French pharmaceutical company Ipsen has agreed to acquire Swiss biotechnology firm Memo Therapeutics in a transaction that could exceed 700 million euros ($800 million), aiming to enhance its rare-disease drug portfolio. The deal centers on Memo’s experimental treatment potravitug, which targets nephropathy linked to BK polyomavirus—an illness that affects kidney transplant patients.

Potravitug received fast-track designation from the U.S. Food and Drug Administration (FDA) in 2023 and is expected to enter mid- and late-stage clinical trials later this year, Ipsen said. As part of the agreement, Memo’s assets and personnel unrelated to potravitug will be spun off into a new independent entity named Memorises Bio, which will remain under the ownership of Memo’s existing shareholders.

Ipsen plans to pay an initial 200 million euros upfront, with the remaining amount contingent on achieving specific development milestones, regulatory approvals, and sales targets. The total acquisition cost could therefore rise above 700 million euros. The company anticipates completing the transaction in the third quarter of 2026, subject to customary closing conditions, and has incorporated the acquisition’s financial impact into its full-year guidance.

The announcement follows Ipsen’s recent agreement to acquire Kartos Therapeutics, a firm developing a treatment for a rare form of blood cancer, in a deal valued at up to $1.75 billion. Investors reacted cautiously to the latest disclosure, with Ipsen’s shares declining by 1.8% in European trading following the news.