Breakthrough designation for Ph III candidate mavorixafor

The US Food and Drug Administration has granted Breakthrough Therapy designation for mavorixafor (X4P-001) for the treatment of adult patients with WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome, a rare, inherited, primary immunodeficiency disease caused by genetic mutations in the CXCR4 receptor gene, says X4 Pharmaceuticals (Nasdaq: XFOR), whose gained 3.5% to $14.70 in morning trading today.

Mavorixafor is a potential first-in-class, once-daily, oral, small molecule antagonist of chemokine receptor CXCR4, and is currently being investigated in a pivotal Phase III global clinical trial, 4WHIM, for the treatment of WHIM syndrome. The Breakthrough Therapy designation granted to mavorixafor is based on data from X4’s Phase II 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.

“Rare diseases such as WHIM don’t often receive the attention and research that patients and their families deserve. The FDA’s decision to grant Breakthrough Therapy designation to mavorixafor for the treatment of adults with WHIM syndrome represents a significant milestone for patients and X4 alike, helping to further highlight the severity of this underdiagnosed disease  and the importance of offering a potential novel, disease-modifying therapeutic option to this underserved patient population,” said Paula Ragan, president and chief executive of X4 Pharmaceuticals. “We are excited to continue to advance our ongoing global Phase III pivotal trial and look forward to working closely with the FDA to bring this potential first-in-class treatment option to patients with WHIM syndrome as quickly as possible through this expedited regulatory pathway,” she added.