By Mark McSherry

Shares of Alderley Park-based Redx Pharma fell about 15% on Monday after it announced that its $425 million all-share merger agreement with Massachusetts-based Jounce Therapeutics has fallen through.

Redx Pharma said it “acknowledges the announcement made today by Jounce Therapeutics … that it has entered into a definitive merger agreement to be acquired by Concentra Biosciences, LLC.”

Jounce Therapeutics said it agreed to be acquired by privately held Concentra Biosciences for $96.46 million, spurning the merger agreement with Redx Pharma.

Redx Pharma’s biggest shareholder has been San Francisco investment firm Redmile Group LLC with a 73% stake.

Redx Pharma said: “The board of directors of Jounce has therefore withdrawn its recommendation for the proposed all-share merger transaction with Redx announced on 23 February 2023 and has notified Redx of the termination of the co-operation agreement between Redx and Jounce in respect of the business combination.”

Redx chair Jane Griffiths said: “The board remains fully confident in the future of Redx despite being disappointed that the board of Jounce has now decided to recommend a cash offer for their company at this late stage.

“We strongly believe in the potential of our clinical stage assets and pipeline of development candidates.

“Whilst the offer for Redx has not formally lapsed under the UK Takeover Code, the board will consider all options available to it in line with our strategy.”