BRAF status as a predictive factor for response in isolated limb perfusion

Background: Isolated limb perfusion (ILP) is a treatment option for unresectable in-transit melanoma metastases of the extremities. Approximately two-thirds of the patients have a complete response, and known predictive factors mainly regard tumor burden. In an attempt to identify subgroups with higher response rates, we retrospectively analyzed the predictive value of the BRAF V600E/K mutation for response at our institution. Methods: Between January 2012 and December 2017, 98 consecutive patients underwent first-time ILP with melphalan for melanoma in-transit metastases and were included in the study. Data was retrieved from our prospectively kept database. Tumor burden was assessed preoperatively as number of lesions and largest tumor diameter. BRAF status was determined according to clinical routine. Response rates were classified according to WHO criteria. Results: Of the 98 patients included in the analysis, 32 patients had a BRAF V600E/K mutation (33%) and 66 patients were BRAF wild type (wt). There was no difference in age, sex or tumor burden between the groups. Comparing response between BRAF V600E/K mutation and BRAF wt, the overall response rate was 69% vs. 77% (p=.36) and the complete response rate was 47% vs. 52% (p=.67). There was no difference in survival, with a median survival of 47 months. Conclusion: In this consecutive series of patients, BRAF V600E/K mutation was not found to be a significant factor for response or survival following ILP.