Spero Therapeutics, Inc.
For the period ended Dec 31, 2025. Filed Mar 26, 2026.
View on SEC.govAbout this filing
A company's yearly report to the SEC, with audited financial statements. It is the fullest account a company gives of its business, its finances and the risks it sees.
FY2025 · Filed Mar 26, 2026
SPRO$1.03+1.0%Stored close · as of Nov 6, 2026
What changed in Risk Factors?
Read the current filingPrevious report: 10-K
Period ended 2024-12-31; filed 2025-03-27.
0000950170-25-046125
Item 1A. Risk FactorsCurrent report: 10-K
Period ended 2025-12-31; filed 2026-03-26.
0001193125-26-126192
Item 1A. Risk FactorsThe baseline is this issuer’s latest earlier reporting period of the same form that was filed before the current report. A previous 10-Q is a different quarter, not a year-over-year comparison. Amendments are excluded.
Compared 389 previous paragraphs and 374 current paragraphs.
182 unchanged; 144 reworded; 44 added; 60 removed; 3 previous and 4 current paragraphs rearranged.
Tables are not compared: 0 previous and 0 current tables excluded. Dates, whitespace, punctuation and numbering changes are ignored; changes to financial figures remain significant.
A changed paragraph is not evidence that risk increased or decreased. An unchanged paragraph does not establish that risk stayed the same.
Added paragraphs (44)
Current report
the number of patients required for clinical trials of any product candidates may be larger than we anticipate, enrollment in these clinical trials may be slower than we anticipate, participants may drop out of these clinical trials at a higher rate than we anticipate or we may fail to recruit suitable patients to participate in clinical trials;
Current report
our third-party contractors, including those manufacturing any product candidates or conducting clinical trials on our behalf, may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all;
Current report
the supply or quality of any product candidates or other materials necessary to conduct clinical trials of any product candidates may be insufficient or inadequate; and
Current report
In June 2024, as mandated by the FDCA, the FDA issued draft guidance outlining the general requirements for DAPs. Unlike most guidance documents issued by the FDA, the DAP guidance when finalized will have the force of law because Food and Drug Omnibus Reform Act of 2022 (“FDORA”) specifically dictates that the form and manner for submission of DAPs are specified in FDA guidance. On January 27, 2025, in response to an executive order issued by President Trump on January 21, 2025 on Diversity, Equity and Inclusion programs, the FDA removed the draft DAP guidance from its website. That action, along with similar actions by the Trump Administration to remove many other healthcare webpages, is currently the subject of ongoing litigation. On July 3, 2025, the U.S. District Court for the District of Columbia ruled that the administration’s actions to remove these webpages, including the draft DAP guidance, is unlawful under the Administrative Procedure Act. The court ordered the restoration of many of these webpages. In late July 2025, the FDA restored the draft DAP guidance to its website with a statement that “information on this page may be modified and/or removed in the future subject to the terms of the court’s order and implemented consistent with applicable law.” Accordingly, in light of these ongoing actions, there is considerable uncertainty surrounding the draft DAP guidance and how the FDA will consider DAPs in connection with its review of marketing applications.
Current report
Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. Our spending on current and future research and development programs and product candidates for specific indications may not yield any commercially viable product candidates. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to the product candidate.
Current report
We may evaluate various acquisitions and strategic collaborations, including licensing or acquiring complementary products, intellectual property rights, technologies or businesses. Any potential acquisition or strategic collaboration may entail numerous risks, including:
Current report
increased operating expenses and cash requirements;
Current report
the diversion of our management’s attention from any existing product candidates and initiatives in pursuing such acquisition or strategic collaboration;
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our inability to generate revenue from acquired technology and/or products sufficient to meet our objectives in undertaking the acquisition or collaboration or even to offset transaction costs.
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In addition, if we undertake acquisitions, we may issue dilutive securities, assume or incur debt obligations, incur large one-time expenses and acquire intangible assets that could result in significant future amortization expense. Moreover, we may not be able to locate suitable acquisition or collaboration opportunities and this inability could impair our ability to grow or obtain access to technology or products that may be important to the development of our business.
Current report
competitors may develop alternatives that render our existing or future product candidates obsolete;
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Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to any of our technologies or product candidates.
Current report
product candidates discovered in collaboration with us may be viewed by our collaborators as competitive with their own product candidates or products, which may cause collaborators to cease to devote resources to the commercialization of any of our product candidates;
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If we are unable to reach agreements with suitable collaborators on a timely basis, on acceptable terms, or at all, we may have to curtail the development of a product candidate, reduce or delay its development program or one or more of our other development programs, delay its potential commercialization or reduce the scope of any sales or marketing activities, or increase our expenditures and undertake development or commercialization activities at our own expense. If we elect to fund and undertake development or commercialization activities on our own, we may need to obtain additional expertise and additional capital, which may not be available to us on acceptable terms or at all. If we fail to enter into collaborations and do not have sufficient funds or expertise to undertake the necessary development and commercialization activities, we may not be able to further develop our existing and future product candidates or bring them to market and our business may be materially and adversely affected.
Current report
serious and unexpected drug-related side effects experienced by participants in our clinical trials or by individuals using drugs similar to any of our product candidates;
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our inability to demonstrate the clinical and other benefits of any of our product candidates outweigh any safety or other perceived risks;
Current report
On June 17, 2025, the FDA announced the creation of a new voucher program to expedite the development and approval of new drug products. Vouchers issued under the new program, which is known as the Commissioner’s National Priority Voucher (“CNPV”) Program, may reportedly be redeemed by sponsors to shorten the review time of an NDA from approximately 10 to 12 months to one to two months. The FDA has indicated that the new CNPV process will convene experts from the FDA’s offices for a team-based review rather than using the standard review system of a drug application being sent to numerous FDA offices. Clinical information will be reviewed by a multidisciplinary team of physicians and scientists who will pre-review the submitted information and convene for a one-day meeting. Vouchers under this program will reportedly be given to companies aligned with U.S. national priorities. As with the FDA’s other programs for expediting review and approval of new drug products, even if we were to avail ourselves of this new program, there is no guarantee it would result in approval of our marketing applications or that such approval, if granted, would be on an expedited basis.
Current report
The FDA and the U.S. Congress may further reevaluate and revise the Orphan Drug Act and its regulations and policies. For example, in September 2021, the Court of Appeals for the Eleventh Circuit held that, for the purpose of determining the scope of orphan drug exclusivity, the term “same disease or condition” means the designated “rare disease or condition” and not the “indication or use” for which the product is approved. Subsequently, in another case, a federal district court in Washington, D.C. followed the reasoning of the Eleventh Circuit decision and that decision was appealed to the U.S. Court of Appeals for the D.C. Circuit. On February 3, 2026, the Consolidated Appropriations Act of 2026 was enacted into law. It overruled these court decisions and codified the FDA’s longstanding interpretation of the scope of orphan drug exclusivity to apply to “the same drug for the same approved use or indication within such [designated] rare disease or condition.” This change, which applies retroactively, expressly authorizes the FDA to approve multiple versions of the same orphan drug for different sub-indications and subpopulations, such as adult and pediatric patients or multiple variations of the same disease that are caused by different genetic variants.
Current report
In addition, the EU pharmaceutical legislation is currently undergoing a complete review process, in the context of the Pharmaceutical Strategy for Europe initiative, launched by the European Commission in November 2020. The European Commission’s proposal for revision of several legislative instruments related to medicinal products, which may reduce the duration of regulatory data protection and exclusivity periods for orphan drugs, and revise the eligibility for expedited pathways in addition to other changes, was published on April 26, 2023. On June 4, 2025, after almost two years of negotiations among the EU Member States, the Council of the EU adopted its position on the proposed overhaul of the EU general pharmaceutical legislative framework, which is known as the new Pharma Package. On December 11, 2025, the European Parliament and European Council reached a provisional political agreement on the legislation. The revisions may have a significant impact on the pharmaceutical industry and our business. The new Pharma Package would, among other things, set a baseline period of eight years of data exclusivity and one year of market exclusivity with possible extensions for new indications up to a maximum of 11 years total. The new framework is expected to be adopted by mid-2026 and there will likely be a transition period of 24 months, with the changes taking effect in mid-2028.
