Survival of patients with advanced metastatic melanoma: The impact of MAP kinase pathway inhibition and immune checkpoint inhibition - Update 2019.

Background: Recent therapeutic strategies, particularly MAP kinase pathway inhibitors (BRAF, MEK) and immune checkpoint blockers (CTLA-4, PD-1), have been put on the test for their differential impact on long-term survival of metastatic melanoma patients. Various agents, dose regimens and combinations have been tested against each other vigorously within these two therapy groups. However, results from prospective head-to-head comparative trials comparing both strategies against each other are still lacking.

Methods: We performed an exploratory analysis of survival data from selected clinical trials representative for these two treatment strategies in advanced metastatic melanoma. 84 Kaplan-Meier survival curves from 26 trials were digitised and grouped by therapy strategy and treatment line. For each of these groups, mean survival curves were generated for progression-free (PFS) and overall survival (OS) by weighted averaging.

Results: Survival curves grouped together by therapy strategy revealed a high concordance, with a larger extent in the first-line setting compared to higher treatment lines. In first-line therapy, the averaged 3-year OS proportions were 41.3% for BRAF plus MEK inhibition, 49.9% for PD-1 inhibition, and 58.4% for CTLA-4 plus PD-1 inhibition. Comparison of the mean PFS and OS curves of kinase inhibition and checkpoint blockade revealed a superiority of combined BRAF plus MEK inhibition within the first 12 months, later changing to a superiority of PD-1 blockers alone or in combination with CTLA-4 blockade. In second-line or higher, BRAF plus MEK inhibition was superior to anti-PD-1 monotherapy throughout the first three years; averaged 3-year OS proportions were 42.4% for BRAF plus MEK inhibition, and 40.1% for PD-1 inhibition.

Conclusions: and relevance: These results need confirmation by head-to-head comparative randomised clinical trials.