Taysha Gene Therapies, Inc.

Good day, and thank you for standing by. Welcome to the Tayshia Gene Therapy's first quarter 2026 financial results conference call. At this time, all participants are in a listen-only mode. After the speaker's presentation, there will be a question and answer session. To ask a question during the session, you'll need to press star 11 on your telephone. You'll then hear an automated message advising that your hand is raised. To withdraw your question, please press star one one again. Please be advised that today's conference is being recorded. I would now like to hand the conference over to your first speaker today, Haley Collins, Senior Director of Corporate Communications and Investor Relations. Please go ahead.

Thank you. Good morning and welcome to Tayshia's first quarter 2026 financial results and corporate update conference call. Earlier today, Tayshia issued a press release announcing financial results for the quarter ended March 31st, 2026. A copy of this press release is available on the company's website and through our SEC filings. Joining me on today's call are Sean Nolan, Tayshia's Chief Executive Officer, Sukumar Nagandran, President and Head of R&D, and Cameron Alaa, Chief Financial Officer. We will hold a question and answer session following our prepared remarks. On today's call, we will be making forward-looking statements, including statements concerning the potential of Tayshia-102, including the reproducibility and durability of any favorable results initially seen in patients' dose-to-date and clinical trials, including with respect to functional milestones to positively impact quality of life and alter the course of disease in the patients we seek to treat, our research, development, and regulatory plans for our product candidates, including the timing of initiating additional trials, Reporting data from our clinical trials, making regulatory submissions, timing our outcomes of communications with the FDA and the regulatory pathway for TASHA-102, the potential for the product candidate to receive regulatory approval from the FDA or equivalent foreign regulatory agencies, our ability to realize benefits of breakthrough therapy designation for TASHA-102, our ability to drive long-term value for stockholders, and the market opportunity for our programs. This call may also contain forward-looking statements relating to Tayshia's growth, forecast of cash runway and future operating results, discovery and development of product candidates, strategic alliances, and intellectual property, as well as matters that are not historical facts or information. Various risks may cause Tayshia's actual results to differ materially from those stated or implied in such forward-looking statements. For a list and description of the risks and uncertainties that we face, please see the reports that we have filed with the SEC including in our annual report on Form 10-K for the full year ended December 31, 2025, that we filed on March 19, 2026, and our quarterly report on Form 10-Q for the quarter ended March 31, 2026, that we filed today. This conference call contains time-sensitive information that's accurate only as of the date of this live broadcast, May 6, 2026. TASHA undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date of this conference call, except as may be required by applicable securities law. With that, I would now like to turn the call over to our CEO, Sean Nolan.