Current report
Additionally, we could face heightened risks with respect to obtaining marketing authorization in the United Kingdom as a result of the withdrawal of the United Kingdom from the EU, commonly referred to as Brexit. The United Kingdom is no longer part of the European Single Market and EU Customs Union. As of January 1, 2025, the Medicines and Healthcare Products Regulatory Agency (“MHRA”) is responsible for approving all medicinal products destined for the U.K. market (i.e., Great Britain and Northern Ireland). On April 28, 2025, the U.K. Parliament adopted amendments to improve and strengthen the United Kingdom’s clinical trials regulatory regime; they will take effect on April 28, 2026. These changes were needed since the current U.K. requirements are based upon the now-repealed EU Clinical Trials Directive (2001/20/EC), which has been replaced by the European Clinical Trials Regulation (Regulation EU No 536/2014). In anticipation of these new requirements, on October 1, 2025, the MHRA updated its guidance for clinical trials to address, among other things, research transparency requirements for clinical trials, the approvals process, the Research Ethics Committee review of clinical trials, simplified arrangements for consent in clinical trials and pharmacovigilance.
Current report
Since the United Kingdom left the EU prior to the date on which the EU CTR took effect, the U.K. legal framework did not benefit from the same revisions as occurred at EU level.
Current report
At the same time, a new international recognition procedure (“IRP”) will apply, which is intended to facilitate approval of pharmaceutical products in the United Kingdom. The IRP is open to applicants that have already received an authorization for the same product from one of the MHRA’s specified Reference Regulators (“RRs”). The RRs notably include the EMA and regulators in the EU/European Economic Area (“EEA”) member states for approvals in the EU centralized procedure and mutual recognition procedure as well as the FDA (for product approvals granted in the United States). However, the concrete functioning of the IRP is currently unclear. Any delay in obtaining, or an inability to obtain, any marketing approvals may force us or any of our future collaborators to restrict or delay efforts to seek regulatory approval in the United Kingdom for any product candidates, which could significantly and materially harm our business.
Current report
For example, on September 9, 2025, the President issued a Memorandum directing HHS to “ensure transparency and accuracy in direct-to-consumer (“DTC”) prescription drug advertising, including by increasing the amount of information regarding any risks associated with the use of any such prescription drug required to be provided in prescription drug advertisements.” To that end, the FDA announced that it is initiating a rulemaking process “to eliminate the ‘adequate provision’ loophole that allows pharmaceutical advertisements to hide safety information by placing it in another format or location.” In this context, the FDA declared that it will no longer tolerate what it characterized as “deceptive practices” in prescription drug advertising and that the agency would “aggressively deploy” its available enforcement tools, with “heightened scrutiny” of fair balance and disclosures in social media promotions. The FDA also issued a generic “notice letter” directing companies to “remove any noncompliant advertising and bring all promotional communications into compliance.”
Current report
On June 6, 2023, Merck & Co. filed a lawsuit against HHS and CMS asserting that, among other things, the IRA’s Drug Price Negotiation Program for Medicare constitutes an uncompensated taking in violation of the Fifth Amendment of the Constitution. Subsequently, a number of other parties also filed lawsuits in various courts with similar constitutional claims. HHS has generally won the substantive disputes in these cases or succeeded in getting claims dismissed for lack of standing or on the merits. For example, on May 8, 2025, the U.S. Court of Appeals for the Third Circuit rejected AstraZeneca L.P.’s challenge to the Medicare price negotiation program, finding that the program did not violate the company’s due process rights under the Constitution. Litigation involving these and other provisions of the IRA will continue with unpredictable and uncertain results.
Current report
Further, on May 12, 2025, President Trump issued an additional executive order calling on pharmaceutical manufacturers to voluntarily reduce the prices of medicines in the United States. The Order directs the Secretary of HHS to communicate most-favored-nation (“MFN”) price targets to pharmaceutical manufacturers to bring prices in line with comparably developed nations. The executive order further provides that if such actions do not lower the costs of pharmaceuticals, the Secretary of HHS would pursue other actions, including proposing a rulemaking that imposes MFN pricing in the United States. Subsequently, on May 20, 2025, HHS indicated that the proposed MFN pricing will apply only to brand products without generic or biosimilar competition and the reference foreign countries will include only those in which the branded product similarly does not have generic or biosimilar competition. Second, HHS indicated that the MFN target price will be the lowest price in a country that is a member of the Organisation for Economic Co-operation and Development (“OECD”) with a gross domestic product (“GDP”), per capita of at least 60% of the U.S. GDP per capita. Based on previous estimates, there are likely at least 22 OECD countries that would satisfy this criterion. The implications of these actions remain unclear and are likely to result in litigation if the administration pursues an MFN regulatory pricing requirement.
Current report
Thereafter, on July 31, 2025, President Trump issued letters to 17 pharmaceutical companies reiterating the requirements of the May 12, 2025, Executive Order and demanding that such companies extend MFN pricing to Medicaid patients, guarantee MFN pricing for newly-launched drug products, return increased revenues abroad to American patients and provide for direct purchasing at MFN pricing. Since that time, virtually all of these pharmaceutical companies have entered into agreements with the administration to provide for lower prices on certain pharmaceuticals. On February 5, 2026, President Trump launched TrumpRx.gov, a website that directs individuals to pharmaceutical manufacturer websites that are offering price discounts based on the administration’s pricing agreements with pharmaceutical manufacturers.
Current report
At the state level, individual states are increasingly aggressive in passing legislation and implementing regulations designed to control pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. This is increasingly true with respect to products approved pursuant to the accelerated approval pathway. State Medicaid programs and other payers are developing strategies and implementing significant coverage barriers, or refusing to cover these products outright, arguing that accelerated approval drugs have insufficient or limited evidence despite meeting the FDA’s standards for accelerated approval.
Current report
Disruptions at the FDA and other government agencies from funding cuts, personnel losses, regulatory reform, government shutdowns and other developments could hinder our ability to obtain guidance from the FDA regarding our clinical development program and develop and secure approval of any of our product candidates in a timely manner, which would negatively impact our business.
Current report
The FDA and comparable regulatory agencies in foreign jurisdictions, such as the EMA and Committee for Medicinal Products for Human Use, play an important role in the development of any of our product candidates by providing guidance on our clinical development programs and reviewing our regulatory submissions, including INDs, requests for special designations and marketing applications. If these oversight and review activities are disrupted, then correspondingly our ability to develop and secure timely approval of any of our product candidates could be impacted in a negative manner.
Current report
For example, the loss of FDA leadership and personnel could lead to disruptions and delays in FDA guidance, review and approval of any of our product candidates. Pursuant to President Trump’s Executive Order 14210, “Implementing the President’s ‘Department of Government Efficiency’ Workforce Optimization Initiative,” the Secretary of HHS announced on March 27, 2025, a reorganization and Reduction in Force (“RIF”) across the Department of approximately 20,000 employees (82,000 to 62,000), with FDA’s workforce of approximately 20,000 to decrease by 3,500 full-time employees. Subsequently, the FDA indicated that roughly a quarter of those employees who received RIF notices had been reinstated. On July 14, 2025, following litigation reaching the U.S. Supreme Court, the administration began to carry out these layoffs across HHS, including the FDA. In November 2025, a Congressional Continuing Resolution ended the government shutdown, providing full-year funding for the FDA for Fiscal Year 2026 through September 30, 2026 at approximately $7 billion with a slight increase in user fees for drug and device companies.
Current report
While the FDA’s review of marketing applications and other activities for new drugs and biologics is largely funded through the user fee program established under the Prescription Drug User Fee Act (“PDUFA”), it remains unclear how the administration’s RIF and budget cuts will impact this program and the ability of the FDA to provide guidance and review any of our product candidates in a timely manner. For example, while the FDA RIF did not reportedly specifically target FDA reviewers, many operations, administrative and policy staff that help support such reviews were affected and those losses could lead to delays in PDUFA reviews and related activities. There has been at least one report in which the FDA failed to meet a PDUFA goal date for approval of an NDA due to heavy workload and limited resources. In addition, while currently unclear, there is a risk that the RIF and budget cutbacks could threaten the integrity of the PDUFA program itself. That is because, for the FDA to obligate user fees collected under PDUFA in the first place, a certain amount of non-user fee appropriations must be spent on the process for the review of applications plus certain other costs during the same fiscal year.
