X4 Pharmaceuticals announced the U.S. FDA has granted Breakthrough Therapy Designation for mavorixafor (X4P-001) for the treatment of adult patients with WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome.
A Breakthrough Therapy Designation may be granted to expedite the development and regulatory review of an investigational new drug that is intended to treat a serious or life-threatening condition where there is an unmet need. The criteria for Breakthrough Therapy Designation require preliminary clinical evidence that demonstrates that the drug may provide substantial improvements over any available therapy on at least one clinically significant endpoint.
The Breakthrough Therapy Designation was based on data from a Phase 2 open-label, multi-center trial of mavorixafor in adult patients with WHIM syndrome. In this trial, proof of concept was established based on clinically meaningful increases in absolute neutrophil counts (ANCs), absolute lymphocyte counts (ALCs), evidence indicating reductions in infection rates and wart burden, and a safety profile showing that mavorixafor is well-tolerated. A phase 3 trial is currently underway and recruiting patients.
Mavorixafor was granted orphan drug status by the FDA in 2018 and by the European Commission in 2019 for the treatment of WHIM syndrome.
About WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis)
WHIM syndrome is a rare, inherited, primary immunodeficiency disease caused by genetic mutations in the CXCR4 receptor gene. Patients with WHIM may experience significant morbidity beginning in early childhood and continuing throughout life with an increased likelihood of various recurrent, potentially life-threatening infections, and may also be susceptible to malignancies such as HPV-related cervical cancer and lymphomas. The overall cancer risk in patients with WHIM is estimated to be 30 percent by 40 years of age. There are no approved therapies for WHIM, and current standards of care are limited to treatment of acute infections with antibiotics or prevention of infections mainly through immunoglobulin substitution or G-CSF.
Mavorixafor (X4P-001) is a potential first-in-class, once-daily, oral inhibitor of CXCR4. WHIM syndrome is a rare genetic primary immunodeficiency that results from a “gain of function” mutation in the single gene that encodes for the CXCR4 receptor. This genetic mutation causes premature truncations in the CXCR4 protein, causing the receptor to remain in an “on” state longer than normal, resulting in compromised immune cell trafficking and surveillance.