SPRO 10-K & 10-Q changes, risk factors and insider trading

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 anticipatedcontained in the forward-looking statements aswe ahave result of factors that are described below and elsewheremade in this Annual Report on Form 10-K.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.

PursuantAs toof March 2025, we have ceased development of our previouslySPR206 announcedprogram, restructuring,and as of November 2025, we suspendedhave ceased development of our SPR720 oral programprogram, and have shifted our focus and resources to advancing the clinical development of ourthe 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, or our collaboration with GSK fails to advance the development of the tebipenem HBr program, our business and prospects may be materially adversely affectedaffected.

OnAs Octoberof 29,March 2024,2025, we announcedhave thatceased development of SPR206. Additionally, as of November 2025, we suspendedhave ceased development activities forof our SPR720 oral program basedand onhave anshifted interimour analysisfocus ofand resources to advancing 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 theclinical development of our tebipenem HBr andprogram, as well as 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.activities. We believe this re-prioritized strategic focus is the best way to optimize our financial and other resources to advance our goal of developingidentifying and commercializingdeveloping productnovel candidatestreatments tofor addressrare thediseases and diseases with high unmet need for solutions to antibiotic resistant pathogens.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, and the regulatory path for SPR720 remains uncertain at this time.programs. If we are unable to execute successfully on this re-prioritized strategic focus, our business and prospects may be materially adversely affected.

As a result, we are currently substantially dependent on our tebipenem program and our collaboration with GSK. As described under “Business—Collaboration,Note License13 andto Serviceour Agreements—Tebipenemconsolidated HBrfinancial Agreements”,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 (including unpaid installments of any earned milestone payments).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.

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.

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 HBrHBr, currently our only product candidate, 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.

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 suchany existing and future product candidates.

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,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 ourany 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.

The clinical development of any ofexisting ouror 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 ourany 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.

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.

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 of 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 ourany product candidates.

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:

clinical trials of ourany product candidates may produce unfavorable or inconclusive results;

the number of patients required for clinical trials of ourany 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;

our third-party contractors, including those manufacturing ourany 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;

regulators or institutional review boards may require that we or our investigators suspend or terminate clinical trials of ourany 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;

the supply or quality of ourany product candidates or other materials necessary to conduct clinical trials of ourany product candidates may be insufficient or inadequate; and the approval policies or regulations of the FDA or comparable foreign regulatory authorities may significantly change in a manner rendering our clinical data insufficient for approval.

If we are required to conduct additional clinical trials or other testing of any ofexisting ouror 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 ofexisting ouror future product candidates, we may:

be delayed in obtaining marketing approval for ourany product candidates;

Our failure to successfully initiate and complete clinical trials of ourany product candidates and to demonstrate the efficacy and safety necessary to obtain regulatory approval to market any ofexisting ouror 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 ourany product candidates or allow our competitors to bring products to market before we do and impair our ability to successfully commercialize ourany 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.

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. WeThe mayinitiation, notcontinuation beand ablecompletion toof initiate, continue or completeour clinical trials ofrelies on our product candidates if we are unableability 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:

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 ourany 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.

Congress also recently 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 diversity action planDAP 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.DAP. It is unknown at this time how the diversity action planDAP may affect the planning and timing of any future Phase 3 clinical trial for ourany product candidates. However, initiation of such trials may be delayed if the FDA objects to our proposed diversity action plansDAPs for any future Phase 3 clinical trial for ourany 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.DAP.

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.

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.

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.

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.

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.

If unexpected adverse events occur in any of our ongoing or planned clinical trials, we may need to abandon development of ourany 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.

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 ourany product candidates. If such an event occurs after such product candidates are approved, a number of potentially significant negative consequences may result, including:

we may be required to implement a REMS,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;

we could be sued and held liable for harm caused to patients exposed to or taking our existing or future product candidates;

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:

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.

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.

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.

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.

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 ourany product candidates.

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 ourany 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.

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 plc and Pfizer Inc.,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., Xerava (eravacycline) from Innoviva, Inc. and Vabomere (meropenem-vaborbactam) from Melinta Therapeutics,CorMedix Inc., and Exblifep (cefepime/enmetazobactam) from Allecra Therapeutics.

Even if we or our partners are able to commercialize anyour ofexisting ouror 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.

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.

We currently expect that some of our product candidates,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 candidatescandidate in light of the additional associated cost. If we are forced to lower the price we charge for our product candidates,candidate, if approved, our gross margins may decrease, which would adversely affect our ability to invest in and grow our business.