Current report
There is also substantial uncertainty as to how regulatory reform measures being implemented by the Trump Administration across the government will impact the FDA and other federal agencies with jurisdiction over our activities. For example, since taking office, the President has issued a number of executive orders that could have a significant impact on the manner in which the FDA conducts its operations and engages in regulatory and oversight activities. These include Executive Order 14192, “Unleashing Prosperity Through Deregulation,” January 31, 2025; Executive Order 14212, “Establishing the President’s Make America Healthy Again Commission,” February 13, 2025; and Executive Order 14219, “Ensuring Lawful Governance and Implementing the President’s ‘Department of Government Efficiency’ Deregulatory Initiative,” February 21, 2025. If these or other orders or executive actions impose constraints on the FDA’s ability to engage in oversight and implementation activities in the normal course, our business may be negatively impacted.
Current report
In addition, government funding of the government agencies on which our operations may rely, including those that fund research and development activities, is subject to the political process, which is inherently fluid and unpredictable. For example, the federal government shut down on October 1, 2025, and did not reopen for 43 days. With the shutdown, the FDA issued a public notice stating that agency operations would continue to the extent permitted by law, such as activities necessary to address imminent threats to the safety of human life and activities funded by carryover user fee funds. The FDA declared that, during the shutdown period, it did not have legal authority to accept user fees assessed for Fiscal Year 2026 until a Fiscal Year 2026 appropriation or Continuing Resolution for the FDA was enacted. As a result, the FDA was not able to accept any regulatory submissions for Fiscal Year 2026 that required a fee payment and that was submitted during the lapse period. In addition, the FDA indicated that some of its regulatory science research, crucial for advancing product innovation, safety, and quality, would be curtailed during the lapse period.
Current report
If any of the foregoing developments and others impact the ability of the FDA to provide us with guidance regarding our clinical development programs or delay the agency’s review and processing of our regulatory submissions, including INDs and NDAs/BLAs, our business would be negatively impacted. Further, any future government shutdown could impact our ability to access the public markets and obtain necessary capital in order to properly capitalize and continue our operations.
Current report
In the spring of 2025, the U.S. government initiated a series of tariff-related actions against U.S. trading partners. On April 2, 2025, an executive order announced a “baseline” reciprocal tariff of 10% on all U.S. trading partners effective April 5, 2025, and higher individualized reciprocal tariffs on 57 countries (with certain product exemptions for pharmaceutical-related products, among others). Previously, the U.S. government had imposed a 25% tariff on Canada and Mexico for goods not covered by the United States-Mexico-Canada Agreement (“USMCA”) and tariffs due to drug trafficking equaling 20% on imports from China. In response, several countries threatened retaliatory measures, including Canada and China, which then imposed retaliatory tariffs. Prior to when the country-specific reciprocal tariffs were scheduled to take effect, the U.S. delayed the effective date of such tariffs for all countries except China to August 1, 2025. Later, the United States and China reached a framework agreement that ultimately resulted in the suspension of the higher reciprocal tariffs on China until November 10, 2025. Shortly before that expiration date, the United States and China reached a one-year agreement with an expiration of November 10, 2026, that includes the continued suspension of the heightened reciprocal tariffs on China and delayed enforcement of new U.S. export rules targeting affiliates of blacklisted firms.
Current report
Since the April reciprocal tariffs announcement, the European Union, Japan, South Korea, Switzerland and the United Kingdom, among others, have reached deals with the U.S. that include reduced tariff rates to varying levels and other measures. On July 31, 2025, the U.S. administration issued an executive order detailing new reciprocal tariff rates for individual countries that took effect on August 7, 2025. The deals with the European Union, Japan, South Korea, Switzerland (and Liechtenstein), the United Kingdom and others cap pharmaceutical tariffs at 15%. In addition, an agreement with Malaysia provides a zero percent tariff exemption for pharmaceutical products that are not patented in the U.S. and are used in pharmaceutical applications and an agreement with Switzerland and Lichenstein caps tariffs on pharmaceuticals imported from those two countries at 15%. Finally, an agreement with Taiwan concluded on January 15, 2026 eliminates tariffs on generic pharmaceuticals and their active ingredients imported from Taiwan.
Current report
The reciprocal tariffs and the fentanyl tariffs were imposed pursuant to the International Emergency Economic Powers Act (the “IEEPA”). These tariffs were found to be unconstitutional by multiple federal courts in the spring and summer of 2025. On February 20, 2026, the Supreme Court held that IEEPA does not authorize the President to impose tariffs, invalidating both the reciprocal tariffs and the drug trafficking tariffs. Shortly thereafter, the President issued a new Executive Order revoking the IEEPA tariffs and Customs and Border Protection ceased collecting the tariffs as of 12:01 am on February 24, 2026. At the same time, however, the Trump
Current report
Administration imposed a new 10% global tariff under Section 122 of the Trade Act of 1974, effective February 24, 2026. Pursuant to the statute, absent an extension by Congress, these tariffs will expire in 150 days on July 24, 2026. For those countries that have concluded trade deals with the United States, the tariff rates agreed to – including with regard to pharmaceuticals and pharmaceutical ingredients – have now reverted to 10% until July 24, 2026.
Current report
Like the IEEPA tariffs, pharmaceuticals and pharmaceutical ingredients are exempt from the Section 122 tariffs along with a list of other products. The Administration has announced that it also plans to initiate new investigations on “most major trading partners” under Section 301 of the same act, which will likely lead to additional tariffs.
Current report
Neither the Supreme Court’s decision nor the Executive Order revoking the IEEPA tariffs addressed refunds, leaving the issue to renewed proceedings before the U.S. Court of International Trade, where importers may need to pursue administrative remedies and/or litigation amid continued uncertainty.
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Removed paragraphs (60)
Previous report
While we currently have an effective shelf registration statement, as of the filing of this Annual Report on Form 10-K, our public float is less than $75 million, and under SEC regulations for so long as our public float remains less than $75 million, the amount we can raise through primary public offerings of securities in any twelve-month period using shelf registration statements is limited to an aggregate of one-third of our public float, which is referred to as the baby shelf rules. As of March 21, 2025, our public float was approximately $45.1 million, based on 54,969,832 shares of outstanding common stock held by non-affiliates and at a price of $0.82 per share, which was the closing price of our common stock on the Nasdaq Global Select Market (“Nasdaq GS”) on March 21, 2025. As a result of our public float being below $75 million, we will be limited by the baby shelf rules until such time our public float exceeds $75 million, which means we only have the capacity to sell shares up to one-third of our public float in primary offerings under our shelf registration statement on Form S-3 in any twelve-month period. Although alternative public and private transaction structures may be available, these may require additional time and cost, may impose operational restrictions on us, and may not be available on attractive terms.
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Risks Related to Our U.S. Government Contracts and to Certain Grant Agreements
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Our use of government funding for certain of our programs adds complexity to our research and commercialization efforts with respect to those programs and may impose requirements that increase the costs of commercialization and production of product candidates developed under those government-funded programs.
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We have received significant non-dilutive financing from various government agencies for the further development of our product candidates. Such funding sources may pose risks to us not encountered in other commercial contracts, including significant regulatory compliance risks. Contracts funded by the United States government and its agencies include provisions that reflect the government’s substantial public policy and compliance requirements, and substantial rights and remedies, many of which are not typically found in commercial contracts, including powers of the government to:
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terminate agreements, in whole or in part, for any reason or no reason;
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reduce or modify the government’s obligations under such agreements without the consent of the contractor;
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claim rights, including intellectual property rights, in products and data developed under such agreements;
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suspend the contractor from receiving new contracts pending resolution of alleged violations of procurement laws or regulations;
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suspend or debar the contractor or grantee from doing future business with the government;
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control and potentially prohibit the export of products; and
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pursue criminal or civil remedies under the False Claims Act (the “FCA”), the False Statements Act and similar remedy provisions specific to government agreements.
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We may not have the right to prohibit the U.S. government from using certain technologies developed by us, and we may not be able to prohibit third-party companies, including our competitors, from using those technologies in providing products and services to the U.S. government. The U.S. government generally takes the position that it has the right to royalty-free use of technologies that are developed under U.S. government contracts.
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In addition, government contracts and grants, and subcontracts and subawards awarded in the performance of those contracts and grants, normally contain additional requirements that may increase our costs of doing business, reduce our profits, and expose us to liability for failure to comply with these terms and conditions. These requirements include, for example:
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specialized accounting systems unique to government awards;
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public disclosures of certain award information, which may enable competitors to gain insights into our research program; and
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mandatory socioeconomic compliance requirements, including labor standards, anti-human-trafficking, non-discrimination and affirmative action programs, energy efficiency and environmental compliance requirements.
