---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-23-035729"
form_type: "8-K"
ticker: "XFOR"
cik: "0001501697"
company_name: "X4 Pharmaceuticals, Inc"
filed_at: "2023-10-31T23:59:59+00:00"
generated_at: "2026-06-09T04:34:09.954412+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# FDA accepts X4's NDA for mavorixafor with Priority Review; PDUFA April 30, 2024

## Summary
- FDA accepted NDA for once-daily oral mavorixafor in WHIM syndrome (ages 12+) with Priority Review.
- PDUFA target action date set for April 30, 2024; six-month review timeline.
- If approved, X4 eligible for Priority Review Voucher due to rare pediatric disease designation.
- NDA supported by Phase 3 4WHIM trial meeting primary endpoint (TAT-ANC p<0.0001) and reducing infections.
- No approved therapies for WHIM syndrome; mavorixafor has Breakthrough Therapy, Fast Track, and Orphan status.

## SEC filing metadata
- accession: 0001628280-23-035729
- form_type: 8-K
- ticker: XFOR
- cik: 0001501697
- company_name: X4 Pharmaceuticals, Inc
- filed_at: 2023-10-31T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1501697/000162828023035729/0001628280-23-035729-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1501697/000162828023035729/xfor-20231031.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-23-035729
- JSON: https://secwatch.observer/filing/0001628280-23-035729.json
- Plain text: https://secwatch.observer/filing/0001628280-23-035729.txt

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