mRNA vaccines have been shown to be safe and effective in individuals with cancer. It is unclear, however, if systemic anti-cancer therapy impacts the coordinated cellular and humoral immune responses elicited by SARS-CoV-2 mRNA vaccines. To fill this knowledge gap, we assessed SARS-CoV-2 mRNA vaccine-elicited immunity in a cohort of patients with advanced solid tumors either under observation or receiving systemic anti-cancer therapy. This analysis revealed that SARS-CoV-2 mRNA vaccine-elicited cellular and humoral immunity was not significantly different in individuals with cancer receiving systemic anti-cancer therapy relative to individuals under observation. Furthermore, even though some patients exhibited suboptimal antibody titers after vaccination, SARS-CoV-2 specific cellular immune responses were still detected. These data suggest that antibody titers offer an incomplete picture of vaccine-elicited SARS-CoV-2 immunity in cancer patients undergoing active systemic anti-cancer therapy, and that vaccine-elicited cellular immunity exists even in the absence of significant quantities of SARS-CoV-2 specific antibodies.
