Hotspot mutations of the oncogenes BRAF and NRAS are the most common genetic alterations in cutaneous melanoma.,Specific inhibitors of BRAF and MEK have shown significant survival benefits in large phase III trials.,However, the prognostic significance of BRAF and NRAS mutations outside of clinical trials remains unclear.,The mutational status of BRAF (exon 15) and NRAS (exon 2 and 3) was determined in melanoma samples of 217 patients with pyrosequencing and Sanger sequencing.,The genotypes were correlated with clinical outcomes and pathologic features of the primary tumors.,Time to disease progression was calculated with the cumulative incidence function.,Survival analyses were performed with Kaplan-Meier estimates and Cox proportional hazards regression analysis.,Relative survival was calculated with the Ederer-II method.,Treatment with BRAF and MEK inhibitors and immune checkpoint blockade (ICB) was allowed.,Mutations in BRAF and NRAS were identified in 40.1 and 24.4% of cases, respectively.,Concurrent mutations in both genes were detected in further 2.3%.,The remaining 33.2% were wild type for the investigated exons (WT).,BRAF mutations were significantly associated with younger age at first diagnosis (p < 0.001) and truncal localization of the culprit primary (p = 0.002).,The nodular subtype was most common in the NRAS cohort.,In addition, NRAS-mutant melanoma patients showed a higher frequency of nodal relapse (p = 0.013) and development of metastatic disease (p = 0.021).,The time to loco-regional nodal relapse was shortest in NRAS-mutant melanoma (p = 0.002).,Presence of NRAS mutation was an independent risk factor for disease progression in multivariate analysis (HR 2.01; 95% CI 1.02 - 3.98).,BRAF-mutant melanoma patients showed a tendency for better overall and relative survival.,Genotype was not a consistent risk factor in multivariate analysis.,Instead, positive sentinel lymph node status (HR 2.65; 95% CI 1.15 - 6.10) and treatment with ICB in stage IV disease (HR 0.17; 95% CI 0.06-0.48) were significant multivariate risk factors.,NRAS-mutant tumors tended to behave more aggressively particularly in early stages of the disease in this high-risk melanoma population.,Treatment with immune checkpoint blockade improved survival in stage IV disease in a real-world setting.,The online version of this article (doi:10.1186/s12885-017-3529-5) contains supplementary material, which is available to authorized users.
The detection of BRAFV600 mutations in patients with metastatic melanoma is important because of the availability of BRAF inhibitor therapy.,However, the clinical relevance of the frequency of BRAFV600 mutant alleles is unclear.,Allele frequencies of BRAFV600 mutations were analyzed by ultra-deep next-generation sequencing in formalin-fixed, paraffin-embedded melanoma tissue (75 primary melanomas and 88 matched metastases).,In a second study, pretreatment specimens from 76 patients who received BRAF inhibitors were retrospectively analyzed, and BRAFV600 allele frequencies were correlated with therapeutic results.,Thirty-five patients had concordantly BRAF-positive and 36 (48%) patients had concordantly BRAF-negative primary melanomas and matched metastases, and four patients had discordant samples with low allele frequencies (3.4-5.2%).,Twenty-six of 35 patients with concordant samples had BRAFV600E mutations, three of whom had additional mutations (V600K in two patients and V600R in one) and nine patients had exclusively non-V600E mutations (V600K in eight patients and V600E -c.1799_1800TG > AA- in one patient).,The frequency of mutated BRAFV600 alleles was similar in the primary melanoma and matched metastasis in 27/35 patients, but differed by >3-fold in 8/35 of samples.,BRAFV600E allele frequencies in pretreatment tumor specimens were not significantly correlated with treatment outcomes in 76 patients with metastatic melanoma who were treated with BRAF inhibitors.,BRAFV600 mutation status and allele frequency is consistent in the majority of primary melanomas and matched metastases.,A small subgroup of patients has double mutations.,BRAFV600 allele frequencies are not correlated with the response to BRAF inhibitors.