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If we fail to maintain compliance with these requirements, we may be subject to potential contract or FCA liability and to termination of our contracts.
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U.S. government agencies have special contracting requirements that give them the ability to unilaterally control our contracts.
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U.S. government contracts typically contain unfavorable termination provisions and are subject to audit and modification by the government at its sole discretion, which will subject us to additional risks. These risks include the ability of the U.S. government to unilaterally:
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audit and object to our government contract-related costs and fees, and require us to reimburse all such costs and fees;
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suspend or prevent us for a set period of time from receiving new contracts or extending our existing contracts based on violations or suspected violations of laws or regulations;
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cancel, terminate or suspend our contracts based on violations or suspected violations of laws or regulations;
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terminate our contracts if in the government’s interest, including if funds become unavailable to the applicable governmental agency;
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change certain terms and conditions in our contract.
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The U.S. government will be able to terminate any of its contracts with us, either for convenience or if we default by failing to perform in accordance with or to achieve the milestones set forth in the contract schedules and terms. Termination-for-convenience provisions generally enable us to recover only our costs incurred or committed and settlement expenses on the work completed prior to termination. Except for the amount of services received by the government, termination-for-default provisions do not permit these recoveries and would make us liable for excess costs incurred by the United States government in procuring undelivered items from another source.
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Our business is subject to audit by the U.S. government and other potential sources for grant funding, including under our contracts with BARDA and NIAID and a negative outcome in an audit could adversely affect our business.
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United States government agencies such as the DHHS and the Defense Contract Audit Agency (the “DCAA”) routinely audit and investigate government contractors. These agencies review a contractor’s performance under its contracts, cost structure and compliance with applicable laws, regulations and standards.
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The DHHS and the DCAA also review the adequacy of, and a contractor’s compliance with, its internal control systems and policies, including the contractor’s purchasing, property, estimating, compensation and management information systems. Any costs found to be improperly allocated to a specific contract will not be paid, while such costs already paid must be refunded. If an audit uncovers improper or illegal activities, we may be subject to civil and criminal penalties and administrative sanctions, including:
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suspension or prohibition from conducting business with the United States government.
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In addition, we could suffer serious reputational harm if allegations of impropriety were made against us, which could cause our stock price to decrease.
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Laws and regulations affecting government contracts make it more expensive and difficult for us to successfully conduct our business.
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We must comply with numerous laws and regulations relating to the formation, administration and performance of government contracts, which can make it more difficult for us to retain our rights under our government contracts. These laws and regulations affect how we conduct business with government agencies. Among the most significant government contracting regulations that affect our business are:
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the Federal Acquisition Regulations (the “FAR”) and agency-specific regulations supplemental to the FAR, which comprehensively regulate the procurement, formation, administration and performance of government contracts;
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business ethics and public integrity obligations, which govern conflicts of interest and the hiring of former government employees, restrict the granting of gratuities and funding of lobbying activities and include other requirements such as the Anti-Kickback Statute and the Foreign Corrupt Practices Act;
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export and import control laws and regulations; and
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Previous wording
Careful consideration should be given to the following risk factors, in addition to the other information set forth in this Annual Report on Form 10-K, including the section of this Annual Report on Form 10-K titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our consolidated financial statements and related notes, and in other documents that we file with the SEC, in evaluating our company and our business. If any of the events described in the following risk factors and the risks described elsewhere in this Annual Report on Form 10-K actually occur, our business, financial condition, results of operations and future growth prospects could be materially and adversely affected, and the trading price of our securities could decline. Our actual results could differ materially from those anticipated in the forward-looking statements as a result of factors that are described below and elsewhere in this Annual Report on Form 10-K. The risks and uncertainties described below are not the only ones we face. Additional risks not presently known to us or other factors not perceived by us to present significant risks to our business at this time also may impair our business operations.
Current wording
Careful consideration should be given to the following risk factors, in addition to the other information set forth in this Annual Report on Form 10-K, including the section of this Annual Report on Form 10-K titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our consolidated financial statements and related notes, and in other documents that we file with the SEC, in evaluating our company and our business. If any of the events described in the following risk factors and the risks described elsewhere in this Annual Report on Form 10-K actually occur, our business, financial condition, results of operations and future growth prospects could be materially and adversely affected, and the trading price of our securities could decline. Our actual results could differ materially from those contained in the forward-looking statements we have made in this Annual Report on Form 10-K and those we may make from time to time. The risks and uncertainties described below are not the only ones we face. Additional risks not presently known to us or other factors not perceived by us to present significant risks to our business at this time also may impair our business operations.
Previous wording
Pursuant to our previously announced restructuring, we suspended development of our SPR720 oral program and have shifted our focus and resources to advancing the clinical development of our tebipenem HBr program, as well as other corporate activities. We have also discontinued development of SPR206. 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, our business and prospects may be materially adversely affected
Current wording
As 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.
Previous wording
On October 29, 2024, we announced that we suspended development activities for our SPR720 oral program based on an interim analysis of the Phase 2a proof-of-concept study of SPR720 for the treatment of NTM-PD not meeting its primary endpoint. While the data showed antimicrobial activity associated with SPR720, the interim analysis did not show sufficient separation from placebo and highlighted potential dose limiting safety issues in subjects dosed at 1,000 mg orally once daily, including three cases of reversible grade 3 hepatotoxicity. In evaluating the totality of both the efficacy and safety data, we have elected to suspend our current development program for SPR720 and continue to evaluate other potential paths forward as the remaining data are collected and analyzed. As a result, we have restructured our operations to focus on supporting the development of tebipenem HBr and other corporate activities while we continue to seek a pathway forward for SPR720. Further, in March 2025, we announced that we have discontinued development of SPR206. We believe this re-prioritized strategic focus is the best way to optimize our financial and other resources to advance our goal of developing and commercializing product candidates to address the unmet need for solutions to antibiotic resistant pathogens. However, there is no assurance that we will successfully execute this strategy. As described below, there are risks inherent in the clinical development process, especially for earlier-stage programs, and the regulatory path for SPR720 remains uncertain at this time. If we are unable to execute successfully on this re-prioritized strategic focus, our business and prospects may be materially adversely affected.
Current wording
As of March 2025, we have ceased development of SPR206. Additionally, as of November 2025, we have ceased development of our SPR720 oral program and have shifted our focus and resources to advancing the clinical development of our tebipenem HBr program, as well as other corporate activities. We believe this re-prioritized strategic focus is the best way to optimize our financial and other resources to advance our goal of identifying and developing novel treatments for rare diseases and diseases with high unmet need. However, there is no assurance that we will successfully execute this strategy. As described below, there are risks inherent in the clinical development process, especially for earlier-stage programs. If we are unable to execute successfully on this re-prioritized strategic focus, our business and prospects may be materially adversely affected.
Previous wording
As a result, we are currently substantially dependent on our tebipenem program and our collaboration with GSK. As described under “Business—Collaboration, License and Service Agreements—Tebipenem HBr Agreements”, GSK has the right to terminate the GSK License Agreement (1) at any time upon a specified number of days’ notice, (2) upon a material breach by us or (3) upon a bankruptcy of Spero. Alternatively, in the case of a material breach by Spero, GSK may, in lieu of terminating the GSK License Agreement, elect to reduce any commercial milestone payments to Spero by 50%. In addition, in such circumstance, GSK may assume the responsibility and expense of development of tebipenem HBr in the United States, in which case no development milestone payments would be payable to Spero (including unpaid installments of any earned milestone payments). In the case of a Change of Control of Spero, GSK similarly may, in lieu of terminating the GSK License Agreement, assume responsibility and expense of development of tebipenem HBr in the United States and no development milestones would be payable to Spero, as described above. Any termination of the GSK License Agreement or any failure to earn, or reduction in, milestone payments may materially adversely affect our business and prospects.
