories at the lower of cost or estimated net realizable value. We determine the cost of our inventories, which includes amounts related to materials and manufacturing overhead, on a first-in, first-out basis. Raw materials and work in process includes all inventory costs prior to packaging and labeling, including raw materials, active pharmaceutical ingredient, and drug product. Finished goods include packaged and labeled products.

Raw materials and work in process that may be used for either research and development or commercial sale are classified as inventory until the material is consumed or otherwise allocated for research and development. If the material is intended to be used for research and development, it is expensed as research and development once that determination is made.

We assess the recoverability of our inventory each reporting period and write-down any inventory that has become obsolete, that has a cost basis in excess of its estimated realizable value, or that is not expected to be sold or otherwise consumed before expiry. Inventory write-downs are recorded as cost of sales in the period the impairment is identified.

Cost of sales includes the cost of producing and distributing inventories related to sales of XPOVIO in the U.S. and sales of selinexor to our partners who commercialize our products outside of the U.S. Cost of sales is recognized in the period the related sales occur and includes compensation expense for employees involved with production and distribution, freight, and indirect overhead costs, as well as third-party royalties payable on net product revenue. Cost of sales may also include excess or obsolete inventory adjustment charges, abnormal costs, unabsorbed manufacturing and overhead costs, and manufacturing variances.

The following table presents our inventory (in thousands), all of which was related to XPOVIO:

5. License Agreements

The following license agreements affected the consolidated financial statements during the years ended December 31, 2025, 2024 and 2023:

Menarini License Agreement

In December 2021, we entered into a license agreement (the “Original Menarini Agreement”) with Berlin-Chemie AG, an affiliate of the Menarini Group (“Menarini”), pursuant to which we granted Menarini a non-exclusive license to develop, and an exclusive license to commercialize, products containing selinexor (the “Product”), for all human oncology indications in the European Economic Area, United Kingdom, Switzerland, Armenia, Azerbaijan, Belarus, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Uzbekistan, Ukraine, Turkey, Mexico, all Central America countries and all South America countries (collectively, the “Menarini Territory”). In March 2023, the Original Menarini Agreement was amended (the “Amended Menarini Agreement”) to expand the Menarini Territory to include all countries in the continent of Africa and Saudi Arabia, United Arab Emirates, Kuwait, Oman, Qatar, Bahrain, Lebanon, Jordan, Iraq, and Yemen (together with the Menarini Territory, the “Expanded Menarini Territory”). In addition, we granted to Menarini a non-exclusive license to package and label the Product in or outside of the Expanded Menarini Territory for all human oncology indications solely to enable Menarini to commercialize the Product within the Expanded Menarini Territory.

Under the terms of the Amended Menarini Agreement, we will use commercially reasonable efforts to develop the Product, transfer any marketing approval or authorization with respect to the Product in the Expanded Menarini Territory to Menarini and to complete any post-marketing approval or authorization studies required by a regulatory authority as a condition of maintaining the approval in any country in the Expanded Menarini Territory. Menarini is obligated to use commercially reasonable efforts to apply for and obtain marketing approval or authorization of the Product, and to obtain price or reimbursement approval for the Product after approval of the relevant marketing approval or authorization, in each country of the Expanded Menarini Territory in each indication for which we have conducted a registrational clinical trial. Menarini is also obligated to use commercially reasonable efforts at its sole cost and expense to launch and commercialize the Product in each country of the Expanded Menarini Territory in each indication for which we have conducted a registrational clinical trial.

We received an upfront cash payment of $75.0 million in December 2021 under the Original Menarini Agreement and $3.5 million in April 2023 upon execution of the Amended Menarini Agreement. In addition, we have received and are entitled to receive additional milestone payments from Menarini if certain development and sales performance milestones are achieved. We have received and are further eligible to receive tiered royalties ranging from the mid-teens to mid-twenties based on future net sales of the Product in the Expanded Menarini Territory. The payments owed by Menarini to us are subject to reduction in specified circumstances. Menarini also reimbursed us $15.0 million per calendar year, or $60 million in total, for development related expenses we incurred for selinexor from 2022 through 2025.

The Amended Menarini Agreement will continue in effect on a country-by-country basis until the last to occur among: (i) the fifteenth anniversary of the first commercial sale of the Product in the applicable country, (ii) the expiration of the last-to-expire of the licensed patent rights in the applicable country or (iii) the expiration of any regulatory exclusivity protection covering the Product in such country. However, the Amended Menarini Agreement may be terminated earlier by either party for (i) an uncured material breach of the Amended Menarini Agreement by the other party (A) on a country-by-country basis with respect to the country to which the breach does not affect the Amended Menarini Agreement as a whole or (B) in its entirety if the breach affects the Amended Menarini Agreement as a whole, or (ii) in the event of the insolvency or bankruptcy of the other party. We may also terminate the Amended Menarini Agreement for certain patent challenges by Menarini.

We assessed this arrangement and concluded that the contract counterparty, Menarini, is a customer. All development and regulatory milestones, which represent variable consideration, will be evaluated each reporting period and included in the transaction price if the milestone is considered likely of achievement and if it is probable that a significant revenue reversal will not occur in future periods. Milestones included in the transaction price will be fully recognized in revenue in the same reporting period because the distinct performance obligation identified at the inception of the contract was fully satisfied.

Any consideration related to sales-based milestones, as well as royalties on net sales upon commercialization by Menarini, are recognized when the related sales occur, as they were determined to relate predominantly to the intellectual property licenses granted to Menarini.

Antengene License Agreement

In May 2020, we entered into an amendment to our May 2018 license agreement (the “Original Antengene Agreement” and, as amended, the “Amended Antengene Agreement”) with Antengene Therapeutics Limited, a corporation organized and existing under the laws of Hong Kong (“Antengene”) and a subsidiary of Antengene Corporation Co. Ltd., a corporation organized and existing under the laws of the People’s Republic of China, pursuant to which we expanded the territory licensed to Antengene in the Original Antengene Agreement for the exclusive development and commercialization rights of selinexor, eltanexor and KPT-9274, each for the diagnosis, treatment and/or prevention of all human oncology indications, as well as verdinexor for the diagnosis, treatment and/or prevention of certain human non-oncology indications (“Antengene Licensed Compounds”).

Under the terms of the Amended Antengene Agreement, Antengene has the exclusive development and commercialization rights for the Antengene Licensed Compounds in mainland China, Taiwan, Hong Kong, Macau, South Korea, Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand, Vietnam, Australia and New Zealand (the “Antengene Territory”). Under the terms of the Original Antengene Agreement, we received an upfront cash payment of $11.7 million in 2018 and in June 2020 we received a one-time upfront cash payment of $11.7 million in connection with the Amended Antengene Agreement. We have received and are entitled to future milestone payments from Antengene if certain development, regulatory and commercialization goals are achieved. Finally, we have received and are further eligible to receive tiered double-digit royalties based on future net sales of selinexor and eltanexor, and tiered single- to double-digit royalties based on future net sales of verdinexor and KPT-9274 in the Antengene Territory. In addition, upon completion of the manufacturing technology transfer plan, we will grant to Antengene non-exclusive rights to manufacture the Antengene Licensed Compounds solely for their development and commercialization in the Antengene Territory.

