{"url_path":"/sec/spro/10-q/2026/cover-page","section_key":"cover-page","section_title":"Cover Page","topic":"sec","document":{"doc_type":"10-Q","doc_date":"2026-05-13","source_url":"https://www.sec.gov/Archives/edgar/data/1701108/0001193125-26-221591-index.html","accession_number":"0001193125-26-221591","cik":"0001701108","ticker":"SPRO","issuer_name":"Spero Therapeutics, Inc.","edgar_url":"https://www.sec.gov/Archives/edgar/data/1701108/0001193125-26-221591-index.html","primary_entity_key":"0001701108","primary_entity_name":"Spero Therapeutics, 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STATES\n\nSECURITIES AND EXCHANGE COMMISSION\n\nWashington, D.C. 20549\n\n \n\nFORM 10-Q\n\n \n\n(Mark One)\n\n☒\n\nQUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934\n\nFor the quarterly period ended March 31, 2026\n\nor\n\n☐\n\nTRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to\n\nCommission File Number: 001-38266\n\n \n\nSPERO THERAPEUTICS, INC.\n\n(Exact name of registrant as specified in its charter)\n\n \n\n \n\nDelaware\n\n46-4590683\n\n \n\n \n\n(State or other jurisdiction of\n\nincorporation or organization)\n\n(I.R.S. Employer\n\nIdentification No.)\n\n \n\n \n\n675 Massachusetts Avenue, 14th Floor\n\nCambridge, Massachusetts\n\n02139\n\n \n\n \n\n(Address of principal executive offices)\n\n(Zip Code)\n\n \n\n(857) 242-1600\n\n(Registrant’s telephone number, including area code)\n\nSecurities registered pursuant to Section 12(b) of the Act:\n\n \n\nTitle of each class\n\nTrading Symbol(s)\n\nName of each exchange on which registered\n\nCommon Stock, $0.001 par value per share\n\nSPRO\n\nThe Nasdaq Global Select Market\n\n \n\nIndicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐\n\nIndicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐\n\nIndicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.\n\n \n\nLarge accelerated filer\n\n \n\n☐\n\n \n\nAccelerated filer\n\n☐\n\nNon-accelerated filer\n\n \n\n☒\n\n \n\nSmaller reporting company\n\n☒\n\n \n\n \n\n \n\n \n\nEmerging growth company\n\n☐\n\n \n\nIf an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐\n\nIndicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒\n\nAs of May 1, 2026, the registrant had 57,901,493 shares of common stock, $0.001 par value per share, outstanding.\n\n \n\n \n\n \n\nReferences to Spero Therapeutics\n\nUnless otherwise stated, all references to “us,” “our,” “we,” “Spero,” “Spero Therapeutics,” “the Company” and similar references in this Quarterly Report on Form 10-Q refer to Spero Therapeutics, Inc. and its consolidated subsidiaries. Spero Therapeutics and its associated logos are registered trademarks of Spero Therapeutics, Inc. Other brands, names and trademarks contained in this Quarterly Report on Form 10-Q are the property of their respective owners.\n\nCautionary Note regarding Forward-Looking STATEMENTS\n\nThis Quarterly Report on Form 10-Q contains forward-looking statements that involve risks and uncertainties. We make such forward-looking statements pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. All statements other than statements of historical facts contained in this Quarterly Report on Form 10-Q are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may,” “will,” “should,” “expects,” “intends,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “potential,” “continue” or the negative of these terms or other comparable terminology. These forward-looking statements include, but are not limited to, statements about:\n\n•\nour estimates regarding expenses, future revenue and capital requirements and our expectations regarding our ability to fund our operating expenses and capital expenditure requirements with our cash and cash equivalents;\n\n•\nthe initiation, timing, design, progress and results of any preclinical studies and clinical trials, and our research and development programs;\n\n•\nthe regulatory path forward for tebipenem HBr and the potential approval of tebipenem HBr by the U.S. Food and Drug Administration (“FDA”);\n\n•\nthe potential receipt of milestone payments and royalties on future sales under our License Agreement, as amended (the “GSK License Agreement”), with GlaxoSmithKline Intellectual Property (No. 3) Limited (“GSK”);\n\n•\nthe implementation of our business model and strategic plans for our business and current and future product candidates;\n\n•\nour ability to retain the continued service of our key professionals and to identify, hire and retain additional qualified professionals;\n\n•\nthe timing of regulatory filings and likelihood of approvals for our product candidate;\n\n•\nthe future development, commercialization, marketing and manufacturing of our current and future product candidates, if approved;\n\n•\nthe pricing, coverage and reimbursement of our product candidate, if approved;\n\n•\nthe scope of protection we are able to obtain and maintain for intellectual property rights covering our current and future product candidates;\n\n•\nour ability to enter into strategic arrangements and/or collaborations and the potential benefits of such arrangements;\n\n•\ndevelopments relating to our competitors and our industry;\n\n•\nthe impact of government laws and regulations;\n\n•\nthe impact of general economic conditions, including inflation; and\n\n•\nother risks and uncertainties, including those listed under Part II, Item 1A. “Risk Factors”.\n\nAny forward-looking statements in this Quarterly Report on Form 10-Q reflect our current views with respect to future events or to our future financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by these forward-looking statements. Factors that may cause actual results to differ materially from current expectations include, among other things, those listed under Part II, Item 1A. “Risk Factors” and elsewhere in this Quarterly Report on Form 10-Q. Given these uncertainties, you should not place undue reliance on these forward-looking statements. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future.