First-line Immunotherapy for Metastatic Merkel Cell Carcinoma: Analysis of Real-world Survival Data and Practice Patterns.

Abstract

Immune checkpoint inhibitors are a promising new therapy for advanced Merkel Cell Carcinoma (MCC). We investigated real-world utilization and survival outcomes of first-line immunotherapies in a contemporary cohort. Using the National Cancer Database (NCDB), we identified 759 patients with MCC between 2015 and 2020 with stage IV disease and known status of first-line systemic therapy. Univariable and multivariable analyses were used to determine predictors of immunotherapy usage. Overall survival (OS) was compared for patients receiving immunotherapy, chemotherapy, or no systemic therapies. We identified 759 patients meeting our inclusion criteria: 329 patients received immunotherapy, 161 received chemotherapy, and 269 received no systemic therapy. Adjusting for demographic, clinical, and facility factors, high facility volume significantly predicted first-line immunotherapy use (OR 1.99; P=0.017). Median OS was 16.2, 12.3, and 8.7 months, among patients who received immunotherapy, chemotherapy, or no systemic therapy, respectively (P<0.001). On Cox multivariable survival analysis, first-line immunotherapy treatment (HR=0.79, P=0.041) and treatment at high-volume centers (HR=0.58, P=0.004) were associated with improved OS. Consistent with clinical trial results, first-line immunotherapy associated with improvement in median overall survival for patients with stage IV MCC, significantly outperforming chemotherapy in this real-world cohort. Treatment at high-volume centers associated with first-line immunotherapy utilization suggesting that familiarity with this rare disease is important to achieving optimal outcomes for metastatic MCC.