---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-23-031405"
form_type: "8-K"
ticker: "XFOR"
cik: "0001501697"
company_name: "X4 Pharmaceuticals, Inc"
filed_at: "2023-09-05T23:59:59+00:00"
generated_at: "2026-06-10T23:56:14.419933+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# X4 Pharma submits NDA to FDA for mavorixafor in WHIM syndrome

## Summary
- Submission supported by positive Phase 3 4WHIM trial results; met primary and key secondary endpoints.
- Requested priority review; if granted, FDA review period would be six months from acceptance.
- Mavorixafor is an oral once-daily candidate for WHIM syndrome, a rare primary immunodeficiency in patients 12+.
- No treatment-related serious adverse events or discontinuations for safety in the Phase 3 trial.
- CEO Paula Ragan calls it a significant milestone; could be first approved U.S. product for WHIM syndrome.

## SEC filing metadata
- accession: 0001628280-23-031405
- form_type: 8-K
- ticker: XFOR
- cik: 0001501697
- company_name: X4 Pharmaceuticals, Inc
- filed_at: 2023-09-05T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1501697/000162828023031405/0001628280-23-031405-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1501697/000162828023031405/xfor-20230905.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-23-031405
- JSON: https://secwatch.observer/filing/0001628280-23-031405.json
- Plain text: https://secwatch.observer/filing/0001628280-23-031405.txt

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