\n\ni\n\n \n\nThis Quarterly Report on Form 10-Q also contains estimates, projections and other information concerning our industry, our business, and the markets for certain diseases, including data regarding the estimated size of those markets, and the incidence and prevalence of certain medical conditions. Information that is based on estimates, forecasts, projections, market research or similar methodologies is inherently subject to uncertainties and actual events or circumstances may differ materially from events and circumstances reflected in this information. Unless otherwise expressly stated, we obtained this industry, business, market and other data from reports, research surveys, studies and similar data prepared by market research firms and other third parties, industry, medical and general publications, government data and similar sources. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we may make or enter into.\n\nRisk Factor Summary\n\nWe are providing the following summary of the risk factors contained in this Quarterly Report on Form 10-Q to enhance the readability and accessibility of our risk factor disclosures. We encourage you to carefully review the full risk factors contained in this Quarterly Report on Form 10-Q in their entirety for additional information regarding the material factors that make an investment in our securities speculative or risky. These risks and uncertainties include, but are not limited to, the following:\n\n•\nAs of March 2025, we have ceased development of our SPR206 program, and as of November 2025, we have ceased development of our SPR720 oral program, and have shifted our focus and resources to advancing the development of the tebipenem HBr program, as well as other corporate activities. Consequently, our business and prospects are substantially dependent on our tebipenem program and our collaboration with GSK. If we fail to execute successfully on this re-prioritized strategic focus, or our collaboration with GSK fails to advance the development of the tebipenem HBr program, our business and prospects may be materially adversely affected.\n\n•\nOur ability to realize the value of tebipenem HBr depends on obtaining FDA approval. Even if such approval is obtained, the timeline of, and any requirements imposed as part of, such approval may impact the attractiveness of commercialization of tebipenem HBr through our partnership with GSK.\n\n•\nAnalyses of preliminary or interim data from our clinical studies that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.\n\n•\nSerious adverse events or undesirable side effects or other unexpected properties of any product candidates may be identified during development or after approval that could delay, prevent or cause the withdrawal of regulatory approval, limit the commercial potential, or result in significant negative consequences following marketing approval.\n\n•\nEven if a product candidate does obtain regulatory approval, it may never achieve the market acceptance by physicians, patients, hospitals, third-party payors and others in the medical community that is necessary for commercial success and the market opportunity may be smaller than we estimate.\n\n•\nIf we or our collaborators are unable to establish sales, marketing and distribution capabilities or enter into sales, marketing and distribution agreements with third parties, we may not be successful in commercializing any product candidates if such product candidates are approved.\n\n•\nWe face substantial competition from other pharmaceutical and biotechnology companies and our operating results may suffer if we fail to compete effectively.\n\n•\nWe have not generated any revenue from the sale of our products, have a history of losses and expect to incur future losses. If we are unable to obtain additional capital, we may not be able to continue our operations on the scope or scale as currently conducted, and that could have a material adverse effect on our business, results of operations and financial condition.\n\n•\nIf we are unable to raise capital when needed, or do not receive payments from our collaboration partnership agreements, it could limit our ability to support our operations.\n\n•\nWe may not achieve the milestones triggering payments to us in our existing, or any future, license and collaboration agreements with third parties.\n\n•\nWe contracted with third parties for the manufacture of clinical supplies of tebipenem HBr and expect to continue to do so in connection with any future clinical trials and commercialization of any potential product candidates. This reliance on third parties increases the risk that we will not have sufficient quantities of our existing and future product candidates or such quantities at an acceptable cost, which could delay, prevent or impair our development or commercialization efforts.\n\nii\n\n \n\n•\nIf we fail to comply with our obligations in the agreements under which we in-license or acquire development or commercialization rights to products, technology or data from or to third parties, we could lose such rights that are important to our business.\n\n•\nIf we are unable to obtain and maintain sufficient patent protection for our technology or our existing or future product candidates, or if the scope of the patent protection is not sufficiently broad, our competitors could develop and commercialize technology and products similar or identical to ours, and our ability to successfully commercialize our technology and product candidates may be adversely affected.\n\n•\nWe have registered trademarks and pending trademark applications. Failure to enforce our registered marks or secure registration of our pending trademark applications could adversely affect our business.\n\n•\nIf we or our collaboration partners are not able to obtain, or if there are delays in obtaining, required regulatory approvals, we will not be able to commercialize our existing and future product candidates, and our ability to generate revenue will be materially impaired.\n\n•\nThe price of our common stock has been and, in the future, may continue to be volatile whether related or unrelated to our operations, which could result in a decline in value for our stockholders.\n\niii\n\n \n\nSpero Therapeutics, Inc.\n\nTable of Contents\n\n \n\n \n\n \n\nPage\n\n \n\n \n\nPART I – FINANCIAL INFORMATION"}