Real-world treatment and outcomes in hairy cell leukemia: a multicenter retrospective cohort including BRAF inhibitor therapy.

Hairy cell leukemia (HCL) is a rare B-cell malignancy traditionally treated with purine analogue-based regimens. Although BRAF inhibitors are established in relapsed or refractory disease, their role as first-line therapy remains incompletely defined. We conducted a multicenter retrospective study evaluating real-world treatment of adults with classic HCL. A total of 110 patients were included. First-line therapies were cladribine (64%), cladribine plus rituximab (11%), rituximab (9%), and vemurafenib-based regimens (9%). Overall, response rate to first-line therapy was 80% (complete response rate of 65%). Median overall survival was 24.4 years. Patients treated first-line with vemurafenib-based regimens achieved an overall response rate of 80%, similar to purine analogue-based therapy. Hospitalization rates were similar across treatment groups. Vemurafenib-based therapy and rituximab monotherapy were preferentially used in older patients with greater baseline anemia. This study provides early insight into BRAF inhibitor use in HCL, highlighting encouraging responses in a limited number of patients.