In Reply We are thankful to Huang et al and Yang et al for the constructive feedback emerging from their letters, which highlighted a crucial question in the interpretation of our findings of whether prior antibiotic (pATB) treatment is truly associated with outcomes from immune checkpoint inhibitor (ICI) therapy.1 Effective induction of ICI-mediated tumor rejection is the net result of a number of tumor-related and host-related factors. Although causation cannot be inferred from our study, a number of factors suggest that the detrimental association of ATB exposure with outcome from ICI therapy should not be overlooked.