FDA Grants Orphan Status to Sanofi’s Riliprubart for Preventing and Treating Transplant Rejection

(IN BRIEF) The FDA has awarded orphan drug designation to Sanofi’s riliprubart for the treatment of antibody-mediated rejection in solid organ transplants, highlighting the therapy’s potential in an area lacking approved options. Riliprubart, a humanized IgG4 antibody targeting activated C1s in the complement pathway, is currently under Phase 2 evaluation in kidney transplant patients at risk of or experiencing AMR (NCT05156710). Additionally, the antibody holds orphan status for chronic inflammatory demyelinating polyneuropathy in both the U.S. and EU, with two ongoing Phase 3 studies—MOBILIZE (NCT06290128) and VITALIZE (NCT06290141)—for patients refractory to standard treatments or receiving IVIg. This designation reflects Sanofi’s commitment to addressing serious immune-mediated conditions and its broader R&D efforts to bring first-in-class therapies to patients with high unmet medical needs.

(PRESS RELEASE) PARIS, 26-Jun-2025 — /EuropaWire/ — Sanofi today announced that the U.S. Food and Drug Administration has granted orphan drug status to riliprubart for the treatment of antibody-mediated rejection (AMR) in solid organ transplants. This designation underscores Sanofi’s dedication to tackling a critical unmet need in transplant care, as AMR continues to threaten graft survival without any approved therapies. In the U.S., orphan status is reserved for treatments targeting conditions impacting fewer than 200,000 patients.

Alyssa Johnsen, Global Therapeutic Area Development Head for Immunology and Inflammation at Sanofi, commented, “Receiving orphan drug designation for riliprubart represents a significant step forward in our efforts to improve transplant outcomes. By targeting the classical complement pathway, riliprubart could offer a novel solution for patients facing antibody-mediated rejection, which poses a serious risk to organ longevity and patient health.”

Riliprubart (SAR445088) is under investigation in several studies spanning transplantation and neurology. A Phase 2 trial (NCT05156710) is enrolling kidney transplant recipients at both risk of developing AMR and those with active rejection episodes, assessing the antibody’s preventive and therapeutic potential. Separately, two Phase 3 trials in chronic inflammatory demyelinating polyneuropathy (CIDP) are underway: MOBILIZE (NCT06290128) for patients unresponsive to standard therapies, and VITALIZE (NCT06290141) for those receiving IVIg. These programs reflect Sanofi’s broader strategy to explore riliprubart across diverse immune-mediated conditions with high unmet needs.

Riliprubart is a first-in-class, humanized IgG4 monoclonal antibody designed to selectively inhibit activated C1s in the classical complement cascade. It remains investigational, and its safety and efficacy have not yet been evaluated by regulatory authorities. Further details on ongoing trials are available at ClinicalTrials.gov.

Antibody-mediated rejection arises when a transplant recipient’s immune system generates antibodies against donor antigens, leading to inflammation and potential graft failure. Sensitized patients, already harboring anti-donor antibodies, face an elevated risk of AMR, which current treatments only partly address.

Sanofi is a research-driven, AI-enabled biopharmaceutical company devoted to advancing global health through innovative medicines and vaccines. Guided by a mission to harness scientific breakthroughs for societal benefit, Sanofi continues to build an extensive pipeline aimed at transforming patient care worldwide.

About Riliprubart
SAR445088 (riliprubart) is a potential first-in-class, IgG4 humanized monoclonal antibody that selectively inhibits activated C1s in the classical complement pathway of the innate immune system. Riliprubart is currently under clinical investigation, and its safety and efficacy have not been evaluated by any regulatory authority. For more information on riliprubart clinical studies, please visit www.clinicaltrials.gov.

About AMR
Antibody-mediated rejection is a serious complication that may arise after solid organ transplantation, occurring when the recipient’s immune system produces antibodies that attack the transplanted organ. Sensitized recipients, who have pre-existing antibodies that target foreign antigens including those found on transplanted organs, face a high risk of developing antibody-mediated rejection. Subsequent immune response can lead to inflammation, organ damage, and organ failure if left untreated.

About Sanofi
Sanofi is an R&D driven, AI-powered biopharma company committed to improving people’s lives and delivering compelling growth. We apply our deep understanding of the immune system to invent medicines and vaccines that treat and protect millions of people around the world, with an innovative pipeline that could benefit millions more. Our team is guided by one purpose: we chase the miracles of science to improve people’s lives; this inspires us to drive progress and deliver positive impact for our people and the communities we serve, by addressing the most urgent healthcare, environmental, and societal challenges of our time.

Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY

Sanofi forward-looking statements
This press release contains forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements are statements that are not historical facts. These statements include projections and estimates and their underlying assumptions, statements regarding plans, objectives, intentions, and expectations with respect to future financial results, events, operations, services, product development and potential, and statements regarding future performance. Forward-looking statements are generally identified by the words “expects”, “anticipates”, “believes”, “intends”, “estimates”, “plans” and similar expressions. Although Sanofi’s management believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned that forward-looking information and statements are subject to various risks and uncertainties, many of which are difficult to predict and generally beyond the control of Sanofi, that could cause actual results and developments to differ materially from those expressed in, or implied or projected by, the forward-looking information and statements. These risks and uncertainties include among other things, the uncertainties inherent in research and development, future clinical data and analysis, including post marketing, decisions by regulatory authorities, such as the FDA or the EMA, regarding whether and when to approve any drug, device or biological application that may be filed for any such product candidates as well as their decisions regarding labelling and other matters that could affect the availability or commercial potential of such product candidates, the fact that product candidates if approved may not be commercially successful, the future approval and commercial success of therapeutic alternatives, Sanofi’s ability to benefit from external growth opportunities, to complete related transactions and/or obtain regulatory clearances, risks associated with intellectual property and any related pending or future litigation and the ultimate outcome of such litigation, trends in exchange rates and prevailing interest rates, volatile economic and market conditions, cost containment initiatives and subsequent changes thereto, and the impact that global crises may have on us, our customers, suppliers, vendors, and other business partners, and the financial condition of any one of them, as well as on our employees and on the global economy as a whole. The risks and uncertainties also include the uncertainties discussed or identified in the public filings with the SEC and the AMF made by Sanofi, including those listed under “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements” in Sanofi’s annual report on Form 20-F for the year ended December 31, 2024. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements.

FDA Grants Orphan Status to Sanofi’s Riliprubart for Preventing and Treating Transplant Rejection

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