CD8A and neoplasm: However, many studies start treatment before injected cell properly established large tumors.38 39 Using two syngeneic mouse tumor models with similar large sizes and growth rates, but differential susceptibility to αPD1 ICB, we first show that heterogeneity in the T-cell response is established before treatment and αPD1 treatment significantly increases the number of effector CD8+PD1− TILs.