To the extent any of our 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.

We cannot predict whether bacteria may develop resistance to our product candidates,candidate, if approved, which could affect theirits revenue potential.

CertainTebipenem ofHBr our product candidates areis designed to treat bacterial infections, including drug-resistant infections. The bacteria responsible for these infections evolve quickly and readily transfer their resistance mechanisms within and between species. We cannot predict whether or when bacterial resistance to anytebipenem of such product candidatesHBr may develop.

For example, as a carbapenem, tebipenem HBr is not active against organisms expressing a resistance mechanism mediated by enzymes known as carbapenemases. Although occurrence of this resistance mechanism is currently rare, we cannot predict whether carbapenemase-mediated resistance will become widespread in regions where tebipenem HBr may be marketed if it is approved. The growth of drug resistantdrug-resistant infections in community settings or in countries with poor public health infrastructures, or the potential use of any of our product candidatescandidate outside of controlled hospital settings, could contribute to the rise of resistance. If resistance to any of our product candidatescandidate becomes prevalent, our ability to generate revenue from such product candidates could suffer.

If we are not successful in discovering, developing and commercializing additional product candidates, our ability to expand our business and achieve our strategic objectives would be impaired.

Although a substantial amount of our efforts willare focuscurrently focused on our ongoing and planned clinical trials and potential approval of our product candidate, tebipenem HBr, as well as exploring clinical and development pathways forward for SPR720, a key element of our strategy is to discover, develop and commercialize a portfolio of therapeutics to treat drug resistant bacterial infections. We are exploring, and intend to explore in the future, strategic partnerships for the development of new product candidates.

We have experienced mostly net losses and significant cash outflows from cash used in operating activities since our inception. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of onetebipenem HBr, or more of ourany product candidates.candidate we may develop in the future. As of December 31, 2024,2025, we had an accumulated deficit of $459.6$451.1 million, and cash and cash equivalents of $52.9$40.3 million. We expect to continue to incur significant expenses and operating losses for at least the nextforeseeable year.future. Based on our current operating plan, we believe that our cash and cash equivalents as of December 31, 2024, together with earned and non-contingent development milestone payments from GSK, as well as other non-dilutive funding commitments, we believe that our cash runway2025 will be sufficient to fund our operating expenses and required capital expenditures into the second quarter of 2026.2028. During this period, we planremain focused on supporting GSK in the FDA approval process pursuant to prioritizeour advancing the Phase 3 clinical trial activities for tebipenem HBrobligations under our GSK License Agreement and completingadvancing other corporate activities, including exploring opportunities to grow our analysisportfolio of theclinical-stage fullproduct datasetcandidates. fromBeyond thethis 25point, treated patientsor in the Phaseevent 2awe proof-of-conceptchange trialour ofcurrent SPR720.operating Beyond this pointplan, we will need additional funding,funding whichto support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect willto primarilyfinance consistour of raising additional capitaloperations through somea combination of equity orofferings, debt financings, potentialgovernment newfunding collaborationsarrangements, collaborations, strategic alliances and marketing, distribution or additionallicensing grant funding.arrangements. If we are not able to secure adequate additional funding, we planwill have to make further reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned development activities. The actions necessary to reduce spending under this plan at a level that mitigates the factors described above isare not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern. As a result, management has concluded that substantial doubt exists about our ability to continue as a going concern.

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

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

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

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

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

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

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

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

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

competition with other therapies; and a continued acceptable safety profile of any of our product candidates, if approved.

Except for year ended December 31, 2022, we have not recorded any income tax benefits for the net losses we have incurred in each year or for our earned research and development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our net operating loss carryforwards and tax credits will not be realized. As of December 31, 2024,2025, we had federalUnited States federal, state and stateforeign net operating loss carryforwards ("NOLs") of $165.2$226.1 million, $184.8 million and $120.6$4.7 million, respectivelyrespectively. which may be available to offset future income tax liabilities. $152.0$212.8 million of the federal NOLs can be carried forward indefinitely and $13.2 million of the federal NOLs begin to expire in 2034. The state NOLs begin to expire in 20342035 and will expire at various dates through 2044.2045. In addition, as of December 31, 2024, we hadThe foreign net operating loss carryforwards of $4.6 million, which may be available to offset future income tax liabilities andNOLs do not expire. As of December 31, 2024,2025, we also had federal and state research and development tax credit carryforwards of $6.2$6.7 million and $2.1$1.7 million, respectively, and federal orphan drug tax credit carryforwards of $3.1 million, which may be available to offset future income tax liabilities. The federal and state research and development tax credits begin to expire in 20362035 and 2033,the respectively.federal orphan drug credits begin to expire in 2044. We have recorded a full valuation allowance against our net deferred tax assets at each balance sheet date.

