S100B and LDH as parameters to monitor the clinical course of patients with advanced melanoma treated with Vemurafenib

Abstract

Vemurafenib is a highly efficient BRAF inhibitor for metastatic melanoma patients carrying the V600 mutation. Progression free survival is prolonged to approximately 6 months and 50 to 80% of the patients show objective tumor responses. S100B and LDH are established tumor markers in routine melanoma follow up. This study evaluated their potential as response and progression markers during vemurafenib treatment. A cohort of 44 patients with stage IV melanoma disease and treated with vemurafenib was retrospectively analyzed. Staging was performed every 6-8 weeks including CT scans, LDH and S100B. RECIST criteria were used for standardized radiological response evaluation. Correlation between response or progression, LDH and S100B was analyzed by accuracy tests, Spearman's rank correlation rho and polynomial regression analyses. There was a decent correlation between LDH and S100B decline and RECIST confirmed response especially in case S100B and/or LDH were elevated at baseline (accuracy 81.2% for S100B and 85.7% for LDH). Accuracy in case of RECIST confirmed progression and S100B/LDH was low with 32.4% for LDH and 30.3% for S100B. Neither polynomial regression analyses nor Spearman's rank correlation rho showed a correlation between the clinical course and S100B/LDH. S100B and LDH seem to predict tumor response with acceptable accuracy in early stages of the disease, especially for those patients with increased S100B and LDH levels at baseline. In this early phase of the disease CT scan intervals could be prolonged or scans could maybe omitted completely to reduce the radiation exposure without missing tumor progression. For detecting tumor progression in later phases of the disease both markers cannot substitute CT scans because of their inacceptable accuracy rates.