As part of the Amended Antengene Agreement, Antengene also has the right to participate in global clinical studies of the Antengene Licensed Compounds and will bear the cost and expense for patients enrolled in such global clinical studies in the Antengene Territory. Antengene is responsible for seeking regulatory and marketing approvals for the Antengene Licensed Compounds in the Antengene Territory, as well as any development of the products necessary to obtain such approvals. Antengene is also responsible for the commercialization of the Antengene Licensed Compounds in the Antengene Territory at its own cost and expense. Until Antengene manufactures its own drug supply, we will furnish clinical and commercial supplies to Antengene pursuant to supply agreements between us and Antengene, the costs of which will be borne by Antengene.

The Amended Antengene Agreement will continue in effect on a product-by-product, country-by-country basis until the later of the tenth anniversary of the first commercial sale of the applicable product in such country or the expiration of specified patent protection and regulatory exclusivity periods for the applicable product in such country. However, the Amended Antengene Agreement may be terminated earlier by (i) either party for breach of the Amended Antengene Agreement by the other party or in the event of the insolvency or bankruptcy of the other party, (ii) Antengene on a product-by-product basis for certain safety reasons or on a product-by-product, country-by-country basis for any reason with 180 days prior notice or (iii) us in the event Antengene challenges or assists with a challenge to certain of our patent rights.

All development and regulatory milestones, which represent variable consideration, will be evaluated each reporting period and included in the transaction price if the milestone is considered likely of achievement and if it is probable that a significant revenue reversal will not occur in future periods. Milestones included in the transaction price will be fully recognized in revenue in the same reporting period because all distinct performance obligations identified at the inception of the contract were fully satisfied.

Any consideration related to sales-based milestones, as well as royalties on net sales upon commercialization of XPOVIO by Antengene, are recognized when the related sales occur, as they were determined to relate predominantly to the intellectual property licenses granted to Antengene.

Summary of License and Other Revenue

The following table presents information about our license and other revenue (in thousands):

During the year ended December 31, 2025, we recognized (i) $15.0 million of revenue for the reimbursement of development-related expenses, $8.2 million of milestone revenue, $4.0 million of royalty revenue, and $1.1 million of other reimbursement revenue from Menarini; (ii) $2.1 million of royalty revenue from Antengene; and (iii) $0.4 million of royalty revenue from our other partners.

During the year ended December 31, 2024, we recognized (i) $15.0 million of revenue for the reimbursement of development-related expenses, $10.0 million of milestone revenue, $2.2 million of royalty revenue, and $0.8 million of other reimbursement revenue from Menarini; (ii) $1.7 million of royalty revenue from Antengene; and (iii) $2.0 million of milestone-related revenue, $0.4 million of royalty revenue, and $0.3 million of other reimbursement revenue from our other partners.

During the year ended December 31, 2023, we recognized (i) $15.0 million of revenue for the reimbursement of development related expenses, $4.0 million of milestone-related revenue, $3.5 million of license-related revenue, $1.1 million of royalty revenue, and $0.8 million of other reimbursement revenue from Menarini; (ii) $1.5 million of royalty revenue and $1.2 million of other reimbursement revenue from Antengene; and (iii) $3.4 million of license-related revenue, $2.5 million of milestone-related revenue, $0.5 million of royalty revenue, and $0.5 million of other reimbursement revenue from our other partners.

License and other revenue of $3.5 million and $2.9 million were included in accounts receivable, net as of December 31, 2025 and 2024, respectively.

6. Fair Value Measurements

Financial instruments, including cash, cash equivalents, accounts receivable, net, other current assets, other assets, restricted cash, accounts payable, and accrued expenses, are presented at amounts that approximate fair value as of December 31, 2025 and 2024.

Items classified as Level 2 consist of corporate debt securities, commercial paper, and U.S. government and agency securities. We estimate the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. We validate the prices provided by our third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances.

The following tables present information about our financial assets that have been measured at fair value and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):

In certain cases where there is limited activity or less transparency around inputs to valuation, the related assets or liabilities are classified as Level 3. The following liabilities are measured at fair value at the end of each reporting period, with changes in fair value recognized as a component of other income (expense), net on our consolidated statements of operations. See Note 10, “Long-Term Obligations”, to our consolidated financial statements for further discussion of the following Level 3 liabilities:

(1)

An embedded derivative liability (the “HCRx Derivative”) which is included as a component of the deferred royalty obligation on our consolidated balance sheets. The valuation method for the HCRx Derivative incorporates certain unobservable Level 3 key inputs including: (i) the probability-weighted net sales of XPOVIO and any of our other future products, including worldwide net product sales, upfront payments, milestones and royalties; (ii) our risk-adjusted discount rate; and (iii) the probability of a change in control occurring during the term of the instrument. The HCRx Derivative was deemed to have a de-minimus value as of December 31, 2025 and 2024 primarily due to a $56.2 million decrease in the deferred royalty obligation during the year ended December 31, 2024.

(2)

The embedded derivative liabilities (the “Convertible Notes Derivatives”) associated with the 2029 Notes, New 2029 Notes, and 2028 Notes are included as components of these debt instruments on our consolidated balance sheets. The valuation method for the Convertible Notes Derivatives incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) our estimated credit spread.

(3)

The warrants to purchase up to 3,051,750 shares of our common stock issued in May 2024 (the “2024 Warrants”) are classified as a long-term liability on our consolidated balance sheets. The valuation method for the 2024 Warrants incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) an estimate of when the 2024 Warrants will be exercised based on an option pricing model.

The following table sets forth a summary of the changes in the estimated fair value of the liabilities described above, which are all classified as Level 3 (in thousands):

7. Investments

The following tables summarize our investments in debt securities, classified as available-for-sale (in thousands):

We didnot hold any investments that were in an unrealized loss position as of December 31, 2025. We held five investments that were in an unrealized loss position as of December 31, 2024. The unrealized losses were caused by changes to interest rates and didnot represent credit losses. We do not intend to sell the investments before recovery of their amortized cost bases, which may be at maturity. All our investments mature within one year from December 31, 2025. The following table summarizes our investments in an unrealized loss position as of December 31, 2024 for which an allowance for credit losses was not recorded, aggregated by major security type and length of time in a continuous unrealized loss position (in thousands):

8. Stockholders’ Equity

Reverse Stock Split and Authorized Common Shares

In January 2025, our stockholders approved an amendment to our Restated Certificate of Incorporation, as amended, to increase the number of authorized shares of our capital stock from 405,000,000 shares to 805,000,000 shares and the number of authorized shares of our common stock from 400,000,000 shares to 800,000,000 shares.

In February 2025, we effected a 1-for-15 reverse stock split of the issued and outstanding shares of our common stock as approved by our stockholders in January 2025. The Reverse Stock Split proportionally reduced the number of authorized shares of our common stock from 800,000,000 shares to 53,333,333 shares. The Reverse Stock Split did not change the par value of our common stock. In addition, proportionate adjustments were made to the number of shares of common stock available for issuance under our equity incentive plans; the number of shares underlying, and the exercise prices of, outstanding equity awards under such plans and outstanding warrants; and the conversion rates of outstanding convertible notes.

