Purpose Biomarkers for outcome after immune-checkpoint blockade are strongly needed as these may influence individual treatment selection or sequence. We aimed to identify baseline factors associated with overall survival (OS) following pembrolizumab treatment in melanoma patients. Experimental design Serum lactate dehydrogenase (LDH), routine blood count parameters, and clinical characteristics were investigated in 616 patients. Endpoints were OS and best overall response following pembrolizumab. Kaplan-Meier analysis and Cox regression were applied for survival analysis. Results Relative eosinophil count (REC) ≥1.5%, relative lymphocyte count (RLC) ≥17.5%, ≤2.5-fold elevation of LDH, and the absence of metastasis other than soft-tissue/lung were associated with favorable OS in the discovery (n=177) and the confirmation (n=182) cohort and had independent positive impact (all P<0.001). Their independent role was subsequently confirmed in the validation cohort (n=257; all P<0.01). The number of favorable factors was strongly associated with prognosis. One-year-OS probabilities of 83.9% vs 14.7% and response rates of 58.3% vs 3.3% were observed in patients with four out of four compared to those with none out of four favorable baseline factors present, respectively. Conclusions High REC and RLC, low LDH, and absence of metastasis other than soft-tissue/lung are independent baseline characteristics associated with favorable OS of patients with melanoma treated with pembrolizumab. Presence of four favorable factors in combination identifies a subgroup with excellent prognosis. In contrast, patients with no favorable factors present have a poor prognosis, despite pembrolizumab, and additional treatment advances are still needed. A potential predictive impact needs to be further investigated.

Purpose To identify baseline peripheral blood biomarkers associated with clinical outcome following ipilimumab treatment in advanced melanoma patients. Experimental design Frequencies of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), serum lactate dehydrogenase (LDH), routine blood counts, and clinical characteristics were assessed in 209 patients. Endpoints were overall survival (OS) and best overall response. Statistical calculations were done by Kaplan-Meier- and Cox-regression-analysis including calibration and discrimination by C-statistics. Results Low baseline LDH, absolute monocyte counts (AMC), Lin−CD14+HLA-DR−/low-MDSC frequencies, and high absolute eosinophil counts (AEC), relative lymphocyte counts (RLC), and CD4+CD25+FoxP3+-Treg frequencies were significantly associated with better survival, and were considered in a combination model. 43.5% of patients presenting with the best biomarker signature had a 30% response rate and median survival of 16 months. In contrast, patients with the worst biomarkers (27.5%) had only a 3% response rate and median survival of 4 months. The occurrence of adverse events correlated with neither baseline biomarker signatures nor the clinical benefit of ipilimumab. In another model, limited to the routine parameters LDH, AMC, AEC, and RLC, the number of favorable factors (4 vs. 3 vs. 2-0) was also associated with OS (p<0.001 for all pairwise comparisons) in the main study and additionally in an independent validation cohort. Conclusions A baseline signature of low LDH, AMC and MDSCs as well as high AEC, Tregs and RLC is associated with favorable outcome following ipilimumab. Prospective investigation of the predictive impact of these markers following ipilimumab and other treatments, e.g. PD-1 antibodies, is warranted.

Purpose: To analyze the prognostic relevance and relative impact of circulating myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg) compared with functional tumor antigen-specific T cells in patients with melanoma with distant metastasis.Experimental Design:Tregs, and the presence of NY-ESO-1-or Melan-A-specific T cells was analyzed in 94 patients and validated in an additional cohort of 39 patients by flow cytometry. Univariate survival differences were calculated according to Kaplan-Meier and log-rank tests. Multivariate analyses were performed using Cox regression models.Results: NY-ESO-1-specific T cells, the M-category, and the frequency of MDSCs were associated with survival. The absence of NY-ESO-1-specific T cells and the M-category M1c independently increased the risk of death. In a second Cox model not considering results on antigen-specific T cells, a frequency of >11% MDSCs showed independent impact. Its association with survival was confirmed in the additional patient cohort. Median survival of patients with a lower frequency of MDSCs was 13 months versus 8 months for others (P < 0.001, combined cohorts). We observed a strong correlation between high levels of MDSCs and the absence of melanoma antigen-specific T cells implying a causal and clinically relevant interaction. No prognostic impact was observed for Tregs.Conclusions: Circulating CD14 þ CD11b þ HLA-DR À/low MDSCs have a negative impact on survival and inversely correlate with the presence of functional antigen-specific T cells in patients with advanced melanoma. Our findings provide a rationale to investigate MDSC-depleting strategies in the therapeutic setting especially in combination with vaccination or T-cell transfer approaches.