Vemurafenib confers a durable and clinically beneficial effect among patients with BRAFV600-mutant Erdheim-Chester disease (ECD) or Langerhans cell histiocytosis (LCH), according to a study published in JAMA Oncology.1
Although patients with ECD or LCH frequently have BRAFV600 mutations and respond to BRAFV600 inhibitor therapy, there is a lack of data describing long-term efficacy and safety.
For this cohort of the open-label VE-BASKET phase 2 study (ClinicalTrials.gov Identifier: NCT01524978), researchers assigned 26 patients (22 patients with ECD, 4 patients with LCH) to receive vemurafenib 960 mg twice daily. Patient response to therapy was assessed twice, separated by at least 4 weeks; 18F-fluorodeoxygluclose (FDG) positon-emission tomography (PET)/computed tomography (CT) scans were performed at baseline and every 8 weeks.
The overall response rate (ORR) was 61.5% (95% CI, 40.6%-79.8%) for the cohort overall and 54.5% (95% CI, 32.2%-75.6%) among patients with ECD. All evaluable patients achieved at least minimum stable disease.
Median progression-free survival (PFS) and overall survival (OS) were not reached after the median follow-up of 28.8 months, but the 2-year PFS and 2-year OS rates were 86% (95% CI, 72%-100%) and 96% (95% CI, 87%-100%), respectively.
Patients evaluated by FDG-PET/CT all had a metabolic response; 80% had a complete metabolic response.
The most frequently reported adverse events (AEs) included arthralgia, fatigue, maculopapular rash, QT prolongation, alopecia, hyperkeratosis, and skin papilloma.
The authors concluded that “vemurafenib had prolonged efficacy in patients with BRAF V600-mutant ECD and LCH and warrants consideration as a new standard of care for these patients.”
- Diamond EL, Subbiah V, Lockhart AC, et al. Vemurafenib for BRAF V600-mutant Erdheim-Chester disease and Langerhans cell histiocytosis. JAMA Oncol. 2017 Nov 29. doi: 10.1001/jamaoncol.2017.5029 [Epub ahead of print]