Ipsen acquires Memo Therapeutics, a portfolio company of Ysios Capital

Ipsen to acquire Memo Therapeutics AG, an Ysios Capital portfolio company, adding first-in-class BK polyomavirus antibody, expanding rare disease portfolio.

Ipsen (Euronext: IPN; ADR: IPSEY) and Memo Therapeutics AG have announced they have entered into a definitive share purchase agreement under which Ipsen has agreed to acquire all issued and outstanding shares of Memo Therapeutics AG. The anticipated acquisition is focused on potravitug, which is a Phase II clinical-stage antibody against the BK polyomavirus (BKPyV). BK polyomavirus associated nephropathy (BKPyVAN) is a serious and frequent clinical complication in renal transplanted patients that can lead to graft loss and transplant failure. Potravitug was granted fast-track designation from the U.S. Food and Drug Administration (FDA) in May 2023 and orphan drug designation in the European Union in December 2025.

“This acquisition reinforces our commitment to delivering transformative solutions for patients with significant unmet needs,” said Christelle Huguet, PhD, EVP, Head of R&D, Ipsen. “With potravitug, we have the opportunity to add a promising first-in-class asset to our rare disease pipeline and address the significant clinical consequences of BK virus–associated nephropathy in kidney transplant recipients, where current standards of care can compromise transplant success and graft outcomes.”

Potravitug is a monoclonal antibody directed against the BK virus VP1 capsid protein. It acts by blocking viral attachment and cellular entry, thereby preventing infection of host cells and subsequent viral replication. The Phase II SAFE Kidney II trial[i] is the largest placebo-controlled clinical trial for the treatment of BKPyVAN in kidney transplanted patients with 95 patients across 22 sites in the U.S. Topline results demonstrated efficacy with potravitug, including higher rates of ≥1-log₁₀viral load reduction or undetectable levels compared to placebo at week 20 alongside histological improvement in BKPyVAN. The totality of data showed strong clinical value with potravitug demonstrating a sustained and significant antiviral effect and reduced the incidence of BKPyVAN. 24.4% of treated patients achieved undetectable BKPyV-DNAemia by week 38 versus 13.0% in the placebo group, with >2-log₁₀ viral load reductions occurring in 40.3% versus 24.7% of patients, respectively. By week 20, biopsy-proven BKPyVAN had declined from 51.2% to 31.6% in the potravitug group, with no change observed in the placebo group. Potravitug was well tolerated, with no treatment-related serious adverse events reported. Following the update at the European Renal Association Congress last month, the full SAFE KIDNEY II dataset presented at ATC 2026 further strengthen the clinical rationale for potravitug ahead of the planned SAFE KIDNEY III trial initiation later this year.

Erik van den Berg, CEO of Memo Therapeutics AG commented, “Today marks a pivotal moment in the Memo Therapeutics AG journey and validates years of scientific innovation. We are thrilled to have attracted Ipsen to take this important medicine forward. With its deep expertise in developing and commercializing medicines for rare diseases, Ipsen can ensure that this breakthrough asset reaches its full potential to deliver a life changing difference for thousands of kidney transplant patients with BKPyV infection.”

“BK polyomavirus associated nephropathy is a significant clinical challenge in kidney transplant recipients,” said Darshana Dadhania, MD, MS, FAST, medical director of the Kidney and Pancreas Transplant Program, assistant director of the Immunogenetics and Histocompatibility Lab and an associate professor of medicine at Weill Cornell Medicine. “With no approved targeted treatment, clinicians are forced to reduce immunosuppressive therapy which increases the risk of graft rejection and graft loss. Given the frequency and serious consequences of BK virus reactivation, there remains an urgent need for effective therapy that avoids this trade-off.”

Transaction details

Under the terms of the agreements, shareholders of Memo Therapeutics AG will receive a 200 million EUR payment on a cash-free and debt-free basis at closing of the transaction, and deferred payments contingent upon the achievement of specified development, regulatory approval and sales-based milestones, for a total potential consideration in excess of 700 million EUR. As a condition precedent to closing the transaction, Memo Therapeutics AG’s assets and employees not related to potravitug, will be transferred to a newly incorporated company, Memorises Bio, retained by Memo Therapeutics AG’s shareholders.

The transaction is expected to close during Q3 2026, subject to fulfilment of customary closing conditions. The impact of this proposed mid-stage acquisition is factored into Ipsen’s current full-year guidance.

Advisors

Kate Romain, Anne Robert and Juliette Grouzet of Bredin Prat (Paris) and Andreas Rötheli, Floran Ponce and Federico Trabaldo Togna of Lenz & Staehelin (Switzerland) were acting as legal counsel to Ipsen. Centerview Partners is acting as exclusive financial advisor to Memo Therapeutics AG with Goodwin (London) and Baker McKenzie (Switzerland) acting as legal counsel.