Open Market Sale Agreement

In February 2023, we entered into an Open Market Sale Agreement (the “Open Market Sale Agreement”) with Jefferies LLC, as agent (“Jefferies”). Under the Open Market Sale Agreement, we may issue and sell shares of our common stock having an aggregate offering price of up to $100.0 million (the “Shares”) from time to time through Jefferies (the “Open Market Offering”).

Under the Open Market Sale Agreement, Jefferies may sell the Shares by methods deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended (the “Securities Act”). We may sell the Shares in amounts and at times to be determined by us from time to time subject to the terms and conditions of the Open Market Sale Agreement, but we have no obligation to sell any of the Shares in the Open Market Offering.

We or Jefferies may suspend or terminate the offering of Shares upon notice to the other party and subject to other conditions. We have agreed to pay Jefferies commissions for its services in acting as agent in the sale of the Shares in the amount of up to 3.00% of gross proceeds from the sale of the Shares pursuant to the Open Market Sale Agreement. We have also agreed to provide Jefferies with customary indemnification and contribution rights.

We didnot sell any Shares under the Open Market Sale Agreement during the years ended December 31, 2025, 2024 and 2023 As of December 31, 2025, $100.0 million of Shares were available for issuance and sale under the Open Market Sale Agreement.

Common Share Issuances

In October 2025, we issued (i)1,487,917 shares of common stock at a price of $5.88 per share and (ii) accompanying warrants (the “2025 Placement Warrants”) to purchase 1,317,771 shares of common stock to certain institutional investors in a private placement for aggregate gross proceeds of approximately $8.8 million. Refer to Note 11, “Common Share Warrants” for additional detail on the 2025 Placement Warrants.

In October 2025, we issued a total of 5,736,065 shares of common stock of which: (i)2,435,146 shares were issued to holders of the 2025 Notes to partially settle the 2025 Notes, (ii)2,024,344 shares were issued to holders of the 2029 Notes to partially settle the 2029 Notes, (iii)949,908 shares were issuedto certain holders of our long-term obligationsto pay various fees incurred in connection with the debt modifications that occurred in October 2025, and (iv)326,667 shares were issued to our financial advisor. Refer to Note 10, “Long-Term Obligations” for additional detail on these transactions.

In October 2025, we issued a total of 2,298,723 shares of common stock pursuant to the cashless exercise of Pre-Funded Warrants (as defined below) to purchase an aggregate of 2,298,756 shares of common stock.

9. Stock-based Compensation

On May 19, 2022, our stockholders approved the 2022 Equity Incentive Plan (the “2022 Plan”), succeeding our 2013 Stock Incentive Plan (the “2013 Plan”), which has expired and under which no further grants may be made. The 2022 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, RSU awards and other stock-based awards. On May 24, 2023, May 29, 2024, and May 28, 2025 our stockholders approved an amendment to the 2022 Plan to increase the number of shares of our common stock available for issuance under the 2022 Plan by 333,333 shares,400,000 shares, and 450,000 shares, respectively. As of December 31, 2025, there were 283,228 shares available for future grants under the 2022 Plan.

Under the terms of the 2022 Plan, we granted stock options, RSUs, and PSUs to our employees, officers, directors, consultants and advisors. Stock options have a ten-year term and an exercise price equal to the fair market value of a share of our common stock on the grant date. Stock options and RSUs vest over a period of one to four years. PSUs will vest if certain performance goals are achieved over a certain performance period. Certain portions of certain PSU awards vest based on continuous service to the Company throughout the performance period even if the performance goal is not achieved.

During 2025, 2024, and 2023, we also granted stock options and RSUs through inducement grants outside of our stockholder approved equity compensation plans as permitted under the Nasdaq Stock Market listing rules to certain employees to induce them to accept employment with us (collectively, “Inducement Awards” which are made under the “2022 Inducement Plan”). In 2023 and 2024, the Board increased the number of shares reserved for issuance under the 2022 Inducement Plan by 80,000 shares and 66,667 shares, respectively. We assessed the terms of these Inducement Awards and determined there was no possibility that we would have to settle these awards in cash and therefore, equity accounting was applied. As of December 31, 2025, there were 39,626 shares available for future grants under the 2022 Inducement Plan.

As of December 31, 2025, we had 2,123,671 shares reserved for issuance, which includes shares available for future grants and outstanding stock options, RSUs and PSUs under the 2013 Plan, the 2022 Plan, and Inducement Awards (including the Inducement Awards granted under the 2022 Inducement Plan).

Stock-based Compensation Expense

Total stock-based compensation expense recognized was as follows (in thousands):

The total stock-based compensation expense recognized by award type was as follows (in thousands):

Stock Options

The following table summarizes stock option activity related to the 2013 Plan, 2022 Plan, and Inducement Awards (including the stock option Inducement Awards granted under the 2022 Inducement Plan):

There wereno stock options exercised during the years ended December 31, 2025 and 2024. The total intrinsic value of stock options exercised for the year ended December 31, 2023 was less than $0.1 million.

The fair value of each stock option granted is estimated on the date of grant using the Black-Scholes option-pricing model. The following table summarizes the assumptions used in calculating the fair value of the stock option awards:

We use the simplified method to calculate the expected term as our historical exercise data does not provide a reasonable basis upon which to estimate the expected term. The expected term is applied to the stock option grant group as a whole, as we do not expect substantially different exercise or post-vesting termination behavior among our employee population. Our expected stock price volatility assumption is based on the historical volatility of our publicly traded stock. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. We account for forfeitures as they occur.

Using the Black-Scholes option-pricing model, the weighted-average grant date fair values of options granted during the years ended December 31, 2025, 2024 and 2023 was $5.86, $9.53 and $23.03 per share, respectively.

As of December 31, 2025, there was $1.5 million of unrecognized compensation expense related to unvested stock option awards, which is expected to be recognized over a weighted-average period of 2.7 years.

Restricted Stock Units and Performance-Based Restricted Stock Units

The following is a summary of RSU and PSU activity for the 2013 Plan, 2022 Plan, and Inducement Awards (including RSU Inducement Awards granted under the 2022 Inducement Plan):

The total fair value of RSUs and PSUs that vested during the years ended December 31, 2025, 2024 and 2023 was $1.6 million, $2.8 million, and $2.9 million, respectively. As of December 31, 2025, there was $8.7 million of unrecognized compensation expense related to unvested RSUs and PSUs, which is expected to be recognized over a weighted-average period of 1.3 years.

Employee Stock Purchase Plan

We have an ESPP that permits eligible employees to enroll insix-month offering periods. Participants may purchase shares of our common stock, through payroll deductions, at a price equal to 85% of the fair market value of the common stock on the first or last day of the applicable offering period, whichever is lower. Purchase dates under the ESPP occur on or about May 1 and November 1 each year. On May 24, 2023, our stockholders approved an amendment and restatement of our ESPP (the “Amended & Restated ESPP”), which increased the number of shares of common stock authorized for issuance under the ESPP by 100,000 shares. On May 29, 2024, our stockholders approved an amendment to the Amended & Restated ESPP to increase the number of shares of our common stock available for issuance under the Amended & Restated ESPP by 333,333 shares. As of December 31, 2025,165,461 shares of our common stock remained available for issuance under the Amended & Restated ESPP.

