Is there some predictive factors for isolated brain PROgression in patients with CErebral metastatic MElanoma after treatment with stereotactic brain radiotherapy ? a retrospective, single-center study. PROCEME

Abstract

Purpose Melanoma is a skin cancer with an excellent prognosis if diagnosed at an early stage. Melanoma has a high potential for brain metastasis, making the prognosis considerably poorer despite the development of local and systemic treatments. In current practice, we observe discordant responses and progression profiles at cerebral and extra-cerebral levels. The aim of this study was to identify predictive factors of isolated brain progression after treatment with stereotactic brain radiotherapy, with or without systemic treatment.Methods Between January 2014 and December 2020, 121 patients treated with stereotactic brain radiotherapy in context of melanoma stage IV were included. Radiotherapy was associated to systemic treatment in the major of cases (Targeted Therapies, Immunotherapy, or Chemotherapy).Results In our cohort, 83 patients showed progression after stereotactic brain radiotherapy: 38 in brain only, 45 in brain and at distance. The study showed a double increase in the risk of isolated brain progression in BRAF V600 mutated patients compared with BRAF V600 WT patients (OR = 2.29; CI 95 [0.94; 5.72] p-value 0.071), but not confirmed after adjustment on confounding factors. BRAF V600 WT patients treated with immunotherapy have a 4-fold greater risk of multi-site progression, compared to BRAF V600 mutated treated with targeted therapies (OR: 0.233 IC95% [0.58 ;0.847]).Conclusion BRAF V600 mutated melanomas seems more at risk of isolated brain escape in our cohort we therefore need to develop new local therapies for these patients in the future, and clarify the mechanisms of intrinsic and extrinsic resistance.