A recent phase 3 trial has shown that blockade of CXCR4 with mavorixafor, an orally bioavailable and selective CXCR4 antagonist, demonstrated clinically meaningful increases in absolute neutrophil and lymphocyte counts in patients with WHIM syndrome, leading to the recent FDA approval of XOLREMDI® (mavorixafor). The gene discussed is CXCR4; the disease is WHIM syndrome.