Item 1A. Risk Factors.

Investing in our common stock involves a high degree of risk. You should carefully consider the risks and uncertainties described below, together with all of the other information contained in this Annual Report, including our consolidated financial statements and their related notes included elsewhere in this Annual Report and the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” before making an investment decision. If any of the following risks actually occurs, our business, prospects, operating results, and financial condition could suffer materially, the trading price of our common stock could decline, and you could lose all or part of your investment. The risks and uncertainties described below are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently believe to be immaterial also may materially and adversely affect our business, prospects, operating results, and financial condition.

Summary of Selected Risk Factors Associated with Our Business

Our business is subject to a number of risks of which you should be aware before making a decision to invest in our common stock. These risks are more fully described in this “Risk Factors” section, including the following:

•We are a clinical-stage biopharmaceutical company with a limited operating history and no history of commercializing products and have incurred substantial losses since our inception. We anticipate incurring substantial and increasing losses for the foreseeable future and may never achieve or maintain profitability.

•Preclinical and clinical development involves a lengthy and expensive process, with an uncertain outcome, and results of earlier studies and trials may not be predictive of future trial results. We may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our current product candidates or any future product candidates.

•We will require substantial additional financing to achieve our goals, and failure to obtain additional capital when needed, or on acceptable terms to us, could cause us to delay, limit, reduce, or terminate our product development or future commercialization efforts.

•We rely heavily on the biomarker data gathered from our Platform. We currently anticipate that certain of our therapeutic product candidates will require us to develop and obtain FDA approval of a companion diagnostic for such therapeutic product candidates. We expect to initiate discussions with the FDA concerning the development of companion diagnostics at our end of Phase 2 meetings with respect to ALTO-100 and ALTO-300. If the FDA does not agree with our biomarker-based approach, or if we are unable to successfully develop and obtain regulatory approval for certain companion diagnostic tools needed to leverage our Platform, or experience significant delays in doing so, our business will be materially harmed.

•Even if we complete the necessary preclinical studies and clinical trials, the marketing approval process is expensive, time-consuming, and uncertain and may prevent us or any future collaboration partners from obtaining approvals for the commercialization of our product candidates, and additional time may be required to obtain marketing authorization for any of our product candidates that we develop as drug/device combination products.

•Even if our product candidates receive regulatory approval, they may fail to achieve the degree of market acceptance by physicians, patients, third-party payors and others in the medical community necessary for commercial success, in which case we may not generate significant revenues or become profitable.

•The successful commercialization of our product candidates, if approved, will depend in part on the extent to which governmental authorities and health insurers establish coverage, adequate reimbursement levels, and favorable pricing policies. Failure to obtain or maintain coverage and adequate reimbursement for our product candidates could limit our ability to market those products and decrease our ability to generate revenue.

•Our business depends on the success of our product candidates. If we are ultimately unable to successfully commercialize our product candidates, or experience significant delays in doing so, our business will be materially harmed.

•We rely on, and intend to continue to rely on, our internal clinical development expertise to conduct our current and future clinical trials, including internal teams and systems as well as external vendors and CROs. If our team is unable to execute according to our strategy, comply with regulatory requirements, or run trials effectively, our ability to obtain regulatory approval may be delayed and our business could be materially harmed.

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•We are currently subject to and may be subject to additional future securities class action litigation and derivative claims.

•The terms of our Loan and Security Agreement, as amended, and the Convertible Grant Agreement place restrictions on our operating and financial flexibility and may cause dilution to our stockholders. If we raise additional capital through debt financing, the terms of any new debt could further restrict our ability to operate our business or result in further dilution to investors in our common stock.

•Competitive products may reduce or eliminate the commercial opportunity for our product candidates for our current or future indications. If our competitors develop technologies or product candidates more rapidly than we do, or their technologies are more effective or safer than ours, our ability to develop and successfully commercialize our current products may be adversely affected.

•We are dependent on the services of our management and other clinical and scientific personnel, including our internal clinical operations team, and if we are not able to retain these individuals or recruit additional management or clinical and scientific personnel, our business will suffer.

•If we are unable to obtain and maintain sufficient intellectual property protection for our Platform, technologies, and product candidates and any future product candidates we may develop, or if the scope of the intellectual property protection obtained is not sufficiently broad, our competitors or other third parties could develop and commercialize products similar or identical to ours, and our ability to successfully develop and commercialize our product candidates may be adversely affected. Further, our issued composition of matter patents covering our pharmaceutical product candidates may expire at such a date that our patents may not prevent competitors from developing, making, and marketing a product that is identical to our product candidates after expiration of any applicable regulatory exclusivities.

•Our rights to develop and commercialize our product candidates, our Platform, or other technologies are subject, in large part, to the terms and conditions of licenses granted to us by others, such as Stanford, Sanofi, and MedRx. The terms of these licenses may be inadequate to protect our competitive position on products or product candidates for a sufficient amount of time. For example, our patent rights under the terms of our exclusive license agreement with Stanford are only exclusive until December 2029, at which time such rights will become nonexclusive, and our rights under certain technology relating to the inventions covered by such patents are nonexclusive. Further, if we fail to comply with our obligations in the agreements under which we in-license or acquire development or commercialization rights to product candidates, or data from third parties, we could lose such rights that are important to our business.

•Patent terms may be inadequate to protect our competitive position on products or product candidates for a sufficient amount of time.

•We may have conflicts with our current or future licensors or collaborators that could delay or prevent the development or commercialization of our product candidates.

•Failure or perceived failure to comply with existing or future laws, regulations, contracts, self-regulatory schemes, standards, and other obligations related to data privacy and security (including security incidents) could harm our business. Compliance or the actual or perceived failure to comply with such obligations could increase the costs of our product candidates, limit their use or adoption, and otherwise negatively affect our operating results and business.

Risks Related to Our Limited Operating History, Financial Position, and Need for Capital

We are a clinical-stage biopharmaceutical company with a limited operating history and no history of commercializing products, which may make it difficult to evaluate our approach to the discovery and development of product candidates and the prospects for our future viability.

We are a clinical-stage biopharmaceutical company with a limited operating history. We were formed in 2019 and our operations to date have been limited to organizing, staffing, and financing our company, in-licensing our technology, and conducting research and development activities, including developing our Platform, conducting clinical trials for our product candidates, and establishing our intellectual product portfolio. If we are successful in achieving regulatory approval

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for our product candidates, we will eventually need to transition from a company with a development focus to a company capable of supporting commercial activities. We may not be successful in such a transition.

Our approach to the discovery and development of product candidates based on our Platform is unproven, and we do not know whether we will be able to develop any product candidates that succeed in clinical development or products of commercial value. Moreover, as an organization, we have not yet demonstrated an ability to obtain regulatory approvals, manufacture a commercial-scale product or arrange for a third party to do so on our behalf, conduct sales and marketing activities necessary for successful product commercialization, or generate revenues. We may encounter unforeseen expenses, difficulties, complications, delays, and other known or unknown factors in achieving our business objectives. Accordingly, you should consider our prospects in light of the costs, uncertainties, delays, and difficulties frequently encountered by companies in clinical development, especially clinical-stage biopharmaceutical companies such as ours. Any predictions you make 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 have incurred substantial losses since our inception. We anticipate incurring substantial and increasing losses for the foreseeable future and may never achieve or maintain profitability.

Investment in biopharmaceutical product development is highly speculative because it entails substantial upfront capital expenditures and significant risk that any potential product candidate will fail to demonstrate adequate efficacy or an acceptable safety profile, gain regulatory approval, and become commercially viable. We have no products approved for commercial sale and have not generated any revenue from product sales to date. As a result, we are not profitable, have incurred substantial losses in each period since our inception, and we expect to incur significant losses for the foreseeable future.

For the years ended December 31, 2025, and 2024, our net losses were approximately $63.2 million and $61.4 million, respectively. As of December 31, 2025, we had an accumulated deficit of approximately $201.6 million. Substantially all of our losses have resulted from expenses incurred in connection with the acquisition and development of our pipeline and Platform, research and development, and clinical trial costs, and from general and administrative costs associated with our operations. We expect to incur significant losses for the foreseeable future, and we expect these losses to increase as we continue our development of our product candidates. We anticipate that our expenses will increase substantially if, and as, we:

•conduct further clinical trials for ALTO-207, ALTO-100, ALTO-300, ALTO-101, ALTO-203, and ALTO-202, and advance our preclinical programs into the clinic;

•identify additional product candidates and acquire rights from third parties to those product candidates through licenses or other acquisitions, and conduct development activities, including preclinical studies and clinical trials;

•procure the manufacturing of preclinical, clinical, and commercial supply of our current and future product candidates;

•seek regulatory approvals for our current product candidates or any future product candidates;

•commercialize our current product candidates or any future product candidates, if approved;

•take steps toward our goal of being an integrated biopharmaceutical company capable of supporting commercial activities, including establishing sales, marketing and distribution infrastructure;

•attract, hire, and retain qualified clinical, scientific, operations, and management personnel;

•add and maintain operational, financial, and information management systems;

•protect, maintain, enforce, and defend our rights in our intellectual property portfolio;

•defend against third-party interference, infringement, and other intellectual property claims, if any;

•address any competing therapies and market developments;

•experience any delays in our preclinical studies or clinical trials and regulatory approval for our product candidates due to macroeconomic conditions, geopolitical conflicts, or other global events; and

•incur additional costs, including legal, accounting, and other expenses, associated with operating as a public company.

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We have no product candidates approved for commercial sale and have not generated any revenue from the sale of products. Our ability to become and remain profitable depends on our ability to generate revenue. We do not expect to generate significant revenue, if any, unless and until we, either alone or with a collaborator, are able to obtain regulatory approval for, and successfully commercialize, one of our product candidates for our initial and potential additional indications, or any other product candidates we may develop.

Successful commercialization will require achievement of many key milestones, including demonstrating safety and efficacy in clinical trials, obtaining regulatory, including marketing approval for these product candidates, manufacturing, marketing, and selling those products for which we, or any of our future collaborators, may obtain regulatory approval, satisfying any post-marketing requirements, and obtaining reimbursement for our products from private insurance or government payors. Because of the uncertainties and risks associated with these activities, we are unable to accurately and precisely predict the timing and amount of revenues, the extent of any further losses, or if or when we might achieve profitability. We and any future collaborators may never succeed in these activities and, even if we do, or any future collaborators do, we may never generate revenues that are large enough for us to achieve profitability. Even if we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Additionally, our expenses could increase if we are required by the FDA, MHRA, or any comparable foreign regulatory authority to perform clinical trials in addition to those currently expected, or if there are any delays in completing our clinical trials or the development of any of our product candidates.

Even if we succeed in commercializing one or more product candidates, we expect to incur substantial development costs and other expenditures to develop and market additional product candidates. We may also encounter unforeseen expenses, difficulties, complications, delays, and other unknown factors that may adversely affect our business. The size of our future net losses will depend, in part, on the rate of future growth of our expenses and our ability to generate revenue or raise additional capital. Our prior losses and expected future losses have had and will continue to have an adverse effect on our stockholders’ equity and our working capital. Our failure to become and remain profitable may depress the market price of our common stock and could impair our ability to raise capital, expand our business, diversify our product offerings, or continue our operations. If we continue to suffer losses as we have in the past, you may not receive any return on your investment and may lose your entire investment.

We will require substantial additional financing to achieve our goals, and failure to obtain additional capital when needed, or on acceptable terms to us, could cause us to delay, limit, reduce, or terminate our product development or future commercialization efforts.

Our operations have consumed substantial amounts of cash since our inception. We expect to continue to spend substantial amounts of cash to conduct further research and development, preclinical studies, and clinical trials of our current and future product candidates, to seek regulatory approvals for our current product candidates, and to launch and commercialize any products if we receive regulatory approval.

