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Abstract:
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Unlike cytotoxic agents, cancer immunotherapies utilize the immune system to attack cancer cells. Due to this unique action mechanism, the proportional hazards (PH) assumption is unlikely to hold when evaluating the survival benefit of immunotherapies. However, almost all immunotherapy studies have been using the log-rank test (the optimal test for PH differences). This implies that current immunotherapy treatment assessments based on the log-rank test are not necessarily optimal. The adaptive long-term restricted mean survival time (ALT-RMST)-based approach is a promising alternative to the conventional approach when the delayed treatment effect is expected. We hypothesized that the ALT-RMST tests could have provided a higher empirical power than the log-rank test in past immunotherapy studies. Using reconstructed patient-level data for overall survival and progression-free survival in past immunotherapy trials, we calculated the empirical power (i.e., the proportion of trials for which the test would have identified a significant result) of ALT-RMST-based tests and compared it with other tests.
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