Oncolys BioPharma Announces Full Marketing Approval in Japan for Telomelysin for the Treatment of Esophageal Cancer

1 Oncolys BioPharma Announces Full Marketing Approval in Japan for Telomelysin™ for the Treatment of Esophageal Cancer Tokyo, Japan, June 8, 2026 — Oncolys BioPharma Inc. (“Oncolys”) today announced that the Japanese Ministry of Health, Labour and Welfare (“MHLW”) has granted marketing approval for Telomelysin™ Injection (generic name: suratadenoturev; development code: OBP-301), an oncolytic adenovirus product, for the treatment of esophageal cancer in patients who are not eligible for curative resection or chemoradiotherapy. Telomelysin™ is the world’s first oncolytic adenovirus product approved for the treatment of esophageal cancer. The approval was granted as a full marketing approval, rather than conditional or time-limited approval, following MHLW review of data from Oncolys’ pivotal clinical study conducted at 17 sites in Japan. Oncolys submitted the marketing authorization application on December 15, 2025. Telomelysin™ is designed to selectively replicate in and lyse cancer cells by utilizing telomerase activity, which is highly expressed in many malignant tumors. Through this mechanism, Telomelysin™ is intended to offer a new treatment option for patients with esophageal cancer who have limited therapeutic alternatives. Under the sales partnership agreement entered into in February 2024, FUJIFILM Toyama Chemical Co., Ltd. will be responsible for the commercialization of Telomelysin™ in Japan following National Health Insurance (“NHI”) price listing. “We are very pleased to have received full marketing approval for Telomelysin™ in Japan,” said Mr. Yasuo Urata, President and CEO of Oncolys BioPharma. “This approval represents a major milestone for Oncolys and, more importantly, for patients with esophageal cancer who are not eligible for curative surgery or chemoradiotherapy. We believe Telomelysin™ has the potential to become a meaningful new treatment option in this difficult-to-treat setting.” As a result of this approval, Oncolys will receive a milestone payment from FUJIFIL M Toyama Chemical, which is expected to be recorded as revenue for the fiscal year ending December 31, 2026. Oncolys also expects to receive the remaining balance of the payment related to product supply during the current fiscal year. This amount will initially be recorded as advances received, or contract liabilities, on Oncolys’ balance sheet and is expected to be recognized as revenue progressively following the commercial launch of Telomelysin™. The amounts have not been disclosed. Oncolys plans to launch Telomelysin™ in Japan in fiscal year 2026 following NHI price listing. The impact of this approval on Oncolys’ financial results for the current fiscal year is currently under review. 2 About Telomelysin™ / OBP-301 Telomelysin™ is an oncolytic adenovirus designed to selectively replicate in cancer cells through activation of the human telomerase reverse transcriptase promoter. Following intratumoral administration, Telomelysin™ replicates within cancer cells and induces tumor cell lysis. Oncolys has been developing Telomelysin™ as a novel cancer therapy, with a focus on indications in which local tumor control and combination with radiotherapy may provide clinical benefit. About Oncolys BioPharma Inc. Oncolys BioPharma Inc. is a Japanese biopharmaceutical company focused on the development of innovative cancer therapies, including oncolytic virus products. The company is committed to developing new treatment options for patients with serious unmet medical needs. Forward-Looking Statements This press release contains forward-looking statements, including statements regarding the expected timing of launch, NHI price listing, revenue recognition, commercialization, and the potential clinical utility of Telomelysin™. These statements are based on Oncolys’ current expectations and assumptions and involve risks and uncertainties that could cause actual results to differ materially from those expressed or implied herein. Oncolys undertakes no obligation to update any forward-looking statements except as required by applicable laws and regulations. Contact: Oncolys BioPharma Inc. Email: [email protected]

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