The European Medicines Agency (EMA) has recommended the refusal of marketing authorization for Rezurock (belumosudil) for treating patients 12 years or older with chronic graft-vs-host disease (cGvHD) following a stem-cell transplant after trying other treatments. 

The company that applied for the authorization, Sanofi Winthrop Industrie, has 15 days to request the opinion to be reexamined. 

“We will continue to work closely with the European Medicines Agency with the aim of bringing this treatment to patients in the EU who are waiting,” said Olivier Charmeil, Sanofi’s executive vice president of general medicines, in a press release. 

cGvHD is a complication that arises when immune cells from transplanted tissues recognize the recipient’s body as foreign and attack its cells. Symptoms include rashes, nausea and vomiting, abdominal cramping, diarrhea, and jaundice. 

The overall survival rate for cGvHD is 42%. Those with progressive onset, however, have a survival rate of 10%. Estimates suggest the condition affects around 41,000 people in Europe.

The active ingredient in Rezurock is belumosudil. It works by blocking an enzyme called Rho-associated protein kinase 2 (ROCK2), which is involved in inflammation that leads to organ damage. Blocking this enzyme is meant to protect the body’s organs from attack by donor cells. 

The EMA’s opinion comes after reviewing a main study presented by Sanofi Winthrop involving 156 patients with cGvHD. The agency wrote that the study did not compare Rezurock with other treatments and that patients being able to take other treatments alongside the drug made it difficult to quantify its true efficacy.

The EMA added that a study of patients with cGvHD who received the drug as a first treatment did not show any clinical benefit. 

The European regulator initially considered granting conditional marketing authorization to Rezurock because of the urgent need for new treatments if the company was going to be able to provide more data in a short timeframe. It decided against this, however, as the company is not expected to provide more data on the drug’s effectiveness before April 2030. 

The drug was designated an “orphan medicine” by the EMA on October 17, 2019. It has been approved in 20 countries for cGvHD, including the US, UK, and Canada. 

Annie Lennon is a medical journalist. Her writing appears on Medscape, WebMD, and Medical News Today, among other outlets.