As of December 31, 2025, we had $177.0 million of cash, cash equivalents and restricted cash. Based upon our current operating plan, we believe that our existing cash and cash equivalents as of the date of filing of this Annual Report, will enable us to fund our operating expenses and capital expenditure requirements for at least the next 12 months. Our future capital requirements and the period for which our existing resources will support our operations may vary significantly from what we expect, and we will in any event require additional capital in order to complete clinical development of any of our current programs. Our monthly spending levels will vary based on new and ongoing development and corporate activities. Because the length of time and activities associated with development of our programs and product candidates is highly uncertain, we are unable to estimate the actual funds we will require for development and any approved marketing and future commercialization activities, if any. Our future capital requirements will depend on many factors, including:

•the scope, timing, progress, costs, and results of discovery, preclinical development, and clinical trials for our current or future product candidates;

•the number of clinical trials required for regulatory approval of our current or future product candidates;

•the costs, timing, and outcome of regulatory review of any of our current or future product candidates;

•the costs associated with acquiring or licensing additional product candidates, technologies, or assets, including the timing and amount of any milestones, royalties, or other payments due in connection with our acquisitions and licenses;

•the cost of manufacturing clinical and commercial supplies of our current or future product candidates;

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•the costs and timing of preparing, filing, and prosecuting patent applications, maintaining and enforcing our intellectual property rights, and defending any intellectual property-related claims, including any claims by third parties that we are infringing upon their intellectual property rights;

•the effectiveness of our Platform in identifying target patient populations and utilizing our approach to enrich our patient population in our clinical trials;

•our ability to maintain existing, and establish new, strategic collaborations or other arrangements and the financial terms of any such agreements, including the timing and amount of any future milestone, royalty, or other payments due under any such agreement;

•the costs and timing of future commercialization activities, including manufacturing, marketing, sales, and distribution, for any of our product candidates for which we receive marketing approval;

•the revenue, if any, received from commercial sales of our product candidates for which we receive marketing approval;

•expenses to attract, hire, and retain skilled personnel;

•the costs of operating as a public company;

•our ability to establish a commercially viable pricing structure and obtain approval for coverage and adequate reimbursement from third-party and government payors;

•our ability to mitigate the impact of adverse macroeconomic conditions or other geopolitical events, the ongoing conflicts between Ukraine and Russia and in the Middle East, geopolitical tensions, inflation, fluctuating interest rates, tariffs, or other factors on our preclinical and clinical development or operations;

•the effect of competing technological and market developments; and

•the extent to which we acquire or invest in business, products, and technologies.

We will require substantial additional capital to achieve our business objectives. Additional funds may not be available on a timely basis, on favorable terms or at all, and such funds, if raised, may not be sufficient to enable us to continue to implement our long-term business strategy. Market volatility resulting from adverse macroeconomic conditions or geopolitical events, including the ongoing conflicts between Ukraine and Russia and in the Middle East, geopolitical tensions, inflation, fluctuating interest rates, tariffs, or other factors may further adversely impact our ability to access capital as and when needed. Until such time, if ever, as we can generate substantial product revenue, we expect to finance our cash needs through equity offerings, debt financings, or other capital sources, including potential collaborations, licenses, and other similar arrangements. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect your rights as a holder of our common stock. Any future debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, selling or licensing our assets, making capital expenditures, declaring dividends, or encumbering our assets to secure future indebtedness. Such restrictions could adversely impact our ability to conduct our operations and execute our business plan.

If we raise additional funds through future collaborations, licenses, and other similar arrangements, we may have to relinquish valuable rights to our future revenue streams or product candidates, or grant licenses on terms that may not be favorable to us and/or that may reduce the value of our common stock. If we are unable to raise additional funds through equity or debt financings or other arrangements when needed or on terms acceptable to us, we would be required to delay, limit, reduce, or terminate our product development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

The obligations from our license and asset acquisition agreements may cause dilution to our stockholders, may be a drain on our cash resources, or may cause us to incur debt obligations to satisfy the payment obligations.

Under the terms of certain of our license and acquisition agreements, the counterparties to such agreements are entitled to substantial contingent payments upon the occurrence of certain events. For example, under the terms of our asset purchase agreement with Chase, we will be obligated to pay Chase up to an aggregate of $71.5 million in clinical, regulatory, and sales milestone payments with respect to ALTO-207, of which $41.0 million in aggregate are tied to commercial success of the product candidates, and certain of these potential milestone payments may be made, at Chase’s election, as restricted shares of our common stock, subject to an overall limitation of a maximum of 5,387,353 shares of common stock that may be issued pursuant to this agreement. Under the terms of our license agreement with Sanofi, we will be required to pay

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Sanofi up to an aggregate amount in the low-mid double digit millions upon the achievement of certain one-time development and regulatory approval milestones with respect to ALTO-101, and, if regulatory approval is achieved, up to an aggregate amount of $102.0 million in commercial milestone payments and a tiered royalty on aggregate annual worldwide net sales at percentages ranging from the mid-to-high single digits. Under the terms of our license agreement with Cerecor, we will be required to pay Cerecor or Merck, depending on the milestone, up to an aggregate of $59.1 million if we achieve certain development, regulatory, and first commercial sale milestones for ALTO-202. If we successfully commercialize ALTO-202, we will be required to pay Merck sales milestones in an amount of up to $15.0 million. Beginning on the date of our first commercial sale of ALTO-202, we will also be obligated to pay Merck and Cerecor tiered royalties on aggregate annual worldwide net sales at percentages in the high single digits, in addition to potential payments in respect of a companion diagnostic product. Pursuant to our asset purchase agreement with Teva, pursuant to which we acquired the rights to ALTO-203, we may be required to pay up to an aggregate of $27.0 million upon the achievement of certain development and regulatory approval milestones ($0.5 million of which was paid to Teva in connection with the initiation of our Phase 2 POC trial evaluating ALTO-203), and up to $35.0 million for the achievement of certain tiered sales milestones, as well as tiered royalties on worldwide annual net sales at percentages ranging from the mid-single-digit to ten percent. Pursuant to our joint development and license agreement with MedRx, we are required to pay MedRx up to an aggregate of $11.0 million for the achievement of certain development and first commercial sale milestones for ALTO-101 with respect to a first indication, an additional milestone in the mid single digit millions for each additional approved distinct indication for ALTO-101, as well as sales milestones based on the achievement of specified levels of aggregate annual worldwide net sales of up to $110.0 million in the aggregate and a mid-single digit royalty on annual, worldwide net sales. In April 2024, we achieved a milestone under the MedRx Agreement and paid MedRx approximately $0.8 million in cash and issued MedRx 46,875 shares of our common stock. If we achieve certain development and regulatory approval milestones for a product that contains ALTO-100 or is otherwise derived from assets we acquired from Palisade we will be required to pay Palisade up to an aggregate of $4.5 million. See “Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Contractual Obligations and Commitments” in this Annual Report for additional information regarding these agreements.

In order to satisfy our obligations to make these payments, if and when they are triggered, we may need to issue equity or convertible debt securities that may cause dilution to our stockholders, or we may use our existing cash and cash equivalents or incur debt obligations to satisfy the payment obligations in cash, which may adversely affect our financial position. In addition, these obligations may impede our ability to raise money in future public offerings of debt or equity securities or to obtain a third-party line of credit.

Risks Related to Product Candidate Development and Commercialization

Preclinical and clinical development involves a lengthy and expensive process, with an uncertain outcome, and results of earlier studies and trials may not be predictive of future trial results. We may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our current product candidates or any future product candidates.

All of our product candidates are in preclinical or clinical development and their risk of failure is high. In particular, our approach to utilizing our Platform to identify biomarkers and conducting clinical trials in patient populations expressing certain biomarkers has not been validated and may not prove to be successful. It is impossible to predict when or if any of our product candidates will receive regulatory approval. To obtain the requisite regulatory approvals to commercialize any product candidates, we must demonstrate through lengthy, complex, and expensive clinical trials that our product candidates are safe and effective in patient populations identified by our Platform for the relevant indication. Preclinical and clinical testing can take many years to complete, and its outcome is inherently uncertain. There is typically a high rate of failure of product candidates proceeding through clinical trials, and failure can occur at any time during the preclinical study or clinical trial process, despite promising preclinical or clinical results. The results of preclinical studies and early clinical trials of our product candidates may not be predictive of the results of later-stage clinical trials, and results in one indication may not be predictive of results to be expected for the same product candidate in another indication. For example, in October 2024, we reported that our Phase 2b trial of ALTO-100 in patients with MDD did not meet its primary endpoint. Differences in trial design between early-stage clinical trials and later-stage clinical trials make it difficult to extrapolate the results of earlier clinical trials to later clinical trials. A number of companies in the biopharmaceutical industry have suffered significant setbacks in advanced clinical trials due to lack of efficacy or unfavorable safety profiles, notwithstanding promising results in earlier trials. Additionally, because ALTO-207 is a fixed combination drug product, we will need to demonstrate that each component of the product candidate makes a contribution to the claimed effect for TRD. Under the 505(b)(2) pathway, existing safety from the approved reference listed drugs will be taken into account, and FDA will still need to consider the two drugs in combination for the TRD indication as part of their safety review. Certain of our product candidates were previously subject to all-comer population studies and were not progressed for further

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development or did not achieve statistically significant outcomes. For example, ALTO-100 demonstrated numerical improvements in MADRS scores but did not achieve statistically significant outcomes in a prior all-comer population study. There can be no assurance that our results to date for these product candidates in our biomarker-characterized patient populations will continue or that the results of our trials will continue to differ from the outcomes of prior all-comer studies. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their product candidates achieved promising results have nonetheless failed to obtain marketing approval of such product candidates. We may be unable to establish clinical endpoints that applicable regulatory authorities would consider clinically meaningful.

In addition, our approach of identifying biomarkers and conducting clinical trials in patient populations expressing those biomarkers is unique, unproven, and does not have significant precedent with the FDA and the FDA has, thus far, not affirmatively adopted our approach. Commencing any future clinical trials is subject to finalizing the trial protocol and submitting an IND to the FDA or similar application to initiate a clinical study to a comparable foreign regulatory authority. Even after we make our submission, the FDA, MHRA, or comparable foreign regulatory authorities could disagree that we have satisfied their requirements to commence our clinical trials or disagree with our study design, which may require us to complete additional preclinical studies or amend our protocols or impose stricter conditions on the commencement of clinical trials, which may lead to delays and increase the costs of our preclinical development programs. The FDA also has the authority to require a panel of experts, referred to as an Advisory Committee, to deliberate on the adequacy of the safety and efficacy data to support approval. The opinion of the Advisory Committee, although not binding, could have a significant impact on our ability to obtain approval of any product candidates. Similar decisions may also be made by foreign regulatory authorities and have similar impact.

Most product candidates that commence clinical trials are never approved as products and there can be no assurance that any of our current or future clinical trials will ultimately be successful or support the approval of our current or any future product candidates.

We expect to continue to rely on our clinical trial sites and clinical trial teams to ensure the proper and timely conduct of our clinical trials, including the participant enrollment process, and we have limited influence over their performance. In addition, we may in the future enter into collaboration agreements pursuant to which our collaborator would be responsible for clinical development. We or our collaborators may experience delays in initiating or completing clinical trials due to unforeseen events or otherwise, that could delay or prevent our ability to receive marketing approval or commercialize our current and any future product candidates, including:

•regulators, such as the FDA, MHRA, or comparable foreign regulatory agencies, IRBs, or ethics committees may impose additional requirements before permitting us to initiate a clinical trial, may not authorize us or our investigators to commence or conduct a clinical trial at a prospective trial site, may not allow us to amend trial protocols, or regulators may disagree as to the design or implementation of our clinical trials and require that we modify or amend our clinical trial protocols;

•we may experience delays in reaching, or fail to reach, agreement on acceptable terms with clinical trial sites, the terms of which can be subject to extensive negotiation and may vary significantly among trial sites;

•delays in identifying, recruiting, and training suitable clinical investigators;

•IRBs refusing to approve, suspending, or terminating the trial at an investigational site, precluding enrollment of additional subjects, or withdrawing their approval of the trial, and similar measures from ethics committees;

•changes or amendments to the clinical trial protocol;

•clinical trial sites may deviate from the trial protocol or drop out of a trial;

•failure by any of our third-party contractors to perform in accordance with GCP requirements or applicable regulatory rules and guidelines in other countries;

•the number of participants required for clinical trials may be larger than we anticipate, we may experience difficulty in finding and enrolling sufficient qualified patients for our biomarker-guided trials, enrollment in clinical trials may be slower than we anticipate, or participants may drop out or fail to return for post-treatment follow-up at a higher rate than we anticipate;

•subjects may fail to enroll or remain in our trials at the rate we expect, or fail to return for post-treatment follow-up, including subjects failing to remain in our trials due to movement;

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•patients choosing an alternative product for the indications for which we are developing our product candidates, or participating in competing clinical trials;

•the cost of clinical trials may be greater than we anticipate;

•the quality or quantity of data relating to our product candidates or other materials necessary to conduct our clinical trials may be inadequate to initiate or complete a given clinical trial;

•we may experience difficulties in manufacturing, or fail to manufacture, sufficient quantities of our product candidates for use in clinical trials;

•we may experience delays in developing and validating our companion diagnostics to be used in a clinical trial, if applicable;

•subjects experiencing severe or serious unexpected drug-related adverse effects;

•reports from clinical testing conducted by other companies of other therapies in the same class of agents that could be considered similar to our product candidates may raise safety, tolerability, or efficacy concerns about our product candidates;

•we may lack adequate funding to initiate or continue one or more of our clinical trials;

•selection of clinical endpoints that require prolonged periods of clinical observation or extended analysis of the resulting data;

•a facility manufacturing our product candidates or any of their components being ordered by the FDA, MHRA, or comparable foreign regulatory authorities to temporarily or permanently shut down due to violations of cGMP, regulations or other applicable requirements, or cross-contaminations of product candidates in the manufacturing process;

•changes to our manufacturing processes may be necessary or desired;

•third-party clinical investigators may lose the licenses or permits necessary to perform our clinical trials and may fail to perform our clinical trials on our anticipated schedule or consistent with the clinical trial protocol, GCP, or other regulatory requirements;

•third-party contractors being unwilling or unable to satisfy their contractual obligations to us in a timely or accurate manner;

•third-party contractors could be debarred or suspended or otherwise penalized by the FDA or other government or regulatory authorities for violations of regulatory requirements, in which case we may need to find a substitute contractor, and we may not be able to use some or all of the data produced by such contractors in support of our marketing applications; and

•clinical trials of our product candidates may fail to show appropriate safety, tolerability, or efficacy, may produce negative or inconclusive results, or may otherwise fail to improve on the existing standard of care, and we may decide, or regulators may require us, to conduct additional clinical trials or we may decide to abandon product development programs.

