Sanofi's investigational drug, riliprubart (SAR445088), has achieved a significant regulatory milestone with the U.S. Food and Drug Administration (FDA) granting it Orphan Drug Designation for the treatment of antibody-mediated rejection (AMR) in solid organ transplantation. This designation underscores the critical unmet medical need in transplant medicine, as AMR poses a serious threat to transplanted organs and patient survival, with no FDA-approved treatments currently available. AMR is a severe complication where the recipient's immune system mistakenly produces antibodies that attack the transplanted organ, leading to inflammation, damage, and potentially organ failure. This risk is particularly high for "sensitized" recipients who already possess pre-existing antibodies against foreign antigens found on donor organs. The Orphan Drug Designation is a testament to riliprubart's potential to address such a rare yet devastating condition, which affects fewer than 200,000 people in the U.S.

Riliprubart is a potential first-in-class, IgG4 humanized monoclonal antibody designed to selectively inhibit activated C1s in the classical complement pathway of the innate immune system. This targeted mechanism aims to prevent the downstream immune responses that cause organ damage in AMR. While still under clinical investigation, its promising profile has led Sanofi to pursue a broad development program. This includes an ongoing Phase 2 clinical study (NCT05156710) specifically evaluating riliprubart's potential for both the prevention and treatment of active AMR in kidney transplant recipients, encompassing cohorts at risk of rejection and those experiencing active forms of the condition.

Beyond transplant medicine, riliprubart's therapeutic potential is also being explored in neurology. It has also been granted Orphan Drug Designation in both the U.S. and EU for its investigational use in chronic inflammatory demyelinating polyneuropathy (CIDP), a rare neurological disorder characterized by progressive muscle weakness and sensory loss. Sanofi is actively conducting two Phase 3 studies for CIDP: MOBILIZE (NCT06290128), for patients whose condition is refractory to standard care, and VITALIZE (NCT06290141), for patients already receiving IVIg treatment. This comprehensive clinical development program across multiple immune-mediated conditions with high unmet medical needs emphasizes Sanofi's commitment to delivering innovative solutions. As an R&D-driven, AI-powered biopharma company, Sanofi is dedicated to leveraging its deep understanding of the immune system to "chase the miracles of science" and develop medicines and vaccines that improve people's lives globally.