X4 Pharmaceuticals has received approval from the US Food and Drug Administration (FDA) for Xolremdi (mavorixafor) capsules to treat patients aged 12 and above with warts, hypogammaglobulinemia, infections and myelokathexis (WHIM) syndrome.

Xolremdi is a selective CXC chemokine receptor 4 (CXCR4) antagonist designed to boost the number of circulating mature neutrophils and lymphocytes. It is said to be the first drug indicated for patients with WHIM syndrome.

The CXCR4 antagonist received breakthrough therapy designation from the FDA for WHIM syndrome, and its new drug application (NDA) underwent priority review.

Its approval was based on the findings from the 4WHIM Phase 3 clinical trial involving 31 people diagnosed with WHIM.

The global, randomised, double-blind, placebo-controlled, 52-week multicentre study evaluated the efficacy and safety of Xolremdi.

X4 Pharmaceuticals evaluated Xolremdi’s efficacy based on improvements in absolute neutrophil counts (ANC), absolute lymphocyte counts (ALC), and a decrease in infections.

In the 4WHIM trial, treatment with Xolremdi showed significantly increased time above the threshold for ANC compared to placebo and increased time above the threshold for ALC compared to placebo.

Additionally, the drug’s efficacy was further examined through a composite endpoint, which included the total infection score and total wart change score using the Win-Ratio method.

Analysis of individual components of this endpoint revealed an approximately 40% decrease in total infection score, weighted by infection severity, in Xolremdi-treated patients compared to those receiving placebo.

Treatment with mavorixafor also led to a reduction of 60% in the annualised infection rate compared to patients treated with a placebo.

X4 Pharmaceuticals president and CEO Paula Ragan said: “The approval of Xolremdi is a transformational milestone both for X4 and, more importantly, for the WHIM syndrome community.

“We are incredibly grateful to the people living with WHIM syndrome, their families, and the investigators who took part in our clinical programme, to US regulators for their continued focus on rare-disease treatment development, and to our dedicated employees for making this targeted breakthrough therapy a reality.”

X4 Pharmaceuticals also received a rare paediatric disease priority review voucher, which can be redeemed for future applications or sold to other drug sponsors.

The pharma company is planning to commercially launch Xolremdi in the US through its speciality pharmacy partner, PANTHERx Rare.

Furthermore, the drug is being assessed for other indications, including certain chronic disorders.