Current wording
As a result, we are currently substantially dependent on our tebipenem program and our collaboration with GSK. As described under Note 13 to our consolidated financial statements, GSK has the right to terminate the GSK License Agreement (1) at any time upon a specified number of days’ notice, (2) upon a material breach by us or (3) upon a bankruptcy of Spero. Alternatively, in the case of a material breach by Spero, GSK may, in lieu of terminating the GSK License Agreement, elect to reduce any commercial milestone payments to Spero by 50%. In addition, in such circumstance, GSK may assume the responsibility and expense of development of tebipenem HBr in the United States, in which case no development milestone payments would be payable to Spero. In the case of a Change of Control (as defined in the GSK License Agreement) of Spero, GSK similarly may, in lieu of terminating the GSK License Agreement, assume responsibility and expense of development of tebipenem HBr in the United States and no development milestones would be payable to Spero, as described above. Any termination of the GSK License Agreement or any failure to earn, or reduction in, milestone payments may materially adversely affect our business and prospects.
Previous wording
Our 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 eventual commercialization of tebipenem HBr through our partnership with GSK.
Current wording
Our 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.
Previous wording
We currently have no products approved for sale and have invested a significant portion of our efforts and financial resources in the development of tebipenem HBr as a product candidate for the treatment of bacterial infections causing cUTI. Our ability to realize the value of tebipenem HBr depends on the potential FDA approval, and the expected timeline and other requirements that would affect the attractiveness of eventual commercialization of tebipenem HBr through our partnership with GSK. Further, as part of any approval, the FDA could impose labeling requirements restricting the use of tebipenem HBr, which could reduce its commercial prospects, unless such requirements are subsequently modified to reduce such restrictions. If any of these outcomes occur, our business could be materially harmed.
Current wording
We currently have no products approved for sale and have invested a significant portion of our efforts and financial resources in the development of tebipenem HBr as a product candidate for the treatment of bacterial infections causing cUTI. Our ability to realize the value of tebipenem HBr, currently our only product candidate, depends on the potential FDA approval, and the expected timeline and other requirements that would affect the attractiveness of commercialization of tebipenem HBr through our partnership with GSK. Further, as part of any approval, the FDA could impose labeling requirements restricting the use of tebipenem HBr, which could reduce its commercial prospects, unless such requirements are subsequently modified to reduce such restrictions. If any of these outcomes occur, our business could be materially harmed.
Previous wording
If our clinical trials fail to produce favorable results, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of such product candidates.
Current wording
If our clinical trials fail to produce favorable results, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of any existing and future product candidates.
Previous wording
We may not commercialize, market, promote or sell any product candidate in the United States without obtaining marketing approval from the FDA or in other countries without obtaining approvals from comparable foreign regulatory authorities, such as the EMA, and we may never receive such approvals. We must complete extensive preclinical development and clinical trials to demonstrate the safety and efficacy of our product candidates in humans before we will be able to obtain these approvals. Clinical testing is expensive, difficult to design and implement, can take many years to complete and is inherently uncertain as to outcome.
Current wording
We may not commercialize, market, promote or sell any product candidate in the United States without obtaining marketing approval from the FDA or in other countries without obtaining approvals from comparable foreign regulatory authorities, such as the European Medicines Agency (“EMA”), and we may never receive such approvals. We must complete extensive preclinical development and clinical trials to demonstrate the safety and efficacy of any product candidates in humans before we will be able to obtain these approvals. Clinical testing is expensive, difficult to design and implement, can take many years to complete and is inherently uncertain as to outcome.
Previous wording
The clinical development of any of our product candidates is susceptible to the risk of failure inherent at any stage of drug development, including failure to demonstrate efficacy in a trial or across a broad population of patients, the occurrence of severe adverse events, failure to comply with protocols or applicable regulatory requirements, and determination by the FDA or any comparable foreign regulatory authority that a drug product is not approvable. A number of companies in the pharmaceutical industry, including biotechnology companies, have suffered significant setbacks in clinical trials, even after promising results in earlier nonclinical studies or clinical trials. The results of preclinical and other nonclinical studies and/or early clinical trials of our product candidates may not be predictive of the results of later-stage clinical trials. Notwithstanding any promising results in early nonclinical studies or clinical trials, we cannot be certain that we will not face similar setbacks.
Current wording
The clinical development of any existing or future product candidates is susceptible to the risk of failure inherent at any stage of drug development, including failure to demonstrate efficacy in a trial or across a broad population of patients, the occurrence of severe adverse events, failure to comply with protocols or applicable regulatory requirements, and determination by the FDA or any comparable foreign regulatory authority that a drug product is not approvable. A number of companies in the pharmaceutical industry, including biotechnology companies, have suffered significant setbacks in clinical trials, even after promising results in earlier nonclinical studies or clinical trials. The results of preclinical and other nonclinical studies and/or early clinical trials of any product candidates may not be predictive of the results of later-stage clinical trials. Notwithstanding any promising results in early nonclinical studies or clinical trials, we cannot be certain that we will not face similar setbacks.
Previous wording
In addition, preclinical and clinical data are often susceptible to varying interpretations and analyses. Many companies that believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval for the product candidates. Even if we believe that the results of our clinical trials warrant marketing approval, the FDA or comparable foreign regulatory authorities may disagree and may not grant marketing approval of our product candidates.
Current wording
In addition, preclinical and clinical data are often susceptible to varying interpretations and analyses. Many companies that believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval for the product candidates. Even if we believe that the results of our clinical trials warrant marketing approval, the FDA or comparable foreign regulatory authorities may disagree and may not grant marketing approval of our existing or future product candidates.
Previous wording
In some instances, there can be significant variability in safety and/or efficacy results between different trials of the same product candidate due to numerous factors, including changes in trial procedures set forth in protocols, differences in the size and type of the patient populations, adherence to the dosing regimen and other trial protocols and the rate of dropout among clinical trial participants, among others. It is possible that even if one or more of our product candidates has a beneficial effect, that effect will not be detected during clinical evaluation as a result of one of the factors listed or otherwise. Conversely, as a result of the same factors, our clinical trials may indicate an apparent positive effect of a product candidate that is greater than the actual positive effect, if any. Similarly, in our clinical trials, we may fail to detect toxicity of or intolerability of our product candidates or may determine that our product candidates are toxic or not well tolerated when that is not in fact the case. In the case of our clinical trials, results may differ on the basis of the type of bacteria with which patients are infected. We cannot make assurances that any clinical trials that we may conduct will demonstrate consistent or adequate efficacy and safety to obtain regulatory approval to market our product candidates.
Current wording
In some instances, there can be significant variability in safety and/or efficacy results between different trials of the same product candidate due to numerous factors, including changes in trial procedures set forth in protocols, differences in the size and type of the patient populations, adherence to the dosing regimen and other trial protocols and the rate of dropout among clinical trial participants, among others. It is possible that even if one or more of our existing or future product candidates has a beneficial effect, that effect will not be detected during clinical evaluation as a result of one of the factors listed or otherwise. Conversely, as a result of the same factors, our clinical trials may indicate an apparent positive effect of a product candidate that is greater than the actual positive effect, if any. Similarly, in our clinical trials, we may fail to detect toxicity or intolerability of our existing or future product candidates or may determine that one of our existing or future product candidates are toxic or not well tolerated when that is not in fact the case. In the case of our clinical trials, results may differ on the basis of the type of bacteria with which patients are infected. We cannot make assurances that any clinical trials that we may conduct will demonstrate consistent or adequate efficacy and safety to obtain regulatory approval to market any product candidates.
Previous wording
We may encounter unforeseen events prior to, during, or as a result of, clinical trials that could delay or prevent us from obtaining regulatory approval for any of our product candidates, including:
Current wording
We may encounter unforeseen events prior to, during, or as a result of, clinical trials that could delay or prevent us from obtaining regulatory approval for any product candidates, including:
Previous wording
clinical trials of our product candidates may produce unfavorable or inconclusive results;
Current wording
clinical trials of any product candidates may produce unfavorable or inconclusive results;
Previous wording
regulators or institutional review boards may require that we or our investigators suspend or terminate clinical trials of our product candidates for various reasons, including noncompliance with regulatory requirements or a finding that the participants are being exposed to unacceptable health risks, undesirable side effects or other unexpected characteristics of the product candidate;
Current wording
regulators or institutional review boards may require that we or our investigators suspend or terminate clinical trials of any product candidates for various reasons, including noncompliance with regulatory requirements or a finding that the participants are being exposed to unacceptable health risks, undesirable side effects or other unexpected characteristics of the product candidate;
Previous wording
If we are required to conduct additional clinical trials or other testing of any of our product candidates beyond the trials and testing that we contemplate, if we are unable to successfully complete clinical trials or other testing of our product candidates, if the results of these trials or tests are unfavorable or are only modestly favorable or if there are safety concerns associated with any of our product candidates, we may:
Current wording
If we are required to conduct additional clinical trials or other testing of any existing or future product candidates beyond the trials and testing that we contemplate, if we are unable to successfully complete clinical trials or other testing of our existing or future product candidates, if the results of these trials or tests are unfavorable or are only modestly favorable or if there are safety concerns associated with any existing or future product candidates, we may:
Previous wording
Our failure to successfully initiate and complete clinical trials of our product candidates and to demonstrate the efficacy and safety necessary to obtain regulatory approval to market any of our product candidates would significantly harm our business. Our product candidate development costs will also increase if we experience delays in testing or marketing approvals and we may be required to obtain additional funds to complete clinical trials. We cannot make assurances that our clinical trials will begin as planned or be completed on schedule, if at all, or that we will not need to restructure our trials after they have begun. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates or allow our competitors to bring products to market before we do and impair our ability to successfully commercialize our product candidates, which may harm our business and results of operations. In addition, many of the factors that cause, or lead to, delays of clinical trials may ultimately lead to the denial of regulatory approval of any of our product candidates.