Clinical trials must be conducted in accordance with the FDA and other applicable regulatory authorities’ legal requirements, regulations, and guidelines, and remain subject to oversight by these governmental agencies and ethics committees or IRBs at the medical institutions where such clinical trials are conducted. We could encounter delays if a clinical trial is suspended or terminated by us, the IRBs or ethics committees of the institutions in which such trials are being conducted, the FDA, MHRA, or comparable foreign regulatory authorities, or the Data Safety Monitoring Board, or the DSMB, for such trial. A suspension or termination may be imposed due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical trial protocols, adverse findings from inspection of the clinical trial operations or trial site by the FDA, MHRA, or comparable foreign regulatory authorities, unforeseen safety issues or adverse side effects, failure to establish or achieve clinically meaningful trial endpoints, changes in governmental regulations or administrative actions, or lack of adequate funding to continue the clinical trial. In addition, changes in regulatory requirements and policies may occur, and we may need to amend clinical trial protocols to comply with these changes. Amendments may require us to resubmit our clinical trial protocols to regulators or to IRBs or ethics committees for reexamination, which may impact the costs, timing, or successful completion of a clinical trial.

Many of the factors that cause, or lead to, a delay in the commencement or completion of, or the termination or suspension of, clinical trials may also ultimately lead to the denial of regulatory approval of our product candidates. Further, the FDA

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may disagree with our interpretation of data from clinical trials, or may change the requirements for approval even after they have reviewed and commented on the design for our clinical trials.

We currently conduct preclinical testing of our patch formulation drug/device combination product candidate with our collaborator MedRx and may in the future, conduct preclinical and clinical research in collaboration with other academic, pharmaceutical, and biotechnology entities in which we combine our development efforts with those of our collaborators. Such collaborations may be subject to additional delays because of the management of the trials, contract negotiations, the need to obtain agreement from multiple parties, and may increase our future costs and expenses.

In addition, certain of our primary or secondary endpoints in our clinical trials, including our currently ongoing Phase 2b clinical trials of ALTO-100 in patients with bipolar depression and ALTO-300, and our currently ongoing Phase 2 clinical trial of ALTO-101 in patients with CIAS, involve subjective assessments by physicians and/or patients, which can increase the uncertainty of clinical trial outcomes. For example, primary endpoints include the change in MADRS score from baseline to week six, which requires patients or examiners to undertake a questionnaire regarding ten symptoms at the beginning and end of the trial. This and other assessments are inherently subjective, which can increase the variability of clinical results across clinical trials and create a significant degree of uncertainty in determining overall clinical benefit. Such subjectivity may cause the indications we study to be more difficult to evaluate than indications for which clinical trials are structured with more objective endpoints, as such indications are often subject to high placebo effect which may make it more challenging to isolate the beneficial effects of our product candidates. Accordingly, these subjective assessments can complicate clinical trial design, adversely impact the ability of a study to show a statistically significant improvement, and generally adversely impact a clinical development program by introducing additional uncertainties.

Our product development costs will increase if we experience delays in clinical testing or marketing approvals. We do not know whether any of our clinical trials will begin as planned, will need to be restructured, or will be completed on schedule, or at all. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates and may allow our competitors to bring products to market before we do, potentially impairing our ability to successfully commercialize our product candidates. Any delays or increase in costs in our clinical development programs may harm our business, financial condition, results of operations, and prospects.

If the FDA does not conclude that ALTO-207 satisfies the requirements for the Section 505(b)(2) regulatory approval pathway, or if the requirements under Section 505(b)(2) are not as we expect, the approval pathway for ALTO-207 will likely take significantly longer, cost significantly more and entail significantly greater complications and risks than anticipated and may not be successful.

We intend to seek FDA approval of ALTO-207 through the Section 505(b)(2) regulatory pathway. The Drug Price Competition and Patent Term Restoration Act of 1984, or the Hatch-Waxman Amendments, added Section 505(b)(2) to the FDCA. Section 505(b)(2) permits the filing of an NDA where at least some of the information required for approval comes from studies that were not conducted by or for the applicant and for which the applicant has not obtained a right of reference. Section 505(b)(2) allows an NDA we submit to FDA to rely in part on data in the public domain or the FDA’s prior conclusions regarding the safety and effectiveness of approved compounds, which could expedite the development program for ALTO-207 by potentially decreasing the amount of clinical data that we would need to generate in order to obtain FDA approval. If the FDA does not allow us to pursue the Section 505(b)(2) regulatory pathway as anticipated, we may need to conduct additional clinical trials, provide additional data and information and meet additional standards for regulatory approval. If this were to occur, the time and financial resources required to obtain FDA approval would likely substantially increase. Moreover, inability to pursue the Section 505(b)(2) regulatory pathway could result in new competitive products reaching the market more quickly than ALTO-207, which would likely materially adversely impact our competitive position and prospects. Even if we are allowed to pursue the Section 505(b)(2) regulatory pathway, we cannot assure you that ALTO-207 will receive the requisite approvals for commercialization.

In addition, notwithstanding the approval of a number of products by the FDA under Section 505(b)(2), certain brand-name pharmaceutical companies and others have objected to the FDA’s interpretation of Section 505(b)(2). If the FDA’s interpretation of Section 505(b)(2) is successfully challenged, the FDA may change its 505(b)(2) policies and practices, which could delay or even prevent the FDA from approving any NDA that we submit under Section 505(b)(2). In addition, the pharmaceutical industry is highly competitive, and Section 505(b)(2) NDAs are subject to special requirements designed to protect the patent rights of sponsors of previously approved drugs that are referenced in a Section 505(b)(2) NDA. These requirements may give rise to patent litigation and mandatory delays in approval of our NDAs for up to 30 months or longer depending on the outcome of any litigation. It is not uncommon for a manufacturer of an approved product to file a citizen petition with the FDA seeking to delay approval of, or impose additional approval requirements for,

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pending competing products. If successful, such petitions can significantly delay, or even prevent, the approval of the new product. However, even if the FDA ultimately denies such a petition, the FDA may substantially delay approval while it considers and responds to the petition.

We may find it difficult to enroll patients in our clinical trials. If we encounter difficulties enrolling subjects in our clinical trials, our clinical development activities could be delayed or otherwise adversely affected.

Patient enrollment is a significant factor in the timing of clinical trials, and the timing of our clinical trials depends, in part, on the speed at which we can recruit patients to participate in our trials, as well as completion of required follow-up periods. For example, we have, and may in the future, delay certain milestones due to enrollment or other factors (see “–If we do not achieve our projected development goals in the time frames we announce and expect, the commercialization of our products may be delayed”). We may not be able to initiate or continue clinical trials for our product candidates if we are unable to identify and enroll a sufficient number of eligible patients to participate in these trials to such trial’s conclusion as required by the FDA, MHRA, or comparable foreign regulatory authorities. Subject enrollment is affected by many factors including the size and nature of the patient population, competing clinical trials in the same or similar indications or at the same trial site, the severity of the disease or condition under investigation, the availability and efficacy of approved drugs and diagnostics for the disease or condition under investigation, the number and location of clinical sites, the proximity of patients to clinical sites, willingness of patients to participate in a decentralized clinical trial, should we conduct future trials in this manner, the eligibility and exclusion criteria for the trial, perceived risks and benefits of the product candidate under study, the design of the clinical trial, continued enrollment of prospective patients by clinical trial sites, the risk that enrolled patients will not complete a clinical trial, our ability to recruit clinical trial investigators with the appropriate competencies and experience, efforts to facilitate timely enrollment in clinical trials, patient referral practices of physicians, the ability to monitor patients adequately during and after treatment, competing clinical trials, and clinicians’ and patients’ perceptions as to the potential advantages and risks of the product candidate being studied in relation to other available therapies, including any new products that may be approved for, or any product candidates under investigation for, the indications we are investigating.

We will be required to identify and enroll a sufficient number of subjects for each of our clinical trials. Utilizing our Platform, we plan to focus our development activities on patients characterized by a biomarker that we believe will be most likely to respond to our product candidates. As a result, the potential patient populations for our clinical trials may be narrowed, and we may experience difficulties in identifying and enrolling a sufficient number of patients in our clinical trials. We may not be able to initiate or continue clinical trials if we are unable to locate a sufficient number of eligible subjects to participate in the clinical trials required by the FDA, MHRA, or comparable foreign regulatory authorities. In addition, the process of finding and diagnosing subjects may prove costly.

We have in the past and may in the future experience participant withdrawals or discontinuations from our trials. Withdrawal of participants from our clinical trials, including participants in any control groups, may compromise the quality of our data. Even if we are able to enroll a sufficient number of participants in our clinical trials, we may have difficulty maintaining enrollment of such patients in our clinical trials, and delays in enrollment may result in increased costs or may affect the timing or outcome of our clinical trials. Any of these conditions may negatively impact our ability to complete such trials or include results from such trials in regulatory submissions, which could adversely affect our ability to advance the development of our product candidates. Additionally, participants with neuropsychiatric disorders, including MDD, BPD, and schizophrenia, constitute a vulnerable patient population and may withdraw from the clinical trial if they are not experiencing improvement in their underlying disease or condition or if they experience other difficulties or issues relating to their underlying disease or condition or otherwise. Further, subjects in MDD trials historically have been documented to show varying levels of medication compliance in such trials. If subjects are not compliant within a trial, the outcome of such trial may not properly reflect the actual effect of the relevant product candidate.

Additionally, other pharmaceutical companies targeting these same diseases are recruiting clinical trial patients from similar patient populations, which may make it more difficult to fully enroll any clinical trials. Our inability to enroll a sufficient number of patients for any of our future clinical trials would result in significant delays or may require us to abandon one or more clinical trials altogether. In addition, we expect to rely on clinical trial sites to ensure proper and timely conduct of our future clinical trials and, while we intend to enter into agreements governing their services, we will have limited influence over their actual performance.

We cannot assure you that our assumptions used in determining expected clinical trial timelines are correct or that we will not experience delays in enrollment, which would result in the delay of completion of such trials beyond our expected timelines.

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Use of our product candidates could be associated with adverse side effects, adverse events, or other properties or safety risks, which could delay or preclude approval, cause us to suspend or discontinue clinical trials, abandon a product candidate, limit the commercial profile of an approved product, or result in other significant negative consequences that could severely harm our business, prospects, operating results, and financial condition.

Results of our clinical trials could reveal a high and unacceptable severity and prevalence of side effects or unexpected characteristics. Undesirable side effects caused by our product candidates could cause us or regulatory authorities to interrupt, delay, or halt clinical trials or the delay or denial of regulatory approval by the FDA, MHRA, or comparable foreign regulatory authorities, or, if such product candidates are approved, result in a more restrictive label and other post-approval requirements. Any treatment-related side effects could also affect patient recruitment or the ability of enrolled patients to complete the trial, or could result in potential product liability claims. Any of these occurrences may harm our business, financial condition, and prospects significantly.

If our product candidates are associated with undesirable side effects or have unexpected characteristics in preclinical studies or clinical trials, we may need to interrupt, delay, or abandon their development or limit development to more narrow uses or subpopulations in which the undesirable side effects or other characteristics are less prevalent, less severe, or more acceptable from a risk-benefit perspective.

Patients in our ongoing and planned clinical trials may in the future suffer significant adverse events or other side effects not observed in our preclinical studies or previous clinical trials. If such significant adverse events or other side effects are observed in any of our ongoing or planned clinical trials, we may have difficulty recruiting patients to the clinical trials, or we may be required to abandon the trials or our development efforts of that product candidate altogether. We, the FDA, MHRA, other comparable regulatory authorities, an IRB or ethics committee may suspend clinical trials of a product candidate at any time for various reasons, including a belief that subjects in such trials are being exposed to unacceptable health risks or adverse side effects. Even if the side effects do not preclude the product candidate from obtaining or maintaining regulatory approval, undesirable side effects may inhibit market acceptance due to tolerability concerns as compared to other available therapies. Any of these developments could materially harm our business, financial condition, and prospects.