During the years ended December 31, 2025, 2024 and 2023, $0.8 million, $1.5 million and $1.1 million, respectively, was withheld from employees, on an after-tax basis, in order to purchase 145,936,131,698 and 42,391 shares of our common stock, respectively. As of December 31, 2025, there was $0.1 million of total unrecognized stock-based compensation expense related to the Amended & Restated ESPP. The expense is expected to be recognized over a period offour months.

The fair value of the option component of the shares purchased under the Amended & Restated ESPP was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions:

10. Long-Term Obligations

2025 Notes

In October 2018, we issued $172.5 million aggregate principal amount of the 2025 Notes in a private offering to qualified institutional buyers in reliance on Rule 144A under the Securities Act. The 2025 Notes were senior unsecured obligations, bore interest at a rate of 3.00% per year, and matured on October 15, 2025. Holders were able to convert the 2025 Notes at an initial conversion rate of 4.2049 shares of common stock per $1,000 principal amount (equivalent to an initial conversion price of approximately $237.82 per share of common stock) following July 15, 2025. No holders elected to convert their 2025 Notes. In connection with the issuance of the 2025 Notes, we incurred $5.6 million of debt issuance costs, which were amortized to interest expense using an effective interest rate of 3.53% over seven years.

In May 2024, we exchanged $148.0 million aggregate principal amount of the 2025 Notes for: (i) $111.0 million aggregate principal amount of the 2029 Notes and (ii) 2024 Warrants to purchase up to 3,051,750 shares of our common stock. In October 2025, we exchanged $24.3 million aggregate principal amount of 2025 Notes for: (i)2,435,146 shares of common stock, (ii) pre-funded warrants to purchase an aggregate of 1,404,087 shares of common stock, and (iii) common stock warrants to purchase an aggregate of 2,502,151 shares of common stock with an exercise price of $6.64 per share and an expiration date of October 10, 2030. We repaid $0.3 million principal amount of 2025 Notes at maturity on October 15, 2025. There wereno 2025 Notes outstanding as of December 31, 2025.

The outstanding balances of the 2025 Notes consisted of the following (in thousands):

The following table sets forth total interest expense recognized related to the 2025 Notes (in thousands):

Senior Secured Term Loan

In May 2024, we entered into a credit and guaranty agreement (the “Credit Agreement”) with certain holders of the 2025 Notes and certain entities managed by HealthCare Royalty Management, LLC (“HCRx”), which was subsequently assigned by HCRx to an affiliate of KKR & Co. Inc. (“KKR”) in connection with its acquisition of a majority ownership stake in HCRx in July 2025. The Credit Agreement provides for a senior secured term loan facility of $100.0 million which bore interest at a variable rate equal to the applicable secured overnight financing rate plus 9.25%, subject to a floor of 3.00% through June 30, 2025.

In October 2025, we entered into the First Amendment and Waiver to Credit and Guaranty Agreement (the “Amended Credit Agreement”), under which we borrowed an additional $12.5 million, resulting in a senior secured term loan facility with aggregate borrowings of $112.5 million (the “Amended Term Loan”) which matures in May 2028 and bears interest at a variable rate equal to the applicable secured overnight financing rate plus 10.25% for all interest incurred after June 30, 2025, subject to a floor of 3.00%. Interest incurred on borrowings under the Amended Term Loan from July 1, 2025 to March 31, 2026 is payable in-kind. Interest incurred on borrowings under the Amended Term Loan after March 31, 2026 is payable in cash quarterly in arrears on March 31, June 30, September 30, and December 31 of each year.

We are required to make quarterly principal payments under the Amended Term Loan on March 10, June 10, September 10, and December 10 of each year beginning on June 10, 2026 in the amount of 6.25% of the aggregate principal amount of the Amended Term Loan, with the remaining principal due when the Amended Term Loan matures in May 8, 2028. We are permitted to prepay the Amended Term Loan at any time, subject to a prepayment premium ranging from 3.00% to 8.00% of the principal prepaid. In addition, we are required to repay the Amended Term Loan with proceeds from certain asset sales and condemnation events, subject, in some cases, to reinvestment rights.

All obligations under the Amended Credit Agreement are secured on a first priority basis, subject to certain exceptions, by substantially all of our assets. The Amended Credit Agreement contains customary covenants, including a requirement to maintain a certain amount of cash, cash equivalents and investments at all times (the “Minimum Liquidity Covenant Amount”). From October 10, 2025 to October 10, 2026, the Minimum Liquidity Covenant Amount will be the lesser of: (x) the sum of $10.0 million plus 50% of the net cash proceeds of any issuance of indebtedness for borrowed money or capital stock of the Company, and (y) $25.0 million.

After October 10, 2026, the Minimum Liquidity Covenant Amount will be $25.0 million. As of December 31, 2025, we were in compliance with the Minimum Liquidity Covenant Amount.

The Amended Credit Agreement contains restrictions on indebtedness, liens, investments, fundamental changes, asset sales, licensing transactions, dividends, modifications to material agreements, payment of subordinated indebtedness, and other matters customarily restricted in such agreements. Specifically, we are prohibited from exclusively licensing, selling or otherwise disposing of U.S. rights to oncology indications of selinexor. As of December 31, 2025, we were in compliance with these covenants. If certain events of default occur, the Amended Term Loan may be due and payable immediately. These events include the withdrawal of approval of certain indications of selinexor, payment defaults, covenant defaults, bankruptcy, cross-defaults to certain other agreements, change in control and lien priority. Additionally, we have an obligation under the Amended Credit Agreement to appoint a candidate selected by the lenders under the Amended Term Loan to serve as a non-voting observer to our board of directors.

The outstanding balance of the Amended Term Loan consisted of the following (in thousands):

We determined the expected life of the Amended Term Loan was equal to its term. The principal value of the Amended Term Loan approximates its fair value due to the variable interest rate. In connection with the issuance of the Term Loan in May 2024, we incurred $6.8 million of debt issuance costs, which were being amortized to interest expense through May 2028 using an effective interest rate of 17%. Total unamortized debt issuance costs immediately following the creation of the Amended Term Loan was $5.2 million, which are being amortized to interest expense through May 2028 using an effective interest rate of 17%.

The following table sets forth total interest expense recognized related to the Term Loan and Amended Term Loan (in thousands):

Future minimum payments on the Amended Term Loan as of December 31, 2025 were as follows (in thousands):

2029 Notes, New 2029 Notes, and 2028 Notes

On May 13, 2024, pursuant to privately negotiated agreements with certain holders of the 2025 Notes, we exchanged $148.0 million aggregate principal amount of the 2025 Notes for: (i) $111.0 million aggregate principal amount of 2029 Notes maturing on May 13, 2029 and (ii) 2024 Warrants to purchase up to 3,051,750 shares of our common stock. We also issued $5.0 million aggregate principal amount of 2029 Notes to HCRx in exchange for a $5.0 million reduction in our deferred royalty obligation. The 2029 Notes bore interest at a rate of 6.00% per year and were convertible into shares of our common stock at an initial conversion rate of 29.6296 shares per $1,000 principal amount, which is equivalent to a conversion price of $33.75 per share of common stock.

