Since abundant lymphocyte infiltration was confirmed in anti‐PD‐1/4‐1BB‐treated mice compared with non‐treated mice by H&E staining of the tumor tissue sections (Figure 7d), our data suggest that Q‐annexin V is a reliable and selective probe for the early detection of apoptosis in tumor tissues, following cancer immunotherapy. This evidence concerns the gene PDCD1 and neoplasm.