Plasma proteome alterations by MAPK inhibitors in BRAF V600 -mutated metastatic cutaneous melanoma ☆ ☆☆

摘要

Highlights ? Based on antibody-based proteomics by proximity extension assays, pre-treatment levels of several proteins were predictive of shorter progression-free survival (PFS) after treatment with MAPK-inhibitors in metastatic cutaneous melanoma (CM), including IL6, IL10, CCL-2/-3/-4, LGALS1, and CSF1. ? By in-depth mass-spectrometry-based proteomic analysis of 1,160 proteins in a subset of metastatic CM patients receiving BRAF- and MEK- inhibitors, we discovered alterations in plasma proteins involved in cell adhesion-, neutrophil degranulation-, and proteolysis- during BRAFi and MEKi treatment. ? CPB1 had the highest increase during BRAF- and MEK- inhibitors’ treatment and was associated with longer PFS. ? Most of the proteins altered in plasma during MAPKi treatment were traceable to BRAF ~(V600E) -mutated metastatic CM tissue at mRNA level, based on expression patterns in 154 patients from the TCGA cohort. Approximately half of metastatic cutaneous melanomas (CM) harbor a mutation in the BRAF protooncogene, upregulating the mitogen-activated protein kinase (MAPK)-pathway. The development of inhibitors targeting the MAPK pathway (MAPKi), i.e., BRAF- and MEK-inhibitors (BRAFi and MEKi), have substantially improved the survival in BRAF ~(V600E/K) -mutated stage IV metastatic CM. However, most patients develop resistance to treatment and no predictive biomarkers exist in practice. This study aimed at discovering plasma proteome changes during treatment MAPKi in patients with metastatic (stage IV) CM. Matched plasma samples before (pre) and during treatment (trm) from 23 patients with stage IV CM, treated with BRAF-inhibitors (BRAFi) alone or BRAF- and MEK- inhibitors combined (BRAFi and MEKi), were collected and analyzed with targeted proteomics by proximity extension assays. Additionally, plasma from 9 patients treated with BRAFi and MEKi was analyzed with in-depth high-resolution isoelectric focusing liquid-chromatography mass-spectrometry proteomics. Alterations of plasma proteins involved in granzyme and interferon gamma pathways were detected in patients treated with BRAFi, and cell adhesion-, neutrophil degranulation-, and proteolysis pathways in patients treated with BRAFi and MEKi. Several proteins were associated with progression-free survival after MAPKi treatment. We show that the majority of the altered plasma proteins were traceable to BRAF ~(V600E) -mutant metastatic CM tissue at mRNA level in 154 patients from the TCGA, further strengthening their involvement in tumoral response to treatment. This wide screen of plasma proteins unravels proteins that may serve as predictive and/or prognostic biomarkers of MAPKi treatment, opening a window of opportunity for plasma biomarker discovery in MAPKi-treatment of BRAF ~(V600) -mutant metastatic CM.