To date, other indolent lymphoid malignancies such as chronic lymphocytic leukemia (CLL), marginal cell lymphoma (MZL) and Waldenström macroglobulinemia (WM) have not shown significant response rates with PD-1/PD-L1 ICB (Table 2) [56,105,110]. Here, PDCD1 is linked to B-cell chronic lymphocytic leukemia.