Thank you, Haley, and welcome everyone to our first quarter 2026 financial results and corporate update conference call. On today's call, I will begin with an update on our recent regulatory, clinical, and commercial readiness activities. Dr. Sukunagendran, President and Head of R&D, will outline recently published preclinical data that continue to validate our novel TASHA 102 construct design and minimally invasive intrathecal route of administration. Cameron Alam, our Chief Financial Officer, will follow up with a financial update, and I will provide closing remarks and open the call for questions. We entered 2026 focused on a disciplined execution across our regulatory, clinical and pre-commercialization activities for TASHA 102 with the goal of delivering a potentially transformative therapy to a broad population of patients with Rett syndrome who continue to face high unmet need. Over the past several months, we have continued to advance our TASHA 102 clinical development program and made progress towards key clinical milestones anticipated in the second quarter of 2026. On the regulatory front, we recently held an initial breakthrough therapy type B multidisciplinary meeting with the FDA. During the meeting, we reaffirmed alignment on the planned pathway toward a BLA submission for TASHA 102, covering the pivotal trial design, endpoints, and BLA submission scenarios, including the potential to submit for approval based on a six-month interim analysis from the revealed pivotal trial. We believe our consistent, constructive dialogue with the FDA continues to support our streamlined path toward a potentially expedited VLA submission. Additionally, in the first quarter of 2026, we held a Type C meeting with the FDA, where the FDA endorsed our proposed process performance qualification, or PPQ campaign strategy, in support of our planned VLA submission. I am pleased to share that we initiated the BLA-enabling PPQ campaign using our Tayshia 102 commercial manufacturing process in April, and we expect to complete execution by the fourth quarter of this year. As a result, we are confident that our CMC activities are on track to support our BLA submission in step with the Pivotal Data Readout. As a reminder, The FDA previously agreed that TASHA 102 material produced from the clinical and final commercial manufacturing processes are comparable and therefore may support our ability to utilize the clinical data across all clinical studies in our TASHA 102 development program in our BLA submission. The ability to leverage the totality of evidence to support the long-term clinical benefit of TASHA 102 would strengthen the overall package and support a potentially expedited BLA submission based on the six-month interim analysis. Turning to our clinical progress, we further advanced dosing in the Reveal Pivotal trial, with multiple patients dosed across multiple clinical trial sites. In parallel, enrollment in the INSPIRE trial is ongoing across multiple sites, and we remain on track to complete dosing in both trials this quarter. I am pleased to share that both high- and low-dose TASHA 102 continue to be generally well-tolerated, with no treatment-related serious adverse events or dose-limiting toxicities observed in all patients treated across the Reveal Phase 1-2 and Reveal Pivotal trials as of the May 2026 data cutoff. We look forward to reporting longer-term data from all 12 pediatric adolescent and adult patients treated in Part A of the Reveal Phase 1-2 trials later this quarter. Our pivotal development strategy is grounded on the rigor of our natural history analysis and Part A data collection and evaluation, with trial design, endpoints, and statistical analyses developed based on discussions and written feedback from the FDA. Accordingly, Developmental milestones in Part A are assessed using three structured criteria, all of which must be met in order for a developmental milestone to qualify as a gain or a regain post-Hacia 102. First, all caregivers must complete the clinician-administered historical milestone questionnaire used in the natural history study. This allows us to identify milestones eligible for gain or regain by confirming whether a milestone was never previously achieved or was lost long enough ago that the likelihood of a spontaneous gain or regain is less than 6.7%. Establishing a documented time since loss is fundamental to accurately differentiate a true regain from natural variability, as each of the 28 milestones has its own determinants. A simple baseline assessment is not sufficient documentation to support a rigorous statistical assessment and is susceptible to false positives. Our approach ensures milestone history is captured accurately so that only true open milestones are counted as gains or regains. Second, the milestone gain must be captured by post-treatment video documentation. This provides evidence of milestone gains that can be objectively reviewed Which brings me to the third criterion. Video evidence must be independently evaluated by multiple external raters using a pre-specified definition of achievement for each milestone from our pivotal trial protocol. We believe these criteria are essential for interpreting functional outcomes and provide a reliable assessment of Tayshia 102's efficacy as we advance towards registration. We believe our Part A data accurately reflect the outcomes we expect to observe in the pivotal trial, as they are evaluated using the same FDA-aligned criteria for the pivotal trial protocol. As a reminder, we presented data from Part A of the Reveal Phase 1-2 trials last year, demonstrating an 83% response rate at six months post-treatment, with five of the six patients treated with the high-dose TASHA-102 gaining or regaining at least one developmental milestone. By nine months post-treatment, the data demonstrated a 100% response rate across the six treated high-dose patients. In addition to the 22 developmental milestones gained across the 10 patients treated with Tayshia-102, patients also demonstrated a total of 165 additional functional skills and improvements across the core domains of Rett syndrome. an average of approximately 19 functional gains per patient. We observed a consistent pattern of early gains that were sustained, with additional gains seen over time, demonstrating the deepening of effect. In our upcoming Part A data readout, we expect to report longer-term follow-up, including at least 12 months of data from all 12 patients treated with Tayshia-102. These results will include functional gains based on natural history defined developmental milestones and additional functional skills and improvements impacting the activities of daily living that are meaningful to the caregivers and clinicians. We will be hoping to see a consistent pattern of early responses that are sustained and deepen over time across functional gains and clinical outcome measures in the treated patients. We believe this longer-term follow-up will provide important context around the durability, deepening of effect, and consistency in responses. With FDA alignment on the potential to pool data across the full TASHA 102 development program and our BLA submission, we believe the longer-term Part A data has the potential to strengthen the overall BLA package and support an expedited submission. In parallel to our clinical and regulatory execution, we continue to build out our internal commercial infrastructure. We have strategically assembled a strong commercial leadership group, including senior hires who have deep expertise in commercial strategy, pre-commercial, and product launch planning, as well as payer and healthcare systems engagement within the gene therapy space. With these key roles now in place, we are focused on developing a strategic commercial strategy to prepare for a potential launch and we expect to share additional details on our commercial plans in the second half of the year. I would now like to turn the call over to Sukhu to discuss evidence that further validates the TASHA 102 program and route of administration in more detail. Sukhu.