Cosette Pharmaceuticals, Inc. (Cosette), a U.S.-based, fully integrated pharmaceutical company, confirms that on 9 December 2025 it served a notice on Mayne Pharma Group Limited (Mayne Pharma, ASX: Ticker MYX) terminating the agreement between Cosette and Mayne Pharma under which Cosette was to acquire all the outstanding shares of Mayne Pharma (Scheme Implementation Deed). Cosette also notes the announcements from Mayne Pharma on 10 December 2025 and 11 December 2025 and confirms that on 11 December 2025 Mayne Pharma served its own notice of termination of the Scheme Implementation Deed on Cosette.

Both parties’ notices of termination follow a ruling from the Treasurer of Australia blocking the proposed transaction and the expiry of the end date under the Scheme Implementation Deed in November.

Cosette strongly rejects Mayne Pharma’s claims that it has breached the Scheme Implementation Deed and believes Mayne Pharma’s 10 December and 11 December ASX announcements contain material inaccuracies. Cosette has at all times been fully transparent in its engagement with Australian regulators and complied with its legal obligations in all respects, including in respect of the Scheme Implementation Deed. Cosette will vigorously defend itself against Mayne’s allegations if required. In addition, Cosette intends to pursue its appeal of the adverse judgment of the Supreme Court of New South Wales, and if necessary, pursue claims against Mayne Pharma for the harm caused to Cosette from its conduct.

Cosette remains well positioned to continue the remarkable transformation its business has achieved over the past five years, driven by an unwavering commitment to strategic business development and operational excellence, and its R&D and business development pipeline remains robust.

Cosette has a diversified product portfolio, with leading brands such as CLOMID^®, VYLEESI^® and INTRAROSA^®. Cosette’s high-growth portfolio is supported by a highly cash-flow generative established products business, including well-known brands such as AMBIEN^®, AMBIEN^® CR, WELCHOL^®, and BENICAR^®, among others. The company also markets more than 100 generic products and operates a state-of-the-art manufacturing facility in Lincolnton, N.C.

About Cosette Pharmaceuticals

Cosette Pharmaceuticals, Inc. is a U.S.-based, fully integrated pharmaceutical company with a fast-growing portfolio of products in women’s health and dermatology. Cosette has a long history in quality manufacturing of complex dosage forms including topical creams, ointments, oral liquids/solutions and suppositories. Cosette has corporate and manufacturing facilities in New Jersey and North Carolina and is supported by 350+ dedicated team members across all functional areas. For more information, please visit www.cosettepharma.com or follow Cosette on LinkedIn.

VYLEESI^®, CLOMID^®, INTRAROSA^®, AMBIEN^®, AMBIEN^® CR, WELCHOL^®, and BENICAR^® are trademarks of Cosette Pharmaceuticals, Inc.

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