Current wording
Our failure to successfully initiate and complete clinical trials of any product candidates and to demonstrate the efficacy and safety necessary to obtain regulatory approval to market any existing or future product candidates would significantly harm our business. Our product candidate development costs will also increase if we experience delays in testing or marketing approvals and we may be required to obtain additional funds to complete clinical trials. We cannot make assurances that our clinical trials will begin as planned or be completed on schedule, if at all, or that we will not need to restructure our trials after they have begun. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize any product candidates or allow our competitors to bring products to market before we do and impair our ability to successfully commercialize any product candidates, which may harm our business and results of operations. In addition, many of the factors that cause, or lead to, delays of clinical trials may ultimately lead to the denial of regulatory approval of any product candidates.
Previous wording
The timely completion of clinical trials in accordance with their protocols depends, among other things, on our ability to enroll a sufficient number of patients who remain in the study until its conclusion. We may not be able to initiate, continue or complete clinical trials of our product candidates if we are unable to locate and enroll a sufficient number of eligible patients to participate in clinical trials as required by the FDA or comparable foreign regulatory authorities, such as the EMA. Patient enrollment is a significant factor in the timing of clinical trials, and is affected by many factors, including:
Current wording
The timely completion of clinical trials in accordance with their protocols depends, among other things, on our ability to enroll a sufficient number of patients who remain in the study until its conclusion. The initiation, continuation and completion of our clinical trials relies on our ability to locate and enroll a sufficient number of eligible patients to participate in clinical trials as required by the FDA or comparable foreign regulatory authorities, such as the EMA. Patient enrollment is a significant factor in the timing of clinical trials, and is affected by many factors, including:
Previous wording
Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays or might require us to abandon one or more clinical trials altogether. Enrollment delays in our clinical trials may result in increased development costs for our product candidates, slow down or halt our product candidate development and approval process and jeopardize our ability to seek and obtain the marketing approval required to commence product sales and generate revenue, which would cause the value of our company to decline and limit our ability to obtain additional financing if needed.
Current wording
Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays or might require us to abandon one or more clinical trials altogether. Enrollment delays in our clinical trials may result in increased development costs for any existing or future product candidates, slow down or halt our product candidate development and approval process and jeopardize our ability to seek and obtain the marketing approval required to commence product sales and generate revenue, which would cause the value of our company to decline and limit our ability to obtain additional financing if needed.
Previous wording
Congress also recently amended the FDCA to require sponsors of a Phase 3 clinical trial, or other “pivotal study” of a new drug to support marketing authorization, to design and submit a diversity action plan for such clinical trial. The action plan must describe appropriate diversity goals for enrollment, as well as a rationale for the goals and a description of how the sponsor will meet them. In the future, we will be required to submit a diversity action plan to the FDA by the time we submit a Phase 3 clinical trial, or pivotal study, protocol to the agency for review, unless we are able to obtain a waiver for some or all of the requirements for a diversity action plan. It is unknown at this time how the diversity action plan may affect the planning and timing of any future Phase 3 clinical trial for our product candidates. However, initiation of such trials may be delayed if the FDA objects to our proposed diversity action plans for any future Phase 3 clinical trial for our product candidates, and we may experience difficulties recruiting a diverse population of patients in attempting to fulfill the requirements of any approved diversity action plan.
Current wording
Congress also amended the Federal Food, Drug, and Cosmetic Act (“FDCA”) to require sponsors of a Phase 3 clinical trial, or other “pivotal study” of a new drug to support marketing authorization, to design and submit a diversity action plan (“DAP”) for such clinical trial. The action plan must describe appropriate diversity goals for enrollment, as well as a rationale for the goals and a description of how the sponsor will meet them. In the future, we will be required to submit a DAP to the FDA by the time we submit a Phase 3 clinical trial, or pivotal study, protocol to the agency for review, unless we are able to obtain a waiver for some or all of the requirements for a DAP. It is unknown at this time how the DAP may affect the planning and timing of any future Phase 3 clinical trial for any product candidates. However, initiation of such trials may be delayed if the FDA objects to our proposed DAPs for any future Phase 3 clinical trial for any product candidates, and we may experience difficulties recruiting a diverse population of patients in attempting to fulfill the requirements of any approved DAP.
Previous wording
We currently have no products approved for sale and we cannot guarantee that we will ever have marketable products. Clinical failure can occur at any stage of clinical development. Clinical trials may produce negative or inconclusive results, and we or any future collaborators may decide, or regulators may require us, to conduct additional clinical trials or preclinical studies. We will be required to demonstrate through well-controlled clinical trials that our product candidates are safe and effective for use in a diverse population before we can seek marketing approvals for their commercial sale. Success in preclinical studies and early-stage clinical trials does not mean that future larger registration clinical trials will be successful. This is because product candidates in later-stage clinical trials may fail to demonstrate sufficient safety and efficacy to the satisfaction of the FDA and comparable foreign regulatory authorities despite having progressed through preclinical studies and early-stage clinical trials.
Current wording
We currently have no products approved for sale and we cannot guarantee that we will ever have marketable products. Clinical failure can occur at any stage of clinical development. Clinical trials may produce negative or inconclusive results, and we or any future collaborators may decide, or regulators may require us, to conduct additional clinical trials or preclinical studies. We will be required to demonstrate through well-controlled clinical trials that our existing or future product candidates are safe and effective for use in a diverse population before we can seek marketing approvals for their commercial sale. Success in preclinical studies and early-stage clinical trials does not mean that future larger registration clinical trials will be successful. This is because product candidates in later-stage clinical trials may fail to demonstrate sufficient safety and efficacy to the satisfaction of the FDA and comparable foreign regulatory authorities despite having progressed through preclinical studies and early-stage clinical trials.
Previous wording
Analyses of preliminary or interim data from our clinical studies are not necessarily predictive of analyses of final data. Analyses of preliminary and interim data are subject to the risk that one or more of the clinical outcomes may materially change, as more patient data become available and we issue our final clinical study report. Preliminary or interim data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. As a result, analyses of interim and preliminary data should be viewed with caution until the analyses of final data are available. Adverse differences between preliminary or interim data and final data could affect our planned clinical path for any of our product candidates we advance into clinical trials, including potentially increasing cost and/or causing delay in such development.
Current wording
Analyses of preliminary or interim data from our clinical studies are not necessarily predictive of analyses of final data. Analyses of preliminary and interim data are subject to the risk that one or more of the clinical outcomes may materially change, as more patient data become available and we issue our final clinical study report. Preliminary or interim data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. As a result, analyses of interim and preliminary data should be viewed with caution until the analyses of final data are available. Adverse differences between preliminary or interim data and final data could affect our planned clinical path for any product candidates we advance into clinical trials, including potentially increasing cost and/or causing delay in such development.
Previous wording
In some instances, there can be significant variability in safety and efficacy results between different clinical trials of the same product candidate due to numerous factors, including changes in trial protocols, differences in size and type of the patient populations, differences in and adherence to the dosing regimen and other trial protocols and the rate of dropout among clinical trial participants. We therefore do not know whether any clinical trials we may conduct will demonstrate consistent or adequate efficacy and safety sufficient to obtain marketing approval to market our product candidates.
