Oncolytics Biotech, Inc.

Item 4.01. Changes in Registrant’s Certifying Accountant. On July 6, 2026, due to the Company’s corporate restructuring, the Audit Committee of the Board of Directors of Oncolytics Biotech Inc. (the “Company”), unanimously voted to disengage Ernst & Young LLP (“EY”) as the Company’s independent registered public accounting firm and to engage Baker Tilly US, LLP (“Baker Tilly”) as the Company’s independent registered public accounting firm for the 2026 fiscal year, subject to completion of Baker Tilly’s client acceptance procedures. EY’s reports on the Company’s financial statements for each of the fiscal years ended December 31, 2025 and December 31, 2024 did not contain an adverse opinion or a disclaimer of opinion and were not qualified or modified as to uncertainty, audit scope, or accounting principles, except EY’s reports contained an explanatory paragraph regarding the Company’s ability to continue as a going concern. During the Company’s fiscal years ended December 31, 2025 and December 31, 2024, and through the date of change, there were no disagreements with EY on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure which, if not resolved to the satisfaction of EY, would have caused EY to make reference to the subject matter of the disagreement in connection with its report. During the fiscal years ended December 31, 2025 and December 31, 2024 and the subsequent period through the date of change, there have been no reportable events within the meaning of Item 304(a)(1)(v) of Regulation S-K promulgated by the Securities and Exchange Commission (the “SEC”). During the fiscal years ended December 31, 2025 and December 31, 2024 and the subsequent period to the date of its engagement, neither the Company nor anyone acting on its behalf has consulted with Baker Tilly regarding (i) the application of accounting principles to a specific transaction, either completed or proposed, or the type of audit opinion that might be rendered on the Company’s financial statements, and neither a written report or oral advice was provided to the Company that Baker Tilly concluded was an important factor considered by the Company in reaching a decision as to any accounting, auditing, or financial reporting issue; (ii) any matter that was the subject of a disagreement within the meaning of Item 304(a)(1)(iv) of Regulation S-K; or (iii) any reportable event within the meaning of Item 304(a)(1)(v) of Regulation S-K. The Company provided EY with a copy of this Form 8-K on July 7, 2026, and requested that EY furnish it with a letter addressed to the SEC stating whether it agrees with the statements made by the Company in this Item 4.01 concerning EY, and, if not, stating the respects in which it does not agree. The letter of EY addressed to the SEC is attached hereto as Exhibit No. 16.1.