---
schema_version: "secwatch.filing_event.v1"
accession: "0001501697-26-000072"
form_type: "8-K"
ticker: "XFOR"
cik: "0001501697"
company_name: "X4 Pharmaceuticals, Inc"
filed_at: "2026-09-08T11:15:54+00:00"
generated_at: "2026-09-08T11:20:10.781205+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# FDA agrees to X4's reduced 4WARD trial sample size (176 to 126); topline data expected H1 2028

## Summary
- FDA agreed to cut 4WARD Phase 3 sample size from 176 to 126 patients, preserving power for co-primary endpoints.
- Safety database deemed acceptable to support potential sNDA for mavorixafor in chronic neutropenia.
- Enrollment of 4WARD expected to complete by end of 2026; topline data in H1 2028.
- Mavorixafor targets ~15,000 patients with serious/recurring infections due to chronic neutropenia.

## SEC filing metadata
- accession: 0001501697-26-000072
- form_type: 8-K
- ticker: XFOR
- cik: 0001501697
- company_name: X4 Pharmaceuticals, Inc
- filed_at: 2026-09-08T11:15:54+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1501697/000150169726000072/0001501697-26-000072-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1501697/000150169726000072/xfor-20260908.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001501697-26-000072
- JSON: https://secwatch.observer/filing/0001501697-26-000072.json
- Plain text: https://secwatch.observer/filing/0001501697-26-000072.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.