Fig. 1

Correlation of T cell subset dynamics with the anti-tumoral action of CTLA-4 blockade in the tumor microenvironment (TME). The action of anti-CTLA-4 on the tumor has been associated with its ability to expand and activate intratumoral CD8⁺ effector T cells, broaden the range of neo-antigens targeted and induce memory CD8⁺ T cell subsets. CD4⁺ effector T cell subsets may also markedly expand in the TME on therapy and contribute to the modulation of the anti-tumoral immune response, a Th-1 response profile in the TME standing as a correlate of response to anti-CTLA-4. Another proposed, yet still debated, mechanism of anti-CTLA-4 action on the tumor is the depletion of intratumoral Tregs via a mechanism of antibody-dependent cell mediated cytotoxicity that is independent of immune checkpoint inhibition