Additionally, if any of our product candidates receives regulatory approval, and we or others later identify undesirable side effects caused by such product, a number of potentially significant negative consequences could result. For example, the FDA could require us to adopt a Risk Evaluation and Mitigation Strategy, or REMS, to ensure that the benefits of treatment with such product candidate outweigh the risks for each potential patient, which may include, among other things, a communication plan to health care practitioners, patient education, extensive patient monitoring, or distribution systems and processes that are highly controlled, restrictive, and more costly than what is typical for the industry. We or our collaborators may also be required to adopt a REMS or engage in similar actions, such as patient education, certification of health care professionals, or specific monitoring, if we or others later identify undesirable side effects caused by any product that we develop alone or with collaborators. Other potentially significant negative consequences associated with adverse events include:

•we may be required to suspend marketing of a product, or we may decide to remove such product from the marketplace;

•regulatory authorities may withdraw or change their approvals of a product;

•regulatory authorities may require additional warnings on the label or limit access of a product to selective specialized centers with additional safety reporting and with requirements that patients be geographically close to these centers for all or part of their treatment;

•we may be required to create a medication guide outlining the risks of a product for patients, or to conduct post-marketing studies;

•we may be required to change the way a product is administered;

•we could be subject to fines, injunctions, or the imposition of criminal or civil penalties, or be sued and held liable for harm caused to subjects or patients; and

•a product may become less competitive, and our reputation may suffer.

In addition, participants with neuropsychiatric disorders, including MDD, BPD, and schizophrenia, constitute a vulnerable patient population and any adverse side effects or adverse events may be exacerbated in such patient population. Any of

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these events could diminish the usage or otherwise limit the commercial success of our product candidates and prevent us from achieving or maintaining market acceptance of our product candidates, if approved by the FDA or other regulatory authorities.

We rely heavily on the biomarker data gathered from our Platform. We currently anticipate that certain of our therapeutic product candidates will require us to develop and obtain FDA approval of a companion diagnostic for such therapeutic product candidates. If the FDA does not agree with our approach, or if we are unable to successfully develop and obtain regulatory approval for certain companion diagnostic tools needed to leverage our Platform, or experience significant delays in doing so, our business will be materially harmed.

Our ability to generate product revenues, which we do not expect will occur for many years, if ever, will depend heavily on the successful development and eventual commercialization of our product candidates, along with the companion diagnostic tools needed to leverage our Platform. Our development programs contemplate the use of our Platform, which uses machine learning to identify appropriate patient populations. Our Platformmeasures biomarkers by analyzing factors such as brain activity patterns detected via EEG readings, cognitive assessment scores, and sleep structure and circadian rhythms captured by wearable data. Analyzing a broad range of biomarkers allows our scientists to develop a comprehensive understanding of the underlying mechanisms of mental health conditions, and target these accordingly. Companion diagnostics, which come in many forms, are the tests needed to identify these biomarkers and, thus, identify an appropriate patient population for our product candidates. The process of obtaining or creating such diagnostic is time consuming and costly. Absent an exemption, these companion diagnostics will be subject to regulation and marketing approval or clearance as medical devices by the FDA, MHRA, and comparable foreign regulatory authorities before we may commercialize our product candidates.

In the United States, the laws and regulations governing the marketing of companion diagnostics are evolving, extremely complex, and in many instances, there are no significant regulatory or judicial interpretations of these laws and regulations. We currently anticipate that certain of our therapeutic product candidates will require us to develop and obtain FDA approval of a companion diagnostic for such therapeutic product candidates. This includes certain software applications, such as software that we are developing to identify biomarkers, that may meet the definition of a medical device and be subject to FDA premarket authorization, depending on its classification and software function. The approval or clearance of the therapeutic with a labeled limitation on use in only those patients who receive certain results using a companion diagnostic will limit the marketing of the product candidate, if approved, to only those patients who express the biomarker detected by the companion diagnostic. We expect to initiate discussions with the FDA concerning the development of companion diagnostics at our end of Phase 2 meetings with respect to ALTO-100 and ALTO-300. See “Item 1. Business—Government Regulation—FDA Regulation of Companion Diagnostics and Clinical Decision Support Software” in this Annual Report.

Moreover, even if data from early clinical trials appear to support development of a companion diagnostic for a product candidate, data generated in later clinical trials may fail to support the analytical and clinical validation of the companion diagnostic. We and/or third-party collaborators may encounter difficulties in developing, obtaining regulatory approval or clearance for, manufacturing, and commercializing companion diagnostics similar to those we face with respect to our product candidates themselves, including issues with achieving marketing authorization, production of sufficient quantities at commercial scale and with appropriate quality standards, and in gaining market acceptance. If we or any third parties we may engage are unable to successfully develop companion diagnostics for our product candidates, or experience delays in doing so:

•we may be unable to identify appropriate patients for enrollment in our clinical trials, which may adversely affect the development of our product candidates;

•our product candidates may not receive marketing approval if the FDA or other regulators determine that the safe and effective use of our product candidates, if any, depends on the companion diagnostic; and

•we may not realize the full commercial potential of any therapeutics that receive marketing approval if, among other reasons, we are unable to appropriately select patients who are likely to benefit from therapy with our medicines, if any.

If we are unable to develop and obtain regulatory approval or clearance for the companion diagnostic tools needed to leverage our Platform, our business, financial condition, results of operations, and prospects could be materially and adversely affected.

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Our approach to the discovery and development of precision medicines based on our Platform is unproven, and we do not know whether we will be able to develop any therapeutics or companion diagnostics of commercial value, or if competing technological approaches will limit the commercial value of our product candidates and Platform.

We have concentrated our research and development efforts on the application of precision medicine to the diagnosis and treatment of psychiatric disorders, including MDD, BPD, and schizophrenia, and our future success depends on the discovery of biomarkers through ourPlatform and the continued development of this Platform. However, neither we nor any other company has received regulatory approval to market therapeutics targeting specific subpopulations of patients with psychiatric disorders based on biomarker identification. The success of our business depends primarily upon our ability to identify, develop, and commercialize precision medicine products based on our Platform, which leverages a novel and unproven approach of applying data analytics and machine learning to the thousands of samples available to us through data collected from both our trials and third party trials. We have not yet succeeded and may not succeed in demonstrating efficacy for any product candidates in clinical trials (e.g., we reported negative topline results in October 2024 with regard to our Phase 2b trial of ALTO-100 in MDD) or in obtaining marketing approval thereafter. Our research methodology and novel approach to precision medicine for MDD, BPD, and schizophrenia may be unsuccessful in identifying biomarkers that lead to effective selection of a specific subpopulation of patients for whom a product candidate would be effective. Further, even if we successfully identify biomarkers that can be used to identify a specific subpopulation of patients for whom a product candidate would be effective, we may not be able to test potential patients for biomarkers on a commercial scale. Additionally, the FDA may not agree with our biomarker-based approach, which would present additional risks to the potential for successful development. Moreover, because all of our product candidates and development programs utilize our Platform, adverse developments with respect to one of our programs may have a significant adverse impact on the actual or perceived likelihood of success and value of our other programs.

In addition, the biotechnology and biopharmaceutical industries are characterized by rapidly advancing technologies. Our future success will depend in part on our ability to maintain a competitive position for our Platform, which relies on our ability to establish predictive biomarkers and segment patients into biomarker-characterized populations corresponding to product candidates in our pipeline. If our Platform is compromised, it may materially and adversely affect our ability to create and develop product candidates and identify biomarkers, and compete effectively. Our competitors may render our approach obsolete, or limit the commercial value of our product candidates and identified biomarkers, by advances in existing technological approaches or the development of new or different approaches, potentially eliminating the advantages in our drug discovery process that we believe we derive from our research approach and proprietary technologies.

If any of these events occur, we may be forced to abandon our development efforts for a program or programs, which would have a material adverse effect on our business and could potentially cause us to cease operations.

We have never commercialized a product candidate and may experience delays or unexpected difficulties in obtaining, or fail to obtain, regulatory approval for our product candidates.

We have never obtained regulatory approval for, or commercialized, a drug. Our clinical trial results may not support regulatory approval. In addition, our product candidates could fail to receive regulatory approval for many reasons, including the following:

•the FDA, MHRA, or comparable foreign regulatory authorities may disagree with the design or implementation of our clinical trials or the use of biomarkers to identify patient populations who will benefit from our product candidates;

•we may be unable to demonstrate to the satisfaction of the FDA, MHRA, or comparable foreign regulatory authorities that our product candidates are safe and effective for any of their proposed indications;

•negative or ambiguous results from our clinical trials, or results may not meet the level of statistical significance required by the FDA, MHRA, or comparable foreign regulatory authorities for approval;

•the population studied in the clinical trial may not be sufficiently broad or representative to assure safety in the full population for which we seek approval;

•such authorities may not accept clinical data from trials that are conducted at clinical facilities or in countries where the standard of care is potentially different from that of their own country, due to data integrity issues, or unfavorable findings during a regulatory inspection;

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•serious and unexpected drug-related side effects may be experienced by participants in our clinical trials or by individuals using drugs similar to our product candidates;

•the FDA, MHRA, or comparable foreign regulatory authorities may disagree with our interpretation of data from preclinical studies or clinical trials;

•the data collected from clinical trials of our product candidates may not be sufficient to the satisfaction of the FDA, MHRA, or comparable foreign regulatory authorities to support the submission of an NDA or other comparable submission in foreign jurisdictions or to obtain regulatory approval in the United States or elsewhere, and such authorities may impose requirements for additional preclinical studies or clinical trials;

•such authorities may disagree with us regarding the formulation, labeling, and/or the product specifications of our product candidates;

•approval may be granted only for indications that are significantly more limited than those sought by us, and/or may include significant restrictions on distribution and use;

•additional time may be required to obtain marketing authorization for any of our product candidates that are regulated as a drug/device combination product;

•such authorities may not accept a submission due to, among other reasons, the content or formatting of the submission; and

•the FDA, MHRA, or comparable foreign regulatory authorities may find deficiencies in or fail to approve the manufacturing processes or facilities of third-party manufacturers with which we contract for clinical and commercial supplies.

Further, ALTO-207 is a fixed-dose combination of pramipexole, which is approved for the treatment of Parkinson’s disease with demonstrated antidepressant effect, and ondansetron, which is approved for the prevention of nausea and vomiting. If there is a recall, safety concern, or adverse regulatory action with respect to either approved drug, it could adversely affect our ability to obtain regulatory approval for ALTO-207.

Finally, the FDA, MHRA, and comparable foreign regulatory authorities may change their approval policies and new regulations may be enacted, which could delay or prevent our ability to obtain approval. If any of our product candidates fail to achieve regulatory approval due to the above factors, or otherwise, any such failure would adversely affect our business, results of operations, and financial condition. In addition, difficulties in obtaining approval of a product candidate in any of the initial indications for which we are developing it could adversely affect our efforts to seek approval from regulatory authorities for other indications.

Additional time may be required to obtain marketing authorizations for any of our product candidates that we develop as drug/device combination products.

We are developing one of our product candidates, ALTO-101, as a drug/device combination product candidate. While we have not had conversations to date with the FDA regarding whether ALTO-101 would be regulated as a combination product, we anticipate that, if successfully developed, ALTO-101 would be regulated as a combination product by the FDA and other regulatory authorities. Combination products require coordination within the FDA and within comparable regulatory agencies for review of their drug and device components. For example, the FDA’s review of a marketing application for ALTO-101 may include the participation of both the FDA’s Center for Drug Evaluation and Research and the FDA’s Center for Devices and Radiological Health. Although the FDA, MHRA, and comparable foreign agencies have or may have systems in place for the review and approval of combination products, we may experience additional delays in the development and commercialization of such product candidates due to regulatory timing constraints and uncertainties in the product development and approval process. Moreover, although we anticipate that the device component of any combination product candidates we develop will be reviewed within the usual time frames expected for the underlying drug component application, and that no separate marketing application for the device components of such product candidates

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will be required in the United States, the FDA or comparable regulatory authorities may delay approval or require us to conduct additional studies with the device which may delay the approval of the combination product.

Even if we complete the necessary preclinical studies and clinical trials, the marketing approval process is expensive, time-consuming, and uncertain and may prevent us or any future collaboration partners from obtaining approvals for the commercialization of our product candidates.

