Obesity is associated with improved progression-free survival in Microsatellite-Instability-High endometrial cancer treated with pembrolizumab

Objectives: To determine the clinical predictors of response rate, progression-free survival (PFS), and overall survival (OS) to pembrolizumab in advanced or recurrent, mismatch repair deficient (MMRd) or Microsatellite Instability-High (MSI-H) endometrial adenocarcinomas. Methods: A retrospective, single institution study was conducted among women with recurrent or advanced MMRd or MSI-H endometrial adenocarcinomas treated with single-agent pembrolizumab at our institution from 2017 to 2021. Logistic regression was used for univariable and multivariable analyses. PFS and OS were estimated using the methods of Kaplan and Meier and modeled via Cox proportional hazards regression. Log-rank test was used for intergroup comparisons based on body mass index (BMI). Results: Among the 44 patients included in the analysis, the median BMI was 32.9 (range 18.5–51.8). Median cycles of pembrolizumab given was 11.5 (range 2–37). Median follow-up was 33 months (range 5–61) with a response rate of 63.6% and stable disease rate of 75%. When stratified by obesity status (BMI≥30), disease control rate was 59.8% in patients with a BMI < 30 and 85.2% in patients with a BMI≥30 patients (p = 0.05). On multivariable analysis, obesity was associated with increased rate of disease control (OR 4.03, 95%CI 1.09, 28) while prior smoking was associated with decreased rate of disease control (OR 0.18, 95%CI 0.03, 0.85). PFS was significantly increased among patients with a BMI≥30 (p = 0.03) but OS was similar (p = 0.5). Conclusion: In this retrospective study, obesity is associated with increased rates of disease control and improved PFS in patients treated with pembrolizumab for recurrent or advanced MMRd/MSI-H endometrial adenocarcinomas.