Spero Therapeutics, Inc.

Previous wording

We are a clinical-stage biopharmaceutical company focused on identifying and developing novel treatments for rare diseases and diseases caused by MDR bacterial infections with high unmet need. Since our inception in 2013, we have focused our efforts and financial resources on acquiring and developing product and technology rights, building our intellectual property portfolio and conducting research and development activities for our product candidates. We do not have any products approved for sale and have not generated any revenue from product sales. We believe that our novel product candidates, if successfully developed and approved, could provide meaningful benefits to patients suffering from serious rare diseases and life-threatening bacterial infections, in both the community and hospital settings. Our pipeline consists of mid-to late-stage clinical assets.

Current wording

We are a clinical-stage biopharmaceutical company focused on identifying and developing novel treatments for rare diseases and diseases with high unmet need.

Previous wording

We have experienced mostly net losses and significant cash outflows from cash used in operating activities since our inception. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of one or more of our product candidates. As of December 31, 2024, we had an accumulated deficit of $459.6 million, and cash and cash equivalents of $52.9 million. We expect to continue to incur significant expenses and operating losses for at least the next year. Based on our cash and cash equivalents as of December 31, 2024, together with earned and non-contingent development milestone payments from GSK, as well as other non-dilutive funding commitments, we believe that our cash runway will be sufficient to fund our operating expenses and required capital expenditures into the second quarter of 2026. During this period, we plan to prioritize advancing the Phase 3 clinical trial activities for tebipenem HBr under our GSK License Agreement and completing our analysis of the full dataset from the 25 treated patients in the Phase 2a proof-of-concept trial of SPR720. Beyond this point we will need additional funding, which we expect will primarily consist of raising additional capital through some combination of equity or debt financings, potential new collaborations or additional grant funding. If we are not able to secure adequate additional funding, we plan to make further reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned development activities. The actions necessary to reduce spending under this plan at a level that mitigates the factors described above is not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern. As a result, management has concluded that substantial doubt exists about our ability to continue as a going concern.

Current wording

We have experienced mostly net losses and significant cash outflows from cash used in operating activities since our inception. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and commercialization of tebipenem HBr, or any product candidate we may develop in the future. As of December 31, 2025, we had an accumulated deficit of $451.1 million, and cash and cash equivalents of $40.3 million. We expect to continue to incur significant expenses and operating losses for the foreseeable future. Based on our current operating plan, we believe that our cash and cash equivalents as of December 31, 2025 will be sufficient to fund our operating expenses and required capital expenditures into 2028. During this period, we remain focused on supporting GSK in the FDA approval process pursuant to our obligations under our GSK License Agreement and advancing other corporate activities, including exploring opportunities to grow our portfolio of clinical-stage product candidates. Beyond this point, or in the event we change our current operating plan, we will need additional funding to support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of equity offerings, debt financings, government funding arrangements, collaborations, strategic alliances and marketing, distribution or licensing arrangements. If we are not able to secure adequate additional funding, we will have to make further reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned development activities. The actions necessary to reduce spending under this plan at a level that mitigates the factors described above are not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern.

Previous wording

We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for our product candidates. If we obtain regulatory approval for any of our product candidates and do not enter into a commercialization partnership, we expect to incur significant expenses related to developing our internal commercialization capability to support product sales, marketing and distribution. Further, we expect to incur additional costs associated with our continued operation as a public company.

Current wording

We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for any of our product candidates. If we obtain regulatory approval for any of our future product candidates and do not enter into a commercialization partnership, we expect to incur significant expenses related to developing our internal commercialization capability to support product sales, marketing and distribution. Further, we expect to incur additional costs associated with our continued operation as a public company.

Previous wording

To date, we have not generated any revenue from product sales. If our development efforts for our product candidates are successful and result in regulatory approval, we may generate revenue in the future from product sales. We cannot predict if, when, or to what extent we will generate revenue from the commercialization and sale of our product candidates. We may never succeed in obtaining regulatory approval for any of our product candidates.

Current wording

To date, we have not generated any revenue from product sales. If our development efforts for any of our product candidates are successful and result in regulatory approval, we may generate revenue in the future from product sales. We cannot predict if, when, or to what extent we will generate revenue from the commercialization and sale of any of our product candidates. We may never succeed in obtaining regulatory approval for any existing or future product candidates.