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

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

The following table summarizes our results of operations for the years ended December 31, 20242025 and 20232024 (in thousands):

Grant Revenue (in thousands):

Grant revenue recognized during 2024the years ended December 31, 2025 and 20232024 consisted of the reimbursement of qualifying expenses incurred in connection with our various government awards. The increasedecrease in grant revenue during 20242025 was primarily due to ana increasedecrease of $15.8$13.0 million in funding under our BARDA contract related to ourthe pivotalconclusion of the Phase 3 clinical trial of tebipenem HBr, partially offset byand a decrease of $2.3$0.4 million in qualified expenses incurred under our NIAID award relating to SPR206.SPR206 as we ceased development of SPR206 and the NIAID award was terminated in April 2025.

Research and Development Expenses (in thousands):

Direct costs related to our tebipenem HBr program increaseddecreased by $43.8$37.9 million during the year ended December 31, 2024,2025, compared to the year ended December 31, 2023,2024, due to increaseddecreased clinical activities related to our Phase 3 clinical trial of tebipenem HBr, which wemet initiatedits inprimary endpoint and was stopped early for efficacy during the fourthfirst quarterhalf of 2023.2025. In December 2025, GSK resubmitted the NDA for tebipenem HBr to the FDA. Direct costs related to our tebipenem HBr program during the yearyears ended December 31, 20242025 and 2024, reflect a $0.5 million and $3.6 million reduction to expense related to a purchase of drug substance material by GSK.GSK, respectively.

Direct costs related to our SPR206SPR720 program decreased by $2.7$15.6 million during the year ended December 31, 2025, compared to the year ended December 31, 2024, primarily due to decreased preclinicalclinical activity.activity during the period and the cessation of development on the program announced in November 2025.

The increasedecrease in personnel-related costs of $0.3$4.5 million was primarily duea toresult increasedof decreased headcount costs in our research and development personnelfunctions costs.between the periods. Personnel-related costs for the years ended December 31, 20242025 and 20232024 included share-based compensation expenses of $2.6$1.7 million and $2.7$2.6 million, respectively.

General and Administrative Expenses (in thousands):

The decrease in personnel-related costs of $2.1$1.4 million was primarily a result of decreased headcount costs in our general and administrative functions duringbetween the period.periods. Personnel-related costs for the years ended December 31, 20242025 and 20232024 included share-based compensation expense of $5.2$2.6 million and $5.3$5.2 million, respectively.

The increasedecrease in professional and consultant fees was primarily due to increaseddecreased legal and consulting expenses incurred during the year ended December 31, 2024.2025.

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

Impairment of Long-Term AssetCharges

Risks Related to ProductOur DevelopmentBusiness and CommercializationProduct Candidates

Our ability to realize the value of tebipenem HBrpivoxil 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 Utebzi (tebipenem HBrpivoxil) through our partnership with GSK.

WeIn currentlyJune have2026, nothe productsFDA approved GSK’s NDA resubmission for saleUtebzi. andWe have invested a significant portion of our efforts and financial resources in the development of tebipenem HBrpivoxil with GSK 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,pivoxil depends on the potential FDA approval, and the expected timeline and other requirements that would affect the attractivenesssuccess of GSK’s commercialization of tebipenemUtebzi. HBrFurther, throughon July 8, 2026, we and our partnershipaffiliates entered into a non-recourse non-dilutive royalty financing transaction with GSK. Further, as partaffiliates of anyHCRx, approval,pursuant to which HCRx will receive a portion of the FDAfuture couldGSK imposeProceeds. labelingAs requirementssuch, restrictingour receipt of royalty and milestone revenues from GSK is limited to 35% of the useGSK Proceeds arising after payment in full of tebipenemthe HBr,Notes. whichIf couldGSK’s reducecommercialization its commercial prospects, unless such requirementsefforts are subsequentlyunsuccessful modifiedor tosignificantly reducedelayed, suchour restrictions. If anyreceipt of theseroyalty outcomesand occur,milestone revenues from GSK may not align with our expectations and our business could be materially harmed.harmed

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.

WeWhile we currently have noone productsproduct approved for sale andthrough our collaboration with GSK, we cannot guarantee that we will ever have additional 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.

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.

