FDA Agrees to Cut 4WARD Trial Size to 126 Patients, Clearing Path to Faster Data

summarizeSummary

X4 Pharmaceuticals announced the FDA agreed to reduce the 4WARD Phase 3 trial size from 176 to 126 patients while maintaining adequate statistical power, with enrollment expected to complete by year-end 2026 and topline data in H1 2028.

check_boxKey Events · Product Development and Regulatory · XFOR

• FDA Agrees to Smaller 4WARD Trial

  FDA agreed to reduce the 4WARD Phase 3 trial sample size from 176 to 126 participants while maintaining adequate power for the co-primary endpoints of annualized infection rate reduction and positive ANC response.

• Safety Database Accepted for sNDA

  FDA indicated the proposed safety database would be acceptable to support a potential supplemental new drug application (sNDA) for mavorixafor in chronic neutropenia.

• Enrollment and Data Timeline

  Company expects to complete 4WARD enrollment by year-end 2026 and report topline data in the first half of 2028.

• Regulatory Risk Remains

  FDA feedback from the Type C meeting is not binding; the agency could take a different position during sNDA review, and the reduced sample size could still fail to show statistical significance.

auto_awesomeAnalysis · XFOR · Life Sciences

The FDA's agreement to reduce the 4WARD Phase 3 trial from 176 to 126 participants is a meaningful regulatory win. It preserves statistical power for the co-primary endpoints while cutting enrollment burden by nearly 30%, which should accelerate completion to year-end 2026 and pull topline data into H1 2028. The FDA also accepted the proposed safety database for a potential sNDA, de-risking the path to a supplemental approval for mavorixafor in chronic neutropenia. This is not a binding commitment — the FDA could still take a different position at review — but it materially improves the probability of a successful, timely filing.