Previous wording

We expect a portion of our revenue will continue to be derived from payments under our active government awards and any awards that we may receive in the future.

Current wording

A portion of our revenue may be derived from payments under any government awards that we may receive in the future.

Previous wording

Current collaboration revenue relates to our agreements with Pfizer and GSK.

Current wording

Collaboration revenue relates to our agreements with Pfizer and GSK.

Previous wording

Research and development expenses consist primarily of costs incurred for our research activities, including our drug discovery efforts, and the development of our product candidates, which include:

Current wording

Research and development expenses consist primarily of costs incurred for our research activities, including our drug discovery efforts, and the development of any of our product candidates, which include:

Previous wording

expenses incurred in connection with the preclinical and clinical development of our product candidates, including under agreements with contract research organizations (“CROs”);

Current wording

expenses incurred in connection with the preclinical and clinical development of any of our product candidates, including under agreements with contract research organizations (“CROs”);

Previous wording

At this time, we cannot reasonably estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any of our product candidates. The successful development and commercialization of our product candidates is highly uncertain. This is due to the numerous risks and uncertainties, including the following:

Current wording

At this time, we cannot reasonably estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any existing or future product candidates. The successful development and commercialization of any of our product candidates is highly uncertain. This is due to the numerous risks and uncertainties, including the following:

Previous wording

launch of commercial sales of our product candidates, if approved, whether alone or in collaboration with others;

Current wording

launch of commercial sales of any of our product candidates, if approved, whether alone or in collaboration with others;

Previous wording

acceptance of our product candidates, if approved, by patients, the medical community and third-party payors;

Current wording

acceptance of any of our product candidates, if approved, by patients, the medical community and third-party payors;

Previous wording

a continued acceptable safety profile of our product candidates, if approved.

Current wording

a continued acceptable safety profile of any of our product candidates, if approved.

Previous wording

Except for year ended December 31, 2022, we have not recorded any income tax benefits for the net losses we have incurred in each year or for our earned research and development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our net operating loss carryforwards and tax credits will not be realized. As of December 31, 2024, we had federal and state net operating loss carryforwards ("NOLs") of $165.2 million and $120.6 million, respectively which may be available to offset future income tax liabilities. $152.0 million of the federal NOLs can be carried forward indefinitely and $13.2 million of the federal NOLs begin to expire in 2034. The state NOLs begin to expire in 2034 and will expire at various dates through 2044. In addition, as of December 31, 2024, we had foreign net operating loss carryforwards of $4.6 million, which may be available to offset future income tax liabilities and do not expire. As of December 31, 2024, we also had federal and state research and development tax credit carryforwards of $6.2 million and $2.1 million, respectively, which begin to expire in 2036 and 2033, respectively. We have recorded a full valuation allowance against our net deferred tax assets at each balance sheet date.

Current wording

Except for year ended December 31, 2022, we have not recorded any income tax benefits for the net losses we have incurred in each year or for our earned research and development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our net operating loss carryforwards and tax credits will not be realized. As of December 31, 2025, we had United States federal, state and foreign net operating loss carryforwards ("NOLs") of $226.1 million, $184.8 million and $4.7 million, respectively. $212.8 million of the federal NOLs can be carried forward indefinitely and $13.2 million of NOLs begin to expire in 2034. The state NOLs begin to expire in 2035 and will expire at various dates through 2045. The foreign NOLs do not expire. As of December 31, 2025, we also had federal and state research and development tax credit carryforwards of $6.7 million and $1.7 million, respectively, and federal orphan drug tax credit carryforwards of $3.1 million, which may be available to offset future income tax liabilities. The federal and state research and development tax credits begin to expire in 2035 and the federal orphan drug credits begin to expire in 2044. We have recorded a full valuation allowance against our net deferred tax assets at each balance sheet date.

Previous wording

We generate revenue from government contracts that reimburse us for certain allowable costs for funded projects. For contracts with government agencies, when we have concluded that we are the principal in conducting the research and development expenses and where the funding arrangement is considered central to our ongoing operations, we classify the recognized funding received as revenue. Revenue from government grants is recognized as the qualifying expenses related to the contracts are incurred, provided that there is reasonable assurance of recoverability. Revenue recognized upon incurring qualifying expenses in advance of receipt of funding is recorded as unbilled receivables, a component of prepaid expenses and other current assets, in the consolidated balance sheet.

