Taysha Gene Therapies, Inc.

Information.

Rule 10b5-1 Plan Elections

Sukumar Nagendran, our President and Head of Research and Development and a member of our board of directors, adopted a prearranged stock trading plan on June 11, 2025. The trading plan provides for the potential exercise and sale of up to 800,000 shares of our common stock, subject to certain price limitations set forth in the plan. The trading plan expires on September 9, 2026, unless terminated sooner in accordance with its terms. This trading plan was entered into during an open insider trading window and is intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act and our policies regarding insider transactions.

New Trinity Term Loans

On August 7, 2025, we entered into the New Trinity Term Loan Agreement, by and among us, the New Trinity Lenders, and Trinity, as administrative agent and collateral agent for the New Trinity Lenders. The New Trinity Term Loan Agreement provides for (i) on the Trinity Refinance Date, $50.0 million aggregate principal amount of term loans (“Tranche A”), (ii) from the Trinity Refinance Date until March 31, 2028, an additional $25.0 million term loan facility contingent on delivering evidence satisfactory to Trinity that we have submitted a BLA to the FDA for TSHA-102 in Rett Syndrome (“Tranche B”), (iii) from the Trinity Refinance Date until March 31, 2029, an additional $25.0 million term loan facility contingent on delivering evidence satisfactory to Trinity that we have received BLA approval from the FDA of TSHA-102 in Rett Syndrome (collectively, the “New Trinity Term Loans”). We drew $50.0 million in term loans on the Trinity Refinance Date. The existing Trinity Term Loan Agreement was terminated and the existing Trinity Term Loans were repaid concurrently with entry into the New Trinity Term Loan Agreement and the draw of Tranche A.

The interest rate applicable to the New Trinity Term Loans is the greater of (a) the WSJ Prime Rate plus 4.00% or (b) 11.50% per annum. The New Trinity Term Loans are interest only from the Trinity Refinance Date through 48 months from the Trinity Refinance Date, which may be extended to 60 months from the Trinity Refinance Date upon the satisfaction of certain milestones set forth in the New Trinity Term Loan Agreement, after which we are required to pay equal monthly installments of principal through August 1, 2030, or the New Maturity Date.

On the Trinity Refinance Date, we paid a commitment fee of $100,000 to Trinity. Upon any future draw of New Trinity Term Loans, we are required to pay an additional commitment fee of 1.00% of the aggregate principal amount of such New Trinity Term Loans.

The New Trinity Term Loans may be prepaid in full (i) from the Trinity Refinance Date through August 7, 2026, with payment of a 3.00% prepayment premium, (ii) from August 8, 2026 through August 7, 2027, with payment of a 2.00% prepayment premium, and (iii) from August 8, 2027 through, but excluding, the New Maturity Date, with payment of a 1.00% prepayment premium. Upon repayment in full of the New Trinity Term Loans, we will pay Trinity an end of term payment equal to 5.00% of the original principal amount of the New Trinity Term Loans.

In connection with the New Trinity Term Loan Agreement, we entered into a Success Fee Agreement with Trinity which specifies the terms regarding a fee in the amount of $500,000 plus 5% of the principal amount of the funded New Trinity Term Loans under Tranche B (the “New Success Fee”). The New Success Fee is payable upon the achievement of certain corporate development value-inflection milestones. The New Success Fee survives the termination of the New Trinity Term Loans and expires on the earlier of ten years from the Trinity Refinance Date, or payment in full in cash of the New Success Fee.

The obligations under the New Trinity Term Loan Agreement are secured by a perfected security interest in all of our assets except for certain customarily excluded property pursuant to the terms of the New Trinity Term Loan Agreement. There are no financial covenants and no warrants associated with the New Trinity Term Loan Agreement. The New Trinity Term Loan Agreement contains various covenants that limit our ability to engage in specified types of transactions without the consent of Trinity and the New Trinity Lenders which include, among others, incurring or assuming certain debt; merging, consolidating or acquiring all or substantially all of the capital stock or property of another entity; changing the nature of our business; changing our organizational structure or type; licensing, transferring or disposing of certain assets; granting certain types of liens on our assets; making certain investments; and paying cash dividends.

The New Trinity Term Loan Agreement contains customary representations and warranties, affirmative and negative covenants, and events of default, including payment default, breach of covenants, change of control, and material adverse effects. Upon the occurrence of an event of default, a default interest rate of an additional 5.00% per annum may be applied to the outstanding loan balances, and the New Trinity Lenders may declare all outstanding obligations immediately due and payable and exercise all of their rights and remedies as set forth in the New Trinity Term Loan Agreement and under applicable law.

The foregoing description of the New Trinity Term Loan Agreement does not purport to be complete and is qualified in its entirety by reference to the text of the New Trinity Term Loan Agreement, a copy of which is to be filed as an exhibit to our next periodic report filed with the SEC.

Termination of Existing Trinity Term Loan Agreement

On August 7, 2025, in connection with the closing of the New Trinity Term Loan Agreement, existing Trinity Term Loan Agreement with the Trinity Lenders was terminated and the existing Trinity Term Loans were repaid in full. For a description of the existing Trinity Term Loan Agreement see Note 7 to our unaudited condensed consolidated financial statements located in “Part I – Financial Information, Item 1. Financial Statements” in this Quarterly Report on Form 10-Q.