Tectonic Therapeutic, Inc.

To the shareholders and the Board of Directors of Tectonic Therapeutic, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Tectonic Therapeutic, Inc. and subsidiaries (the "Company") as of December 31, 2024 and 2023, the related consolidated statements of operations and comprehensive loss, convertible preferred stock and stockholders' deficit, and cash flows, for the years then ended, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for the years then ended, in conformity with accounting principles generally accepted in the United States of America .

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matters communicated below are matters arising from the current-period audit of the financial statements that were communicated or required to be communicated to the audit committee and that (1) relate to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

Accrued and prepaid contract research and development, and manufacturing expenses— Refer to Notes 2 and 6 to the financial statements

Critical Audit Matter Description

As disclosed in Note 2 to the financial statements, the Company records accrued and prepaid research and development and manufacturing expenses for third-party contract research organizations (“CROs”) and contract development and manufacturing organizations (“CDMOs”). Estimates of expenses incurred are determined by reviewing information provided to the Company by its service providers and through discussions with both internal personnel and external service providers as to the status of specific tasks within arrangements. Expenses incurred in excess of amounts invoices are recorded as accrued expenses. Payments made in excess of costs incurred are recorded as prepaid expenses.

We identified auditing the estimates of the progress to completion of specific tasks performed by CROs and CDMOs as a critical audit matter due to the (i) level of judgment required by management and the volume of such estimates made by management and (ii) the degree of auditor judgment, subjectivity, and increased extent of effort in performing procedures to evaluate the reasonableness of management’s estimates of progress to completion.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to accrued and prepaid research and development expenses and manufacturing costs included the following, among others:

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We tested the design and implementation of controls over the estimation of accrued and prepaid research and development expenses and manufacturing costs.

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For a sample of contracts with service providers performing research and development and manufacturing activities, we performed the following:

o

Evaluated the appropriateness of the method used by management to develop its estimates of progress to completion of specific tasks.

o

Tested the completeness and accuracy of the underlying data used in the estimates of progress to completion through inspection of the terms of contracts and statements of work between the Company and its service providers and testing of actual billed expenses under the contracts.

o

Performed corroborating inquiries with Company personnel responsible for overseeing the activities performed by the Company’s CRO and CDMO, which may include the service providers’ estimate of completed tasks or progress of completion of certain tasks within the arrangement.

Accounting for the Merger — Refer to Notes 1 and 3 to the financial statements

Critical Audit Matter Description

As disclosed in Notes 1 and 3 to the financial statements, on June 20, 2024, the Company completed a merger with AVROBIO, Inc. (“AVROBIO”). The merger was accounted for as a reverse recapitalization in accordance with U.S. GAAP with the Company as the accounting acquirer of AVROBIO.

We identified the evaluation of the accounting for the merger with AVROBIO, Inc. as a critical audit matter due to the (i) level of judgment required by management related to the determination of the accounting acquirer and the assessment of the transaction as a reverse recapitalization and (ii) the moderate degree of auditor judgment and extensive audit effort in evaluating the Company’s determination of the accounting acquirer and assessment of the transaction as a reverse recapitalization.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to the reverse merger included the following, among others:

•

We tested the design and implementation of controls related to the transaction, including controls over management’s determination of the (i) accounting acquirer and (ii) accounting model as a reverse recapitalization.

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We evaluated the Company’s determination of the (i) accounting acquirer and (ii) accounting model as a reverse recapitalization.

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We tested the retrospective application of the reverse recapitalization to all outstanding common shares, convertible preferred shares, stock options, and restricted stock.

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We inspected minutes of Board of Directors’ meetings, executed merger transaction agreements, and other information to assess the nature and structure of the reverse merger in evaluating management’s conclusions.

/s/Deloitte & Touche LLP

Boston, Massachusetts

March 20, 2025

We have served as the Company's auditor since 2022.