X4P-001-110

The purpose of this study is to demonstrate the efficacy and evaluate the safety, and tolerability of mavorixafor in participants with congenital or acquired primary autoimmune and idiopathic chronic neutropenic disorders who are experiencing recurrent and/or serious infections as assessed by demonstrating its clinical benefit and increasing levels of circulating neutrophils. All participants will continue their pre-study background therapy, defined as the participant’s current treatment regimen. Options include, but are not limited to granulocyte-colony stimulating factor (G-CSF), immunoglobulin replacement therapy, prophylactic antibiotics, or “watchful waiting”.