M-CSF as a therapeutic target in BRAFV600E melanoma resistant to BRAF inhibitors.

BACKGROUND: Disseminated BRAFV600E melanoma responds to BRAF inhibitors (BRAFi) but easily develops resistance with poor prognosis. Secretome plays a pivotal role during tumour progression causing profound effects on therapeutic efficacy. Secreted M-CSF is involved in both cytotoxicity suppression and tumour progression in melanoma. We aimed to analyse the M-CSF contribution in resistant metastatic melanoma to BRAF-targeted therapies. METHODS: Conditioned media from melanoma cells were analysed by citoarray. Viability and migration/invasion assays were performed with paired melanoma cells and tumour growth in xenografted SCID mice. We evaluated the impact of M-CSF plasma levels with clinical prognosis from 35 metastatic BRAFV600E-mutant melanoma patients. RESULTS: BRAFi-resistant melanoma cells secretome is rich in pro-tumour cytokines. M-CSF secretion is essential to induce a Vemurafenib-resistant phenotype in melanoma cells. Further, we demonstrated that M-CSF mAb in combination with Vemurafenib and autophagy blockers synergistically induce apoptosis, impair migration and reduce tumour growth in BRAFi-resistant melanoma cells. Interestingly, lower M-CSF plasma levels are associated with better prognosis in metastatic melanoma patients. CONCLUSIONS: Secreted M-CSF induces a BRAFi-resistant phenotype and means worse prognosis in BRAFV600E metastatic melanoma patients. These results identify secreted M-CSF as a promising therapeutic target toward BRAFi-resistant melanomas.

Inherited MC1R variants in patients with melanoma are associated with better survival in women.

BACKGROUND: Women have a better melanoma prognosis, and fairer skin/hair colour. The presence of inherited MC1R variants has been associated with a better melanoma prognosis, but its interaction with sex is unknown. OBJECTIVES: To evaluate the relationship between germline MC1R status and survival, and determine any association with sex. METHODS: This was a cohort study including 1341 patients with melanoma from the Melanoma Unit of the Hospital Clinic of Barcelona, between January 1996 and April 2018. We examined known sex-related prognosis factors as they relate to features of melanoma and evaluated the sex-specific role of MC1R in overall and melanoma-specific survival. Hazard ratios (HRs) were calculated using univariate and multivariate Cox logistic regression. RESULTS: Men showed lower overall survival than women (P < 0·001) and the presence of inherited MC1R variants was not associated with better survival in our cohort. However, in women the presence of MC1R variants was associated with better overall survival in the multivariate analysis [HR 0·57, 95% confidence interval (CI) 0·38-0·85; P = 0·006] but not in men [HR 1·26, 95% CI 0·89-1·79; P = 0·185 (P-value for interaction 0·004)]. Analysis performed for melanoma-specific survival showed the same level of significance. CONCLUSIONS: Inherited MC1R variants are associated with improved overall survival in women with melanoma but not in men. Intrinsic sex-dependent features can modify the role of specific genes in melanoma prognosis. We believe that survival studies of patients with melanoma should include analysis by sex and MC1R genotype. What's already known about this topic? Inherited MC1R variants have been associated with a better melanoma prognosis, but their interaction with sex is unknown. What does this study add? MC1R variants are related to better overall survival and melanoma-specific survival in women but not in men. What is the translational message? These differences between the sexes could imply future changes in melanoma follow-up and treatment strategies. This provides a basis for understanding the interaction between sex-related genes and germline variants in cancer.

Detection of cell-free circulating BRAFV 600E by droplet digital polymerase chain reaction in patients with and without melanoma under dermatological surveillance.

BACKGROUND: The p.V600E mutation in the BRAF protein is the most frequent mutation in cutaneous melanoma and is a recurrent alteration found in common benign naevi. Analysis of the cell-free BRAF c.1799T>A, p.V600E mutation (cfBRAFV 600E ) in plasma has emerged as a biomarker for monitoring prognosis and treatment response in patients with melanoma. OBJECTIVES: To quantify cfBRAFV 600E levels in plasma from patients with melanoma and from patients without melanoma undergoing regular follow-up of their melanocytic lesions, in order to assess the clinical significance of the test. METHODS: We quantified cfBRAFV 600E by droplet digital polymerase chain reaction in plasma from 146 patients without melanoma undergoing continuous dermatological screening, from 26 stage III and seven stage IV patients with BRAF-mutant melanoma, and from 32 patients with melanoma who were free of disease for 3 or more years. RESULTS: Among disease-free patients and individuals without melanoma, 52% presented a high naevus count (> 50) and 49% had clinically atypical naevi. cfBRAFV 600E was detected in 71% of patients with stage IV melanoma and 15% with stage III, and in 1·4% of individuals without melanoma. No cfBRAFV 600E mutation was detected in disease-free patients with melanoma. Individuals without melanoma had lower cfBRAFV 600E levels than patients with melanoma. We established a variant allelic frequency of 0·26% or 5 copies mL-1 of cfBRAFV 600E as the optimal cutoff value for identifying patients with melanoma with > 99% specificity. CONCLUSIONS: This study suggests that naevus-related factors do not influence the detection of cfBRAFV 600E in individuals without melanoma, and supports the clinical diagnostic value of plasma cfBRAFV 600E quantification in patients with melanoma. What's already known about this topic? The analysis of the BRAF c.1799T>A (p.V600E) mutation in cell-free (cf)DNA has emerged as a potential biomarker for monitoring prognosis and treatment response in patients with metastatic BRAFV600E melanoma. The BRAFV600E alteration is a common genetic alteration found in benign proliferations such as melanocytic naevi. No information exists about the impact of the number of common acquired naevi or the presence of clinically atypical naevi in cfBRAFV600E detection in an individual. What does this study add? The cfBRAFV600E mutation is detected in plasma from a reduced number of individuals without melanoma undergoing continuous dermatological follow-up. A high number of naevi or the presence of clinically atypical naevi are factors that do not influence cfBRAFV600E detection in an individual. Both total cfBRAF concentration and cfBRAFV600E frequency are effective biomarkers in patients with advanced melanoma but not in patients at early stages or with micrometastases. What is the translational message? Detection of cfBRAFV600E in an individual is not influenced by naevus-related factors. cfBRAFV600E is a robust and reliable biomarker that can be used in dermatological surveillance programmes.