Current wording

We have generated revenue from government contracts that reimburse us for certain allowable costs for funded projects. For contracts with government agencies, when we have concluded that we are the principal in conducting the research and development expenses and where the funding arrangement is considered central to our ongoing operations, we classify the recognized funding received as revenue. Revenue from government grants is recognized as the qualifying expenses related to the contracts are incurred, provided that there is reasonable assurance of recoverability. Revenue recognized upon incurring qualifying expenses in advance of receipt of funding is recorded as unbilled receivables, a component of prepaid expenses and other current assets, in the consolidated balance sheet.

Previous wording

We recognize funding received from BARDA and the NIAID of the NIH, as revenue, rather than as a reduction of research and development expenses, because we are the principal in conducting the research and development activities and these contracts are central to our ongoing operations. We recognize revenue only after the qualifying expenses related to the contracts have been incurred, we are reasonably assured that the expenses will be reimbursed and the revenue is collectible. We record revenue recognized upon incurring qualifying expenses in advance of billing as unbilled revenue, which is included in other receivables in our consolidated balance sheet. The related costs incurred by us are included in research and development expense in our consolidated statements of operations and comprehensive loss.

Current wording

We recognize funding received from BARDA and the NIAID of the NIH, as revenue, rather than as a reduction of research and development expenses, because we are the principal in conducting the research and development activities and these contracts are central to our ongoing operations. We recognize revenue only after the qualifying expenses related to the contracts have been incurred, we are reasonably assured that the expenses will be reimbursed and the revenue is collectible. We record revenue recognized upon incurring qualifying expenses in advance of billing as unbilled revenue, which is included in other receivables in our consolidated balance sheet. The related costs incurred by us are included in research and development expense in our consolidated statements of operations and comprehensive loss. In March 2025, we announced that we ceased development of SPR206 and in April 2025, NIAID communicated to us that it had terminated the contract for convenience effective immediately. We do not anticipate receiving any additional funding under the BARDA contract.

Previous wording

The following table summarizes our results of operations for the years ended December 31, 2024 and 2023:

Current wording

The following table summarizes our results of operations for the years ended December 31, 2025 and 2024 (in thousands):

Previous wording

Grant revenue recognized during 2024 and 2023 consisted of the reimbursement of qualifying expenses incurred in connection with our various government awards. The increase in revenue during 2024 was primarily due to an increase of $15.8 million in funding under our BARDA contract related to our pivotal Phase 3 clinical trial of tebipenem HBr, partially offset by a decrease of $2.3 million in qualified expenses incurred under our NIAID award relating to SPR206.

Current wording

Grant revenue recognized during the years ended December 31, 2025 and 2024 consisted of the reimbursement of qualifying expenses incurred in connection with our various government awards. The decrease in grant revenue during 2025 was primarily due to a decrease of $13.0 million in funding under our BARDA contract related to the conclusion of the Phase 3 clinical trial of tebipenem HBr, and a decrease of $0.4 million in qualified expenses incurred under our NIAID award relating to SPR206 as we ceased development of SPR206 and the NIAID award was terminated in April 2025.

Previous wording

During the years ended December 31, 2024 and 2023, collaboration revenue - related party related to revenue recognized under the GSK License Agreement. During the year ended December 31, 2024, we recognized $27.0 million in collaboration revenue - related party under the GSK License Agreement. During the year ended December 31, 2023, we recognized $95.8 million in collaboration revenue - related party, of which $21.2 million was recognized upon achievement of the $30.0 million milestone under the GSK License Agreement and $64.7 million upon achievement of the $95.0 million milestone under the GSK License Agreement.

Current wording

During the years ended December 31, 2025 and 2024, collaboration revenue - related party related to revenue recognized under the GSK License Agreement. During the year ended December 31, 2025, we recognized $47.0 million in collaboration revenue - related party under the GSK License Agreement, of which $25.0 million was recognized upon GSK's filing of an NDA for tebipenem HBr with the FDA in December 2025, one of the milestones under the agreement. We received payment in February 2026. During the year ended December 31, 2024, we recognized $27.0 million in collaboration revenue - related party under the GSK License Agreement.

