Background: The approved doses of the single agent nivolumab - an anti-programmed cell death protein 1 (PD-1) monoclonal antibody - for renal cell carcinoma (RCC) are 3 mg/kg and a 240-mg flat dose, despite efficacy shown at lower doses in earlier CheckMate trials. In view of financial constraints, the minimum dose of nivolumab required for efficacy remains a critical area of inquiry.
Methods: A retrospective review of RCC patients receiving single-agent anti-PD-1 treatment was conducted. Using the median cutoff of the maximum dose per body weight received, we investigated the effect of lower dosages on overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and immune-related adverse event-free survival (irAE-FS). Survival analysis was made by Kaplan-Meier, by uni- and multivariable Cox models, and by modeling the statistical interaction between dosages and survival.
Results: 32 patients were recruited: 8 patients (25%) receiving first-line treatment and 24 (75%) receiving second-line treatment and beyond. A median split at 2.15 mg/kg yielded 16 patients in both the lower-dose (LD) and the higher-dose (HD) cohort. Hazard ratios (HRs) demonstrated no difference in OS after adjustment for gender (HR = 0.22, 95% CI 0.05-1.05, p = 0.054; favoring LD), as well as in PFS after adjustment for gender and concurrent radiation therapy (HR = 0.58, 95% CI 0.25-1.34, p = 0.210; favoring LD). No differences in ORR were observed (50.0 vs. 43.8%, p = 1.00, in the LD and the HD cohort, respectively). Immune-related phenomena were observed in the LD group, including pseudoprogression and increased all-grade immune-related toxicities (irAE-FS: HR = 1.72, 95% CI 0.48-6.14, p = 0.293; favoring HD). Iterative dichotomization of dosages showed no dose-OS or dose-irAE-FS relationship.
Conclusion: Our study suggests no apparent reduction in efficacy when using a low-dosage nivolumab regimen.
Keywords: Immunotherapy; Nivolumab; Programmed cell death protein 1 inhibitor; Renal cell carcinoma.
© 2021 S. Karger AG, Basel.