Karyopharm Therapeutics Inc.

1. Nature of Business, Basis of Presentation and Segment Information

Nature of Business

Karyopharm Therapeutics Inc., a Delaware corporation (collectively with its subsidiaries, the “Company,” “we,” “us,” or “our”), is 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 in multiple myeloma, as well as developing and seeking regulatory approval of selinexor in myelofibrosis. 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 in July 2019 and is currently approved and marketed in the U.S. 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 and (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. 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 approvals in various indications in more than 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.

Liquidity, Capital Resources and Going Concern

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 June 30, 2026, we had$65.1 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 support our continued operations and maintain our research and development programs, including as we continue to develop and seek regulatory approval of selinexor for myelofibrosis. As a result, our continued operations are dependent on our ability to raise additional funding or enter into other strategic alternatives and marketing XPOVIO in its currently approved indications. Based on our current business plan and current capital resources, combined with 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 condensed consolidated financial statements are issued.

We expect that our existing liquidity, including cash, cash equivalents, and investments together with anticipated cash flow from net product revenue and license and other revenue, will enable us to fund our current operating plans into September 2026. With the assistance of our advisors, including our financial advisor Centerview Partners and other advisors, we are actively evaluating a range of financing opportunities and strategic alternatives with the objective of extending our cash runway, preserving strategic flexibility and maximizing long-term shareholder value as we advance our myelofibrosis program. On September 10, 2026, a $15.8 million principal payment is due under our senior secured term loan facility; if this payment is made without additional financing or a waiver from our lenders, we expect that (i) our cash, cash equivalents and investments will fall below our $10.0 million minimum liquidity covenant, which would trigger a default on our term loan and (ii) we will not have sufficient resources to fund our operations following such payment. In addition to the $15.8 million principal payment due on September 10, 2026, we have approximately $10.1 million of aggregate interest payments due on September 30, 2026 under our senior secured term loan, 2028 Notes and 2029 Notes, all as defined below.

Our ability to successfully consummate a financing transaction or execute on a strategic alternative is dependent on a number of factors. There is no assurance that these efforts will result in additional funding, executing a strategic alternative transaction, will increase value for stakeholders, or will sufficiently address our ability to continue as a going concern. Absent additional funding or our ability to successfully complete one or more strategic transactions to extend our cash runway beyond September 10, 2026, we will be unable to continue as a going concern. There can be no assurance that we will be able to obtain additional funding or complete a strategic transaction, and we may have to consider seeking protection under the bankruptcy laws, liquidating our assets or ceasing our operations. If we decide to seek protection under the bankruptcy laws, we expect that we would file for bankruptcy protection at a time that is earlier than when we would otherwise exhaust our cash resources. 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 condensed 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.

Total estimated cash payments due under the financial instruments described in Note 10, “Long-Term Obligations” (excluding the Amended Revenue Interest Agreement as amounts due under this agreement are calculated based on future revenues) are as follows (in thousands):

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial reporting and as required by Regulation S-X, Rule 8-03. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In our opinion, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, we must make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three and six months ended June 30, 2026 are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2026. For further information, refer to the financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2025 as filed with the Securities and Exchange Commission on February 13, 2026 (“Annual Report”).

Basis of Consolidation

The condensed consolidated financial statements as of June 30, 2026 include the accounts of Karyopharm Therapeutics Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

The significant accounting policies used in preparation of these condensed consolidated financial statements in this Form 10-Q are consistent with those discussed in Note 2, “Summary of Significant Accounting Policies,” in our Annual Report.

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 asingle 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 condensed 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:

2. Product Revenue

To date, our only source of product revenue has been from the U.S. sales of XPOVIO. Net product revenue, including provisions primarily consisting of distribution fees and cash discounts, as well as reserves for chargebacks, rebates and returns, were as follows (in thousands):

As of June 30, 2026 and December 31, 2025, net product revenue of $27.1 million and $22.7 million, respectively, were included in accounts receivable. To date, we have hadno bad debt write-offs and we do not currently have credit issues with any customers. There wereno credit losses associated with accounts receivable as of June 30, 2026 and December 31, 2025.

3. Inventory

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

4. License Agreements

In prior periods, we entered into license agreements with Berlin-Chemie AG, an affiliate of the Menarini Group (“Menarini”), and Antengene Therapeutics Limited (“Antengene”), both of which are accounted for within the scope of Accounting Standards Codification 606, Revenue from Contracts with Customers. For further details on the terms and accounting treatment considerations for these contracts, please refer to Note 5, “License Agreements,” to our consolidated financial statements contained in Item 8 of our Annual Report.

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

During the three months ended June 30, 2026, we recognized $1.8 million of royalty revenue from Menarini and $0.7 million of royalty revenue from Antengene.

