Why Did TSHA Stock Surge Today: FDA Breakthrough Therapy Designation

Taysha Gene Therapies, Inc. (NASDAQ:TSHA) experienced a dramatic surge in its stock price on Thursday, October 2, 2025, jumping approximately 39% in premarket trading. The rally was triggered by the announcement that the U.S. Food and Drug Administration granted Breakthrough Therapy designation to the company’s lead gene therapy candidate, TSHA-102, for the treatment of Rett syndrome. Additionally, Taysha confirmed it has reached alignment with the FDA on its pivotal trial protocol and statistical analysis plan, positioning the company for an expedited path toward a Biologics License Application submission.

Breakthrough Therapy Designation Marks Pivotal Step for Taysha

The FDA granted Breakthrough Therapy designation based on clinical evidence from Part A of the REVEAL Phase 1/2 trials, which demonstrated a 100% response rate for the primary endpoint of achieving or regaining at least one defined developmental milestone. This designation accelerates the development and regulatory review process for therapies addressing significant unmet medical needs. Rumana Haque-Ahmed, Taysha’s Chief Regulatory Officer, emphasized that the designation highlights the FDA’s recognition of both the substantial unmet need affecting an estimated 10,000 Rett syndrome patients in the U.S. and TSHA-102’s potential to transform treatment for this devastating disease.

The company has finalized its pivotal REVEAL trial protocol with the FDA, which will assess a single intrathecal dose of high-dose TSHA-102 in 15 female patients aged 6 to under 22 with Rett syndrome. The study includes a six-month interim analysis that could potentially form the basis for the BLA submission, accelerating the timeline by at least two full quarters. Patient enrollment is scheduled to begin in the fourth quarter of 2025, marking a critical milestone in the therapy’s development path.

The Breakthrough Therapy designation provides Taysha with intensive regulatory guidance throughout the research and development process, along with potential eligibility for priority review upon BLA submission. TSHA-102 is an intrathecally delivered AAV9 gene therapy designed to address the underlying genetic cause of Rett syndrome, a rare neurodevelopmental disorder that primarily affects females and causes severe cognitive and physical impairments.

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TSHA Stock Soars on Heavy Volume and Investor Optimism

As of 11:11 AM EDT on October 2, 2025, TSHA stock was trading at $4.6792, representing a remarkable gain of $1.4992 or +47.28% for the day. The stock opened at $4.0350, significantly above the previous close of $3.18, and traded within a daily range of $3.98 to $4.83. The surge generated exceptional trading volume of over 80.7 million shares, compared to the average volume of approximately 3.4 million shares, reflecting intense investor interest following the FDA announcement.

The dramatic price movement pushed Taysha’s market capitalization to approximately $1.264 billion, a substantial increase from the previous day. The stock’s year-to-date return reached +162.14%, while the one-year return stood at +121.22%, significantly outperforming the S&P 500’s returns of +13.90% and +17.33% respectively over the same periods. The 52-week range for TSHA expanded to $1.05 – $4.83, with the current price approaching the new 52-week high established during today’s rally.

Analyst sentiment remains constructive on Taysha, with a consensus price target of $8.67, suggesting potential upside from current levels. The company’s balance sheet shows total cash of $312.76 million as of the most recent quarter, providing runway to fund operations through the pivotal trial and toward potential commercialization. However, investors should note that Taysha remains pre-revenue with a negative profit margin, typical for clinical-stage biotechnology companies focused on developing transformative therapies.

Disclaimer: The author does not hold or have a position in any securities discussed in the article. All stock prices were quoted at the time of writing.