Results of Operations and Financial Condition. On August 6, 2026, Tectonic Therapeutic, Inc. announced its financial results for the second quarter ended June 30, 2026 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is furnished to comply with

Results of Operations and Financial Condition. On May 7, 2026, Tectonic Therapeutic, Inc. announced its financial results for the quarter ended March 31, 2026 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is furnished to comply with

Director — Jessica Chutter: Jessica Chutter was appointed as a member of the Board and Audit Committee, effective at the Company's 2026 annual stockholder meeting.

Results of Operations and Financial Condition. On February 26, 2026, Tectonic Therapeutic, Inc. announced its financial results for the fourth quarter and full year ended December 31, 2025 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is furnished to comply with

Chair of the Board — François Nader: Dr. Nader was appointed as Chair of the Board, and Terrance McGuire is resigning from his role as Chair.

Results of Operations and Financial Condition. On November 6, 2025, Tectonic Therapeutic, Inc. announced its financial results for the quarter ended September 30, 2025 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K.

Results of Operations and Financial Condition. On August 7, 2025, Tectonic Therapeutic, Inc. announced its financial results for the quarter ended June 30, 2025 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K.

Results of Operations and Financial Condition. On May 8, 2025, Tectonic Therapeutic, Inc. announced its financial results for the quarter ended March 31, 2025 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is furnished to comply with

Results of Operations and Financial Condition. On March 20, 2025, Tectonic Therapeutic, Inc. announced its financial results for the fourth quarter and full year ended December 31, 2024 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is furnished to comply with

Entry into a Material Definitive Agreement. Securities Purchase Agreement On February 3, 2025, Tectonic Therapeutic, Inc. (the “Company”) entered into a securities purchase agreement (the “Purchase Agreement”) with certain accredited investors (the “Purchasers”). The Purchase Agreement provides that, subject to the satisfaction of customary closing conditions, the Purchasers will purchase an aggregate of 3,689,465 shares (the “Shares”) of common stock, $0.0001 par value per share (“Common Sto…

Regulation FD Disclosure. On February 3, 2025, the Company issued a press release announcing the Private Placement. A copy of the press release is filed as Exhibit 99.1 hereto and incorporated by reference herein. The information furnished under this Item 7.01, including Exhibit 99.1, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or subject to the liabilities of that section or Sections 11 and 12(a)(2) of the Securities Act. The inf…

Based in part upon the representations of the Purchasers in the Purchase Agreement, the offering and sale of the Shares will be made in reliance on the exemption afforded by Regulation D of the Securities Act of 1933, as amended (the “Securities Act”), and corresponding provisions of state securities or “blue sky” laws. The Shares have not been registered under the Securities Act or any state securities laws and may not be offered or sold in the United States absent registration with the SEC…

Results of Operations and Financial Condition. On November 7, 2024, Tectonic Therapeutic, Inc. announced its financial results for the three and nine months ended September 30, 2024 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is furnished to comply with

Results of Operations and Financial Condition. On August 14, 2024, Tectonic Therapeutic, Inc. announced its financial results for the quarter ended June 30, 2024 and provided a general business update. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference. The information in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is furnished to comply with

Other Events. The Company announced today that the U.S. Food and Drug Administration (the “FDA”) has cleared its Investigational New Drug (“IND”) application for TX45, an Fc-relaxin fusion protein being evaluated for the treatment of patients with Group 2 Pulmonary Hypertension (“PH”) due to Heart Failure with Preserved Ejection Fraction (“HFpEF”). The Company is also updating its guidance in regard to the TX45 program as follows: • Topline trial results of the Phase 1a clinical trial of TX45…

Chief Operating Officer — Dr. Christian Cortis: Dr. Christian Cortis separated from the Company as Chief Operating Officer.

Other Events. Proposed TX000045 (“TX45”) Phase 2 Trial Design As previously disclosed, the Company plans to initiate its Phase 2 randomized, placebo-controlled, double-blind proof-of-concept clinical trial to evaluate TX45 in patients with Group 2 Pulmonary Hypertension (“PH”) in the setting of Heart Failure with Preserved Ejection Fraction (“HFpEF”) in the second half of 2024. The Phase 2 clinical trial is expected to be conducted globally, including at clinical trial sites in the United Sta…

of Form 8-K under the Exchange Act) effected by the Company. (d) There have been no formal internal investigations regarding financial reporting or accounting policies and practices discussed with, reviewed by or initiated at the direction of the chief executive officer, chief financial officer or general counsel of the Company, the Company Board or any committee thereof. Neither the Company nor its independent auditors have identified (i) any significant deficiency or material weakness in th…

Other Events In connection with the Merger, AVRO held a special meeting of its stockholders on June 11, 2024 (the “ Special Meeting ”), at which AVRO’s stockholders approved effecting a reverse stock split of AVRO’s issued common stock at a ratio in the range between 1:3 and 1:30, inclusive, with the final ratio and effectiveness of all other ratios of such amendment and the abandonment of such amendment to be mutually agreed by the board of directors of AVRO and the board of directors of Tec…

Other Events In connection with the Merger, AVRO held a special meeting of its stockholders on June 11, 2024 (the “ Special Meeting ”), at which AVRO’s stockholders approved effecting a reverse stock split of AVRO’s issued common stock at a ratio in the range between 1:3 and 1:30, inclusive, with the final ratio and effectiveness of all other ratios of such amendment and the abandonment of such amendment to be mutually agreed by the board of directors of AVRO and the board of directors of Tec…

Other Events. As previously disclosed, AVROBIO, Inc., a Delaware corporation (“ AVROBIO ”), and Tectonic Therapeutic, Inc., a Delaware corporation (“ Tectonic ”), entered into an Agreement and Plan of Merger and Reorganization (the “ Merger Agreement ”) on January 30, 2024, pursuant to which, among other matters, Alpine Merger Subsidiary, Inc., a direct, wholly owned subsidiary of AVROBIO (“ Merger Sub ”), will merge with and into Tectonic, with Tectonic surviving as a wholly owned subsidiary…