Mavorixafor - (4WARD)

September 8, 2026: X4 Pharmaceuticals (NASDAQ: XFOR) said the FDA, in a Type C meeting, agreed to reduce the sample size of the global pivotal Phase 3 4WARD trial of mavorixafor in chronic neutropenia from 176 to 126 patients, while maintaining adequate power for the co-primary endpoints: reduction in annualized infection rate and positive absolute neutrophil count response. FDA also indicated the proposed safety database would be acceptable to support a potential supplemental NDA.

4WARD is a 52-week, randomized, double-blind, placebo-controlled, multicenter study of once-daily oral mavorixafor, with or without G-CSF, in patients age 12 and older with congenital, acquired primary autoimmune, or idiopathic chronic neutropenia, trough ANC below 1,000 cells/µL, and at least two serious and/or recurrent infections in the prior year.

The company said it expects to complete enrollment by year-end 2026 and report topline Phase 3 data in H1 2028. The release also states that mavorixafor has FDA Fast Track designation for chronic neutropenia.