Even if we obtain FDA or other regulatory approvals and are able to launch any of our current or future 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, physiciansUtebzi, which was approved in June 2026, may fail to gain sufficient market acceptance despite commercialization efforts by GSK. 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:

the emergence of bacterial resistance to the productproduct, in the case of Utebzi; and the rate at which resistance to other drugs in the target infections grows.grows, in the case of Utebzi.

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, weexample,we have ceasedterminated developmentour ofSPR206 program and our SPR720 oral program and have shifted our focus and resources to advancing the clinical development of our tebipenem HBr program,SP001, as well as other corporate activities. Additionally, in March 2025, we announced that we have ceased development of SPR206.

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 or our collaborators may not be successful in commercializing Utebzi or any of our future product candidatescandidates, if such product candidates are approved.

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.Utebzi. 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.

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 in immunology and inflammation for patients with serious diseases, and 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.

There are a variety of available oral therapies marketed for the treatment of cUTIs that we would expect wouldto compete with tebipenem HBr, if approved,Utebzi, such as Levaquin, Cipro and Bactrim. Many of the available therapies are well established and widely accepted by physicians, patients and third-party payors. Insurers and other third-party payors may also encourage the use of generic products, for example in the fluoroquinolone class. However, the susceptibility of urinary tract pathogens to the existing treatment alternatives is waning. IfIn tebipenemaddition, HBr is approved, theGSK’s pricing of Utebzi may be at a significant premium over other competitive products.products, Thiswhich may make it difficult for tebipenem HBrUtebzi to compete with these other products.

Even if weUtebzi, or our partners are able to commercialize ourany existing or future product candidates,candidates thethat productwe may commercialize, may become subject to unfavorable pricing regulations, or third-party payor coverage and reimbursement policies that could harm our business.business

We currently expect that our product candidate, if approved,Utebzi 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.

We cannot predict whether bacteria may develop resistance to ourtebipenem product candidate, if approved,pivoxil, which could affect its revenue potential.

Tebipenem HBrpivoxil is designed to treat bacterial infections, including drug-resistant infections. The bacteria responsible for these infections evolve quickly and readily transfer their resistance mechanisms within and between species. We cannot predict whether or when bacterial resistance to tebipenem HBrpivoxil may develop.

For example, as a carbapenem, tebipenem HBrpivoxil is not active against organisms expressing a resistance mechanism mediated by enzymes known as carbapenemases. Although occurrence of this resistance mechanism is currently rare, we cannot predict whether carbapenemase-mediated resistance will become widespread in regions where tebipenem HBrpivoxil may be marketed if it is approved. The growth of drug resistant infections in community settings or in countries with poor public health infrastructures, or the potential use of our product candidate outside of controlled hospital settings, could contribute to the rise of resistance. If resistance to ourtebipenem product candidatepivoxil becomes prevalent, our ability to generate revenue could suffer.

Although a substantial amount of our efforts are currently focused on our potential approval of our product candidate, tebipenem HBr, aA key element of our strategy is to develop and commercialize a portfolio of therapeutics to treat drugimmunology resistantand bacterialinflammation infections.patients. We arerecently exploring,entered into the Innovent Agreement for the in-license of SP001, and intend tomay explore in the future, strategic partnerships for the development of new product candidates.

Despite the implementation of security measures, our internal computer systems and those of our contract research organizations and other contractors and consultants are vulnerable to damage or disruption from hacking, computer viruses, malware, including ransomware, software bugs, unauthorized access, natural disasters, terrorism, war, and telecommunication, equipment and electrical failures. We have measures in place that are designed to prevent, and if necessary, to detect and respond to such cybersecurity incidents and breaches of privacy and security mandates. Our measures to prevent, respond to, and minimize such risks may be unsuccessful. While we have not, to our knowledge, experienced any significant system failure, accident or material cybersecurity incident to date, if such an event were to occur and cause interruptions in our operations or the operations of those third parties with which we contract, it could result in a material disruption of our programs and our business operations, as well as our financial condition. For example, the loss of clinical trial data from completed or ongoing clinical trials for any of our current or future product candidates could result in delays in our development and regulatory approval efforts and significantly increase our costs to recover or reproduce the data. Such a loss could also expose us to regulatory enforcement, civil liability and reputational damage. To the extent that any disruption or cybersecurity incident results in a loss of or damage to our data or applications, or inappropriate disclosure or theft of confidential or proprietary information, in addition to incurring liability, the further development of any product candidates could be delayed or our competitive position could be compromised. Additionally, such disruptions or cybersecurity incidents could result in enforcement actions by U.S. or foreign regulatory authorities, regulatory penalties, and other legal liabilities such as but not limited to private litigation, the incurrence of significant remediation costs, disruptions to our development programs, business operations and collaborations, diversion of management efforts and damage to our reputation, all of which could harm our business and operations.