During the three months ended June 30, 2025, we recognized $6.5 million of revenue for the reimbursement of development-related expenses and $1.0 million of royalty revenue from Menarini. We also recognized $0.5 million of royalty revenue from Antengene.

During the six months ended June 30, 2026, we recognized $3.2 million of royalty revenue from Menarini, $1.2 million of royalty revenue from Antengene, and $3.5 million of milestone revenue under a licensing agreement with a privately-held biotech company related to the research, development and commercialization of verdinexor for the treatment of cancer in certain animals.

During the six months ended June 30, 2025, we recognized $13.5 million of revenue for the reimbursement of development-related expenses and $1.9 million of royalty revenue from Menarini. We also recognized $1.1 million of royalty revenue from Antengene.

License and other revenue of $2.7 million and $3.5 million were included in accounts receivable as of June 30, 2026 and December 31, 2025, respectively.

5. Fair Value Measurements

Cash, cash equivalents, investments, and restricted cash are presented at fair value as of June 30, 2026 and December 31, 2025. Other financial instruments, including accounts receivable, net, other current assets, other assets, accounts payable, and accrued expenses, are presented at amounts that approximate fair value as of June 30, 2026 and December 31, 2025 due to their short-term nature.

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 - Quoted prices in active markets for identical assets or liabilities

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

Level 3 - Unobservable inputs that reflect the assumptions market participants would use in pricing the asset or liability

We estimate the fair value of our cash equivalents and investments 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 (expense) income, net on our condensed consolidated statements of operations. See Note 10, “Long-Term Obligations” to our condensed consolidated financial statements for further discussion of these liabilities:

(1)

The embedded derivative liabilities (the “Convertible Notes Derivatives”)associated with the 9.00% senior secured convertible notes due 2029 (the “New 2029 Notes”) and 9.00% senior secured convertible notes due 2028 (the “2028 Notes”) are included as components of these debt instruments on our condensed 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.

(2)

The warrants to purchase up to 3,068,417 shares of our common stock issued in May 2024 (the “2024 Warrants”) are classified as a long-term liability on our condensed consolidated balance sheets. The warrants to purchase up to 4,421,518 shares of our common stock issued in March 2026 (the “2026 Warrants”) are classified as a current liability on our condensed consolidated balance sheets. The 2024 Warrants and 2026 Warrants are collectively referred to as the “Liability Classified Warrants”. The valuation method for the Liability Classified 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 these liabilities, which are all classified as Level 3 (in thousands):

6. Investments

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

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, the present value of cash flows expected to be collected from the investment is compared to its amortized cost basis. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded on our condensed 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. We do not intend to sell the investments before recovery of their amortized cost bases, which may be at maturity. All of our investments mature within one year from June 30, 2026.

7. 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”) and 6.00% senior secured convertible notes due 2029 (the “2029 Notes”)when outstanding, were potentially settleable in common shares. No 2025 Notes or 2029 Notes were outstanding during the three and six months ended June 30, 2026. The 2025 Notes and 2029 Notes did not impact the calculation of dilutive loss per common share during the three and six months ended June 30, 2025 because they were anti-dilutive in those periods.

As discussed further in Note 10, “Long-Term Obligations”, the conversion obligation for our New 2029 Notes and 2028 Notes can potentially be settled in common shares. The New 2029 Notes and 2028 Notes did not impact the calculation of dilutive loss per common share during the three and six months ended June 30, 2026 because they were anti-dilutive in those periods. No 2028 Notes or New 2029 Notes were outstanding during the three and six months ended June 30, 2025.

As discussed further in Note 11, “Common Share Warrants”, warrants to purchase common shares were outstanding as of June 30, 2026 and 2025. All outstanding warrants, except pre-funded warrants, are excluded from the calculation of basic net loss per share because the warrant holders do not have an obligation to share in our losses. All warrants, except pre-funded warrants, did not impact the calculation of dilutive loss per common share during the three and six months ended June 30, 2026 and 2025 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-minimis exercise price.

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

8. Stock-based Compensation Expense

The following table summarizes stock-based compensation expense included in operating expenses (in thousands):

Our 2022 Equity Incentive Plan, as amended (the “2022 Plan”), provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards and other stock-based awards. On May 21, 2026, our stockholders approved an increase of 3,000,000 shares to the number of shares of our common stock available for issuance under the 2022 Plan.

On May 21, 2026, our stockholders also approved an increase of 1,400,000 shares to the number of shares of our common stock available for issuance under our employee stock purchase plan.

