Differential effects of two therapeutic cancer vaccines on short- and long-term survival populations among patients with advanced lung cancer

Abstract Background Progress in immunotherapy has revolutionized the treatment landscape for advanced lung cancer, with emerging evidence of patients experiencing long-term survivals. The goal of this study was to explore the existence of short- and long-term survival populations and to assess the effect of immunotherapy on them. Methods Data from two randomized, multicenter, controlled clinical trials was used to evaluate the effect of two therapeutic vaccines (anti-idiotypic vaccine VAXIRA and anti-EGF vaccine CIMAVAX) on survival curves in advanced non–small cell lung cancer patients. Data were fitted to Kaplan-Meier, standard Weibull survival, and two-component Weibull mixture models. Bayesian Information Criterion was used for model selection. Results VAXIRA did not modify, neither the fraction of patients with long-term survivals (0.18 in the control group v 0.19 with VAXIRA, P = .88), nor the median overall survival of the patients in the short-term survival subpopulation (6.8 v 7.8 months, P = .24). However, this vaccine showed great benefit for the patients belonging to the subpopulation of patients with long-term survival (33.8 v 76.6 months, P v 8.8 months, P = .005 and 33.8 v 61.8 months, P = .007). It also increased the proportion of patients with long-term survival (from 0.18 to 0.28, P = .02). Conclusions This study shows that therapeutic vaccines produce differential effects on short- and long-term survival populations and illustrates the application of advanced statistical methods to deal with the long-term evolution of patients with advanced lung cancer in the era of immunotherapy.