We have not generated any revenue from the sale of our products and have incurred losses in most years since our inception in 2013. Our net loss was $7.2$9.6 million and $13.9$16.8 million for the three and six months ended MarchJune 31,30, 2026 and 2025,2026, respectively. WeWhile the FDA approved GSK’s NDA resubmission for Utebzi, we do not have yetany to have aother product candidatecandidates approved for sale and we may never have aanother product candidate approved for commercialization. The success of Utebzi depends on GSK’s ability to commercialize the product.

In accordance with ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), we have evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. Based on our current operating plan, we believe that our cash and cash equivalents as of MarchJune 31,30, 20262026, together with and including the net proceeds from the royalty financing transaction that closed in July 2026, will be sufficient to fund our operating expenses and capital expenditure requirements at least into 2028.the second half of 2029. During this period, we remainare focused on supportingadvancing GSKnext-generation medicines in the FDA approval process pursuant to our obligations under our GSK License Agreementimmunology and advancinginflammation otherfor corporatepatients activities,with includingserious exploringdiseases opportunitiesand tomajor growtreatment our portfolio of clinical-stage product candidates.gaps. Beyond this point, or in the event we change our current operating plan, we will need additional funding, which we expect will primarily consist of raising additional capital through some combination of equity or debt financings, potential new collaborations or grant funding. If we are not able to secure adequate additional funding, we plan to make further reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned development activities. The actions necessary to reduce spending under this plan at a level that mitigates the factors described above is not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern.

conduct additional clinical trials and studies of our existing or future product candidates;

We currently have noone productsproduct approved for sale and have historically invested a significant portion of our efforts and financial resources in the development of any of our product candidates, including tebipenem HBr,pivoxil, SPR206, and SPR720. Although we decided to cease further development of SPR206 and SPR720, our business remains heavily dependent on the successful commercialization of tebipenem pivoxil, the success of which depends on GSK’s ability to commercialize Utebzi, and the successful development, regulatory approval, and, if approved, commercialization of tebipenem HBrSP001 and any future product candidates. We cannot be certain that any product candidate will receive regulatory approval or will be successfully commercialized even if it receives regulatory approval.

If any of our current or future product candidates fail to demonstrate safety and efficacy in clinical trials, do not gain regulatory approval, or do not achieve market acceptance following regulatory approval and commercialization, we may never become profitable. Even if we achieve profitability in the future, we may not be able to sustain profitability in subsequent periods. Our prior losses, combined with expected future losses, have had and will continue to have an adverse effect on our stockholders’ equity and working capital. If we are unable to achieve and sustain profitability, the market value of our common stock will likely decline.

Because of the numerous risks and uncertainties associated with developing biopharmaceutical products, we are unable to predict the extent of any future losses or when, if ever, we will become profitable. Our expenses would increase significantly if we are required by the FDA, or any comparable foreign regulatory authority to perform studies in addition to those currently expected, or if there are any delays in completing our clinical trials or the development of any of our current and future product candidates.

If we are unable to raise capital when needed, or do not receive payments from our collaboration partnership agreements or royalty financing agreements, it could limit our ability to support our operations.

Developing pharmaceutical products, including conducting preclinical studies and clinical trials, is a time-consuming, expensive and uncertain process that takes years to complete. OurWe expect that our expenses are likely towill increase if and as we commence and advance additional preclinical studies and clinical trials for any future product candidates. If we obtain marketing approval for any product candidate, we expect to incur significant expenses related to development, product sales, marketing, distribution and manufacturing. Some of these expenses may be incurred in advance of marketing approval and could be substantial. Accordingly, we will be required to obtain further funding through public or private equity offerings, debt financings, royalty financing transactions, collaborations, licensing arrangements, government funding or other sources. Adequate additional financing may not be available to us on acceptable terms, or at all. Our failure to raise capital as and when needed would have a negative effect on our financial condition and our ability to pursue our business strategy.

