FDG-PET metabolic tumor volume in advanced melanoma treated with ipilimumab and nivolumab (ipi/nivo).

10041 Background: Predictors of outcomes of immune checkpoint inhibitors (ICI) are desirable. We aim to investigate the prognostic value of 18 F-fluorodeoxyglucose-PET/CT (FDG-PET) parameters at baseline and response monitoring of patients (pts) with advanced melanoma receiving ipi/nivo. Methods: From 2016-2019, melanoma pts who received ipi/nivo and had PET Response Criteria In Solid Tumors (PERCIST) measurable lesions on baseline FDG-PET were included. Baseline whole-body metabolic tumor volume (wbMTV), tumor stage, mutational status, ECOG performance score, lactate dehydrogenase (LDH) and treatment-line were correlated with overall survival (OS) in univariate and multivariate Cox-regression analysis. Response were assessed for a subset of pts with post-treatment FDG-PET based on PERCIST. Results: Of 162 pts receiving ipi/nivo, 122 pts (median age: 61; male: 73%; ECOG 0: 78%; raised LDH: 52%; M1c: 39%, M1d: 45% and BRAF V600E/K mutation: 45%) met eligibility criteria. Forty percent received ipi/nivo as first-line treatment, 48% as second-line (25% post BRAF inhibitor(i)/MEKi and 23% post single-agent ICI) and 12% as third-line. At median follow-up of 21 months (mths), median OS was 20 mths (95% CI 11-not reached[NR]). Pts with above the median wbMTV had shorter OS than those with below the median wbMTV (NR vs 10 mths, 95% CI 8-NR; HR 2.0, 95% CI 1.2-3.4, p = 0.009). In multivariate analysis, wbMTV, ECOG and treatment-line were independently associated with OS. In 106 pts with post-treatment FDG-PET, 24 mths OS rate was higher for those with objective response (OR): 91% (95% CI 82-100%) vs stable disease:55% (27-100%) vs progressive disease:17% (8-35%) as best response, p < 0.001. OR was higher in first-line compared to second or third-line treatment, 75% vs 29-33% vs 23%, respectively, p = 0.0012. Conclusions: Increased baseline FDG-PET wbMTV is an independent prognostic biomarker in pts with advanced melanoma receiving ipi/nivo. FDG-PET response accurately predicts outcome. [Table: see text]