In October 2025, we entered into privately negotiated agreements with the holders of the 2029 Notes to exchange $101.0 million aggregate principal amount of the 2029 Notes for $103.5 million aggregate principal amount of newly issued New 2029 Notes maturingon May 13, 2029. We also exchanged $15.0 million aggregate principal amount of the 2029 Notes for: (i)2,024,344 shares of common stock and (ii) pre-funded warrants to purchase an aggregate of 552,164 shares of common stock. All 2029 Notes were fully cancelled after these exchange transactions. There wereno 2029 Notes outstanding as of December 31, 2025.

The New 2029 Notes are second-lien secured obligations of the Company and are convertible by the holders into shares of our common stock at an initial conversion rate of 44.444 shares per $1,000 principal amount (the “New 2029 Notes Conversion Option”) which is equivalent to an initial conversion price of $22.50 per share andsubject to customary anti-dilution adjustments. Holders of the New 2029 Notes may convert their New 2029 Notes at any time prior to the close of business on May 11, 2029. Upon conversion of the New 2029 Notes, we will deliver shares of our common stock plus cash in lieu of any fractional shares to the holders.

In October 2025, we issued $15.0 million aggregate principal amount of new 9.00% senior secured convertible notes maturing on October 15, 2028 (the “2028 Notes”) for cash proceeds of $15.0 million. The 2028 Notes are senior secured second-lien obligations and are convertible by the holders into shares of our common stock at an initial conversion rate of 150.6024 shares per $1,000 principal amount of 2028 Notes (the “2028 Notes Conversion Option”) which is equivalent to an initial conversion price of $6.64 per share of common stock andsubject to customary anti-dilution adjustments. Holders of the 2028 Notes may convert at any time prior to the close of business on October 13, 2028. Upon conversion of the 2028 Notes, we will deliver shares of our common stock plus cash in lieu of any fractional shares to the holders.

Both the New 2029 Notes and 2028 Notes bear interest at a rate of 9.00% per year. Interest on the New 2029 Notes and 2028 Notes incurred from October 10, 2025 to March 31, 2026 will be payable in-kind. Interest incurred after March 31, 2026 will be payable in cash quarterly in arrears on March 31, June 30, September 30, and December 31 of each year.

On or after May 13, 2026 (for the New 2029 Notes) or October 15, 2026 (for the 2028 Notes), we may redeem all or a portion of the New 2029 Notes or all of the 2028 Notes if the last reported sale price of our common stock equals or exceeds 130% (for the New 2029 Notes) or 165% (for the 2028 Notes) of the applicable conversion price then in effect for at least 20 trading days during any 30 consecutive trading day period (the “New 2029 Notes and 2028 Notes Redemption Options”). Upon redemption, we will pay the redemption price in a cash payment, which will be equal to the principal amount of the notes to be redeemed and any accrued and unpaid interest, if any, up to but excluding the redemption date. The number of shares of common stock deliverable as make-whole consideration is subject to a cap of 85.1374 shares per $1,000 principal amount for the New 2029 Notes or 173.3102 shares per $1,000 principal amount for the 2028 Notes. In some cases, we will be required to make an offer to repurchase the New 2029 Notes or 2028 Notes at a 101% premium with proceeds from certain asset sales, subject, in some cases, to reinvestment rights.

If certain corporate events occur prior to the maturity date of the New 2029 Notes or the 2028 Notes, a holder that elects to convert their New 2029 Notes or 2028 Notes, as applicable, may be entitled to receive additional shares of common stock based on a fundamental change make-whole adjustment in the conversion rate in connection with such corporate event. However, in no event can the conversion rate exceed 85.1374 shares per $1,000 principal amount for the New 2029 Notes or 173.3102 shares per $1,000 principal amount for the 2028 Notes. In addition, if we undergo certain fundamental changes, holders may require us to repurchase for cash all or any portion of their New 2029 Notes or 2028 Notes at a price equal to the principal amount to be repurchased, plus any accrued and unpaid interest, up to but excluding the fundamental change repurchase date.

No holder will be entitled to receive shares of our common stock in connection with the New 2029 Notes or 2028 Notes if such receipt would cause the holder (together with its affiliates) to own more than 4.99% (subject to increase or decrease at the election of the holder, but in no event to exceed 19.99%) of the number of shares of the common stock outstanding immediately after giving effect to such event. In addition, a holder may elect to receive pre-funded warrants with respect to any shares of common stock that would otherwise be issuable in connection with the New 2029 Notes or 2028 Notes but for the foregoing ownership limitations. These pre-funded warrants will have an exercise price of $0.0001 per share and will not expire. As of December 31, 2025, no New 2029 Notes or 2028 Notes have been converted into shares of common stock or pre-funded warrants.

All obligations under the New 2029 Notes and 2028 Notes are secured on a second priority basis by the same collateral that secures the obligations under the Amended Term Loan. The 2028 Notes rank pari passu with the New 2029 Notes, ahead of indebtedness under the Amended Revenue Interest Agreement (as defined below) and behind indebtedness under the Amended Credit Agreement with respect to distributions of proceeds of the enforcement of certain collateral. The New 2029 Notes and 2028 Notes contain covenants and events of default that are generally consistent with the Amended Term Loan, including the Minimum Liquidity Amount. As of December 31, 2025, we were in compliance with these covenants.

We have determined that the New 2029 Notes Conversion Option, the 2028 Notes Conversion Option, and the New 2029 Notes and 2028 Notes Redemption Options are embedded derivatives that require bifurcation from the debt instrument and fair value recognition. These derivatives are referred to as the Convertible Notes Derivatives in Note 6, “Fair Value Measurements” to our consolidated financial statements.

The outstanding balance of the New 2029 Notes and 2029 Notes consisted of the following (in thousands):

The outstanding balance of the 2028 Notes consisted of the following (in thousands):

We determined the expected life of the New 2029 Notes and 2028 Notes is equal to their contractual terms. As of December 31, 2025, the “if-converted value” did not exceed the remaining principal amount for both the New 2029 Notes and 2028 Notes. The fair value of the New 2029 Notes and 2028 Notes are influenced by market interest rates, our stock price and stock price volatility, and have been classified as Level 3 within the fair value hierarchy as they use unobservable inputs. The estimated fair value of the New 2029 Notes and 2028 Notes as of December 31, 2025 was approximately$92.7 million and$22.8 million, respectively.

Debt issuance costs and discounts related to the New 2029 Notes of $33.3 million are being amortized to interest expense over the term of the New 2029 Notes at an effective interest rate of 22%. The following table sets forth total interest expense recognized related to the New 2029 Notes and 2029 Notes (in thousands):

Debt issuance costs and discounts related to the 2028 Notes of $5.6 million are being amortized to interest expense over the term of the 2028 Notes at an effective interest rate of 25%. We recognized interest expense of $0.6 million related to the 2028 Notes for the year ended December 31, 2025, which included $0.3 million of contractual interest expense and $0.3 million of amortization.

