Fresh off layoffs, X4 scores a phase 3 win for immune deficiency disorder drug

Four months after laying off a chunk of its staff, X4 Pharmaceuticals has some good news to share, as the biotech’s WHIM syndrome therapy improved white blood cell counts in patients during a phase 3 trial.

Mavorixafor is being developed for WHIM syndrome, a rare immune deficiency disorder characterized by warts, hypogammaglobulinemia, infections and myelokathexis, which form the acronym. Patients with WHIM have an increased risk of infection and certain cancers.

In the late-stage trial, the therapy beat placebo on a measure of time that patients maintained counts of neutrophils, a type of white blood cell, beating placebo and meeting the main goal. The study also met a key secondary endpoint by similarly maintaining counts of lymphocyte white blood cells. Increases in the white blood cells were noted throughout the duration of the 52-week trial, which suggests that mavorixafor has a durable response.

The therapy was generally well tolerated, and X4 did not report any treatment-related serious adverse events. No discontinuations were noted, either, with 90% of eligible patients opting to continue on into an open-label extension.

X4 will now meet with regulators in the first half of 2023 to discuss advancing the therapy toward a submission for approval. This could become the first treatment for patients with WHIM, interim Chief Medical Officer Murray Stewart, M.D., said in a Tuesday statement.

The company also sees the data as aiding in the development of mavorixafor for other chronic neutropenic disorders, CEO Paula Ragan, Ph.D., said.

X4 cut 20% of staff in June and discontinued its oncology program in an effort to streamline resources.