Abstract
BACKGROUND: Immunotherapy has revolutionized advanced melanoma treatment. Several prognostic factors have been studied to predict survival in this setting. We aimed to develop a prognostic score. MATERIALS AND METHODS: A multicentre, retrospective cohort study was conducted including patients with advanced melanoma who started anti-programmed cell death protein 1 (PD-1) monotherapy between January 2016 and October 2019 with ≤2 prior treatment lines. The study endpoint was overall survival (OS). Univariate and multivariate Cox regression identified independent prognostic factors, with 95% confidence intervals (CIs). The predictive accuracy of the model was evaluated by the receiver operating characteristic (ROC) curve model. RESULTS: We identified 147 patients with a median follow-up of 28.9 months (95% CI 22.5-33.5 months). The median OS (mOS) for the whole cohort was 14.8 months (95% CI 10.8-18.7 months). Overall, 43 and 104 patients were treated with nivolumab and pembrolizumab, respectively. We identified four prognostic factors at baseline: ≥3 metastatic sites [hazard ratio (HR) 1.90, 95% CI 1.21-2.97], performance status by Eastern Cooperative Oncology Group ≥1 (HR 2.02, 95% CI 1.28-3.18), lymphopenia (HR 2.85, 95% CI 1.54-5.27) or increased lactate dehydrogenase (HR 2.08, 95% CI 1.19-3.63). The MELimmune score grouped patients into three risk categories: favourable prognosis (no risk factors; n = 34), intermediate prognosis (one risk factor; n = 65) and poor prognosis (two or more risk factors; n = 48). The mOS was 43.4 (95% CI 32.1-54.7), 14.4 (95% CI 6.8-22.0) and 6.5 (95% CI 3.6-9.4) months for favourable, intermediate and poor prognosis groups, respectively (P < 0.001). The area under the ROC curve was 0.74 (95% CI 0.66-0.82). CONCLUSION: Using easily accessible variables from daily practice, the MELimmune prognostic score for patients with advanced melanoma treated with anti-PD-1 monotherapy holds potential to be used in clinical practice and prospectively validated in clinical trials.