Taysha Gene Therapies (TSHA) investor relations material

Executive summary

• Achieved FDA Breakthrough Therapy designation for TSHA-102 in Rett syndrome, reflecting strong clinical evidence and significant unmet need, with all 12 patients in Part A of REVEAL trials showing no treatment-related serious adverse events or dose-limiting toxicities.

• Finalized alignment with FDA on pivotal REVEAL trial protocol and statistical analysis plan, including a 6-month interim analysis to potentially expedite BLA submission.

• Regained full, unencumbered global rights to TSHA-102 after expiration of the Astellas option agreement, providing strategic flexibility.

• Strengthened commercial leadership with the appointment of a new Chief Commercial Officer to support late-stage development and commercialization.

• Received multiple regulatory designations for TSHA-102, including Breakthrough Therapy, RMAT, Orphan Drug, Fast Track from FDA, and ILAP from UK MHRA.

Financial highlights

• Research and development expenses rose to $25.7 million for Q3 2025, up from $14.9 million in Q3 2024, and totaled $61.5 million for the nine months ended September 30, 2025, driven by clinical trial, manufacturing activities, and increased headcount.

• General and administrative expenses were $8.3 million for Q3 2025, up from $7.9 million year-over-year, mainly due to debt issuance costs.

• Net loss for Q3 2025 was $32.7 million ($0.09 per share), compared to $25.5 million ($0.10 per share) in Q3 2024; net loss for the nine months ended September 30, 2025 was $81.1 million.

• Cash and cash equivalents stood at $297.3 million as of September 30, 2025, following a $215.6 million equity raise in May 2025 and a $50 million term loan draw in August 2025, expected to fund operations into 2028.

• Revenue for the nine months ended September 30, 2025 was $4.3 million, down from $6.3 million in the prior year, all related to Astellas research and development activities.

Outlook and guidance

• Current cash resources are projected to support planned operating expenses and capital requirements into 2028, with additional capital needed for future development, manufacturing, and commercialization activities.

• Dosing of the first patient in the pivotal REVEAL trial is scheduled for Q4 2025, with rapid enrollment expected across multiple sites.

• Longer-term Part A clinical data expected in the first half of 2026.

• Aim to include data from both pediatric and adult populations in BLA submission for a broad label.

• Company anticipates increased expenses as it advances TSHA-102 through pivotal trials and prepares for potential commercialization.