Previous wording

During the year ended December 31, 2024 we recognized $0.4 million in collaboration revenue related to our agreement with Pfizer. During the year ended December 31, 2023 we recognized $0.9 million in collaboration revenue related to our agreement with Pfizer.

Current wording

During the year ended December 31, 2025 we recognized $12.6 million in collaboration revenue related to our agreement with Pfizer, all of which was recognized upon termination of our agreement with Pfizer in December 2025. During the year ended December 31, 2024 we recognized $0.4 million in collaboration revenue related to our agreement with Pfizer.

Previous wording

Direct costs related to our tebipenem HBr program increased by $43.8 million during the year ended December 31, 2024, compared to the year ended December 31, 2023, due to increased clinical activities related to our Phase 3 clinical trial of tebipenem HBr, which we initiated in the fourth quarter of 2023. Direct costs related to our tebipenem HBr program during the year ended December 31, 2024 reflect a $3.6 million reduction to expense related to a purchase of drug substance material by GSK.

Current wording

Direct costs related to our tebipenem HBr program decreased by $37.9 million during the year ended December 31, 2025, compared to the year ended December 31, 2024, due to decreased clinical activities related to our Phase 3 clinical trial of tebipenem HBr, which met its primary endpoint and was stopped early for efficacy during the first half of 2025. In December 2025, GSK resubmitted the NDA for tebipenem HBr to the FDA. Direct costs related to our tebipenem HBr program during the years ended December 31, 2025 and 2024, reflect a $0.5 million and $3.6 million reduction to expense related to a purchase of drug substance material by GSK, respectively.

Previous wording

Direct costs related to our SPR206 program decreased by $2.7 million during the year ended December 31, 2024, primarily due to decreased preclinical activity.

Current wording

Direct costs related to our SPR206 program decreased by $0.5 million during the year ended December 31, 2025, primarily due to decreased preclinical activity and the cessation of development of the program announced in March 2025.

Previous wording

The increase in personnel-related costs of $0.3 million was primarily due to increased research and development personnel costs. Personnel-related costs for the years ended December 31, 2024 and 2023 included share-based compensation expenses of $2.6 million and $2.7 million, respectively.

Current wording

The decrease in personnel-related costs of $4.5 million was primarily a result of decreased headcount costs in our research and development functions between the periods. Personnel-related costs for the years ended December 31, 2025 and 2024 included share-based compensation expenses of $1.7 million and $2.6 million, respectively.

Previous wording

The decrease in personnel-related costs of $2.1 million was primarily a result of decreased headcount costs in our general and administrative functions during the period. Personnel-related costs for the years ended December 31, 2024 and 2023 included share-based compensation expense of $5.2 million and $5.3 million, respectively.

Current wording

The decrease in personnel-related costs of $1.4 million was primarily a result of decreased headcount costs in our general and administrative functions between the periods. Personnel-related costs for the years ended December 31, 2025 and 2024 included share-based compensation expense of $2.6 million and $5.2 million, respectively.

Previous wording

The increase in professional and consultant fees was primarily due to increased legal and consulting expenses incurred during the year ended December 31, 2024.

Current wording

The decrease in professional and consultant fees was primarily due to decreased legal and consulting expenses incurred during the year ended December 31, 2025.

Previous wording

During the year ended December 31, 2024, we incurred restructuring expenses of $0.9 million related to our strategic restructuring that we announced in October 2024. Restructuring expenses for the period were primarily comprised of severance and other employee costs. For further information, refer to Note 9 – Restructuring to the consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K.

Current wording

During the years ended December 31, 2025 and 2024, we incurred restructuring expenses of $0.3 million and $0.9 million, respectively, related to our strategic restructuring that we announced in October 2024. Restructuring expenses for both periods were primarily comprised of severance and other employee costs. For further information, refer to Note 9 to the consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K.

Previous wording

Other income, net was $4.8 million during 2024, compared to $3.9 million during 2023. Total other income for the year ended December 31, 2024 included $4.7 million of interest income, of which $1.5 million related to the significant financing component recognized under the GSK License Agreement, offset by immaterial fluctuations in unrealized foreign currency. Total other income for the year ended December 31, 2023 included $3.9 million of interest income, offset by fluctuations in unrealized foreign currency.

