Background: Cutaneous melanoma (CM) can be molecularly classified into four groups:BRAFmutant,NRASmutant,NF1mutant and triple wild-type (TWT) tumors lacking any of these three alterations. In the era of immune checkpoint inhibition (ICI) and targeted molecular therapy, the clinical significance of these groups remains unclear. Here, we integrate targeted DNA sequencing with comprehensive clinical follow-up in CM patients. Methods: This was a retrospective cohort study that assessed clinical and molecular features from patients with localized or metastatic CM who underwent targeted next-generation sequencing as part of routine clinical care. A total of 254 patients with CM who had a CLIA-certified targeted sequencing assay performed on their tumor tissue were included. Results: Of the 254 patients with cutaneous melanoma, 77 wereBRAFmutant (30.3%), 77 wereNRASmutant (30.3%), 47 wereNF1mutant (18.5%), 33 were TWT (13.0%) and the remaining 20 (7.9%) carried mutations in multiple driver genes (BRAF/NRAS/NF1co-mutated). The majority of this co-mutation group carried mutations inNF1(n= 19 or 90%) with co-occurring mutations inBRAForNRAS,often with a weaker oncogenic variant. Consistently,NF1mutant tumors harbored numerous significantly co-altered genes compared toBRAForNRASmutant tumors. The majority of TWT tumors (n= 29, 87.9%) harbor a pathogenic mutation within a known Ras/MAPK signaling pathway component. Of the 154 cases with available TMB data, the median TMB was 20 (range 0.7–266 mutations/Mb). A total of 14 cases (9.1%) were classified as having a low TMB (≤5 mutations/Mb), 64 of 154 (41.6%) had an intermediate TMB (>5 and ≤20 mutations/Mb), 40 of 154 (26.0%) had a high TMB (>20 and ≤50 mutations/Mb) and 36 of 154 (23.4%) were classified as having a very high TMB (>50 mutations/Mb).NRASmutant melanoma demonstrated significantly decreased overall survival on multivariable analysis (HR for death 2.95, 95% CI 1.13–7.69,p= 0.027, log-rank test) compared with other TCGA molecular subgroups. Of the 116 patients in our cohort with available treatment data, 36 received a combination of dual ICI with anti-CTLA4 and anti-PD1 inhibition as first-line therapy. Elevated TMB was associated with significantly longer progression-free survival following dual-agent ICI (HR 0.26, 95% CI 0.07–0.90,p= 0.033, log-rank test). Conclusions:NRASmutation in CMs correlated with significantly worse overall survival. Elevated TMB was associated with increased progression-free survival for patients treated with a combination of dual ICI, supporting the potential utility of TMB as a predictive biomarker for ICI response in melanoma.
背景：皮肤黑色素瘤（CM）在分子水平上可分为四类：BRAF突变型、NRAS突变型、NF1突变型以及不携带这三种突变的"三野生型"（TWT）肿瘤。在免疫检查点抑制剂（ICI）和靶向分子治疗时代，这些分子亚型的临床意义尚不明确。本研究通过整合靶向DNA测序数据与CM患者的全面临床随访资料进行探讨。 方法：本研究为回顾性队列研究，评估了接受靶向二代测序作为常规临床诊疗一部分的局部或转移性CM患者的临床与分子特征。共纳入254例经CLIA认证的肿瘤组织靶向测序检测的CM患者。 结果：在254例皮肤黑色素瘤患者中，77例为BRAF突变型（30.3%），77例为NRAS突变型（30.3%），47例为NF1突变型（18.5%），33例为TWT型（13.0%），其余20例（7.9%）携带多驱动基因突变（BRAF/NRAS/NF1共突变）。该共突变组中绝大多数（n=19，90%）存在NF1突变，并伴有BRAF或NRAS突变，且常伴随致癌性较弱的变异。与BRAF或NRAS突变型肿瘤相比，NF1突变型肿瘤持续表现出大量显著共变基因。绝大多数TWT肿瘤（n=29，87.9%）在已知Ras/MAPK信号通路组分中存在致病性突变。在154例具有可用肿瘤突变负荷（TMB）数据的病例中，中位TMB为20（范围0.7-266个突变/Mb）。其中14例（9.1%）为低TMB（≤5个突变/Mb），64例（41.6%）为中等TMB（>5且≤20个突变/Mb），40例（26.0%）为高TMB（>20且≤50个突变/Mb），36例（23.4%）为极高TMB（>50个突变/Mb）。多变量分析显示，与其他TCGA分子亚组相比，NRAS突变型黑色素瘤患者的总生存期显著缩短（死亡风险比HR 2.95，95% CI 1.13-7.69，p=0.027，对数秩检验）。在队列中116例具有可用治疗数据的患者中，36例接受抗CTLA4与抗PD1双重ICI联合方案作为一线治疗。TMB升高与双重ICI治疗后显著延长的无进展生存期相关（HR 0.26，95% CI 0.07-0.90，p=0.033，对数秩检验）。 结论：CM中NRAS突变与显著较差的总生存期相关。TMB升高与接受双重ICI联合治疗患者无进展生存期的改善相关，这支持TMB作为黑色素瘤ICI反应预测性生物标志物的潜在应用价值。
Targeted DNA Sequencing of Cutaneous Melanoma Identifies Prognostic and Predictive Alterations
肿瘤(癌症)患者之家