X4 Pharmaceuticals Receives Positive FDA Feedback for 4WARD Trial

X4 Pharmaceuticals has received a positive outcome from a meeting with the U.S. Food and Drug Administration (FDA) regarding its global 4WARD Phase 3 clinical trial for the treatment of chronic neutropenia with mavorixafor. The company announced that the FDA agreed to reduce the sample size of the trial from 176 to 126 participants, maintaining adequate statistical power for the co-primary endpoints of the reduction in annualized infection rate and positive absolute neutrophil count (ANC) response.

Adam Craig, M.D., Ph.D., Executive Chairman of X4 Pharmaceuticals, stated, "After a rigorous re-examination of the statistical plan for 4WARD, we determined that the trial was overpowered and that we could reduce the sample size to 126 participants while preserving good statistical power for our co-primary endpoints." Craig added, "We are pleased that the FDA agreed with our analysis. With continued execution from our new Clinical Research Organization (CRO), we expect to complete the enrollment of 4WARD by the end of this year and report topline data in the first half of 2028."

Chronic neutropenia is a rare blood condition characterized by abnormally low levels of circulating neutrophils, increasing the risk of serious and life-threatening infections. Mavorixafor is a small molecule delivered in a capsule for oral dosing as a selective antagonist of the chemokine receptor, CXCR4. The drug has been shown to mobilize functional neutrophils from the bone marrow into the peripheral bloodstream, addressing a significant unmet need in the treatment of chronic neutropenia.

The 4WARD trial is a global, pivotal Phase 3 clinical study evaluating the efficacy, safety, and tolerability of mavorixafor in patients with congenital, acquired primary autoimmune, or idiopathic chronic neutropenia who experience recurrent and/or serious infections. The study aims to enroll 126 patients aged 12 years and older with confirmed trough absolute neutrophil count (ANC) levels less than 1,000 cells per microliter at baseline screening and a history of two or more serious and/or recurrent infections in the prior year. The co-primary endpoints of the study are the reduction in annualized infection rate and positive ANC response.

X4 Pharmaceuticals, based in Boston, Massachusetts, is focused on improving the lives of people with rare hematology diseases by developing and commercializing innovative therapies. The company has successfully developed mavorixafor, which is commercially available in the U.S. as XOLREMDI® in its first indication. The U.S. FDA has granted Fast Track designation to mavorixafor for the treatment of chronic neutropenia.

With approximately 15,000 patients experiencing serious and/or recurring infections due to chronic neutropenia, X4 Pharmaceuticals believes that mavorixafor can address a significant market opportunity. The company continues to work towards the completion of the 4WARD trial and the potential approval of mavorixafor for the treatment of chronic neutropenia.