Sanofi (SNY) Receives Conditional Approval from European EMA for ROCK2 Inhibitor Rezurock (Belumosudil)
First ROCK2 Inhibitor Enters European Market
The European Medicines Agency (EMA) granted Conditional Marketing Authorisation for Sanofi's chronic graft-versus-host disease (cGVHD) treatment Rezurock (belumosudil) on March 24, 2026. Rezurock is a first-in-class drug that selectively inhibits Rho-associated coiled-coil kinase 2 (ROCK2), targeting patients aged 12 and older who have failed at least two prior systemic therapies. This European approval marks a key milestone for Sanofi following its 2021 U.S. Food and Drug Administration (FDA) approval, enabling the company to expand its global market presence. The drug is expected to significantly improve the quality of life for patients with refractory cGVHD by offering a novel mechanism of action.
Efficacy Proven in Phase 2 ROCKstar Trial
The conditional approval is primarily based on robust data from the open-label Phase 2 ROCKstar trial involving 156 patients. The trial demonstrated an impressive 73% overall response rate (ORR) at six months in the 200mg once-daily dosing group, successfully meeting the primary endpoint. Five percent of patients achieved complete response (CR), 68% achieved partial response (PR), and 44% maintained their response at six months. These efficacy results are considered to demonstrate meaningful tissue recovery in cGVHD patients with severe fibrosis across multiple organs.
Sanofi's 1.9 Billion Dollar Bet and Commercial Performance
Sanofi significantly strengthened its transplant and rare disease portfolio in 2021 by acquiring Kadmon Holdings, the original developer of Rezurock, for 1.9 billion U.S. dollars (USD) in an all-cash deal. The acquisition, which involved a 79% premium at $9.50 per share, reflected the high commercial value of Rezurock. Since its U.S. launch, Rezurock has seen rapid growth, generating 132 million euros (EUR) in revenue in 2024 and surging to 490 million euros in 2025. This European approval validates Sanofi's M&A strategy and completes the commercial foundation for Rezurock to become a global blockbuster.
Intensifying cGVHD Market Competition
The global cGVHD treatment market is estimated to be worth 3.08 billion U.S. dollars in 2025 and is expected to continue double-digit annual growth. Key market players include Novartis's Jakavi (ruxolitinib) and AbbVie's Imbruvica (ibrutinib). The market has become increasingly competitive with the recent August 2024 approval of Syndax's Niktimvo (axatilimab). Rezurock aims to establish a differentiated position through its unique fibrosis-inhibiting mechanism and favorable tolerability profile compared to other competitors.
Obligations and Future Challenges of Conditional Approval
However, as the approval is conditional, Sanofi must conduct a confirmatory randomized controlled trial to demonstrate long-term efficacy. The EMA will re-evaluate new data on Rezurock annually, and failure to achieve meaningful efficacy in the confirmatory trial could result in the withdrawal of approval. While this approval presents both short-term revenue expansion opportunities in Europe and mid-to-long-term regulatory obligations for Sanofi, the rapid market adoption expected for a rare disease treatment has generated high expectations within the medical and investment communities.
Following the 2021 acquisition of Kadmon for 1.9 billion U.S. dollars and the subsequent rapid U.S. revenue growth (490 million euros in 2025), Sanofi has now secured a strong growth driver with the EMA conditional approval in Europe. From a research perspective, Rezurock is the first selective ROCK2 inhibitor in the refractory cGVHD field, offering a dual anti-inflammatory and anti-fibrotic mechanism that differentiates it from existing treatments like Jakavi (Jakavi) and Imbruvica (Imbruvica). With the recent FDA approval of Syndax's Niktimvo and the cGVHD market (3.08 billion U.S. dollars in 2025) becoming increasingly competitive, securing early European conditional approval will be critical for Sanofi to gain market share. However, the results of the confirmatory randomized controlled trial that Sanofi must conduct to maintain and finalize the conditional approval will serve as the most important milestone in determining its long-term global market dominance.
Source: EMA (ema)