9. Stockholders’ Equity

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. 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 sold an aggregate of 2,994,441 Shares underthe Open Market Sale Agreement during the six months ended June 30, 2026, resulting in net proceeds of $19.8 million. We didnot sellany Shares under the Open Market Sale Agreement during the three and six months ended June 30, 2025 or during the three months ended June 30, 2026. Pursuant to a prospectus we thereafter filed with the Securities and Exchange Commission as part of a registration statement on Form S-3 on May 4, 2026, as of June 30, 2026, $100.0 million of Shares were available for issuance and sale under the Open Market Sale Agreement.

On February 18, 2026, 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 58,333,333 shares to 111,000,000 shares and the number of authorized shares of our common stock from 53,333,333 to 106,000,000 shares.

On March 24, 2026, we entered into a Securities Purchase Agreement with RA Capital Healthcare Fund, L.P. pursuant to which we issued and sold in a private placement: (i)1,030,354 shares of common stock, (ii) pre-funded warrants to purchase up to 3,391,164 shares of common stock, and (iii) accompanying 2026 Warrants to purchase 4,421,518 shares of common stock with an exercise price of $10.00 per share for aggregate net proceedsof $26.9 million. The 2026 Warrants are exercis able until August 29, 2026 and the pre-funded warrants do not expire. As of June 30, 2026, none of these warrants have been exercised.

As of June 30, 2026, we had 22,680,288 shares of common stock issued and outstanding. In addition, as of June 30, 2026 we had reserved (i)474,615 shares of common stock for issuance upon the exercise of outstanding stock options, including shares reserved under unvested options, with a weighted-average exercise price of $59.06 per share; (ii)5,209,631 shares of common stock for issuance upon the vesting of outstanding RSUs and PSUs (assuming all performance milestones are satisfied), (iii)1,493,758 shares of common stock available for future issuance under our 2022 Equity Incentive Plan, 2022 Inducement Stock Incentive Plan, and 2013 Employee Stock Purchase Plan, in the aggregate; (iv)14,043,996 shares of common stock for issuance upon the exercise of outstanding warrants, with a weighted-average exercise price of $11.71 per share, including 5,739,289 that expire on August 29, 2026 if not exercised; (v)4,005,544 shares of common stock for issuance upon the exercise of outstanding pre-funded warrants; (vi)11,904,630 shares of common stock for issuance upon conversion of the 2028 Notes and 2029 Notes, in the aggregate (assuming all make-whole adjustments and assuming payment in-kind of interest payments as permitted by the applicable indenture); and (vii)5,000 shares of common stock issuable to Neumedicines Inc. upon the satisfaction of certain milestones under that certain Asset Purchase Agreement dated as of November 24, 2020. As of June 30, 2026, based on 106,000,000 shares of common stock authorized, we had 46,182,538 shares of common stock that were unissued and unreserved.

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 which matured on October 15, 2025. 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, after which no 2025 Notes were outstanding.

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, under which we borrowed an additional $12.5 million. In February 2026, we entered into a Second Amendment to Credit and Guaranty Agreement (as amended, the “Amended Credit Agreement”) which became effective in March 2026. The senior secured term loan facility under the Amended Credit Agreement (the “Amended Term Loan”) 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 June 30, 2026 was payable in-kind. Interest incurred on borrowings under the Amended Term Loan after June 30, 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. The first principal payment is due on September 10, 2026 and will equal$15.8 million. All subsequent principal payments will equal 6.25% of the aggregate principal amount of the Amended Term Loan, not including the effect of previous principal payments. The remaining principal is due when the Amended Term Loan matures on May 8, 2028. We are permitted to prepay the Amended Term Loan at any time, subject to a prepayment premium equal to 5% of the principal prepaid through May 8, 2027 (and 0% thereafter). Any principal that is prepaid, repaid pursuant to a mandatory prepayment, or accelerated must be accompanied by a fee equal to 3.00% of the principal amount so prepaid, repaid, or accelerated. 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”). The Minimum Liquidity Covenant Amount is the lesser of (i) $10.0 million plus 50% of the net cash proceeds received from certain debt and equity issuances and (ii) $25.0 million, and after October 10, 2026, it will be $25.0 million. As of June 30, 2026, we were in compliance with the Minimum Liquidity Covenant Amount and all other covenants under the Amended Credit Agreement.

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 June 30, 2026, 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. Total debt issuance costs related to the Amended Term Loan of $5.2 million are being amortized to interest expense through May 2028 using an effective interest rate of 16%.

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

Estimated future minimum payments on the Amended Term Loan as of June 30, 2026 were as follows (in thousands):

2029 Notes, New 2029 Notes, and 2028 Notes

In May 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 interestat 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 maturing on 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. After whichno 2029 Notes were outstanding.

