Ipsen has agreed to acquire Memo Therapeutics AG in a deal designed to strengthen its rare disease pipeline with potravitug, a Phase II clinical-stage monoclonal antibody for BK polyomavirus-associated nephropathy in kidney transplant recipients.
The acquisition will give Ipsen ownership of all issued and outstanding shares of Memo Therapeutics. Financial terms of the transaction were not disclosed. The deal remains focused on advancing potravitug, a potential first-in-class therapy targeting BK polyomavirus, or BKPyV, a virus that can cause serious complications after kidney transplantation.
BK polyomavirus-associated nephropathy, also known as BKPyVAN, is a major clinical concern for kidney transplant patients. The virus can reactivate when patients receive immunosuppressive medicines to prevent organ rejection. If left uncontrolled, BKPyV infection can damage the transplanted kidney, increase the risk of graft loss and lead to transplant failure.
There are currently no approved targeted treatments for BKPyVAN. Physicians often manage the condition by reducing immunosuppressive therapy, but that approach can increase the risk of organ rejection. Ipsen said potravitug could address this treatment gap by offering a targeted antiviral approach without requiring clinicians to rely solely on reducing immunosuppression.
Potravitug is a monoclonal antibody designed to target the VP1 capsid protein of the BK virus. By blocking the virus from attaching to and entering host cells, the therapy aims to prevent viral replication and limit further infection.
The candidate has received regulatory support in both the United States and Europe. The U.S. Food and Drug Administration granted Fast Track designation to potravitug in May 2023, while the European Union granted orphan drug designation in December 2025.
Clinical data from the Phase II SAFE Kidney II trial supported Ipsen’s interest in the asset. The placebo-controlled study enrolled 95 kidney transplant patients across 22 sites in the United States and is described as the largest placebo-controlled clinical trial conducted in BKPyVAN.
At week 20, potravitug showed higher rates of at least a 1-log10 reduction in BK viral load or undetectable BKPyV DNA levels compared with placebo. The treatment also demonstrated histological improvement in BKPyVAN, suggesting potential benefits beyond viral load reduction.
By week 38, 24.4% of patients treated with potravitug achieved undetectable BKPyV DNAemia, compared with 13.0% in the placebo group. More than 2-log10 reductions in viral load were reported in 40.3% of treated patients, compared with 24.7% of placebo recipients. Biopsy-proven BKPyVAN declined from 51.2% to 31.6% in the potravitug group by week 20, while no change was reported in the placebo group.
Potravitug was generally well tolerated, with no treatment-related serious adverse events reported in the study. The full SAFE Kidney II dataset was presented at the American Transplant Congress 2026, following an earlier update at the European Renal Association Congress.
Ipsen plans to initiate the Phase III SAFE Kidney III trial later this year. The company said the acquisition reflects its strategy to develop treatments for rare diseases with significant unmet medical needs, particularly in areas where current standards of care can compromise transplant outcomes.