Among patients with relapsed or refractory BRAFV600E-positive hairy cell leukemia (HCL), combination dabrafenib and trametinib shows promise as a therapeutic option without introducing excessive toxicity, according to research published in Blood.

There are few treatment options available among patients with HCL who relapse or who have refractory disease. As combination BRAF and MEK inhibition has shown high efficacy in other cancer settings, such as melanoma, researchers in the present study aimed to determine the safety and efficacy of combination dabrafenib and trametinib in relapsed or refractory BRAFV600E-positive HCL.

Overall, 55 patients were enrolled and treated on this study. The median age at baseline was 66 years, 85.5% of patients were male sex, 50.9% of patients had an Eastern Cooperative Oncology Group performance status of 0, and 50.9% of patients had received at least 4 prior treatment regimens.

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Analysis showed that the objective response rate, as assessed by the investigators, was 89% (95% CI, 77.8%-95.9%). Furthermore, 65.5% of patients had a complete response, 9.1% of which had no minimal residual disease; 23.6% of patients had a partial response.

The 24-month duration of response, progression-free survival, and overall survival rates were 97.7%, 94.4%, and 94.5%, respectively. Common treatment-related adverse events included pyrexia (58.2%), chills (47.3%), and hyperglycemia (40.0%). Serious treatment-related events occurred in 34.5% of patients overall.

“In conclusion, dabrafenib plus trametinib demonstrated a high rate of durable responses in patients with relapsed/refractory [BRAFV600E]-mutated HCL with a manageable safety profile,” the authors wrote in their report. “Dabrafenib plus trametinib should be considered a meaningful, rituximab-free therapeutic option for patients with relapsed or refractory [BRAFV600E]-mutated HCL.”

Disclosure: This study was sponsored by Novartis Pharmaceuticals. Please see the original reference for a full list of authors’ disclosures. 


Kreitman RJ, Moreau P, Ravandi F, et al. Dabrafenib plus trametinib in patients with relapsed/refractory BRAF V600E mutation-positive hairy cell leukemia. Blood. 2023;141(9):996-1006. doi:10.1182/blood.2021013658