Improved survival at the population level for patients with advanced Merkel cell carcinoma following availability of immunotherapy

Abstract

Background: Merkel cell carcinoma (MCC) is an aggressive skin cancer with poor survival rates. Immune checkpoint inhibitors (ICIs) were Food and Drug Administration-approved for advanced MCC in 2017, but their real-world survival impact remains unclear.

Objective: Evaluate whether ICI introduction in the United States corresponded with improved survival.

Methods: This cohort study analyzed Surveillance, Epidemiology, and End Results data for MCC patients diagnosed from 2010 to 2021, grouped by 3-year periods, to calculate 2-year overall and relative survival.

Results: For 453 patients with metastatic MCC, 2-year relative survival improved from 23% (2010-2012) to 37% (2013-2015), 42% (2016-2018), and 54% (2019-2021) (P < .001). Median overall survival also increased from 9 to 16 months among these patients. In 4786 MCC patients overall, 2-year relative survival rose from 73% (2010-2012) to 81% (2019-2021) (P = .004), while overall survival improved from 67% to 72% (P = .012).

Limitations: Surveillance, Epidemiology, and End Results lacks case-level data to link ICI treatment directly to survival, although ICIs represent the major recent treatment advance for MCC.

Conclusions: The introduction of ICIs aligns with a >2-fold increase in survival for advanced MCC patients at the population level, translating to ∼220 fewer deaths per year in the United States.

Keywords: Merkel cell carcinoma; PD-(L)-1 inhibitor; SEER; immune checkpoint inhibitors; immunotherapy; overall survival; relative survival; survival.