Future minimum payments on the New 2029 Notes and 2028 Notes as of December 31, 2025 were as follows (in thousands):

Deferred Royalty Obligation

In September 2019, we entered into a Revenue Interest Financing Agreement (the “Revenue Interest Agreement”) with HCRx which was subsequently amended in June 2021, August 2023, May 2024, August 2025, and October 2025, and which was subsequently assigned by HCRx to KKR in connection with its acquisition of a majority ownership stake in HCRx in July 2025 (as amended, the “Amended Revenue Interest Agreement”) under which we have received a total of $135.0 million, less certain transaction expenses. In exchange for this amount, KKR (as successor in interest to HCRx) receives payments from us at a percentage (the “Royalty Rate”) of net revenues of selinexor and any of our other future products, including worldwide net product sales and upfront payments, milestones, and royalties. Total aggregate payments to HCRx and KKR under the Amended Revenue Interest Agreement are capped at $263.3 million (the “Payment Cap”).

In May 2024, we entered into an amendment (the “HCRx Amendment”) to the Amended Revenue Interest Agreement with HCRx, pursuant to which we:

(1)

made a cash payment to HCRx in the amount of $49.5 million;

(2)

delivered to HCRx a Term Loan note with a principal amount of $15.0 million; and

(3)

delivered to HCRx 2029 Notes with a principal amount of $5.0 million.

As the repayment of the funded amount is contingent upon worldwide net product sales and upfront payments, milestones, and royalties, the repayment term may be shortened or extended depending on actual worldwide net product sales and upfront payments, milestones, and royalties. The repayment period expires on the earlier of (i) the date on which HCRx and KKR have received cash payments in the aggregate totaling $263.3 million or (ii) the legal maturity date of September 26, 2035. If HCRx and KKR have not received total payments in the aggregate equal to $263.3 million by September 26, 2035, we will be required to pay an amount equal to $135.0 million plus a specific annual rate of return less aggregate payments previously paid to HCRx and KKR.

In the event of a change of control, an event of default, including, among others, our failure to pay any amounts due to KKR, insolvency, our failure to pay indebtedness when due, the revocation of regulatory approval of XPOVIO in the U.S. or our breach of any covenant contained in the Amended Revenue Interest Agreement and our failure to cure the breach within the prescribed time frame, we are obligated to pay KKR an amount equal to $263.3 million less aggregate payments previously paid to HCRx and KKR.

After giving effect to the above, as of May 2024, we had made aggregate payments under the Amended Revenue Interest Agreement totaling $135.0 million and the maximum remaining amount we owed to KKR, as successor in interest to HCRx, was $128.3 million. After May 2024, we are obligated to make quarterly payments in the amount of a fixed percentage of our net product revenues, upfront payments, milestones, and royalties earned in the applicable quarter, except that in connection with the October 2025 amendment, KKR waived our obligation to pay royalties on revenue recognized between April 1, 2025 and March 31, 2026.

The HCRx Amendment also subordinates the indebtedness and liens under the Amended Revenue Interest Agreement to the indebtedness and liens under the Amended Term Loan, and, subject to certain exceptions, makes the indebtedness and liens under the Amended Revenue Interest Agreement pari passu with the indebtedness and liens under the New 2029 Notes.

We have evaluated the terms of the Amended Revenue Interest Agreement and concluded that its features are similar to those of a debt instrument. Accordingly, we have accounted for the transaction as long-term debt and presented it as a deferred royalty obligation on our consolidated balance sheets.

As of December 31, 2025, we have made $147.1 million in payments to HCRx. The effective interest rate as of December 31, 2025 was approximately 16%. We have incurred debt issuance costs totaling $2.8 million which have been netted against the debt and are being amortized over the estimated term of the debt using the effective interest method, adjusted on a prospective basis for changes in the underlying assumptions and inputs.

The carrying value of the deferred royalty obligation as of December 31, 2025 and December 31, 2024 was $72.3 million and $73.5 million, respectively, which includes the carrying amount of the debt and unamortized debt issuance costs. The carrying value of the deferred royalty obligation approximated fair value as of December 31, 2025 and 2024 and was based on our estimates of future payments over the life of the arrangement, which are considered Level 3 inputs.

11. Common Share Warrants

On December 5, 2022, we issued to certain institutional investors, in a private placement offering of securities, warrants to purchase up to 635,703 shares of common stock at an exercise price of $95.37 per share (the “2022 Warrants”). The 2022 Warrants are exercisable through December 7, 2027.

On August 1, 2023, we issued warrants to HCRx to purchase up to 16,667 shares of common stock at an exercise price of $33.75 per share (the “2023 Warrants”) which are exercisable through August 1, 2030. In May 2024, we reduced the exercise price from $33.75 per share to $16.50 per share. In October 2025, we further reduced the exercise price from $16.50 per share to $6.64 per share.

In connection with the exchange of the 2025 Notes for the 2029 Notes in May 2024 described in further detail in Note 10, “Long-Term Obligations”, we issued 2024 Warrants to purchase 3,051,750 shares of our common stock at an exercise price of $16.50 per share. In October 2025, we reduced the exercise price from $16.50 per share to $6.64 per share, subject to customary antidilution adjustments. The 2024 Warrants are exercisable through May 13, 2029. If the closing price of our common stock exceeds $33.00 for 20 trading days during any 30 consecutive trading day period, we can require the holder to exercise the 2024 Warrants. Under the terms of the 2024 Warrants, a holder cannot receive shares of our common stock if such receipt would cause the holder (together with its affiliates) to own more than 4.99% (subject to increase or decrease at the election of the holder, but in no event to exceed 19.99%) of our common stock outstanding on the date of receipt. In addition, a holder may elect to receive pre-funded warrants with respect to any common stock that would otherwise be issuable but for the foregoing ownership limitations. These pre-funded warrants will have an exercise price of $0.0001 per share and will not expire. The 2024 Warrants were classified as a long-term liability in our consolidated balance sheets because they did not meet the criteria for equity classification and are measured at fair value at the end of each reporting period as further described in Note 6, “Fair Value Measurements”.

In October 2025, we issued the 2025 Placement Warrants as described in Note 8, “Stockholders’ Equity” to purchase 1,317,771 shares of common stock. The 2025 Placement Warrants have an exercise price of $6.64 per share, subject to customary anti-dilution adjustments, and are exercisable until the date that is the first to occur of (i) thirty (30) days following the public announcement by the Company of the top-line results from the Phase 3 XPORT-EC-042 clinical trial of selinexor in patients with endometrial cancer or (ii) October 10, 2028.

In October 2025, we issued warrants (the “2025 Warrants”) to purchase of 4,600,587 shares of common stock at an exercise price of $6.64 per share, subject to customary antidilution adjustments, of which: (i)2,502,151 were issued to holders of the 2025 Notes as partial consideration for the exchange of the 2025 Notes, (ii)1,882,530 were issued to certain holders of our long-term obligations described in Note 10, “Long-Term Obligations” to pay various fees incurred in connection with the debt modifications that occurred in October 2025, and (iii)215,906 were issued to a financial advisor in connection with the debt modifications that occurred in October 2025. The 2025 Warrants are exercisable through October 10, 2030.

In October 2025, we issued warrants (the “Pre-Funded Warrants”) to purchase of 2,913,136 shares of common stock at an exercise price of $0.0001 per share to certain holders of our long-term obligations described in Note 10, “Long-Term Obligations”, of which: (i)1,404,087 Pre-Funded Warrants were issued in lieu of common stock and as partial consideration for the exchange of the 2025 Notes, (ii)552,164 Pre-Funded Warrants were issued in lieu of common stock and as partial consideration for the exchange the 2029 Notes, and (iii)956,885 Pre-Funded Warrants were issued in lieu of common stock to pay various fees incurred in connection with the debt modifications that occurred in October 2025.