Any product candidate we may develop and the activities associated with their development and commercialization, including their design, testing, manufacture, recordkeeping, labeling, storage, approval, advertising, promotion, import, export, marketing, and distribution, are subject to comprehensive regulation by the FDA and other regulatory authorities in the United States and by comparable foreign regulatory authorities. Failure to obtain marketing approval for a product candidate will prevent us from commercializing the product candidate in a given jurisdiction. We have not received approval to market any product candidates from regulatory authorities in any jurisdiction and it is possible that none of the product candidates we may seek to develop in the future will ever obtain regulatory approval. We have no experience in filing and supporting the applications necessary to gain marketing approvals. Although we believe that we have the capabilities to conduct preclinical studies and clinical trials and complete these applications using our internal resources, we selectively employ and may in the future rely on third-party contract research organizations, or CROs, or regulatory consultants to assist us in this process. Securing regulatory approval requires the submission of extensive preclinical and clinical data and supporting information to the various regulatory authorities for each therapeutic indication to establish the product candidate’s safety and efficacy. Securing regulatory approval also requires the submission of information about the product manufacturing process to, and inspection of manufacturing facilities by, the relevant regulatory authority. Any product candidates we develop may not be effective, may be only moderately effective, or may prove to have undesirable or unintended side effects, toxicities, or other characteristics that may preclude our obtaining marketing approval or prevent or limit commercial use.

The process of obtaining marketing approvals, both in the United States and abroad, is expensive, often takes many years following the commencement of clinical trials, if approval is obtained at all, and can vary substantially based upon a variety of factors, including the type, complexity, and novelty of the product candidates involved, as well as the target indications and patient populations. Changes in marketing approval policies during the development period, changes in or the enactment of additional statutes or regulations, or changes in regulatory review for each submitted product application, may cause delays in the approval or rejection of an application. Prior to obtaining approval to commercialize a product candidate in the U.S. or abroad, we must demonstrate with substantial evidence from adequate and well-controlled clinical trials, and to the satisfaction of the FDA or comparable foreign regulatory authorities, that such product candidates are safe and effective for their intended uses. The FDA, MHRA, and comparable foreign regulatory authorities have substantial discretion in the approval process and may delay, limit, or deny approval of a product candidate for many reasons, or may decide that our data are insufficient for approval and require additional preclinical, clinical, or other studies. In addition, varying interpretations of the data obtained from preclinical and clinical testing could delay, limit, or prevent marketing approval of a product candidate. Despite the time and expense invested in clinical development of product candidates, regulatory approval of a product candidate is never guaranteed. Of the large number of drugs in development, only a small percentage successfully complete the FDA or foreign regulatory approval processes and are commercialized. With respect to foreign markets, approval procedures vary among countries and, in addition to the foregoing risks, may involve additional product testing, administrative review periods, and agreements with pricing authorities.

Even if we eventually complete clinical trials and receive approval of an NDA or comparable foreign marketing application for our product candidates, the FDA or comparable foreign regulatory authority may grant approval contingent on the performance of costly additional clinical trials and/or the implementation of REMS, which may be required because the FDA believes it is necessary to ensure safe use of the product after approval.

If we experience delays in obtaining approval or if we fail to obtain approval of any product candidates we may develop, the commercial prospects for those product candidates, including for other indications, may be harmed, and our ability to generate revenues will be materially impaired.

Interim, “topline,” and preliminary data from our clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we may publicly disclose preliminary or topline data from our preclinical studies and clinical trials, which are based on preliminary analyses of then-available data, and the results and related findings and conclusions are

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subject to change following a more comprehensive review of the data related to the particular preclinical study or clinical trial. We also make assumptions, estimations, calculations, and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. As a result, the topline or preliminary results that we report may differ from future results of the same studies or trials, or different conclusions or considerations may qualify such results, once additional data have been received and fully evaluated. Topline and preliminary data also remain subject to audit and verification procedures that may result in the final data being materially different from the topline or preliminary data we previously published. As a result, topline and preliminary data should be viewed with caution until the final data are available.

From time to time, we may also disclose interim data from our preclinical studies and clinical trials. For example, in February 2025, we reported the results of an interim analysis of our clinical trial of ALTO-300 in MDD. Interim data from clinical trials that we may complete are subject to the risk that one or more of the clinical outcomes may materially change as participant enrollment continues and more participant data become available or as participants from our clinical trials continue other treatments for their disease. Adverse differences between interim data and final data could significantly harm our business prospects and may cause the trading price of our common stock to fluctuate significantly.

Further, others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions, or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular program, the approvability or commercialization of the particular product candidate or product and could adversely affect the success of our business. In addition, the information we choose to publicly disclose regarding a particular study or clinical trial is based on what is typically extensive information, and you or others may not agree with what we determine is material or otherwise appropriate information to include in our disclosure.

If the interim, topline or preliminary data that we report differ from actual results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize, our product candidates may be harmed, which could harm our business, financial condition, results of operations, and prospects. Further, disclosure of interim, topline, or preliminary data by us or by our competitors could result in volatility in the price of our common stock.

Furthermore, if we fail to replicate the positive results from our preclinical studies or clinical trials in our future clinical trials, we may be unable to successfully develop, obtain regulatory approval for, and commercialize our current or future product candidates.

If we fail to develop and commercialize our current product candidates for additional indications or fail to discover, develop, and commercialize other product candidates, we may be unable to grow our business and our ability to achieve our strategic objectives would be impaired.

Although the development and commercialization of our current product candidates for the treatment of MDD, BPD, and schizophrenia are our primary focus, as part of our longer-term growth strategy, we plan to potentially evaluate our current product candidates in other indications and develop other product candidates. We intend to evaluate internal opportunities from our current product candidates or other potential product candidates, and also may choose to in-license or acquire other product candidates as well as commercial products to treat patients suffering from other disorders with significant unmet medical needs and limited treatment options. These other potential product candidates will require additional, time-consuming development efforts prior to commercial sale, including preclinical studies, clinical trials, and approval by the FDA and/or comparable foreign regulatory authorities. All product candidates are prone to the risks of failure that are inherent in pharmaceutical product development, including the possibility that the product candidate will not be shown to be sufficiently safe and effective for approval by regulatory authorities. In addition, we cannot assure you that any such products, if approved, will be manufactured or produced economically, successfully commercialized, or widely accepted in the marketplace, or be more effective than other commercially available alternatives.

Research programs to identify product candidates require substantial technical, financial, and human resources, whether or not any product candidates are ultimately identified. Our research programs may initially show promise in identifying potential product candidates, yet fail to yield product candidates for clinical development for many reasons, including the following:

•the research methodology used may not be successful in identifying potential product candidates;

•competitors may develop alternatives that render our product candidates obsolete;

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•product candidates that we develop may nevertheless be covered by third parties’ patents or other exclusive rights;

•a product candidate may, on further study, be shown to have harmful side effects or other characteristics that indicate it is unlikely to be effective or otherwise does not meet applicable regulatory criteria;

•a product candidate may not be capable of being produced in commercial quantities at an acceptable cost, or at all; and

•a product candidate may not be accepted as safe and effective by patients, the medical community, or third-party payors.

If we are unsuccessful in identifying and developing additional product candidates, our potential for growth and achieving our strategic objectives may be impaired.

If we do not achieve our projected development goals in the time frames we announce and expect, the commercialization of our products may be delayed.

From time to time, we may estimate the timing of the accomplishment of various scientific, clinical, regulatory, manufacturing and other product development goals, which we sometimes refer to as milestones. These milestones may include the commencement or completion of preclinical studies and clinical trials and the submission of regulatory filings. From time to time, we may publicly announce the expected timing of some of these milestones. All of these milestones are, and will be, based on a variety of assumptions. The actual timing of these milestones can vary significantly compared to our estimates, in some cases for reasons beyond our control. We may experience numerous unforeseen events during, or as a result of, any future clinical trials that we conduct that could delay or prevent our ability to receive marketing approval or commercialize our product candidates.

We may expend our resources to pursue a particular product candidate or indication and forgo the opportunity to capitalize on product candidates or indications that may ultimately be more profitable or for which there is a greater likelihood of success.

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 regulatory approval and commercialization. We also may acquire product candidates that we identify as promising and expend resources towards their development, including ALTO-207. 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.

Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. Our spending on 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.

Obtaining and maintaining regulatory approval of our product candidates in one jurisdiction does not mean that we will be successful in obtaining regulatory approval of our product candidates in other jurisdictions.

We may seek regulatory approval for our product candidates outside the United States. Foreign regulatory authorities have requirements for approval of product candidates with which we must comply prior to marketing in those jurisdictions. Obtaining and maintaining regulatory approval of our product candidates in one jurisdiction does not guarantee that we will be able to obtain or maintain regulatory approval in any other jurisdiction. However, a failure or delay in obtaining regulatory approval in one jurisdiction may have a negative effect on the regulatory approval process in others. For example, even if the FDA grants marketing approval of a product candidate, comparable regulatory authorities in foreign jurisdictions also must approve the manufacturing, marketing, and promotion of the product candidate in those jurisdictions. Approval procedures vary among jurisdictions and can involve requirements and administrative review periods different from, and greater than, those in the United States, including additional preclinical studies or clinical trials, as clinical trials conducted in one jurisdiction may not be accepted by regulatory authorities in other jurisdictions. In some jurisdictions outside the United States, a product candidate must be approved for reimbursement before it can be approved for sale in that jurisdiction. In some cases, the price that we intend to charge for our products also is subject to approval.

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Obtaining foreign regulatory approvals and compliance with foreign regulatory requirements could result in significant delays, difficulties, and costs for us and could delay or prevent the introduction of our products in certain countries. If we fail to comply with the regulatory requirements in international markets and/or receive and maintain applicable marketing approvals, or if regulatory approvals in international markets are delayed, our target market will be reduced and our ability to realize the full market potential of our product candidates will be harmed, which could adversely affect our business, results of operations, and financial condition.

We may conduct certain of our clinical trials for our product candidates outside of the United States. However, the FDA may not accept data from such trials, in which case our development plans may be delayed, which could materially harm our business.

We may conduct one or more of our clinical trials for our product candidates outside the United States. For example, we intend to include sites from the United Kingdom in our clinical trials of ALTO-207 and ALTO-100. Although the FDA may accept data from clinical trials conducted outside the United States, acceptance of this data is subject to certain conditions imposed by the FDA. For example, to accept data from a clinical trial that was conducted only at sites outside of the United States and not subject to an IND, the FDA requires such clinical trial to have been conducted in accordance with GCPs, and the FDA must be able to validate the data from the clinical trial through an on-site inspection if the FDA deems such inspection necessary. In cases where data from foreign clinical trials are intended to serve as the sole basis for marketing approval in the United States, the FDA will generally not approve the application on the basis of foreign data alone unless (i) the data are applicable to the U.S. population and U.S. medical practice; (ii) the trials were performed by clinical investigators of recognized competence and pursuant to GCP regulations; and (iii) the data may be considered valid without the need for an on-site inspection by the FDA, or if the FDA considers such inspection to be necessary, the FDA is able to validate the data through an on-site inspection or other appropriate means. For studies not subject to an IND, the FDA generally does not review clinical protocols for the studies, and therefore there is an additional potential risk that the FDA could determine that the study design, protocol, and/or results from a non-U.S. clinical trial were inadequate for the purposes we intend, which could require us to conduct additional clinical trials. Many foreign regulatory authorities have similar requirements for clinical data gathered outside of their respective jurisdictions. In addition, such foreign trials would be subject to the applicable local laws of the foreign jurisdictions where the trials are conducted. There can be no assurance the FDA or any comparable foreign regulatory authority will accept data from clinical trials conducted outside of the United States or the relevant jurisdiction. If the FDA or any comparable foreign regulatory authority does not accept data from our clinical trials of our product candidates, it may result in the need for additional clinical trials, which would be costly and time consuming and delay or permanently halt our development of our therapeutic product candidates.

Conducting clinical trials outside the United States also exposes us to additional risks, including risks associated with:

•additional foreign regulatory requirements;

•foreign exchange fluctuations;

•compliance with foreign manufacturing, customs, shipment, and storage requirements;

•cultural differences in medical practice and clinical research; and

•diminished protection of intellectual property in some countries.

Even if our product candidates receive regulatory approval, they may fail to achieve the degree of market acceptance by physicians, patients, third-party payors and others in the medical community necessary for commercial success, in which case we may not generate significant revenues or become profitable.

We have never commercialized a product candidate for any indication. Even if our product candidates are approved by the appropriate regulatory authorities for marketing and sale, testing for biomarkers and pairing biomarker identification with our product candidates may not gain acceptance among physicians, patients, third-party payors, and others in the medical community. If both our approach to precision psychiatry and product candidates for which we obtain regulatory approval do not gain an adequate level of market acceptance, we may not generate sufficient product revenue or become profitable. Further, the number of patients with the relevant biomarkers that our product candidates are designed to treat may be smaller than expected.

The degree of market acceptance of both our approach to precision psychiatry and our product candidates will depend on a number of factors, some of which are beyond our control, including:

•the pricing and cost-effectiveness of our product candidates, as well as the ease of administration, time burden, and market acceptance of testing for biomarkers in relation to alternative treatments and therapies;

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•the safety, efficacy, and tolerability of our product candidates;

•acceptance of our approach to precision psychiatry by patients, the medical community, and third-party payors;

•changes in the standard of care for targeted indications and the reluctance of physicians to switch their patients’ current standard of care;

•the reluctance of patients to switch from their existing therapy regardless of the safety and efficacy of newer products and the ability to test for identified biomarkers;

•the clinical indications for which the products are approved and the approved claims that we may make for the products;

•any restrictions on the use of our products, and the prevalence and severity of any adverse effects;

•distribution and use restrictions imposed by the FDA with respect to such product candidates or to which we agree as part of a mandatory REMS or voluntary risk management plan;

•the availability of adequate coverage and reimbursement by third parties, such as insurance companies and other healthcare payors, and by government healthcare programs, including Medicare and Medicaid;

•the willingness of patients to pay all, or a portion of, out-of-pocket costs associated with our products in the absence of sufficient third-party coverage and adequate reimbursement;

•the extent and strength of our marketing and distribution of such product candidates;

•the timing of market introduction of such product candidates, as well as competitive products;

•our ability to offer our product candidates for sale at competitive prices;

•adverse publicity about our product or favorable publicity about competitive products; and

•potential product liability claims.

In addition, the product candidate we are developing as ALTO-300 is already an approved antidepressant in Europe and Australia with the International Nonproprietary Name agomelatine. While we are developing ALTO-300 solely in the United States, if there is a recall, safety concern, or adverse regulatory action with respect to agomelatine in Europe or Australia, it could prevent us from achieving or maintaining market acceptance of ALTO-300 or otherwise adversely affect our ability to successfully commercialize ALTO-300 in the United States. Similarly, any recall, safety concern, or adverse regulatory action with respect to pramipexole or ondansetron could prevent us from achieving or maintaining market acceptance of ALTO-207 or otherwise adversely affect our ability to successfully commercialize ALTO-207.

Our efforts to educate the medical community and third-party payors as to the benefits of both our approach to precision psychiatry and our product candidates may require significant resources and may never be successful. Even if the medical community accepts the ability to test for identified biomarkers and that our products, if approved, are safe and effective for their approved indications, physicians and patients may not immediately be receptive to such product candidates and may be slow to adopt them as an accepted treatment for the approved indications. If our current or future product candidates are approved, but do not achieve an adequate level of acceptance among physicians, patients, and third-party payors, we may not generate meaningful revenue from our product candidates and may never become profitable.

The successful commercialization of our product candidates, if approved, will depend in part on the extent to which governmental authorities and health insurers establish coverage, adequate reimbursement levels, and favorable pricing policies. Failure to obtain or maintain coverage and adequate reimbursement for our product candidates could limit our ability to market those products and decrease our ability to generate revenue.

The availability of coverage and the adequacy of reimbursement by governmental healthcare programs such as Medicare and Medicaid, private health insurers, and other third-party payors are essential for most patients to be able to afford prescription medications such as our product candidates, if approved. Our ability to achieve coverage and acceptable levels of reimbursement for our products by third-party payors will have an effect on our ability to successfully commercialize those products. Even if we obtain coverage for a given product by a third-party payor, the resulting reimbursement payment rates may not be adequate or may require co-payments that patients find unacceptably high. We cannot be sure that coverage and reimbursement in the United States, the EU, or elsewhere will be available for any product that we may develop, and any reimbursement that may become available may be decreased or eliminated in the future.

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Third-party payors increasingly are challenging prices charged for biopharmaceutical products and services, and many third-party payors may refuse to provide coverage and reimbursement for particular drugs when an equivalent generic drug or a less expensive therapy is available. It is possible that third-party payors may not see the benefit of using biomarkers to identify patient populations who will benefit from our product candidates. It is possible that a third-party payor may consider our product candidates as substitutable and only offer to reimburse patients for the less expensive product. These payors may deny or revoke the reimbursement status of a given product or establish prices for new or existing marketed products at levels that are too low to enable us to realize an appropriate return on our investment in product development. If reimbursement is not available or is available only at limited levels, we may not be able to successfully commercialize our products, if approved, and may not be able to obtain a satisfactory financial return on products that we may develop.

There is significant uncertainty related to third-party payor coverage and reimbursement of newly approved products. Regulatory approvals, pricing, and reimbursement for new drug products vary widely from country to country. In the United States, third-party payors, including private and governmental payors, such as the Medicare and Medicaid programs, play an important role in determining the extent to which new drugs will be covered. Some third-party payors may require pre-approval of coverage for new or innovative devices or drug therapies before they will reimburse healthcare providers who use such therapies. It is difficult to predict at this time what third-party payors will decide with respect to the coverage and reimbursement for our products.

Obtaining and maintaining reimbursement status is time consuming, costly, and uncertain. The Medicare and Medicaid programs increasingly are used as models for how private payors and other governmental payors develop their coverage and reimbursement policies for drugs. However, no uniform policy for coverage and reimbursement for products exists among third-party payors in the United States. Therefore, coverage and reimbursement for products can differ significantly from payor to payor. As a result, the coverage determination process is often a time consuming and costly process that will require us to provide scientific and clinical support for the use of our products to each payor separately, with no assurance that coverage and adequate reimbursement will be applied consistently or obtained in the first instance. Furthermore, rules and regulations regarding reimbursement change frequently, in some cases at short notice, and we believe that changes in these rules and regulations are likely. Thus, even if favorable coverage and reimbursement status is attained for one or more products for which we receive regulatory approval, less favorable coverage policies and reimbursement rates may be implemented in the future.

Some or all of our companion diagnostic tests may require coverage and reimbursement separate and apart from the coverage and reimbursement for their companion pharmaceutical products. If any companion diagnostic provider is unable to obtain reimbursement or is inadequately reimbursed, that may limit the availability of such companion diagnostic, which would negatively impact prescriptions for our product candidates, if approved.

Outside the United States, international operations are generally subject to extensive governmental price controls and other market regulations, and we believe the increasing emphasis on cost-containment initiatives in Europe and other countries has and will continue to put pressure on the pricing and usage of our products. In many countries, the prices of medicinal products are subject to varying price control mechanisms as part of national health systems. Other countries allow companies to fix their own prices for medical products but monitor and control company profits. Additional foreign price controls or other changes in pricing regulation could restrict the amount that we are able to charge for our product candidates, if approved. Accordingly, in markets outside the United States, the reimbursement for our product candidates may be reduced compared with the United States and may be insufficient to generate commercially reasonable revenue and profits. See “—Drug marketing and reimbursement regulations in the EU may materially affect our ability to market and receive coverage for our products in the EU member states” below for further discussion of risks related to foreign marketing and reimbursement regulations.

Moreover, increasing efforts by governmental and third-party payors in the United States and abroad to cap or reduce healthcare costs may cause such organizations to limit both coverage and the level of reimbursement for newly approved products and, as a result, they may not cover or provide adequate payment for our products. We expect to experience pricing pressures in connection with the sale of any of our product candidates due to the trend toward managed healthcare, the increasing influence of health maintenance organizations, and additional legislative changes. The downward pressure on healthcare costs in general, particularly prescription drugs and surgical procedures and other treatments, has become very intense. As a result, increasingly high barriers are being erected to the entry of new products.

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Risks Related to Our Business and Operations

We were founded with a mission to redefine neuropsychiatric drug development, a field that has seen very limited success. The ability to successfully develop drugs in this field is extremely difficult and is subject to a number of unique challenges.

Drug development in the field of neuropsychiatry and CNS disorders has seen very limited success historically, with a 7.3% and 6.2% likelihood of approval from Phase 1 in psychiatry and neurology, respectively. Clinical success depends on a number of factors and employing a patient selection biomarker approach does not guarantee that our product candidates will be approved and commercialized. Developing a product candidate for treatment of CNS disorders is extremely difficult and subjects us to a number of unique challenges. For example, clinical trials focused on neuropsychiatric diseases rely on subjective patient-reported outcomes as key endpoints. This makes them more difficult to evaluate than indications with more objective endpoints. Furthermore, these indications are often subject to a placebo effect, which may make it more challenging to isolate the beneficial effects of our product candidates. There can be no guarantee that we will successfully overcome these challenges in our ongoing or any future clinical trials of our product candidates or that we will not encounter other challenges in the development of our product candidates.

Moreover, obtaining regulatory approval from the FDA and other regulatory authorities who only have a limited set of precedents to rely on augments challenges in neuropsychiatric drug development. We intend to work closely with the FDA and comparable foreign regulatory authorities to perform the requisite scientific analyses and evaluation in an effort to obtain regulatory approval for our product candidates; however, the process of developing our product candidates may be more complex and time-consuming relative to other more well-known approaches to drug development. We cannot be certain that our approach will lead to the development of product candidates that effectively and safely address CNS disorders.

Moreover, given the history of clinical failures in this field, future clinical or regulatory failures by us or others may result in further negative perception of the likelihood of success in this field, which may significantly and adversely affect the market price of our common stock.

Our business depends on the success of our product candidates. If we are ultimately unable to successfully commercialize our product candidates, or experience significant delays in doing so, our business will be materially harmed.

We currently have no products approved for commercial sale or for which regulatory approval to market has been sought. We have invested a significant portion of our efforts and financial resources in the development of our product candidates, each of which is still in clinical development, and expect that we will continue to invest heavily in these product candidates, as well as in any future product candidates we may develop. Our business and our ability to generate revenue, which we do not expect will occur for many years, if ever, are substantially dependent on our ability to develop, obtain regulatory approval for, and then successfully commercialize our product candidates, which may never occur.

If approved for marketing by applicable regulatory authorities, our ability to generate revenue from our product candidates will depend on our ability to:

•scale our ability to test potential patients for biomarkers so that we can identify patients for whom we believe our product candidates would be effective;

•demonstrate the superiority of pairing biomarker identification with our product candidates compared to the standard of care, as well as other therapies in development;

•achieve market acceptance of our Platform by patients, the medical community, and third-party payors;

•create market demand for our product candidates through our marketing and sales activities, and any other arrangements to promote these product candidates that we may otherwise establish;

•receive regulatory approval for the targeted patient populations and claims that are necessary or desirable for successful marketing;

•price our products competitively such that third-party and government reimbursement permits broad product adoption;

•effectively commercialize any of our products that may receive regulatory approval;

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•manufacture or otherwise have access to EEG testing mechanisms that can be used by physicians and patients to test for identified biomarkers;

•manufacture product candidates through CMOs in sufficient quantities and at acceptable quality and manufacturing cost to meet commercial demand at launch and thereafter;

•establish and maintain agreements with wholesalers, distributors, pharmacies, and group purchasing organizations on commercially reasonable terms;

•obtain, maintain, protect, and enforce patent and other intellectual property protection and regulatory exclusivity for our products;

•maintain compliance with applicable laws, regulations, and guidance specific to commercialization including interactions with health care professionals, patient advocacy groups, and communication of health care economic information to payors and formularies; and

•assure that our products, if approved, will be used as directed and that additional unexpected safety risks will not arise.

We rely on, and intend to continue to rely on, our internal clinical development expertise to conduct our current and future clinical trials. This model includes internal teams and systems as well as external vendors and CROs to comprise a full clinical trial team. If our clinical trial team does not comply with applicable regulatory requirements, meet expected deadlines, or run trials effectively, our development programs and our ability to seek or obtain regulatory approval for or commercialize our product candidates may be delayed.

We conduct much of our clinical trial work (e.g., clinical and medical monitoring, data management, and project management) with internal personnel, though we selectively employ CROs when conducting our Phase 1 pharmacodynamic trials and use certain CRO and/or vendor services (e.g., biostatistics, pharmacovigilance, central raters, and rater training and remediation services) to augment our internal expertise. We also rely on our internal, proprietary systems for some data, Spectra, Altoscope, and TechCheck. See “Item 1. Business—Our Platform.” Moreover, some of our trials have included in the past, and may include in the future, a decentralized clinical trial component supported by our internal personnel wherein clinical trial activity occurs in the participant’s home or at a local health care facility and includes virtual elements of care, exposing us to increased risk of variability and lack of control of the clinical trial.

Although we believe that we have the capabilities to conduct clinical trials through our insourced model, we may need to rely on third party CROs to conduct clinical trials if our internal capabilities cannot scale as we work to progress our current product candidates through development, as we potentially expand our product candidate portfolio, or if we do not have sufficient or applicable personnel to support any future potential decentralized clinical trials. Moreover, without the use of an experienced CRO, our insourced team is responsible for the coordination of drug supply through various shipping vendors, the supply of certain equipment (e.g., EEG devices) for our trials, and the management of potential future decentralized clinical trials; our failure to coordinate such matters in an effective and efficient manner could have a material adverse effect on our trials, including our ability to execute upon any future potential decentralized clinical trials. Our failure or the failure of any CROs we may employ to conduct the trials in compliance with FDA regulations could result in a delay or failure in obtaining FDA approval and could require us to repeat any preclinical studies or clinical trials we or the CRO administered. Our insourced personnel could fail to meet deadlines or run less effectively than a CRO, which could delay development of our product candidates and our ability to seek or obtain regulatory approval or marketing approval for our product candidates.

Further, under our insourced model we presently contract directly with all of our clinical trial sites, and therefore have to negotiate budgets and contracts with each trial site, which may result in delays to our development timelines and increased costs. If any of our relationships with trial sites terminate, we may not be able to enter into arrangements with alternative trial sites or do so on commercially reasonable terms. Switching or adding additional trial sites can also involve additional costs and requires time and focus of our clinical trial operations management team.

Additionally, if we ever transition to relying on a CRO to manage the conduct of any of our clinical trials, we will also have to negotiate budgets and contracts with such CRO, which may similarly lead to delays and increased costs. There is a natural transition period when a new CRO begins work which could result in delays that could materially impact our ability to meet our desired clinical development timelines.

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The terms of our Amended Loan Agreement and our Convertible Grant Agreement place restrictions on our operating and financial flexibility and may cause dilution to our stockholders. If we raise additional capital through debt financing, the terms of any new debt could further restrict our ability to operate our business or result in further dilution to you.

In December 2022, we entered into a loan and security agreement, or the Original Loan Agreement, with K2 HealthVentures, as a lender and the other lenders from time to time party thereto, or collectively, the Lender, K2 HealthVentures, as administrative agent for the Lender, and Ankura Trust Company, LLC, as collateral agent for the Lender. In January 2025, we entered into an amendment to this facility, or the Amendment (and collectively with the Original Loan Agreement, the Amended Loan Agreement), pursuant to which the Lender has agreed to make available to us term loans in an aggregate principal amount of up to $75.0 million, including a $20.0 million tranche funded on January 13, 2025 (approximately $10.0 million of which was used to refinance all obligations under the Original Loan Agreement and pay fees and expenses incurred in connection with the Amendment). Based upon the terms of the Amended Loan Agreement, up to an additional $25.0 million is available at our request subject to the Lender’s approval. Our obligations under the Amended Loan Agreement are secured by a security interest in substantially all of our assets, other than intellectual property assets. The Amended Loan Agreement includes customary affirmative and negative covenants, as well as standard events of default, including an event of default based on the occurrence of a material adverse event. The negative covenants include, among others, restrictions on our ability to transfer collateral, incur additional indebtedness, engage in mergers or acquisitions, pay cash dividends or make other distributions, make investments, create liens, sell assets, and make any payment on subordinated debt, in each case subject to certain exceptions. In addition, following an initial period with no financial covenants, beginning January 1, 2026, we must maintain a cash runway of at least five months, provided that this covenant will be waived during any period in which our market capitalization exceeds $700.0 million. These restrictive covenants could limit our flexibility in operating our business and our ability to pursue business opportunities that we or our stockholders may consider beneficial and failure to comply with these restrictive covenants would make us ineligible to receive future additional funding under the Amended Loan Agreement.

In July 2024, we entered into the Convertible Grant Agreement with Wellcome. The Convertible Grant Agreement provides for the Convertible Loan from Wellcome of up to approximately $11.7 million, payable in six tranches. As of December 31, 2025, we had drawn down $2.0 million under the Convertible Grant Agreement, and the remainder will be funded upon draw down of payments following the completion of certain milestones as set forth in the Convertible Grant Agreement, subject to certain conditions described therein which may or may not be met in a timely manner or at all. In addition to the funds that we have drawn down as of December 31, 2025, we have achieved clinical milestones that allow us to draw down an incremental $3.0 million under the Convertible Grant Agreement. Proceeds from the Convertible Loan may be used by the Company solely to advance development of ALTO-100 in bipolar depression. The Convertible Grant Agreement also includes customary covenants, representations and warranties, including with respect to the conduct of our Phase 2b clinical trial evaluating ALTO-100 in patients with bipolar depression and certain information and audit rights of Wellcome in connection therewith, as well as with respect to our efforts to develop and exploit ALTO-100.

The Lender could declare a default upon the occurrence of any event that it interprets could have a material adverse effect, as defined in the Amended Loan Agreement, and Wellcome may declare an event of default upon the occurrence of certain specified events set forth in the Convertible Grant Agreement. Upon the occurrence and continuance of an event of default, the Lender or Wellcome, as applicable, may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Amended Loan Agreement and the Convertible Grant Agreement, respectively. Any declaration of an event of default could significantly harm our business and prospects and could cause the price of our common stock to decline. We may not have enough available cash or be able to raise additional funds through equity or debt financings to repay these outstanding obligations at the time any event of default occurs. Further, if we raise any additional capital through debt financing, the terms of such additional debt could further restrict our operating and financial flexibility.

In addition, pursuant to the Amended Loan Agreement, the Lender has converted $4.0 million and may, at its option, elect to convert up to an additional $5.0 million of the then outstanding term loan amount into shares of our common stock. The Lender also has warrants to purchase shares of our common stock, and we may be required to issue additional warrants to the Lender in the future. At any time after the second anniversary of the date of the Convertible Grant Agreement, Wellcome has the right, from time to time, to convert some or all of the Convertible Loan into shares of our common stock at a 20% discount to the 30-day volume-weighted average price on the New York Stock Exchange at the date of conversion. Any conversion of debt into equity by the Lender or Wellcome pursuant to the Amended Loan Agreement or the Convertible Grant Agreement, respectively, or exercise of any warrants held by the Lender now or in the future would cause dilution to our stockholders.

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Competitive products may reduce or eliminate the commercial opportunity for our product candidates for our current or future indications. If our competitors develop technologies or product candidates more rapidly than we do, or their technologies are more effective or safer than ours, our ability to develop and successfully commercialize our current products may be adversely affected.

The biopharmaceutical industry is characterized by the rapid innovation and intense competition. While we believe that our innovative precision psychiatry approach and pipeline of clinical assets provide us with competitive advantages, we face competition from multiple biopharmaceutical and biotechnology companies that are similarly working to develop therapeutics targeting neuropsychiatry and CNS disorders, as well as from academic institutions, governmental agencies, and public and private research institutions. Many of our potential competitors, either alone or with collaboration partners, have significantly greater financial resources than we do, as well as equal or greater experience in the discovery and development of product candidates, obtaining FDA and other regulatory approvals of products, and the commercialization of those products. Accordingly, our potential competitors may be more successful than we are in achieving regulatory approvals and commercializing their products. We anticipate that we will face intense and increasing competition from existing, approved drugs, as well as new drugs entering the market and emerging technologies that become available. In particular we are developing our product candidates in the areas of major depressive disorder, bipolar depression, and schizophrenia. Notable examples of companies with either approved therapies or product candidates in development in areas that may be competitive in our areas of focus are AbbVie Inc.; Atai Beckley, Inc.; Axsome Therapeutics, Inc.; Compass Pathways, Inc.; Neumora Therapeutics, Inc.; Neurocrine Biosciences, Inc.; and Xenon Pharmaceuticals, Inc., among others.

We believe the key competitive factors affecting the success of our product candidates that we develop to address MDD, BPD, schizophrenia, and other CNS disorders, if approved, are likely to be efficacy, safety, convenience, price, the level of generic competition, and the availability of reimbursement from government and other third-party payors. Our profitability and financial position will suffer if our product candidates receive regulatory approval but cannot compete effectively in the marketplace.

We will need to grow our organization, and we may experience difficulties in managing our growth and expanding our operations, which could adversely affect our business.

As of December 31, 2025, we had 68 total employees. As our development and commercialization plans and strategies develop, and as we transition into fully operating as a public company, we expect to expand our employee base for managerial, operational, financial, and other resources. In addition, we have limited experience in manufacturing and commercialization. As our product candidates enter and advance through clinical trials, we will need to expand our development and regulatory capabilities and contract with other organizations to provide manufacturing and other capabilities for us. In the future, we expect to have to manage additional relationships with collaborators or partners, suppliers and other organizations. Our ability to manage our operations and future growth will require us to continue to improve our operational, financial, and management controls, reporting systems and procedures, which may lead to significant costs and may divert management attention. We may not be able to implement improvements to our management information and control systems in an efficient or timely manner and may discover deficiencies in existing systems and controls.

Our inability to successfully manage our growth and expand our operations could adversely affect our business, financial condition, results of operations, and prospects.

We are dependent on the services of our management and other clinical and scientific personnel, and if we are not able to retain these individuals or recruit additional management or clinical and scientific personnel, our business will suffer.

Our success depends in part on our continued ability to attract, retain, and motivate highly qualified management, clinical, and scientific personnel. We are highly dependent upon our Founder, President, and Chief Executive Officer, Amit Etkin, M.D., Ph.D., and other members of our management team. The loss of services of any of these individuals could delay or prevent the successful development of our product pipeline, initiation or completion of our preclinical studies and clinical trials or the commercialization of our product candidates. Although we have executed employment agreements or offer letters with each member of our senior management team, these agreements are terminable at will with or without notice and, therefore, we may not be able to retain their services as expected. We maintain “key person” life insurance for

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Dr. Etkin, but the insurance proceeds may not be sufficient to compensate for the adverse effects that we expect would arise from the loss of Dr. Etkin and the costs associated with recruiting a new Chief Executive Officer.

Additionally, in light of our insourced clinical trial model, we are heavily reliant on the expertise of our clinical trial team, and the loss of even a small number of those employees could have a significant adverse impact on our ability to conduct our clinical trials in a compliant and timely manner. Additionally, as we expand our clinical trial operations, or if we experience turnover within our clinical trial team, even if we are able to recruit qualified personnel to support our insourced clinical trial model, the onboarding and integration process takes time and can result in delays to our clinical development timeline.

We will need to expand and effectively manage our managerial, operational, financial, and other resources in order to successfully pursue our clinical development and commercialization efforts. We may not be successful in maintaining our company culture and continuing to attract or retain qualified management and scientific and clinical personnel in the future due to the intense competition for qualified personnel among biopharmaceutical, biotechnology, and other businesses, particularly in the greater San Francisco Bay Area. If we are not able to attract, integrate, retain, and motivate necessary personnel to accomplish our business objectives, we may experience constraints that will significantly impede the achievement of our development objectives, our ability to raise additional capital, and our ability to implement our business strategy.

Our employees, independent contractors, consultants, commercial partners, and vendors may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements.

We are exposed to the risk of employee fraud or other illegal activity by our current and any future employees, independent contractors, consultants, commercial partners, CROs, CMOs, and vendors. Misconduct by these parties could include intentional, reckless, and/or negligent conduct that fails to comply with FDA or other regulations, provide true, complete and accurate information to the FDA, European Medicines Agency, MHRA, and other comparable foreign regulatory authorities, comply with manufacturing standards we may establish, comply with healthcare fraud and abuse laws and regulations, report financial information or data accurately, or disclose unauthorized activities to us. If we obtain FDA approval of any of our product candidates and begin commercializing those products in the United States, our potential exposure under these laws will increase significantly, and our costs associated with compliance with these laws are likely to increase. In particular, sales, marketing, and business arrangements in the healthcare industry are subject to extensive laws and regulations intended to prevent fraud, kickbacks, self-dealing, and other abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, customer incentive programs, and other business arrangements. Employee misconduct could also involve the improper use of information obtained in the course of clinical trials, which could result in regulatory sanctions and serious harm to our reputation. Additionally, we are subject to the risk that a person could allege such fraud or other misconduct, even if none occurred. It is not always possible to identify and deter employee misconduct, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to comply with such laws or regulations. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a material and adverse effect on our business, financial condition, results of operations, and prospects, including the imposition of significant civil, criminal, and administrative penalties, damages, fines, disgorgement, imprisonment, the curtailment or restructuring of our operations, loss of eligibility to obtain approvals from the FDA, exclusion from participation in government contracting, healthcare reimbursement or other government programs, including Medicare and Medicaid, integrity oversight and reporting obligations, or reputational harm.

Our future growth may depend, in part, on our ability to operate in foreign markets, where we would be subject to additional regulatory burdens and other risks and uncertainties.

Our future growth may depend, in part, on our ability to develop and commercialize our product candidates in foreign markets, including in the EU, United Kingdom and Japan, for which we may rely on collaboration with third parties. We are not permitted to market or promote any of our product candidates before we receive regulatory approval from the applicable regulatory authority in that foreign market and may never receive such regulatory approval for any of our product candidates. To obtain separate regulatory approval in many other countries, we must comply with numerous and varying regulatory requirements of such countries regarding safety and efficacy and governing, among other things, clinical trials and commercial sales, pricing, and distribution of our product candidates, and we cannot predict success in these jurisdictions. If we fail to comply with the regulatory requirements in international markets and receive applicable marketing approvals, our target market will be reduced and our ability to realize the full market potential of our product

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candidates will be harmed and our business will be adversely affected. We may not obtain foreign regulatory approvals on a timely basis, if at all. Our failure to obtain approval of any of our product candidates by regulatory authorities in another country may significantly diminish the commercial prospects of that product candidate and our business, financial condition, results of operations, and prospects could be adversely affected. Moreover, even if we obtain approval of our product candidates and ultimately commercialize our product candidates in foreign markets, we would be subject to the risks and uncertainties, including the burden of complying with complex and changing foreign regulatory, tax, accounting, and legal requirements, and reduced protection of intellectual property rights in some foreign countries.

Our business entails a significant risk of product liability and our ability to obtain sufficient insurance coverage could adversely affect our business, financial condition, results of operations, and prospects.

As we conduct clinical trials of our current or future product candidates, we are exposed to significant product liability risks inherent in the development, testing, manufacturing, and marketing of new treatments. Product liability claims could delay or prevent completion of our development programs. If we succeed in obtaining approval for, and market, our products, such claims could result in an investigation by the FDA, MHRA, comparable foreign regulatory authorities, or other regulators of the safety and efficacy of our future product candidates, our manufacturing processes and facilities, or our marketing programs and potentially a recall of our products or more serious enforcement action, limitations on the approved indications for which they may be used, or suspension or withdrawal of approvals. Regardless of the merits or eventual outcome, liability claims may also result in decreased demand for our product candidates, termination of clinical trial sites or entire trial programs, withdrawal of clinical trial participants, injury to our reputation and significant negative media attention, significant costs to defend the related litigation, a diversion of management’s time and our resources from our business operations, substantial monetary awards to trial participants or patients, loss of revenue, the inability to commercialize any products that we may develop, and a decline in our stock price. We may need to obtain higher levels of product liability insurance for later stages of clinical development or marketing any of our product candidates. Any insurance we may obtain may not provide sufficient coverage against potential liabilities. Furthermore, clinical trial and product liability insurance is becoming increasingly expensive. As a result, we may be unable to obtain sufficient insurance at a reasonable cost to protect us against losses caused by product liability claims that could adversely affect our business, financial condition, results of operations, and prospects.

We do not carry insurance for all categories of risk that our business may encounter. Some of the policies we currently maintain include property, general liability, clinical trials, cybersecurity, and directors’ and officers’ liability insurance. We do not know, however, if we will be able to maintain insurance with adequate levels of coverage. Any significant uninsured liability may require us to pay substantial amounts, which would adversely affect our business, financial condition, results of operations, and prospects.

We may seek Breakthrough Therapy Designation by the FDA for a product candidate that we develop, and we may be unsuccessful. If we are successful, the designation may not lead to a faster development or regulatory review or approval process, and it does not increase the likelihood that our product candidates will receive marketing approval.

We may seek Breakthrough Therapy Designation for our product candidates where we believe the clinical data support such designation. A “Breakthrough Therapy” designation may be available for a drug candidate that is intended, alone or in combination with one or more other drugs, to treat a serious or life-threatening disease or condition, and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. For drugs that have been designated as Breakthrough Therapies, increased interaction and communication between the FDA and the sponsor of the trial can help to identify the most efficient path for clinical development while minimizing the number of patients placed in ineffective control regimens. Drugs designated as Breakthrough Therapies by the FDA also receive the same benefits associated with Fast Track Designation, including eligibility for rolling review of a submitted NDA, if the relevant criteria are met.

Designation as a Breakthrough Therapy is within the discretion of the FDA. Accordingly, even if we believe a product candidate we develop meets the criteria for designation as a Breakthrough Therapy, the FDA may disagree and instead determine not to make such designation. In any event, the receipt of Breakthrough Therapy Designation for a product candidate may not result in a faster development process, review, or approval compared to drugs considered for approval under conventional FDA procedures and does not assure ultimate approval by the FDA. In addition, even if one or more of the product candidates we develop qualify as Breakthrough Therapies, the FDA may later decide that the drugs no longer meet the conditions for qualification and rescind the designation, or otherwise decide that the time period required for FDA review or approval will not be reduced.

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We may seek Fast Track Designation by the FDA for a product candidate that we develop, and we may be unsuccessful. If we are successful, the designation may not actually lead to a faster development or regulatory review or approval process, and would not increase the likelihood that our product candidates will receive marketing approval.

We may seek Fast Track Designation for the product candidates we develop, and we have received Fast Track Designation for ALTO-101 for the treatment of CIAS. The Fast Track program is intended to expedite or facilitate the process for reviewing new product candidates that meet certain criteria. Specifically, if a new drug is intended for the treatment of a serious or life-threatening disease or condition and preclinical or clinical data demonstrate the potential to address an unmet medical need for this disease or condition, the drug sponsor may apply for Fast Track Designation.

Fast Track Designation applies to the combination of the product candidate and the specific indication for which it is being studied. The sponsor of a Fast Track product candidate has opportunities for more frequent interactions with the applicable FDA review team during product development and, once an NDA is submitted, the application may be eligible for priority review. An NDA submitted for a Fast Track product candidate may also be eligible for rolling review, where the FDA may consider for review sections of the NDA on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the NDA, the FDA agrees to accept sections of the NDA and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the application. The FDA has broad discretion whether or not to grant this designation, so even if we believe a particular product candidate is eligible for this designation, we cannot assure you that the FDA would decide to grant it. Even if we do receive Fast Track Designation for any of our product candidates, such product candidates may not experience a faster development process, review or approval compared to conventional FDA procedures. The FDA may also withdraw the Fast Track Designation if it believes that the designation is no longer supported by data from our clinical development program. Furthermore, such a designation does not increase the likelihood that any product candidate that may be granted Fast Track Designation will receive regulatory approval in the United States. Many product candidates that have received Fast Track Designation have ultimately failed to obtain approval.

If our telecommunications or information technology systems, or those used by our collaborators, CROs, CMOs, clinical sites, third-party logistics providers, distributors, or other contractors, consultants, or third parties with whom we work, are or were compromised, to become unavailable, or to suffer security breaches, loss, or leakage of data or other disruptions, we could suffer adverse consequences resulting from such compromise, including but not limited to, operational or service interruption, harm to our reputation, litigation, fines, penalties and liability, compromise of sensitive information related our business, and other adverse consequences.

In the ordinary course of our business, we, and the third parties with whom we work, collect, receive, store, process, generate, use, transfer, disclose, make accessible, protect, secure, dispose of, transmit, and share (collectively, “process”) sensitive data and as a result, we and the third parties with whom we work face a variety of evolving threats that could cause security incidents and other disruptions to such information technology systems. If any of our sensitive or proprietary data is compromised, including our Platform and our internal, proprietary systems for data collection, it may materially and adversely affect our ability to create and develop product candidates and identify biomarkers, and compete effectively.

Our Platform, our internal, proprietary systems for data collection, and our information technology systems and those of our collaborators, CROs, CMOs, clinical sites, third-party logistics providers, distributors, and other contractors and consultants with whom we work are vulnerable to attack, damage, and interruption from cyberattacks, computer viruses, bugs, worms, or other malicious codes, malware (including ransomware, and as a result of advanced persistent threat intrusions), model poisoning, and other attacks by computer hackers, nation-state and nation-state-supported actors, cracking, application security attacks, social engineering (including through deep fakes, which may be increasingly more difficult to identify as fake, and phishing attacks), supply chain attacks and vulnerabilities through our third-party service providers, denial- or degradation-of-service attacks, credential stuffing attacks, credential harvesting, personnel misconduct or error, supply-chain attacks, software bugs, server malfunctions, software or hardware failures, loss of data or other information technology assets, adware, telecommunications or electrical failures, natural disasters (e.g., earthquakes, fires, and floods), terrorism, war, attacks enhanced or facilitated by AI/ML, and other similar threats. Such systems are also vulnerable to intentional or inadvertent acts or lack of action by those with authorized access to our systems that could lead to exposure or exploitation of those systems.

Such threats are prevalent and continue to rise, are increasingly difficult to detect, and come from a variety of sources, including traditional computer “hackers,” threat actors, “hacktivists,” organized criminal threat actors, personnel (such as through theft or misuse), sophisticated nation states, and nation-state-supported actors. In particular, ransomware attacks, including those from organized criminal threat actors, nation-states, and nation-state supported actors, are becoming

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increasingly prevalent and severe and can lead to significant interruptions, delays, or outages in our operations, loss of data (including sensitive information), loss of income, significant extra expenses to restore data or systems, reputational loss, and the diversion of funds. To alleviate the negative impact of a ransomware attack, it may be preferable to make extortion payments, but we may be unwilling or unable to do so (including, for example, if applicable laws or regulations prohibit such payments).

Some actors also now engage and are expected to continue to engage in cyber-attacks for geopolitical reasons and in conjunction with military conflicts and defense activities. During times of war and other major conflicts, we, the third parties upon which we rely, and our customers may be vulnerable to a heightened risk of these attacks, including retaliatory cyber-attacks, that could materially disrupt our systems and operations, supply chain, and ability to produce, sell, and distribute our goods and services. In addition to experiencing a security incident, third parties may gather, collect, or infer sensitive information about us from public sources, data brokers, or other means that reveals competitively sensitive details about our organization and could be used to undermine our competitive advantage or market position.

It may be difficult and/or costly to detect, investigate, mitigate, contain, and remediate a security incident. Our efforts to do so may not be successful. Actions taken by us or our collaborators, CROs, CMOs, clinical sites, third-party logistics providers, distributors, and other contractors and consultants, or other third parties with whom we work to detect, investigate, mitigate, contain, and remediate a security incident could result in outages, data losses, and disruptions of our business. Threat actors may also gain access to other networks and systems after a compromise of our networks and systems. For example, threat actors may use an initial compromise of one part of our environment to gain access to other parts of our environment, or leverage a compromise of our networks or systems to gain access to the networks or systems of third parties with whom we work, such as through phishing or supply chain attacks.

Our sensitive information could be leaked, disclosed, or revealed as a result of or in connection with the use by our personnel or vendors of AI/ML technologies. Additionally, remote work has increased risks to our information technology systems and data, as our employees utilize network connections, computers and devices outside our premises or network, including working at home, while in transit and in public locations.

Furthermore, future or past business transactions (such as acquisitions or integrations) could expose us to additional cybersecurity risks and vulnerabilities, as our systems could be negatively affected by vulnerabilities present in acquired or integrated entities’ systems and technologies. Additionally, we may discover security issues that were not found during due diligence of such acquired or integrated entities, and it may be difficult to integrate companies into our information technology environment and security program.

We and certain of our service providers are from time to time subject to system failures, cyberattacks, and security incidents. While we do not believe that we have experienced any significant system failure, accident or security breach to date, and take steps to detect and remediate vulnerabilities, we may not be able to detect, adequately investigate, or remediate all vulnerabilities or breaches because the tools and techniques used to exploit such vulnerabilities change frequently are often sophisticated in nature, and are designed to circumvent controls, to avoid detection, and to remove or obfuscate forensic evidence. Therefore, such vulnerabilities could be exploited but may not be detected until after a security incident has occurred or for an extended period. Further, we may experience delays in developing and deploying remedial measures designed to address any such identified vulnerabilities.

We rely on third-party service providers and technologies to process sensitive information in a variety of contexts, including, without limitation, cloud-based infrastructure, encryption and authentication technology, employee email, and other functions. We also rely on third-party service providers to assist with our clinical trials, provide other products or services, or otherwise to operate our business. Our ability to monitor these third parties’ information security practices is limited, and these third parties may not have adequate information security measures in place. If our third-party service providers experience a security incident or other interruption, as some in the past have, we could experience adverse consequences. While we may be entitled to damages if our third-party service providers fail to satisfy their privacy or security-related obligations to us, any award may be insufficient to cover our damages, or we may be unable to recover such award. In addition, supply-chain attacks have increased in frequency and severity, and we cannot guarantee that third parties and infrastructure in our supply chain or our third-party partners’ supply chains have not been compromised or that they do not contain exploitable defects or bugs that could result in a breach of or disruption to our information technology systems (including our services) or the third-party information technology systems that support us and our services.

Any of the previously identified or similar threats could cause a security incident or other interruption that could result in unauthorized, unlawful, or accidental acquisition, modification, destruction, loss, alteration, encryption, disclosure of, or access to our sensitive data or our information technology systems, or those of the third parties upon whom we rely. A

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security incident or other interruption could disrupt our ability (and that of third parties upon whom we rely) to provide our services including clinical trials. For example, we have been the target of unsuccessful phishing attempts in the past, and expect such attempts will continue in the future.

ANRO US Equity

ANRO · 10-K · period ended 2025-12-31

Item 1A. Risk Factors.

ANRO US Equity☆

ANRO · 10-K · period ended 2025-12-31

Item 1A. Risk Factors.

ANRO US Equity