Sanofi's $11.6bn Bioverativ bet faces new doubts after drug trial failure

Sanofi’s $11.6bn acquisition of Bioverativ in 2018 remains under scrutiny. The success of the deal hinges on whether the acquired drugs can justify the high cost. Recent setbacks have raised further questions about its value. Sanofi bought Bioverativ in 2018 for $11.6bn, aiming to strengthen its haemophilia and rare disease portfolio. One key asset, Altuviiio, has since become a blockbuster, reporting around €325 million in sales in the first quarter of 2026. The company also sold Enjaymo, another Bioverativ drug, to Recordati for $825 million. Approved in 2022, Enjaymo was used to treat cold agglutinin disease.

However, Sanofi recently halted the Phase 3 MOBILIZE study of riliprubart, a C1s inhibitor designed to treat chronic inflammatory demyelinating polyneuropathy (CIDP). The study involved 140 patients across 134 global sites but failed to show effectiveness. Riliprubart works by targeting activated C1s in the classical complement pathway.

The failure of riliprubart highlights the pressure on the remaining Bioverativ pipeline to prove its worth. Despite Altuviiio’s strong performance, the acquisition’s overall success is still uncertain. Sanofi’s focus now shifts to Altuviiio and other Bioverativ drugs to offset the acquisition cost. The abandonment of riliprubart underscores the challenges in drug development. The company must rely on its remaining pipeline to validate the investment.