Indeed, the selective p110δ inhibitor IC87114 is able to dampen the activity of the mutated PI3Kδ in vitro in APDS1 patients’ T cells (52), and both p110δ (APDS1) and p85α (APDS2) are strongly inhibited in vitro by the PI3Kδ-specific inhibitor idelalisib (GS-1101 or CAL-101), which is currently approved by the US-Food and Drug Administration for the treatment of chronic lymphocytic leukemia (50, 75). Here, PIK3CD is linked to B-cell chronic lymphocytic leukemia.