Based on our current operating plan, we believe that our cash and cash equivalents as of MarchJune 31,30, 20262026, together with and including the net proceeds from the royalty financing transaction that closed in July 2026, will be sufficient to fund our operating expenses and capital expenditure requirements at least into 2028.the second half of 2029. During this period, we remainare focused on supportingadvancing GSKnext-generation medicines in the FDA approval process pursuant to our obligations under our GSK License Agreementimmunology and advancinginflammation otherfor corporatepatients activities,with includingserious exploringdiseases opportunitiesand tomajor growtreatment our portfolio of clinical-stage product candidates.gaps. Beyond this point, or in the event we change our current operating plan, we will need additional funding to support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of equity offerings, debt financings, government funding arrangements, collaborations, strategic alliances and marketing, distribution or licensing arrangements. If we are not able to secure adequate additional funding, we plan to make further reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned development activities, including:

Unless and until we can generate a substantial amount of revenue from our existing and future product candidates, we expect to finance our future cash needs through public or private equity offerings, debt financings, royalty financing transactions, collaborations, licensing arrangements and government funding arrangements. In addition, we may seek additional capital due to favorable market conditions or strategic considerations, even if we believe that we have sufficient funds for our current or future operating plans.

If we raise additional funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, or royalty financing transactions, we may have to relinquish valuable rights to our technologies, future revenue streams or product candidates or grant licenses on terms that may not be favorable to us.

Our operations to date have been limited to financing and staffing our company, and performing research and development activities to advance our existing or future product candidates. We have notonly yetrecently demonstrated an ability to successfully obtain marketing approval, through the FDA approval of Utebzi in June 2026, and have not yet demonstrated an ability to successfully manufacture a commercial scale product, or arrange for a third party to do so on our behalf, or conduct sales and marketing activities necessary for successful product commercialization. Consequently, predictions about our future success or viability may not be as accurate as they could be if we had a longer operating history or a history of successfully developing and commercializing pharmaceutical products.

We expect our financial condition and operating results to continue to fluctuate significantly from quarter to quarter and year to year due to a variety of factors, many of which are beyond our control. Accordingly, stockholders should not rely upon the results of any quarterly or annual periods as indications of future operating performance.performance

We may not achieve the milestones triggering payments to usus, inor may not receive royalty payments pursuant to, our existing,existing or any future,future license and collaboration or royalty financing agreements with third parties.

We have and may continue to seek third-party collaborators for development and commercialization of certain of our existing or future product candidates. Currently we are party to license and collaboration agreements with third parties as described in Note 99, License, Collaboration and Service Agreements, and Note 12, Subsequent Events, to our condensed consolidated financial statements appearing elsewhere in this Quarterly Report on Form 10-Q. Our likely collaborators for any other marketing, distribution, development, licensing or broader collaboration arrangements we may pursue include large and mid-size pharmaceutical companies, regional and national pharmaceutical companies and biotechnology companies.

We may derive revenue from research and development fees, license fees, milestone payments and royalties under any collaborative arrangement into which we enter. Our ability to generate revenue from these arrangements will depend on our collaborators’ abilities to successfully perform the functions assigned to them in these arrangements.arrangements and also the limitations of any royalty financing transaction we may have entered into. In addition, our collaborators may have the right to abandon research or development projects and terminate applicable agreements, including funding obligations, prior to or upon the expiration of the agreed upon terms. As a result, we can expect to relinquish some or all of the control over the future success of a product candidate that we license to a third party.

collaborators may not pursue development and commercialization of any of our current or future product candidates or may elect not to continue or renew development or commercialization programs based on clinical trial results, changes in the collaborators’ strategic focus or available funding or external factors, such as an acquisition, that divert resources or create competing priorities;

collaborators may not be able to develop, manufacture, market and sell any of our current or future product candidates and use our intellectual property without infringing or misappropriating the intellectual property and other proprietary rights of third parties;

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 current or future product candidates;

We will require additional funds to complete the development and potential commercialization of our existing and future product candidates. For any of our current or future product candidates, we may decide to collaborate with pharmaceutical and biotechnology companies for the development and potential commercialization of those product candidates. Moreover, we intend to utilize a variety of types of collaboration arrangements for the potential commercialization of our existing or future product candidates outside the United States. Whether we reach a definitive agreement for a collaboration will depend, among other things, upon our assessment of the collaborator’s resources and expertise, the terms and conditions of the proposed collaboration and the proposed collaborator’s evaluation of a number of factors. Those factors may include:

We are a clinical-stage biopharmaceutical company focusedadvancing onnext identifyinggeneration and developing novel treatmentsmedicines for rare diseases and diseasespatients with highimmune-mediated unmet need.diseases.

