Relapse-free survival (RFS) should not be used as a surrogate for overall survival (OS) in cancer trials testing adjuvant immunotherapy, according to researchers.
The researchers found no significantly strong association between RFS and OS in a meta-analysis of trials designed to test adjuvant immunotherapy in patients with early-stage solid tumors.
The researchers reported their findings in the Journal of the National Cancer Institute.
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The meta-analysis included data from 13,715 patients with early-stage cancers. The patients were enrolled in 15 phase 2 and phase 3 randomized controlled trials designed to test adjuvant immunotherapy.
The trials enrolled patients with melanoma (7 trials), non-small cell lung cancer (2 trials), renal cell carcinoma (3 trials), triple-negative breast cancer (1 trial), muscle-invasive urothelial carcinoma (1 trial), and esophageal squamous cell carcinoma (1 trial). The immunotherapies included anti-PD-1 antibodies (9 trials), anti-PD-L1 antibodies (4 trials), and anti-CTLA-4 antibodies (2 trials).
The researchers assessed the efficacy of RFS as a surrogate for OS at the treatment arm level and at the trial level.
When the researchers looked at the arm-level correlations between RFS and OS, the association between 2-year RFS and 3-year OS was moderate (R2=0.58; 95% CI, 0.25-0.92). The association between 3-year RFS and 5-year OS was strong (R2=0.72; 95% CI, 0.38-1.00).
However, at the trial level, there was a moderate association between RFS and OS (R2=0.63; 95% CI, 0.33-0.94). The researchers found weak associations for the treatment effect on 2-year RFS and 3-year OS (R2=0.20; 95% CI, 0.00-0.58) and 3-year RFS and 5-year OS (R2=0.21; 95% CI, 0.00-0.74).
“Our meta-analysis failed to find a significantly strong association between RFS and OS in RCTs [randomized controlled trials] of adjuvant immunotherapy,” the researchers concluded. “Our findings challenge the use of RFS as the primary efficacy endpoint and suggest the use of OS in this clinical context.”
Reference
Li Y, Yuan S, Chen Y, et al. Evaluating relapse-free survival as an endpoint for overall survival in adjuvant immunotherapy trials. J Natl Cancer Inst. Published online June 30, 2023. doi:10.1093/jnci/djad125
This article originally appeared on Cancer Therapy Advisor