May 17, 2023 11:13 AM EDT R&D
Tyler Patchen
News Reporter
X4 Pharmaceuticals lifted the veil on more positive data from its Phase III study of mavorixafor as a treatment of WHIM syndrome, a rare immunodeficiency disorder that puts patients at higher risk of sometimes fatal bacterial infections.
The Boston-based biotech’s drug hit the primary endpoint in the trial last year, reaching “clinical and statistical superiority” over placebo when measuring patients’ “absolute neutrophil counts” above 500 cells per microliter over 24-hour periods throughout the trial, giving a p-value of <0.0001.
On Tuesday, X4 broke down the data into several sections, including infection rate, severity and duration. In the trial, called the 4WHIM trial, X4 reported that mavorixafor resulted in a statistically significant reduction in the annualized infection rate against placebo, earning a p-value of <0.01. The company also said that those taking the drug had less than one infection per year versus 4.5 for those taking a placebo.
For severity, 7% of patients taking the drug had a “Grade 3” or higher infection occurring in the first three months of treatment, compared to 29% of patients on placebo. Those who received the treatment also saw the duration of infection drop by 70% against the placebo, with a mean of seven weeks over the 52-week trial period. No serious side effects were identified during the trial.
“Mavorixafor has all the components to potentially deliver a transformative new option to people with CN (chronic neutropenia) disorders starting with WHIM syndrome,” X4 CEO Paula Ragan said in an investor presentation on Tuesday. “We’ve just successfully completed our first registration trial demonstrating clinically relevant increases in white blood cell counts and clinically significant impact on infections. We have a path forward to an NDA submission to support the potential US launch and WHIM syndrome and we are pulling out all the stops to advance the study of mavorixafor support in broader CN disorders.”
X4 said it had a pre-NDA meeting with the FDA, with Ragan stating the biotech is on track to submit the drug for US approval for WHIM syndrome in the second half of the year. X4 is also planning to present the full data at the Clinical Immunology Society meeting taking place in St. Louis, MO on May 18-21 and the European Hematology Society annual meeting in Frankfurt, Germany on June 8-15th.
X4’s stock $XFOR was up about 9% on Wednesday.
X4 slashes pipeline, lays off staff just three weeks after netting a $55M PIPE Stifel’s Stephen Willey told investors that the data “did not disappoint” and said he believes that the data improve his perception of the regulatory risk and utility in WHIM.
“More importantly, [it] de-risks a subsequent path forward in a much-larger/well-established CN market where supplanting standard-of-care G-CSF [Granulocyte colony-stimulating factor] with this kind of event-driven data seems a fairly straightforward exercise,” Willey said.
That said, Marc Frahm from TD Cowen was not impressed with the results for the “preexisting wart burden,” as the pathway could be less effective for warts or takes longer to show impact. X4 did note in the release that there was a “slight improvement” for warts in both the treatment and placebo arms.
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