Current wording
In some instances, there can be significant variability in safety and efficacy results between different clinical trials of the same product candidate due to numerous factors, including changes in trial protocols, differences in size and type of the patient populations, differences in and adherence to the dosing regimen and other trial protocols and the rate of dropout among clinical trial participants.
Previous wording
Serious adverse events or undesirable side effects or other unexpected properties of any of our 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.
Current wording
Serious 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.
Previous wording
Serious adverse events or undesirable side effects caused by, or other unexpected properties of, our product candidates could cause us, an IRB, or regulatory authorities to interrupt, delay or halt our clinical trials and could result in a more restrictive label, the imposition of distribution or use restrictions or the delay or denial of regulatory approval by the FDA or comparable foreign regulatory authorities. If any of our other product candidates are associated with serious or unexpected adverse events or undesirable side effects, the FDA, the IRBs responsible for overseeing our studies, or a DSMB, could suspend or terminate our clinical trials or the FDA or comparable foreign regulatory authorities could order us to cease clinical trials or deny approval of our product candidates for any or all targeted indications. Treatment-related side effects could also affect patient recruitment or the ability of enrolled patients to complete the trial or result in potential product liability claims. Any of these occurrences may harm our business, financial condition and prospects significantly.
Current wording
Serious adverse events or undesirable side effects caused by, or other unexpected properties of, our existing or future product candidates could cause us, an IRB, or regulatory authorities to interrupt, delay or halt our clinical trials and could result in a more restrictive label, the imposition of distribution or use restrictions or the delay or denial of regulatory approval by the FDA or comparable foreign regulatory authorities. If any of our other product candidates are associated with serious or unexpected adverse events or undesirable side effects, the FDA, the IRBs responsible for overseeing our studies, or a DSMB, could suspend or terminate our clinical trials or the FDA or comparable foreign regulatory authorities could order us to cease clinical trials or deny approval of our existing or future product candidates for any or all targeted indications. Treatment-related side effects could also affect patient recruitment or the ability of enrolled patients to complete the trial or result in potential product liability claims. Any of these occurrences may harm our business, financial condition and prospects significantly.
Previous wording
If unexpected adverse events occur in any of our ongoing or planned clinical trials, we may need to abandon development of our product candidates, or limit development to lower doses or to certain uses or subpopulations in which the undesirable side effects or other unfavorable characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective. Many compounds that initially showed promise in clinical or earlier stage testing are later found to cause undesirable or unexpected side effects that prevented further development of the compound.
Current wording
If unexpected adverse events occur in any of our ongoing or planned clinical trials, we may need to abandon development of any product candidates, or limit development to lower doses or to certain uses or subpopulations in which the undesirable side effects or other unfavorable characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective. Many compounds that initially showed promise in clinical or earlier stage testing are later found to cause undesirable or unexpected side effects that prevented further development of the compound.
Previous wording
Undesirable side effects or other unexpected adverse events or properties of any of our other product candidates could arise or become known either during clinical development or, if approved, after the approved product has been marketed. If such an event occurs during development, our trials could be suspended or terminated and the FDA or comparable foreign regulatory authorities could order us to cease further development of, or could deny approval of our product candidates. If such an event occurs after such product candidates are approved, a number of potentially significant negative consequences may result, including:
Current wording
Undesirable side effects or other unexpected adverse events or properties of any of our other product candidates could arise or become known either during clinical development or, if approved, after the approved product has been marketed. If such an event occurs during development, our trials could be suspended or terminated and the FDA or comparable foreign regulatory authorities could order us to cease further development of, or could deny approval of any product candidates. If such an event occurs after such product candidates are approved, a number of potentially significant negative consequences may result, including:
Previous wording
we may be required to implement a REMS, which may include the creation of a medication guide outlining the risks of such side effects for distribution to patients or restrictions on distribution or other elements;
Current wording
we may be required to implement a risk evaluation and mitigation strategy (“REMS”), which may include the creation of a medication guide outlining the risks of such side effects for distribution to patients or restrictions on distribution or other elements;
Previous wording
we could be sued and held liable for harm caused to patients exposed to or taking our product candidates;
Current wording
we could be sued and held liable for harm caused to patients exposed to or taking our existing or future product candidates;
Previous wording
Even if we obtain FDA or other regulatory approvals and are able to launch any of our product candidates commercially, the approved product candidate may nonetheless fail to gain sufficient market acceptance among physicians, patients, hospitals (including pharmacy directors) and third-party payors and, ultimately, may not be commercially successful. For example, physicians are often reluctant to switch their patients from existing therapies even when new and potentially more effective or convenient treatments enter the market. Further, patients often acclimate to the therapy that they are currently taking and do not want to switch unless their physicians recommend switching products or they are required to switch therapies due to lack of coverage and reimbursement for existing therapies. If an approved product candidate does not achieve an adequate level of acceptance, we may not generate significant product revenues or any profits from operations. The degree of market acceptance of any product candidate for which we receive approval depends on a number of factors, including:
Current wording
Even if we obtain FDA or other regulatory approvals and are able to launch any product candidates commercially, the approved product candidate may nonetheless fail to gain sufficient market acceptance among physicians, patients, hospitals (including pharmacy directors) and third-party payors and, ultimately, may not be commercially successful. For example, physicians are often reluctant to switch their patients from existing therapies even when new and potentially more effective or convenient treatments enter the market. Further, patients often acclimate to the therapy that they are currently taking and do not want to switch unless their physicians recommend switching products or they are required to switch therapies due to lack of coverage and reimbursement for existing therapies. If an approved product candidate does not achieve an adequate level of acceptance, we may not generate significant product revenues or any profits from operations. The degree of market acceptance of any product candidate for which we receive approval depends on a number of factors, including:
Previous wording
Any failure of any of our product candidates that obtains regulatory approval to achieve market acceptance or commercial success would adversely affect our business prospects.
Current wording
Any failure of any product candidates that obtains regulatory approval to achieve market acceptance or commercial success would adversely affect our business prospects.
Previous wording
Because we have limited financial and managerial resources, we intend to focus on developing product candidates for specific indications that we identify as most likely to succeed, in terms of both their potential for marketing approval and commercialization. As a result, we may forego or delay pursuit of opportunities with other product candidates or for other indications that may prove to have greater commercial potential.
Current wording
Because we have limited financial and managerial resources, we intend to focus on developing product candidates for specific indications that we identify as most likely to succeed, in terms of both their potential for marketing approval and commercialization. As a result, we may forego or delay pursuit of opportunities with other product candidates or for other indications that may prove to have greater commercial potential. For example, as of November 2025, we have ceased development of our SPR720 oral program and have shifted our focus and resources to advancing the clinical development of our tebipenem HBr program, as well as other corporate activities. Additionally, in March 2025, we announced that we have ceased development of SPR206.
Previous wording
If 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 of our product candidates if such product candidates are approved.
Current wording
If 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.
Previous wording
We intend to use collaborators to assist with the commercialization of any of our product candidates, including the GSK License Agreement for the development and commercialization of tebipenem HBr. As a result of entering into arrangements with third parties to perform sales, marketing and distribution services, our product revenues or the profitability of these product revenues to us would likely be lower than if we were to directly market and sell products in those markets. Furthermore, we may be unsuccessful in entering into the necessary arrangements with third parties or may be unable to do so on terms that are favorable to us. In addition, we likely would have little control over such third parties, and any of them might fail to devote the necessary resources and attention to sell and market our products effectively.
Current wording
We intend to use collaborators to assist with the commercialization of any of our current and future product candidates, including the GSK License Agreement for the development and commercialization of tebipenem HBr. As a result of entering into arrangements with third parties to perform sales, marketing and distribution services, our product revenues or the profitability of these product revenues to us would likely be lower than if we were to directly market and sell products in those markets. Furthermore, we may be unsuccessful in entering into the necessary arrangements with third parties or may be unable to do so on terms that are favorable to us. In addition, we likely would have little control over such third parties, and any of them might fail to devote the necessary resources and attention to sell and market our products effectively.
Previous wording
If we or our collaborators do not establish sales and marketing capabilities successfully, either on our own or in collaboration with third parties, we will not be successful in commercializing our product candidates.
Current wording
If we or our collaborators do not establish sales and marketing capabilities successfully, either on our own or in collaboration with third parties, we will not be successful in commercializing any product candidates.
