A recent study examining immune dysfunctions in chronic lymphocytic leukemia (CLL) found that PD-1 triggering on monocytes resulted in impaired glycolysis, phagocytosis and Bruton’s tyrosine kinase (BTK) signaling and that blocking the PD-1 pathway reverted the metabolic dysfunction [74] (Figure 3A). The gene discussed is PDCD1; the disease is B-cell chronic lymphocytic leukemia.