Current wording

Other income, net was $2.5 million during the year ended December 31, 2025, compared to $4.8 million during the year ended December 31, 2024. Total other income for the year ended December 31, 2025 included $2.5 million of interest income, of which $0.9 million related to the significant financing component recognized under the GSK License Agreement, offset by immaterial fluctuations in unrealized foreign currency. Total other income for the year ended December 31, 2024 included $4.7 million of interest income, of which $1.5 million related to the significant financing component recognized under the GSK License Agreement, offset by immaterial fluctuations in unrealized foreign currency.

Previous wording

Since our inception, we have incurred significant operating losses. We have recognized revenue to date from funding arrangements with the DoD, NIAID, CARB-X and BARDA, the GSK License Agreement and our license agreements with Everest and Pfizer. We have not yet commercialized any of our product candidates and we may not generate revenue from sales of any product candidates. To date, we have funded our operations with payments received under license and collaboration agreements and funding from government contracts, and from the proceeds of multiple common stock offerings. As of December 31, 2024, we had cash and cash equivalents of $52.9 million.

Current wording

Since our inception, we have incurred significant operating losses. We have recognized revenue to date from funding arrangements with the DoD, NIAID, CARB-X and BARDA, the GSK License Agreement and our license agreements with Everest and Pfizer. We have not yet commercialized any of our product candidates and we may not generate revenue from sales of any product candidates. To date, we have funded our operations with payments received under license and collaboration agreements and government contracts and from the proceeds of multiple common stock offerings. As of December 31, 2025, we had cash and cash equivalents of $40.3 million. In February 2026, we received a $25.0 million milestone payment under the GSK agreement, which we were entitled to receive upon GSK’s filing of an NDA for tebipenem HBr with the FDA.

Previous wording

The following table summarizes our sources and uses of cash for the years ended December 31, 2024 and 2023:

Current wording

The following table summarizes our sources and uses of cash for the years ended December 31, 2025 and 2024 (in thousands):

Previous wording

Net cash used in operating activities for the year ended December 31, 2023 was $33.0 million, primarily resulting from our net income of $22.8 million, adjusted for net non-cash items of $14.6 million (primarily due to stock-based compensation and asset impairment). Net cash used by our operating assets and liabilities was $70.4 million and consisted primarily of a $95.7 million increase in our related party collaboration receivable, $29.0 million net increase in deferred revenue and a decrease of $1.7 million in accrued expenses and accounts payable.

Current wording

Net cash used in operating activities for the year ended December 31, 2025 was $12.6 million, primarily resulting from our net income of $8.6 million, adjusted for net non-cash items of $6.0 million (primarily due to share-based compensation). Net cash provided by changes in our operating assets and liabilities was $27.2 million and consisted primarily of a $24.0 million decrease in our related party collaboration receivable, primarily due to the receipt of the third and fourth installments of the development milestone payments from GSK, offset by the addition of the milestone for submission of an NDA for tebipenem HBr (see Note 13 to the consolidated financial statements), a $34.7 million net decrease in deferred revenue, and a net decrease of $18.8 million in accrued expenses and accounts payable.

Previous wording

Net cash used in operating activities for the year ended December 31, 2024 was $23.4 million, primarily resulting from our net loss of $68.6 million, adjusted for net non-cash items of $8.8 million (primarily due to stock-based compensation). Net cash provided by changes in our operating assets and liabilities was $36.3 million and consisted primarily of a $46.4 million decrease in our related party collaboration receivable, primarily due to the receipt of the first and second installments of the development milestone payments from GSK (see Note 13 - License, Collaboration and Service Agreements), a $26.6 million net decrease in deferred revenue, offset by an increase of $17.1 million in accrued expenses and accounts payable.

Current wording

Net cash used in operating activities for the year ended December 31, 2024 was $23.4 million, primarily resulting from our net loss of $68.6 million, adjusted for net non-cash items of $8.8 million (primarily due to share-based compensation). Net cash provided by changes in our operating assets and liabilities was $36.3 million and consisted primarily of a $46.4 million decrease in our related party collaboration receivable, primarily due to the receipt of the first and second installments of the development milestone payments from GSK (see Note 13 to the consolidated financial statements), a $26.6 million net decrease in deferred revenue, offset by an increase of $17.1 million in accrued expenses and accounts payable.