The 2025 Placement Warrants, 2025 Warrants, and Pre-Funded Warrants met the criteria for equity classification and were recorded to additional paid-in capital within stockholders’ deficit. Additionally, we may not effect the exercise of any 2025 Placement Warrants, 2025 Warrants, or Pre-Funded Warrants, and a holder will not be entitled to exercise any portion of these warrants, which, upon giving effect to such exercise, would cause the holder (together with its affiliates) to own more than 4.99% (subject to increase or decrease at the election of the holder, but in no event to exceed 19.99%) of our common stock outstanding on the date of receipt.

The following is a summary of activity related to our common stock warrants:

12. Extinguishment Accounting

We accounted for the exchange of the 2025 Notes for the 2029 Notes and 2024 Warrants in May 2024 as a debt extinguishment because the terms of the 2029 Notes are substantially different from the terms of the 2025 Notes. To record the extinguishment, we de-recognized the carrying value of the 2025 Notes that were exchanged, including accrued interest and unamortized debt issuance costs and recognized the 2029 Notes and 2024 Warrants received by the holders of the 2025 Notes at their initial fair values. The initial fair value of the 2029 Notes was estimated using a risk-neutral convertible bond model implemented using a binomial lattice which incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) our estimated credit spread. The initial fair value of the 2024 Warrants was estimated using the methodology described in Note 6, “Fair Value Measurements”. The above activity resulted in the recognition of a $44.7 million gain on extinguishment of debt in 2024.

We accounted for the exchange of the 2025 Notes for common shares, Pre-Funded Warrants, and 2025 Warrants in October 2025 as a debt extinguishment because the equity received by the 2025 Note holders was substantially different from the 2025 Notes that were settled. We de-recognized the carrying value of the 2025 Notes that were exchanged, including accrued interest and unamortized debt issuance costs, and recognized the common shares, Pre-Funded Warrants, and 2025 Warrants the 2025 Note holders received at their initial fair values. We recorded the difference of the above items as a loss on extinguishment as shown in the following table:

The debt modifications with the holders of the 2029 Notes that occurred in October 2025 as described in Note 10, “Long-Term Obligations” and Note 11, “Common Share Warrants” involved: (i) the exchange of the 2029 Notes for New 2029 Notes, (ii) modifications to the Term Loan, (iii) modifications to the deferred royalty obligation, (iv) a reduction to the exercise price of the 2023 Warrants and 2024 Warrants, (v) the issuance of common shares, Pre-Funded Warrants, and 2025 Warrants, (vi) the issuance of 2028 Notes, and (vii) the receipt of cash related to the additional $12.5 million borrowing under the Amended Term Loan and the issuance of the 2028 Notes. We performed an analysis by holder to determine the difference between the discounted cash flows under the modifications and issuances described above and the discounted cash flows under the 2029 Notes, Term Loan, and deferred royalty obligation immediately prior to these modifications and issuances. Extinguishment accounting was applied to all affected financial instruments held by any holder (the “Extinguishment Holders”) whose total difference in discounted cash flows was greater than 10%.

To calculate the loss on extinguishment for the Extinguishment Holders, we: (i) de-recognized the carrying value of the 2029 Notes and Term Loan held by the Extinguishment Holders including the accrued interest, unamortized debt issuance costs and discounts, and embedded derivative, (ii) recognized the New 2029 Notes, Amended Term Loan, and 2028 Notes held by the Extinguishment Holders at their initial fair values, (iii) recognized the receipt of cash from the Extinguishment Holders, and (iv) recognized the common shares, Pre-Funded Warrants, and 2025 Warrants issued to the Extinguishment Holders at their initial fair values. The calculation of the loss on extinguishment for the Extinguishment Holders is shown in the following table:

For the loss on extinguishment for the Extinguishment Holders, the initial fair value of the New 2029 Notes and 2028 Notes was estimated using a risk-neutral convertible bond model implemented using a binomial lattice which incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) our estimated credit spread. The carrying amount of the Amended Term Loan approximates fair value due to the variable interest rate.

For both the loss on extinguishment for the Extinguishment Holders, and the loss on extinguishment of the 2025 Notes, the initial fair value of the common shares and Pre-Funded Warrants is equal to the closing market price per share of our common stock on the Nasdaq Global Select Market on October 7, 2025 and the initial fair value of the 2025 Warrants was estimated using the Black-Scholes option-pricing model which incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) an estimate of when the warrants will be exercised.

13. Commitments and Contingencies

Operating Leases

We determine if an arrangement contains a lease at contract inception based on the facts and circumstances in the arrangement. Lease classification, recognition, and measurement are then determined at the lease commencement date. For arrangements that contain a lease we (i) identify lease and non-lease components, (ii) determine the consideration in the contract, (iii) determine whether the lease is an operating or financing lease; and (iv) recognize lease right-of-use assets and liabilities. Lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. We have elected not to separate lease components and non-lease components for leases of office or other space.

The interest rate implicit in lease contracts is typically not readily determinable and as such, we use our incremental borrowing rate based on the information available at the lease commencement date, which represents an internally developed rate that would be incurred to borrow, on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment. In determining the incremental borrowing rate, we consider (i) our estimated public credit rating, (ii) our observable debt yields, as well as other bonds in the market issued by other companies with similar credit ratings as us, and (iii) adjustments necessary for collateral, lease term, and inflation or foreign currency.

Most leases include options to renew and/or terminate the lease, which can impact the lease term. The exercise of these options is at our discretion and we do not include any of these options within the expected lease term as we are not reasonably certain we will exercise these options. Leases that have a lease term of 12 months or less at commencement date are excluded from this treatment and are recognized on a straight-line basis over the term of the lease.

Fixed, or in substance fixed, lease payments on our operating lease are recognized over the expected term of the lease on a straight-line basis. Variable lease expenses that are not considered fixed, or in substance fixed, are recognized as incurred. Fixed and variable lease expense on our operating lease is recognized within operating expenses on our consolidated statements of operations.

We are party to an operating lease where we currently lease a total of 52,224 square feet of office space in Newton, Massachusetts (the “Newton, MA Lease”) which expires on September 30, 2030. The Newton, MA Lease contains a renewal option for an additional five years which was not included in the lease term as its exercise is not reasonably certain. Pursuant to the Newton, MA Lease, we have provided a security deposit in the form of a cash-collateralized letter of credit in the amount of $0.3 million, which is classified within long-term restricted cash on the consolidated balance sheets.

The Newton, MA Lease provides for increases in future minimum annual rental payments, as defined in the lease agreement. The operating lease expense for the years ended December 31, 2025, 2024 and 2023 was $2.4 million, $2.8 million, and $2.8 million, respectively. Variable lease costs pertain to reimbursement of certain landlord expenses and were immaterial for each of the years ended December 31, 2025, 2024 and 2023.

In addition, we are party to certain short-term leases having a term of twelve months or less at the commencement date. We recognize short-term lease expense on a straight-line basis and do not record a related right-of use asset or lease liability for such leases. These costs were immaterial for the years ended December 31, 2025, 2024 and 2023.

