EMA Recommends Rezurock for Chronic Graft-Versus-Host Disease

The European Medicines Agency (EMA) has issued a recommendation for a conditional marketing authorization for Sanofi Winthrop Industrie’s Rezurock, also known as belumosudil, to treat chronic graft-versus-host disease. Chronic graft-versus-host disease is a long-term, life-threatening condition in which donor cells from stem cell or bone marrow transplants attack the recipient's body. The condition can affect 30% to 70% of adults and 6% to 33% of children receiving transplants for immunodeficiency syndromes or blood cancers.¹ The recommendation for Rezurock applies to adult and pediatric patients aged 12 and older who weigh at least 40 kilograms and have not found success with other therapies.

The current therapeutic landscape relies heavily on corticosteroids and other immune-suppressing agents, which often provide limited long-term benefit and carry the risk of severe side effects, such as low blood cell count, infection, and secondary cancer. Statistics show that approximately 50% to 75% of patients require multiple lines of therapy, yet second-and third-line options remain insufficient.¹ In the long term, roughly one-third of patients remain on treatment, while another one-third either die or experience a relapse of their original disease.

How Do the Regulatory and Clinical Requirements for Rezurock Influence the Pharmaceutical Development Pathway?

Rezurock functions as a protein kinase inhibitor that targets ROCK2, a protein involved in the immune reactions driving the disease. The product is formulated as a tablet for once-daily oral administration with food. The clinical data supporting this recommendation stem from an open-label study involving patients whose condition was inadequately controlled by corticosteroids and at least two prior systemic therapies. In this study, 73% of patients responded to treatment within six months, with 44% maintaining that response at the six-month mark.¹ Specifically, 5% of patients achieved a complete response, meaning all symptoms in all affected organs resolved, while 68% achieved a partial, response meaning at least one organ improved and no other organ worsened or was affected.

The recommendation for a conditional marketing authorization is one of the EU regulatory mechanisms to facilitate early access to medicines that fulfill an unmet medical need. This pathway allows the agency to recommend a medicine with less complete data than is typically required if the benefit of immediate availability outweighs the inherent risks of incomplete data. Consequently, Sanofi Winthrop Industrie has committed to a confirmatory randomized controlled study to further validate efficacy.¹ Following the designation of Rezurock as an orphan medicine in 2019, the Committee for Orphan Medicinal Products will now evaluate whether this status should be maintained.

While common side effects such as nausea, diarrhea, fatigue, and elevated liver enzymes were reported,¹ the recommendation by the Committee for Medicinal Products for Human Use marks a critical intermediary step toward patient access. The final decision now rests with the European Commission, after which individual member states will determine pricing and reimbursement based on the medicine's role within their specific national health systems.

How else are Researchers Treating Graft-Versus-Host Disease?

While new treatments for established chronic graft-versus-host disease are emerging, researchers are also exploring prophylactic strategies to prevent the condition from developing initially.² Traditionally, prevention involves a medication regimen started immediately after hematopoietic stem cell transplantation. However, standard protocols often fail to prevent the chronic form of the disease, which significantly impairs long-term quality of life and return to work for survivors.

Recent clinical data suggest that a drug combination consisting of sirolimus, cyclosporine, and cyclophosphamide significantly reduces the incidence of moderate to severe chronic graft-versus-host disease compared with standard regimens.² This shift toward prevention addresses the disease before donor cells attack the recipient's body and cause potentially life-threatening organ damage. In phase II trials, only 3% of patients receiving this new combination developed the chronic condition, a significant reduction from the 33% seen with older drug combinations.

What Manufacturing and Clinical Considerations Arise From Multi-drug Prophylactic Regimens?

Managing these complex combinations requires careful consideration of immune balance. While the new regimen effectively prevented disease without increasing cancer relapse, it did increase the frequency of certain infections.² This highlights a manufacturing and clinical development challenge, balancing the immunosuppressive potency of agents like mammalian target of rapamycin inhibitors with the need to maintain infection-fighting capability. Future development will likely focus on large-scale, multicenter trials to ensure these results remain consistent across diverse patient groups.

References

1. EMA. New Medicine to Treat Chronic Graft-Versus-Host Disease. Press Release. Jan 30, 2026.
2. Oshima, MU; Vo, PT; Boeckh, M; et al. Sirolimus and Cyclosporine With Post-Transplant Cyclophosphamide or Mycophenolate Mofetil as Graft-Versus-Host Disease Prophylaxis in Unrelated Donor Hematopoietic Cell Transplantation. J Clin Oncol. 2025;43(33):3600-3609.