About potravitug

Potravitug is a first-in-class monoclonal antibody targeting BK polyomavirus (BKPyV) reactivation in kidney transplant recipients. It has shown promising results in clinical trials, demonstrating a significant viral response and resolution of BKPyV associated nephropathy. These findings are based on the Phase II SAFE KIDNEY II trial, the largest placebo-controlled study conducted in this patient population, with additional analyses presented at leading international renal and transplant congresses further supporting its clinical profile and the next stages of clinical development.

About BK polyomavirus

BK polyomavirus (BKPyV) is a common virus that most people are exposed to in childhood and usually remains inactive in the body.[ii] However, in people with a weakened immune system, including kidney transplant recipients taking anti-rejection medication, the virus can reactivate and multiply. Around 90% of kidney transplant recipients are positive for BKPyV serotype,[iii] and high levels of BKPyV in the blood affect approximately 30% of patients within the first year after transplant indicating reactivation of the virus.[iv] BK polyomavirus reactivation and associated nephropathy (BKVAN) can have serious consequences, including an increased risk of graft loss and the need for dialysis or re-transplantation. There are currently no approved targeted therapies for BKPyV and clinical management is focused on balancing graft protection with BKPyV control through reducing the immunosuppression.[v]^,[vi] Over 100,000 kidney transplants are performed each year worldwide, and in the U.S. >28,000 are performed each year, with a further >90,000 patients on the waiting list for a transplant.[vii]

About Ipsen

We are a global biopharmaceutical company with a focus on bringing transformative medicines to patients in three therapeutic areas: Oncology, Rare Disease and Neuroscience. Our pipeline is fueled by internal and external innovation and supported by nearly 100 years of development experience and global hubs in the U.S., France and the U.K. Our teams in more than 40 countries and our partnerships around the world enable us to bring medicines to patients in more than 100 countries.

Ipsen is listed in Paris (Euronext: IPN) and in the U.S. through a Sponsored Level I American Depositary Receipt program (ADR: IPSEY). For more information, visit ipsen.com.

About Memo Therapeutics AG

Memo Therapeutics AG is a late-stage biotech company translating unique human immune responses into superior medicines through the development of best-in-class antibodies to treat viral infections and cancer. The Company’s lead program, potravitug, targeting BKPyV infection in kidney transplant recipients has the potential to become a first-in-class BKPyV disease-modifying therapy. Underpinning MTx’s core assets is its proprietary DROPZYLLA^® technology, an antibody repertoire copying engine with high-throughput screening capabilities. By retrieving and expressing antibody genes from millions of B cells at single-cell resolution and preserving cognate heavy- and light-chain pairing, DROPZYLLA® also perfectly enables the development and manufacture of recombinant polyclonal IgG.

Memo Therapeutics AG is a private company located in Schlieren / Zurich and backed by investors including Ysios Capital, Kurma Partners, Pureos Bioventures, Swisscanto, Vesalius Biocapital and Adjuvant Capital. Learn more at www.memo-therapeutics.com, and on LinkedIn.

Memo Therapeutics AG’s assets not related to potravitug, notably including its collaboration with CSL on the Rec-IgG Project and the DROPZYLLA^® antibody discovery platform, as well as Memo Therapeutics AG’s employees who are not directly involved in the potravitug program, will be transferred to a newly incorporated subsidiary, Memorises Bio, and retained by Memo Therapeutics AG’s shareholders via a carve-out implemented prior to the closing of the transaction.

[i] https://clinicaltrials.gov/study/NCT05769582

[ii] https://www.kidney.org/kidney-topics/bk-virus-what-transplant-patients-need-to-know

[iii] B. Demey et al. Risk factors for BK viremia and nephropathy after kidney transplantation: a systematic review. J Clin Virol. 2018 Dec;109:6-12. B. Demey et al. Risk factors for BK viremia and nephropathy after kidney transplantation: a systematic review. J Clin Virol. 2018 Dec;109:6-12.

[iv] S. Kant et al. BK Virus Nephropathy in Kidney Transplantation: A State-of-the-Art Review. Viruses 2022 Jul 25; 14 (8):1616

[v] C.N. Kotton et al. The second international consensus guidelines on the management of BK polyomavirus in kidney transplantation. Transplantation. 2024 Sep 1;108(9):1834-1866.

[vi] UK Guidelines: UK Guideline on Management of Bk Polyomavirus (BKPyV) Infection and Disease Following Kidney Transplantation – British Transplantation SocietyUK Guideline on Management of Bk Polyomavirus (BKPyV) Infection and Disease Following Kidney Transplantation – British Transplantation Society

[vii] K.L. Lentine et al. OPTN/SRTS 2021 annual data report: kidney. Am. J. Transplant. 23 (2 Suppl 1) (2023). P. S21-S120