We review the carrying values of our lease assets for possible impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets may not be recoverable. We have not recorded an impairment in any period since inception.

Lease Commitments

As of December 31, 2025, future minimum lease payments under non-cancellable operating lease agreements for which we have recognized operating lease right-of-use assets and liabilities are as follows (in thousands):

As of December 31, 2025, the remaining lease term on the Newton, MA Lease was 4.8 years and the discount rate used to calculate the operating lease liability was 14.5%.

Litigation

From time to time we may face legal claims or actions in the normal course of business. There areno outstanding legal claims or material actions as of December 31, 2025.

14. Accrued Expenses

Accrued expenses consisted of the following (in thousands):

15. Property and Equipment, Net

Propertyand equipment are recorded at cost, less accumulated depreciation and amortization. Depreciation and amortization expense is recorded using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful economic lives of the related assets. Expenditures for maintenance and repairs are charged to expense while the costs of significant improvements are capitalized. Upon retirement or sale, the costs of the assets disposed of and the related accumulated depreciation or amortization is removed from the consolidated balance sheets and any related gains or losses are reflected on the consolidated statements of operations. Property and equipment, net consisted of the following (in thousands):

16. 401(k) Plan

We have a 401(k) retirement and profit-sharing plan (the “401(k) Plan”) covering all qualified employees. The 401(k) Plan allows each participant to contribute a portion of their base wages up to an amount not to exceed an annual statutory maximum and the Company provides a match up to 4% of components of employee compensation. We contributed a match of $2.3 million, $2.5 million, and $3.7 million to the 401(k) Plan for the years ended December 31, 2025, 2024 and 2023, respectively.

17. Income Taxes

We recorded an income tax provision of less than $0.1 million in each of the years ended December 31, 2025 and 2024 and $0.3 million for the year ended December 31, 2023. Our current income tax provision consists of state income tax due from our KSC entity through its dissolution in October 2024, as well as foreign income taxes due from our German and Israel subsidiaries, both of which operate on a cost-plus profit margin. We didnot have a deferred income tax provision for the years ended December 31, 2025, 2024 and 2023.

The components of income (loss) before income taxes were as follows (in thousands):

Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The significant components of our deferred tax assets are comprised of the following (in thousands):

Federal tax law requires taxpayers to capitalize and amortize research and development expenditures under section 174 (“174 R&D Expenditures”) incurred after December 31, 2021. From January 1, 2022 to December 31, 2024, the Company capitalized all 174 R&D Expenditures and amortized: 1) 174 R&D Expenditures performed in the U.S. over five years; and 2) 174 R&D Expenditures performed outside the U.S. over 15 years. In July 2025, federal tax law was changed to allow the immediate expensing of 174 R&D Expenditures performed in the U.S. after January 1, 2025. Beginning with the year ended December 31 2025, the Company will: 1) continue to amortize all 174 R&D Expenditures that were capitalized between January 1, 2022 and December 31, 2024 as described above; 2) continue to capitalize and amortize over 15 years all 174 R&D Expenditures performed outside the U.S after January 1, 2025; and 3) immediately expense all 174 R&D Expenditures performed in the U.S. after January 1, 2025. 174 R&D Expenditures of $50.7 million, $120.7 million, and $135.9 million were capitalized during the years ended December 31, 2025, 2024, and 2023, respectively.

On May 13, 2024, we exchanged $148.0 million aggregate principal amount of the 2025 Notes for (i) $111.0 million aggregate principal amount of the 2029 Notes and (ii) 2024 Warrants to purchase up to 3,051,750 shares of our common stock, as described in further detail in Note 10, “Long-Term Obligations”, Note 11, “Common Share Warrants” and Note 12, “Extinguishment Accounting”. This created $93.2 million of taxable income related to the cancellation of debt, which was fully offset by our net operating loss carryforwards.

In October 2025, we executed a series of transactions described in further detail in Note 10, “Long-Term Obligations”, Note 11, “Common Share Warrants” and Note 12, “Extinguishment Accounting” which created a $12.9 million tax deduction.

We have evaluated the positive and negative evidence bearing upon the realizability of our deferred tax assets. Based on our history of operating losses, we have concluded that it is more likely than not that the benefit of our deferred tax assets willnot be realized. Accordingly, we have provided a full valuation allowance for deferred tax assets as of December 31, 2025 and 2024. The valuation allowance decreased by approximately$133.8 million during the year ended December 31, 2025 primarily due to the write-off of certain net operating loss carryforwards and tax credit carryforwards due to limitations resulting from certain cumulative changes in the ownership interest of significant shareholders which occurred during the year ended December 31, 2025.

A reconciliation of income tax expense computed at the statutory federal income tax rate to income taxes as reflected in the financial statements is as follows:

As of December 31, 2025, 2024 and 2023, we had U.S. federal net operating loss carryforwards of approximately$770.3 million,$728.1 million and $768.5 million, respectively, which may be able to offset future income tax liabilities. Of the$770.3 million carryforward as of December 31, 2025,$595.8 million of the carryforward has an indefinite life and$174.5 million will expire at various dates through 2037. As of December 31, 2025, 2024 and 2023, we had U.S. state net operating loss carryforwards of approximately$349.9 million,$645.2 million and $655.7 million, respectively, which may be available to offset future state income tax liabilities and expire at various dates through 2045. As of December 31, 2025, 2024 and 2023, we didnot have any foreign net operating loss carryforwards to offset future foreign income tax liabilities.

As of December 31, 2024 and 2023, we had federal research and development and orphan drug tax credit carryforwards of approximately$107.3 million and $99.3 million, respectively, available to reduce future tax liabilities, which expire at various dates through 2045. As of December 31, 2024 and 2023, we had state research and development tax credit carryforwards of approximately$13.1 million and $11.9 million, respectively, available to reduce future tax liabilities, which expire at various dates through 2040. We did not have any of these federal or state tax credit carryforwards as of December 31, 2025 due to limitations resulting from certain cumulative changes in the ownership interest of significant shareholders which occurred during the year ended December 31, 2025.

Under the provisions of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over athree-year period in excess of 50 percent, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of us immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. Previously, we have completed several financings since our inception, which have resulted in changes in control as defined by Sections 382 and 383 of the Internal Revenue Code. We reduced our deferred tax assets for tax attributes we believe will expire unused. In the future, we may complete financings that could result in a change in control, which will reduce our deferred tax assets for tax attributes we believe will expire unused due to the change in control limitations.

We will recognize interest and penalties related to uncertain tax positions in the income tax provision. As of December 31, 2025, 2024 and 2023, we hadno accrued interest or penalties related to uncertain tax positions and no such amounts have been recognized.

We or one of our subsidiaries file income tax returns in the U.S. and various state and foreign jurisdictions. Our federal, state and foreign income tax returns are generally subject to tax examinations for the tax years ended December 31, 2022 through December 31, 2025. To the extent we have tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service, state or foreign tax authorities to the extent utilized in a future period.

EXHIBIT INDEX

† Confidential treatment has been granted as to portions of the exhibit.

• Indicates a management contract or compensatory plan or arrangement.

** Certain portions of this exhibit (indicated by “*” or “”) have been omitted pursuant to Item 601(b)(10)(iv) of Regulation S-K.