COSCIENS COMPLETES SECOND TRANCHE OF CONVERTIBLE DEBENTURE OFFERING

TORONTO, ONTARIO, Sept. 16, 2026 (GLOBE NEWSWIRE) — COSCIENS Biopharma Inc. (TSX: CSCI) (OTCQB: CSCIF) (“ COSCIENS ” or the “ Company ”) is pleased to announce, further to the press release dated September 10, 2026, the closing of the second tranche of a non-brokered private placement of the 15% unsecured convertible debentures (the “ Offering ”).

In the second tranche of the Offering, the Company issued additional unsecured convertible debentures (the “ Debentures ”) in an aggregate principal amount of US$4,375,000 million, for an aggregate principal amount, together with the first closing, of US$10,706,250. The terms of the Offering contemplate the issuance of an aggregate principal amount of Debentures up to US$20 million, and the Company anticipates closing one or more additional tranches in the coming weeks. Completion of additional tranches is subject to customary closing conditions, and there can be no assurance that additional tranches will be completed.

As previously disclosed, pursuant to the rules and policies of the Toronto Stock Exchange (the “ TSX ”), the conversion rights and certain related terms of the Debentures require shareholder approval. The Company has agreed to call a meeting of shareholders (the “ Meeting ”) within six months to seek the necessary approvals. Additional details will be provided in a forthcoming management information circular, which, once filed, will be available on SEDAR+ at www.sedarplus.ca .

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In connection with the second tranche, the Company agreed to pay finders’ fees (a “ Finder’s Fee ”) on certain subscriptions, which Finder’s Fees may be satisfied in cash or through the issuance of Debentures. Total Finder’s Fees for the second tranche amounted to US$35,000 aggregate principal amount of Debentures and US$100,000 in cash. Any Debentures issued as Finder’s Fees are counted towards the aggregate principal amount outstanding, and the maximum of US$20,000,000.

The Debentures (and Common Shares issuable upon conversion of the Debentures) are subject to a four-month hold period under Canadian securities laws.

This news release does not constitute an offer to sell or a solicitation of an offer to buy any of the securities described in this news release in the United States. Such securities have not been, and will not be, registered under the United States Securities Act of 1933, as amended (the “ U.S. Securities Act ”), or any state securities laws, and, accordingly, may not be offered or sold within the United States, or to or for the account or benefit of persons in the United States or “U.S. Persons”, as such term is defined in Regulation S promulgated under the U.S. Securities Act, unless registered under the U.S. Securities Act and applicable state securities laws or pursuant to an exemption from such registration requirements.

COSCIENS Biopharma Inc. is a holding company operating through its subsidiaries, including Ceapro Inc.