Previous wording
The development and commercialization of new drug products is highly competitive. We face competition from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide with respect to our product candidates that we may seek to develop and commercialize in the future. There are a number of large pharmaceutical and biotechnology companies that currently market and sell products or are pursuing the development of product candidates for the treatment of resistant infections. Potential competitors also include academic institutions, government agencies and other public and private research organizations. Our competitors may succeed in developing, acquiring or licensing technologies and drug products that are more effective or less costly than the product candidates that we are currently developing or that we may develop, which could render our product candidates obsolete and noncompetitive.
Current wording
The development and commercialization of new drug products is highly competitive. We face competition from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide with respect to any product candidates that we may seek to develop and commercialize in the future. There are a number of large pharmaceutical and biotechnology companies that currently market and sell products or are pursuing the development of product candidates for the treatment of resistant infections. Potential competitors also include academic institutions, government agencies and other public and private research organizations. Our competitors may succeed in developing, acquiring or licensing technologies and drug products that are more effective or less costly than the product candidates that we are currently developing or that we may develop, which could render our existing or future product candidates obsolete and noncompetitive.
Previous wording
There are several IV-administered products marketed for the treatment of infections resistant to first-line therapy for Gram-negative infections, including Avycaz (ceftazidime-avibactam) from Allergan plc and Pfizer Inc., Zerbaxa (ceftolozane-tazobactam) from Merck & Co., imipenem/cilastatin and Recarbrio (relebactam) from Merck & Co., Zemdri (plazomicin) from Cipla Therapeutics, Inc., Fetroja (cefiderocol) from Shionogi & Co. Ltd., Xerava (eravacycline) from Innoviva, Inc. and Vabomere (meropenem-vaborbactam) from Melinta Therapeutics, Inc., and Exblifep (cefepime/enmetazobactam) from Allecra Therapeutics.
Current wording
There are several IV-administered products marketed for the treatment of infections resistant to first-line therapy for Gram-negative infections, including Emblaveo (Aztreonam-avibactam) from Allergan, Avycaz (ceftazidime-avibactam) from Allergan and Pfizer, Zerbaxa (ceftolozane-tazobactam) from Merck & Co., imipenem/cilastatin and Recarbrio (relebactam) from Merck & Co., Zemdri (plazomicin) from Cipla Therapeutics, Inc., Fetroja (cefiderocol) from Shionogi & Co. Ltd., and Vabomere (meropenem-vaborbactam) from CorMedix Inc., and Exblifep (cefepime/enmetazobactam) from Allecra Therapeutics.
Previous wording
Even if we or our partners are able to commercialize any of our product candidates, the product may become subject to unfavorable pricing regulations, or third-party payor coverage and reimbursement policies that could harm our business.
Current wording
Even if we or our partners are able to commercialize our existing or future product candidates, the product may become subject to unfavorable pricing regulations, or third-party payor coverage and reimbursement policies that could harm our business.
Previous wording
Marketing approvals, pricing, coverage and reimbursement for new drug products vary widely from country to country. Some countries require approval of the sale price of a drug before it can be marketed. In many countries, the pricing review period begins after marketing or product licensing approval is granted. In some foreign markets, prescription pharmaceutical pricing remains subject to continuing governmental control even after initial approval is granted. As a result, we might obtain marketing approval for a product in a particular country, but then be subject to price regulations that delay our commercial launch of the product, possibly for lengthy time periods, which may negatively affect the revenues that we are able to generate from the sale of the product in that country. Adverse pricing limitations may hinder our ability to recoup our investment in one or more product candidates, even if our product candidates obtain marketing approval.
Current wording
Marketing approvals, pricing, coverage and reimbursement for new drug products vary widely from country to country. Some countries require approval of the sale price of a drug before it can be marketed. In many countries, the pricing review period begins after marketing or product licensing approval is granted. In some foreign markets, prescription pharmaceutical pricing remains subject to continuing governmental control even after initial approval is granted. As a result, we might obtain marketing approval for a product in a particular country, but then be subject to price regulations that delay our commercial launch of the product, possibly for lengthy time periods, which may negatively affect the revenues that we are able to generate from the sale of the product in that country. Adverse pricing limitations may hinder our ability to recoup our investment in one or more product candidates, even if our existing or future product candidates obtain marketing approval.
Previous wording
We currently expect that some of our product candidates, if approved, will be administered in a hospital inpatient setting. In the United States, governmental and other third-party payors generally reimburse hospitals a single bundled payment established on a prospective basis intended to cover all items and services provided to the patient during a single hospitalization. Hospitals bill third-party payors for all or a portion of the fees associated with the patient’s hospitalization and bill patients for any deductibles or co-payments. Because there is typically no separate reimbursement for drugs administered in a hospital inpatient setting, some of our target customers may be unwilling to adopt our product candidates in light of the additional associated cost. If we are forced to lower the price we charge for our product candidates, if approved, our gross margins may decrease, which would adversely affect our ability to invest in and grow our business.
Current wording
We currently expect that our product candidate, if approved, will be administered in a hospital inpatient setting. In the United States, governmental and other third-party payors generally reimburse hospitals a single bundled payment established on a prospective basis intended to cover all items and services provided to the patient during a single hospitalization. Hospitals bill third-party payors for all or a portion of the fees associated with the patient’s hospitalization and bill patients for any deductibles or co-payments. Because there is typically no separate reimbursement for drugs administered in a hospital inpatient setting, some of our target customers may be unwilling to adopt our product candidate in light of the additional associated cost. If we are forced to lower the price we charge for our product candidate, if approved, our gross margins may decrease, which would adversely affect our ability to invest in and grow our business.
Previous wording
To the extent any of our product candidates we develop are used in an outpatient setting, the commercial success of our product candidates will depend substantially, both domestically and abroad, on the extent to which coverage and reimbursement for these products and related treatments are available from government health programs and third-party payors. If coverage is not available, or reimbursement is limited, we may not be able to successfully commercialize our product candidates. Even if coverage is provided, the approved reimbursement amount may not be high enough to allow us to establish or maintain pricing sufficient to realize a sufficient return on our investments. Government authorities and third-party payors, such as health insurers and managed care organizations, publish formularies that identify the medications they will cover and the related payment levels. The healthcare industry is focused on cost containment, both in the United States and elsewhere. Government authorities and third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications, which could affect our ability to sell our product candidates profitably.
Current wording
To the extent any product candidates we develop are used in an outpatient setting, the commercial success of our existing or future product candidates will depend substantially, both domestically and abroad, on the extent to which coverage and reimbursement for these products and related treatments are available from government health programs and third-party payors. If coverage is not available, or reimbursement is limited, we may not be able to successfully commercialize our existing or future product candidates. Even if coverage is provided, the approved reimbursement amount may not be high enough to allow us to establish or maintain pricing sufficient to realize a sufficient return on our investments. Government authorities and third-party payors, such as health insurers and managed care organizations, publish formularies that identify the medications they will cover and the related payment levels. The healthcare industry is focused on cost containment, both in the United States and elsewhere. Government authorities and third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications, which could affect our ability to sell our existing or future product candidates profitably.
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Current report — wording carried from elsewhere
be delayed in obtaining marketing approval for any product candidates;
Current report — wording carried from elsewhere
We therefore do not know whether any clinical trials we may conduct will demonstrate consistent or adequate efficacy and safety sufficient to obtain marketing approval to market our existing or future product candidates.
Current report — wording carried from elsewhere
Trademark Office (“USPTO”) or become involved in opposition, derivation, reexamination, inter partes review or interference proceedings, in the United States or elsewhere, challenging our patent rights or the patent rights of others. An adverse determination in any such submission, proceeding or litigation could reduce the scope of, or invalidate, our patent rights, allow third parties to commercialize our technology or product candidates and compete directly with us, without payment to us, or result in our inability to manufacture or commercialize products without infringing third-party patent rights.
Current report — wording carried from elsewhere
the timing of clinical trials of any of our product candidates;
Rearranged previous paragraphs (3)
Previous report — wording carried elsewhere
We recently completed a Section 382 study and concluded that we underwent several ownership changes as defined by the Code, the last of which occurred during the year ended December 31, 2018. Any carryforwards that will expire prior to utilization were removed from deferred tax assets, with a corresponding reduction of the valuation allowance. Future ownership changes may limit our ability to utilize remaining tax attributes.
Previous report — wording carried elsewhere
the timing of clinical trials of our product candidates;
Previous report — wording carried elsewhere
results of clinical trials of any of our product candidates;