Previous wording

the initiation, progress, timing, costs and results of preclinical studies and clinical trials of our product candidates and potential new product candidates;

Current wording

the initiation, progress, timing, costs and results of any preclinical studies and clinical trials of any of our product candidates and potential new product candidates;

Previous wording

the amount of funding that we receive under government contracts that we have applied for or may apply for in the future;

Current wording

the amount of funding that we receive under government contracts that we may apply for in the future;

Previous wording

the number and characteristics of product candidates that we pursue;

Current wording

the number and characteristics of product candidates that we may pursue;

Previous wording

the costs of commercialization activities for our product candidates if we receive marketing approval, including the costs and timing of establishing product sales, marketing, distribution and manufacturing capabilities;

Current wording

the costs of commercialization activities for our future product candidates if we receive marketing approval, including the costs and timing of establishing product sales, marketing, distribution and manufacturing capabilities;

Previous wording

As of December 31, 2024, we had cash and cash equivalents of $52.9 million. In accordance with ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), we are required to evaluate whether there are conditions and events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern from the issuance date of our financial statements. Based on the Company’s current operating plan and existing cash and cash equivalents, the Company has determined that there is substantial doubt regarding its ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. Based on our cash and cash equivalents as of December 31, 2024, together with earned and non-contingent development milestone payments from GSK, as well as other non-dilutive funding commitments, we believe that our cash runway will be sufficient to fund our operating expenses and capital expenditure requirements into the second quarter of 2026.

Current wording

As of December 31, 2025, we had cash and cash equivalents of $40.3 million. In accordance with ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), we are required to evaluate whether there are conditions and events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern from the issuance date of our financial statements. Based on our current operating plan, we believe that our cash and cash equivalents as of December 31, 2025 will enable us to fund our operating expenses and required capital expenditure requirements for at least 12 months from the issuance of the financial statements included in this report and into 2028.

Previous wording

This timeline is subject to uncertainty as to the timing of future expenditures. We have developed plans to mitigate this risk, which primarily consist of raising additional capital through some combination of equity or debt financings, potential new collaborations and/or reducing cash expenditures. If we are not able to secure adequate additional funding, we plan to make reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned clinical trials, and research stage. The actions necessary to reduce spending under this plan at a level that mitigates the factors described above is not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern. As a result, management has concluded that substantial doubt exists about our ability to continue as a going concern.

Current wording

This timeline is uncertain and subject to change as we explore opportunities to grow our pipeline. We have developed plans to mitigate this risk, which primarily consist of raising additional capital through some combination of equity or debt financings, potential new collaborations and/or reducing cash expenditures. If we are not able to secure adequate additional funding, we plan to make reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned clinical trials, and research stage programs. The actions necessary to reduce spending under this plan at a level that mitigates the factors described above are not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern.

Previous wording

The following table summarizes our contractual obligations as of December 31, 2024 and the effects that such obligations are expected to have on our liquidity and cash flows in future periods:

Current wording

The following table summarizes our contractual obligations as of December 31, 2025 and the effects that such obligations are expected to have on our liquidity and cash flows in future periods (in thousands):

Previous wording

Under an agreement we entered into with PBB, we are obligated to make milestone payments of up to $5.8 million upon the achievement of specified clinical milestones and a payment of £5.0 million ($6.3 million as of December 31, 2024) upon the achievement of a specified commercial milestone for SPR206. In addition, we have agreed to pay to PBB royalties, on a product-by-product and country-by-country basis, of a low single-digit percentage based on net sales of products licensed under the agreement.

Current wording

Under an agreement we entered into with PBB, Cantab Anti-Infectives Ltd. and New Pharma License Holdings Limited, we are obligated to make milestone payments of up to $5.8 million upon the achievement of specified clinical milestones and a payment of £5.0 million ($6.7 million as of December 31, 2025) upon the achievement of a specified commercial milestone for SPR206. In addition, we have agreed to pay PBB royalties, on a product-by-product and country-by-country basis, of a low single-digit percentage based on net sales of products licensed under the agreement. In March 2025, we notified the parties to the Cantab Agreement of our decision to cease development of SPR206 and as such we will not be liable for any milestones or royalties under the agreement.