Our clinical-stage product candidate, tebipenem HBr, has completed a second Phase 3 trial, and we believe has the potential to be the first oral carbapenem to treat adult patients with complicated urinary tract infections (“cUTIs”), including pyelonephritis, caused by certain microorganisms. In September 2022, we entered into an exclusive licenselicensing agreement with GSK for theUtebzi development, manufacture and commercialization of (tebipenem HBr,pivoxil), which includes theincluded transfer of the IND application and the New Drug Application (“NDA”) ownership to GSK. We initially developed Utebzi as tebipenem HBr. In May 2025, we and GSK announced that the pivotal Phase 3 PIVOT-PO trial evaluating tebipenem HBrUtebzi met its primary endpoint and was stopped early for efficacy. GSK has submitted the data from the trial as part of an NDA Class 2 resubmission for tebipenem HBr to the FDA in December 2025,2025. whichOn hasJune been17, accepted2026, bywe the FDA.and GSK reportedannounced that the PrescriptionFDA Drugapproved UserUtebzi, Feean Actoral antibiotic for the treatment of complicated urinary tract infections (“PDUFA”cUTIs) dateincluding haspyelonephritis, beencaused setby ascertain Junesusceptible 18,pathogens 2026.in adult patients who have limited or no alternative oral treatment options.

We have experienced mostly net losses and significant cash outflows from cash used in operating activities since our inception. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development of SP001 and commercializationany of tebipenem HBr, or anyother product candidate we may develop in the future.future, as well as GSK’s commercialization of Utebzi. As of MarchJune 31,30, 2026, we had an accumulated deficit of $458.3$467.8 million, and cash and cash equivalents of $56.1$50.8 million. We expect to continue to incur significant expenses and operating losses for the foreseeable future. Based on our current operating plan, we believe that our cash and cash equivalents as of MarchJune 31,30, 20262026, together with and including the net proceeds from the royalty financing transaction that closed in July 2026, offset by the upfront payment the Company is obligated to pay to Innovent in connection with the Innovent Agreement, will be sufficient to fund our operating expenses and capital expenditure requirements at least into 2028.the second half of 2029. During this period, we remainare focused on supportingadvancing GSKnext-generation medicines in the FDA approval process pursuant to our obligations under our GSK License Agreementimmunology and advancinginflammation otherfor corporatepatients activities,with includingserious exploringdiseases opportunitiesand tomajor growtreatment our portfolio of clinical-stage product candidates.gaps. Beyond this point, or in the event we change our current operating plan, we will need additional funding to support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of equity offerings, debt financings, government funding arrangements, collaborations, strategic alliances and marketing, distribution or licensing arrangements. If we are not able to secure adequate additional funding, we will have to make further reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned development activities. The actions necessary to reduce spending under this plan at a level that mitigates the factors described above are not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern.

We will not generate revenue from product sales on SP001 or any future product candidates unless and until we successfully complete clinical development and obtain regulatory approval for any of oursuch product candidates.candidate. If we obtain regulatory approval for any of our futuresuch product candidatescandidate and do not enter into a commercialization partnership, we expect to incur significant expenses related to developing our internal commercialization capability to support product sales, marketing and distribution. Further, we expect to incur additional costs associated with our continued operation as a public company.

Tebipenem HBrPivoxil

In May 2025, we and GSK announced that the pivotal Phase 3 PIVOT-PO trial evaluating tebipenem HBr,pivoxil, an investigational oral treatment for cUTIs, including pyelonephritis, caused by certain microorganisms, met its primary endpoint and the trial was stopped early for efficacy. The decision followed a recommendation from an Independent Data Monitoring Committee (“IDMC”) that completed a pre-specified interim analysis of data from 1,690 patients enrolled in the trial.

Following the review of the interim analysis data by the IDMC, it was determined that the Phase 3 PIVOT-PO trial met the primary endpoint of non-inferiority of tebipenem HBrpivoxil compared to intravenous imipenem-cilastatin in hospitalized adult patients with cUTI, including pyelonephritis, on overall response (composite of clinical cure plus microbiological eradication) at the test-of-cure visit. The IDMC review did not identify any new safety concerns beyond what has been reported in other studies with tebipenem,tebipenem pivoxil, with diarrhea and headache as the two most reported adverse events. In December 2025, GSK resubmitted the NDA for tebipenem HBrpivoxil to the FDA. In accordance with the terms of the GSK License Agreement, we became entitled to receive a $25.0 million milestone payment upon the filing of the NDA with the FDA, which we received in February 2026.

