0001501697 2026-05-11 2026-05-11 0001501697 true 8-K/A 2026-05-11 X4 PHARMACEUTICALS, INC. DE 001-38295 27-3181608 61 North Beacon Street, 4th Floor Boston, MA 02134 857 529-8300 false false false false Common Stock, par value $0.001 per share XFOR NASDAQ false