A treatment study in patients with WHIM Syndrome.

You likely can't join if

• Exclusion criteria for Randomized Period: 1. Has known systemic hypersensitivity to the mavorixafor drug substance, its inactive ingredients, or the placebo. 2. Is pregnant or breastfeeding. 3. Has a known history of a positive serology or viral load for HIV or a known history of AIDS. 4. Has, at screening, laboratory tests meeting 1 or more of the following criteria: − A positive hepatitis C virus antibody with confirmation by hepatitis C virus ribonucleic acid polymerase chain reaction reflex testing. − A positive hepatitis B surface antigen (HBsAg) or hepatitis B core antibody (HBcAb). − NOTE: If a participant tests negative for HBsAg, but positive for HBcAb, the participant would be considered eligible if the participant tests positive for hepatitis B surface antibody (also referred to as anti-HBsAg) on reflex testing. 5. Has, at screening, safety laboratory tests meeting 1 or more of the following criteria: − Hemoglobin < 8.0 g/dL − Platelets < 75,000 cells/μL − Estimated glomerular filtration rate based on the Modification of Diet in Renal Disease of ≤ 29 mL/min/1.73 m2 (Stage 4 or 5 chronic kidney disease) − Serum aspartate aminotransferase > 2.5 × ULN − Serum alanine aminotransferase > 2.5 × ULN − Total bilirubin > 1.5 × ULN (unless due to Gilbert’s syndrome, in which case total bilirubin ≥ 3.0 × ULN and direct bilirubin > 1.5 × ULN) 6. Had surgery requiring general anesthesia within the 4 weeks prior to Day 1. 7. Received any of the following treatments: − Plerixafor within 6 months prior to Day 1. − Chronic or prophylactic use of antibiotics (systemic or inhaled) within 4 weeks prior to Day 1. − Chronic or prophylactic use of G-CSF or granulocyte macrophage-colony stimulating factor within 2 weeks of Day 1. − Chronic or prophylactic use of systemic glucocorticoid use (> 5 mg prednisone equivalent per day) within 2 weeks prior to Day 1. − Any investigational therapy within 5 half-lives or 2 weeks prior to Day 1, whichever is longer. Prior use of any investigational therapies must be discussed with the Medical Monitor. 8. Is currently taking or has, within 2 weeks prior to Day 1, received any medication that is prohibited (see Section 6.4.1), based on potential for drug-drug interactions. 9. Has, at the planned initiation of study drug, a clinically diagnosed active infection (excluding warts) that has the potential to raise the ANC counts. 10. Has had a total splenectomy within 1 year. 11. Has a current diagnosis of myelofibrosis. 12. Has a medical history of hematological malignancies. 13. Has any other medical or personal condition that, in the opinion of the Investigator, may potentially compromise the safety or compliance of the participant or may preclude the participant’s successful completion of the clinical study. 14. Has corrected QT interval using Fridericia’s formula of > 450 ms.