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

Research and development expenses consist primarily of costs incurred for our research activities and the development of any of our current or future product candidates, which include:

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

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

obtainment and maintenance of patent, trade secret protection and regulatory exclusivity, both in the United States and internationally,internationally includingfor our abilitycurrent toand maintainfuture ourproduct license agreement with Meiji with respect to tebipenem HBrcandidates;

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

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

competition with other therapies; and a continued acceptable safety profile of any of our current our future product candidates, if approved.

A change in the outcome of any of these variables with respect to the development of any of our current or future product candidates would significantly change the costs and timing associated with the development of that product candidate. We may never succeed in obtaining regulatory approval for any of our current or future product candidates.

Interest income (expense) consists of interest income related to the significant financing component related to the GSK License AgreementAgreement, from the first quarter of 2024 through the third quarter of 2025, and interest earned on our cash equivalents, which are primarily invested in money market accounts, as well as interest earned on our investments in marketable securities.

Funding Received from Government Contracts and Collaborations

Since our inception, we were able to obtain partial funding for our research and development activities from government contracts, government tax incentives and collaboration arrangements. The classification within our statement of operations and comprehensive loss of the funding received under these arrangements was subject to management judgment based on the nature of the arrangements we enter into, the source of the funding and whether the funding is considered central to our business operations.

CMOs in connection with the production of preclinical study and clinical trial materials;

CROs in connection with preclinical studies and clinical studiestrials; and investigative sites in connection with clinical trials.

Comparison of the Three Months Ended MarchJune 31,30, 2026 and 2025

The following table summarizes our results of operations for the three months ended MarchJune 31,30, 2026 and 2025 (in thousands):

No grant revenue was recognized during the three months ended MarchJune 31,30, 2026. Grant revenue recognized during the three months ended March 31, 2025 consisted of the reimbursement of qualifying expenses incurred in connection with our variousBARDA government awards.contract. The decrease in grant revenue during the three months ended MarchJune 31,30, 2026 was primarily due to a decrease of $0.7$2.4 million of committed funds remaining available under our BARDA contract for tebipenem HBr,pivoxil. On July 6, 2026, we and aBARDA decreasemutually ofagreed $0.1to millionterminate inthe qualifyingcontract expensesbetween incurred under our U.S. National Institute of Allergyus, and InfectiousBARDA Diseasesdeobligated (“NIAID”)all award relating to SPR206. We ceased development of SPR206 and the NIAID award was terminated in April 2025 and the committedremaining funds under the contract. We will not receive any additional funding from BARDA contractunder havethis been fully utilized by the Company.contract.

Direct costs related to our tebipenem HBrpivoxil program decreased by $8.3$5.4 million during the three months ended MarchJune 31,30, 2026, compared to the three months ended MarchJune 31,30, 2025, due to decreased clinical activities related to our pivotal Phase 3 clinical trial of tebipenem HBr,pivoxil, which was stopped early for efficacy during the first half of 2025.2025 and later approved by the FDA in June 2026.

Direct costs related to our SPR720 program decreased by $0.4$0.3 million during the three months ended MarchJune 31,30, 2026, as compared to the three months ended MarchJune 31,30, 2025, due to the cessation of development and subsequent termination of the SPR720 program, which was announced in November 2025.

The decrease in personnel-related costs of $1.7$1.3 million was primarily a result of decreased headcount costs in our research and development functions between the periods. Personnel-related costs for the three months ended MarchJune 31,30, 2026 and 2025 included share-based compensation expense of $0.3 million and $0.5$0.4 million, respectively.

The decrease in personnel-related costs of $1.8$1.6 million was primarily a result of decreased headcount costs in our general and administrative functions between the periods. Personnel-related costs for the three months ended MarchJune 31,30, 2026 and 2025 included share-basedstock-based compensation expense of $0.8$0.5 million and $1.0$0.3 million, respectively.

The decreaseincrease in professional and consultant fees of $0.6$2.2 million was primarily due to aan decreaseincrease in business development, legal and consulting expenses incurred in the three months ended MarchJune 31,30, 2026.

Other income (expense), net was $0.3$0.4 million for the three months ended MarchJune 31,30, 2026, compared to $0.9$0.7 million for the three months ended MarchJune 31,30, 2025. Total other income for the three months ended MarchJune 31,30, 2026, included $0.4 million of interest income, offset by immaterial fluctuations in unrealized foreign currency. Total other income for the three months ended June 30, 2025, included $0.9$0.7 million of interest income, of which $0.4 million related to the significant financing component recognized under the GSK License Agreement, offset by immaterial fluctuations in unrealized foreign currency.