CANTON, Mass. — Orthogon Therapeutics has raised an additional $11 million in follow-on financing, bringing its total funding to $36 million, as the company pushes forward development of a first-in-class antiviral targeting BK polyomavirus, a significant cause of complications in transplant patients.
The funding will support continued advancement of the company’s lead drug candidate, an oral therapy designed to treat the full spectrum of BK virus infection, from early-stage reactivation to severe systemic disease. Currently, there are no approved treatments for BK virus infections, which can lead to serious outcomes in immunocompromised patients.
Orthogon’s approach focuses on targeting viral proteins that have traditionally been considered difficult to reach with small-molecule drugs. Its lead candidate is designed to act on the VP1 capsid protein, aiming to deliver antiviral activity directly at the site of viral replication and provide sustained control across multiple BK virus variants and related polyomaviruses.
“We built this program to meet the realities of transplant care,” said Ali H. Munawar, Ph.D., CEO of Orthogon Therapeutics. “These patients are treated within a narrow balance of immunosuppression, organ function, and high pill burden. We designed around those constraints, arriving at a candidate profile that we’re excited to take into development.”
The company said its research also includes analysis of hundreds of patient-derived BK virus sequences, which revealed significant genetic diversity in regions targeted by antibodies and suggested the virus can replicate beyond the reach of circulating immune defenses. These findings help explain the limited effectiveness of antibody-based treatments and support Orthogon’s small-molecule strategy.
In addition to targeting the VP1 capsid, Orthogon is developing compounds against another viral protein, large T antigen (LTAg), an approach the company said has been difficult to achieve in the field. The program is expected to be featured at major transplant and virology conferences in 2026, following earlier presentations at the American Society of Nephrology meeting in 2025.
Beyond its BK virus program, Orthogon is also advancing therapies aimed at other transplant-related infections.
