A new study has reported that the oral BRAF inhibitor vemurafenib is effective in treating patients with relapsed or refractory hairy cell leukemia. 

Researchers conducted two phase II group studies of vemurafenib, one in Italy and one in the United States. The treatment (960 mg twice daily) was administered for a median of 16 weeks in the Italian study and a median of 18 weeks in the U.S. study. 

In the 24 U.S. patients, the overall response rate was 100%, the complete response rate was 42%, and the one-year progression-free survival rate was 73%. In the 26 Italian patients, the overall response rate was 96%, the complete response rate was 35%, and the median treatment-free survival was 22 months. 

Drug-related adverse events were usually grade 1 or 2 and included rash, arthralgia, or arthritis. Skin tumors secondary to the treatment developed in 14% of the patients. 

The response to BRAF inhibition confirms the role of the V600E mutation in this rare type of leukemia. According to the researchers, vemurafenib now joins the other treatment options available for the treatment of refractory hairy cell leukemia. Trials of combination regimens incorporating vemurafenib and other BRAF inhibitors are anticipated.