X4 Pharmaceuticals closed an upsized $85 million private placement in August 2025, marking a significant funding milestone for the rare disease-focused biotechnology company. The financing, which was increased from the originally announced $60 million offering, involved the sale of 11,040,776 shares of common stock and pre-funded warrants to purchase 48,852,772 shares of common stock.
Financing Details and Investor Participation
The private placement was led by Coastlands Capital with strong support from existing investors including Empery Asset Management, LP, Bain Capital Life Sciences, and New Enterprise Associates (NEA). Additional participation came from other leading life science investors, including BVF Partners LP, Deep Track Capital, Kalehua Capital, Nantahala Capital, Stonepine Capital Management, and Trails Edge Capital Partners.
The offering size was increased to $85 million to allow for the inclusion of an investor who had a pre-existing investment right, demonstrating continued confidence in X4's therapeutic pipeline and commercial prospects.
Strategic Use of Proceeds
X4 expects to deploy the net proceeds from the financing for two primary objectives: continued development towards a potential additional approval of mavorixafor in chronic neutropenia and the commercialization of WHIM syndrome treatment. This dual focus reflects the company's strategy to expand the therapeutic applications of its lead CXCR4 antagonist while building its commercial infrastructure.
Clinical Development Pipeline
The company is currently conducting a global, pivotal Phase 3 clinical trial called 4WARD in people with certain chronic neutropenic disorders. This trial represents a key milestone in X4's efforts to expand the approved indications for mavorixafor beyond its current FDA approval for WHIM syndrome, where it is marketed as XOLREMDI®.
Mavorixafor is an orally available CXCR4 antagonist that leverages X4's expertise in CXCR4 and immune system biology. The company has positioned itself as a leader in developing innovative therapies for rare diseases of the immune system with significant unmet medical needs.
Company Background and Focus
X4 Pharmaceuticals is headquartered in Boston, Massachusetts, and has established itself as a company dedicated to improving the lives of people with rare diseases of the immune system. The company's focus on CXCR4 pathway dysfunction has enabled it to develop mavorixafor as a first-in-class therapeutic approach for multiple rare disease indications.
The successful completion of this financing provides X4 with the capital necessary to advance its clinical programs and support the commercial launch activities for its approved therapy, positioning the company to potentially serve thousands of patients across multiple rare disease indications.
