K2 HealthVentures (K2HV) has provided a senior secured term loan facility of up to $150m to Boston-based X4 Pharmaceuticals (Nasdaq: XFOR), refinancing its existing loan from Hercules Capital (NYSE: HTGC).
The first tranche of $80m was funded at closing and used to repay in full all obligations under the prior Hercules loan and security agreement, including $75m of principal and related fees, plus closing costs. A further $70m may be made available at X4's request, subject to K2HV approval and other conditions.
The facility has a 48-month maturity and a longer interest-only period than under the Hercules loan. The interest-only period can be extended further on first US commercial sales of mavorixafor in chronic neutropenia. It carries a floating interest rate linked to the prime rate and includes minimum cash and minimum revenue covenants.
An August 2023 amendment upsized the prior Hercules facility to up to $115m, and X4's 2025 annual report later stated it as up to $107.5m. X4 had drawn $75m under the interest-only loan, which was due to mature on 1 July 2027 and bore interest at the greater of 10.15% or the Wall Street Journal prime rate plus 3.15%.
X4 chief financial officer David Kirske said, "The new structure provides additional flexibility on more favorable terms and is aligned with our strategic priorities."
X4 said the facility supports corporate activities, including a potential future commercial launch of mavorixafor in chronic neutropenia. Mavorixafor is sold as XOLREMDI, an oral CXCR4 antagonist for WHIM syndrome that was approved in the US in April 2024 and in the EU in April 2026, with Norgine leading European commercialisation. X4 expects to complete enrolment in the 4WARD Phase 3 trial by the end of 2026 and report topline data in the first half of 2028.
X4 had $208.0m of cash, cash equivalents and short-term marketable securities at 30 June 2026. It reported net product revenue of $4.8m in the first half of 2026.
K2 HealthVentures is a Boston-based alternative investment firm launched in May 2019 with a $400m initial capital commitment backed by L1 Health. It invests from a permanent, evergreen capital base with no fixed fund cycles and has a primary focus on customised debt financing for life sciences and healthcare companies. K2HV says it has made more than $1bn of capital commitments since inception. In May 2026 it agreed a credit facility of up to $150m with Nasdaq-listed Cartesian Therapeutics.