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 44.4444 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 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 was 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 with respect to the New 2029 Notes or October 15, 2026 with respect to 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% with respect to the New 2029 Notes or 165% with respect to 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: (1) make a cash payment 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; and (2) deliver a number of shares of common stock equal to the aggregate value of all remaining interest payments on the amount to be redeemed from the redemption date through maturity divided by the market price per share of our common shares on the redemption date. The number of shares of common stock deliverable 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 June 30, 2026, no New 2029 Notes or 2028 Notes have been converted into shares of common stock or pre-funded warrants.

In February 2026, we entered into a Forbearance Agreement (the “Forbearance Agreement”) with: (i) all the lenders under the Amended Credit Agreement, (ii) all the holders of the New 2029 Notes and 2028 Notes, and (iii) the investor representative for the investors under our Revenue Interest Agreement, as defined below (collectively, the “Consenting Parties”). The Forbearance Agreement became effective in March 2026 and prevents the exercise of certain rights and remedies with respect to specified matters, including: (i) payment-related defaults through September 30, 2026 that would result from our non-payment of the interest due on

June 30, 2026 for the New 2029 Notes and 2028 Notes and (ii) any defaults that result from a requirement under the indentures of the New 2029 Notes and 2028 Notes for us to have a Minimum Liquidity Covenant Amount greater thanthe lesser of (i) $10.0 million plus 50% of the net cash proceeds received from certain debt and equity issuances and (ii) $25.0 million through October 10, 2026, which effectively aligns the Minimum Liquidity Covenant Amount required under the New 2029 Notes and 2028 Notes with the Minimum Liquidity Covenant Amount required under the Amended Term Loan. The Forbearance Agreement does not constitute a waiver of any defaults or events of default, and the Consenting Parties reserve their rights and remedies, subject to the terms of the Forbearance Agreement.

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, senior to 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. As of June 30, 2026, 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 5, “Fair Value Measurements” to our condensed consolidated financial statements.

The outstanding balance of the New 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. 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 June 30, 2026 was approximately$100.7 million and$27.5 million, respectively. 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 2029 Notes and New 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 $0.7 million related to the 2028 Notes for thethree months ended June 30, 2026, which included $0.4 million of contractual interest expense and $0.3 million of amortization. We recognized interest expense of $1.3 million related to the 2028 Notes for thesix months ended June 30, 2026, which included $0.7 million of contractual interest expense and $0.6 million of amortization.

Future minimum payments on the New 2029 Notes and 2028 Notes as of June 30, 2026 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, 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 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 has received cash payments in the aggregate totaling $263.3 million or (ii) the legal maturity date of September 26, 2035. If HCRx has 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.

In the event of a change of control, an event of default, including, among others, our failure to pay any amounts due to HCRx, 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 HCRx an amount equal to $263.3 million less aggregate payments previously paid to HCRx.

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 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, HCRx 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 condensed consolidated balance sheets.

As of June 30, 2026, we have made $147.1 million in payments to HCRx. The effective interest rate as of June 30, 2026 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 both June 30, 2026 and December 31, 2025 was $72.3 million, 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 June 30, 2026 and December 31, 2025 because the obligation is measured using our current estimates of future payments over the life of the arrangement, which are considered Level 3 inputs.

11. Common Share Warrants

In December 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.

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 3,068,417 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 exceedstwo times the then current exercise price of the warrants, which is currently equal to$33.00, for 20 trading days during any 30 consecutive trading day period, we can require the holder to exercise the 2024 Warrants. The 2024 Warrants were classified as a long-term liability in our condensed 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 5, “Fair Value Measurements”.

In October 2025, we issued warrants (the “2025 Placement Warrants”) 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 August 29, 2026.

In October 2025, we issued warrants (the “2025 Warrants”) to purchase 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 (“Pre-Funded Warrants”) to purchase 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 of 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 Pre-Funded Warrants do not expire.

In March 2026, we issued the 2026 Warrantsto purchase 4,421,518 shares of common stock with an exercise price of $10.00 per share which areexercisable until August 29, 2026. In March 2026, we also issued Pre-Funded Warrants to purchase up to 3,391,164 shares of common stockat an exercise price of $0.0001 per share which do not expire.

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. The 2026 Warrants were classified as a current liability in our condensed 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 5, “Fair Value Measurements”.

The 2024 Warrants, 2025 Placement Warrants, 2025 Warrants, 2026 Warrants, and Pre-Funded Warrants cannot be exercised if such an exercise results in the holder (together with its affiliates) to own more than 4.99% (for the 2024 Warrants, 2025 Placement Warrants, 2025 Warrants, and Pre-Funded Warrants issued in 2025) or 9.99% (for the 2026 Warrants and Pre-Funded Warrants issued in 2026) of our common stock outstanding on the date of receipt. These percentages are subject to increase or decrease at the election of the holder, but cannot exceed 19.99% of our common stock outstanding on the date of receipt.

The holders of the 2024 Warrants and 2026 Warrants 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 following is a summary of activity related to our common stock warrants: