​ For a discussion of our risks, please see “Item 1A. Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2025. The information presented below updates, and should be read in conjunction with, the risk factors disclosed in our Annual Report on Form 10-K for the year ended December 31, 2025. Except as presented below, there have been no material changes from the risk factors described in our Annual Report on Form 10-K for the year ended December 31, 2025. ​ We are dependent on the success of our lead clinical product candidate, AMT-130, for the treatment of Huntington’s disease. A failure of AMT-130 in clinical development, including inability to demonstrate sufficient safety or efficacy, or challenges associated with its regulatory approval, manufacturing or commercialization could adversely affect our business. ​ We have invested a significant portion of our development efforts and financial resources in the development of our lead clinical product candidate, AMT-130 for the treatment of Huntington’s disease. ​ In June 2026, we held a Type B meeting with the FDA. Official meeting minutes received in July 2026 confirmed that we and the FDA reached alignment that a BLA submission under the accelerated approval pathway for AMT-130, based on the existing clinical data, is reasonable. In addition, the FDA seeks to align on the confirmatory study design prior to the BLA submission, including consideration of a randomized standard-of-care control design instead of a sham procedure. The FDA also stated that, in accordance with the FDA’s draft public guidance for accelerated approvals, the confirmatory study should be feasible to conduct within a reasonable timeline and be well underway, and potentially fully enrolled, at the time of accelerated approval. We expect to submit a BLA in the third quarter of 2026. We can provide no assurance that we will align with the FDA on a confirmatory study design or that our BLA will be accepted for review or, if accepted, that our BLA will result in approval of AMT-130 in Huntington’s disease by the FDA, or that the FDA will agree that we have met the FDA’s requirements for our confirmatory study at the time of the BLA action date. ​ In March 2026, we held a successful pre-submission meeting with the UK MHRA, and the regulatory submission is progressing as planned for the third quarter of 2026. We can provide no assurance that any such submission will result in approval of AMT-130 in the UK. ​ There are numerous other factors that could impede or otherwise negatively impact our further development of AMT-130, including, but not limited to: our inability to reach agreement with the FDA on the design of a confirmatory study prior to a BLA submission; potential patient safety issues; our failure to demonstrate sufficient clinical efficacy or durability of response data to warrant further development or approval by the FDA, MHRA or any other regulatory authority; shifting regulatory standards for approval; our current beliefs regarding the further development of and approval pathway for AMT-130, which are based on our interpretation of communications and interactions with regulatory authorities to date, and the success of our efforts to address such communications and interactions; the results from future interim or topline data analyses and readouts from our ongoing Phase I/II trials, including as additional patient data becomes available; any requirement for additional studies to obtain approval, including a confirmatory study; our ability to fund and enroll a confirmatory study, including engaging sites that may be needed to enroll participants in a confirmatory study; the timing, cost and resources associated with our planned marketing applications; our ability to successfully commercialize AMT-130 should we choose to do so without a partner; challenges with potential development or commercial partners, should we choose to pursue further development or commercialization of AMT-130 with a partner; and our ability to fund the further development and commercialization of the AMT-130 program. ​ Any one or combination of these factors could force us to halt or discontinue the ongoing clinical trials of AMT-130 or related commercialization efforts or could prevent us from obtaining marketing approval within the predicted timeframes or at all. Certain of these risks are heightened in the context of drug development for rare diseases like Huntington’s disease and novel investigational products like gene therapies in which non-traditional study designs may be utilized to demonstrate efficacy and safety, including open-label studies, single arm studies, studies utilizing active comparators or natural history data, biomarkers or other forms of surrogate endpoints, which may be utilized due to the challenges inherent in designing and conducting clinical trials for severe diseases that progress slowly and that affect small patient populations. 38 Table of Contents The FDA has broad discretion with regard to licensure, including through the Accelerated Approval Program, and even if we believe that the Accelerated Approval Program is appropriate for AMT-130, the FDA may require additional studies and trials beyond those that we currently contemplate. Furthermore, even if the FDA reviews a BLA seeking approval, including accelerated approval, there can be no assurance that licensure will be granted on a timely basis, or at all. The FDA may disagree that the design of, or results from, our studies and statistical analysis plan (“SAP”) support accelerated approval. Additionally, the FDA may require us to conduct further studies or trials prior to granting licensure of any type, including by determining that licensure through the Accelerated Approval Program is not appropriate and that our clinical trials and SAP for AMT-130 may not be used to support licensure through the conventional pathway. We might not be able to fulfill the FDA’s requirements in a timely manner, which would cause delays, or licensure might not be granted because our submission is deemed incomplete by the FDA. Furthermore, the feedback or requests we receive from the FDA, or other non-U.S. regulatory authority, may be difficult or impossible to implement. There also can be no assurance that after subsequent FDA feedback we will continue to pursue licensure, including through the Accelerated Approval Program or otherwise. A failure to obtain licensure for AMT-130 could delay or prevent our ability to launch and commercialize AMT-130 in the U.S., could result in a longer time period to pursue licensure of our other clinical product candidates or increase the cost of development of our other clinical product candidates, and could significantly harm our financial position and competitive position in the marketplace. ​ We cannot be certain that AMT-130, or any of our clinical product candidates, will be successful in clinical trials or ultimately receive regulatory approval. If we were required, or if we chose, to discontinue development of AMT-130 or any other current or future product candidate, or if any of them were to fail to receive regulatory approval or achieve sufficient market acceptance, we could be prevented from or significantly delayed in achieving profitability and our business would be adversely affected. ​ 39 Table of Contents