The Phase III clinical failure of Pfizer 's tremelimumab anti-CTLA - 4 monoclonal antibody provided the first large - scale evidence of the utility of the irRC .
Pfizer 's tremelimumab anti-CTLA - 4 monoclonal antibody competed with ipilimumab .
The Phase III clinical failure of Pfizer 's tremelimumab anti-CTLA - 4 monoclonal antibody , which competed with ipilimumab , provided the first large - scale evidence of the utility of the irRC .