Skyhawk Therapeutics Announces First Patient Dosed in Phase 2/3 FALCON-HD Trial of SKY-0515 for Huntington’s Disease

BOSTON, MA., June 19, 2025 – Skyhawk Therapeutics, Inc., a clinical-stage biotechnology company developing novel small molecule therapies designed to modulate critical RNA targets, on June 17 through a press release announced that the first patient has been dosed in its Phase 2/3 FALCON-HD trial evaluating SKY-0515, an investigational oral RNA splicing modulator for the treatment of Huntington’s disease (HD).

SKY-0515 is designed to reduce the production of both HTT and PMS1 proteins—two key drivers of HD pathology. In a Phase 1 study in healthy volunteers, SKY-0515 demonstrated dose-dependent HTT mRNA reduction, achieving an average of 72% lowering at the highest dose tested. The compound was generally well tolerated across all doses. Additionally, the Company’s Phase 1 trial in HD patients, which began in January 2025, completed enrollment ahead of schedule in March 2025.

“Dosing the first patient in our FALCON-HD trial marks a significant milestone in our mission to develop a disease-modifying therapy for Huntington’s patients,” said Bill Haney, Founder and Chief Executive Officer of Skyhawk Therapeutics. “Building on our compelling Phase 1 data, we are eager to assess SKY-0515’s potential to make a meaningful difference in the lives of patients affected by this devastating condition.”

FALCON-HD is a Phase 2/3 randomized, double-blind, placebo-controlled, dose ranging study to evaluate the pharmacodynamics, safety, and efficacy of SKY-0515 in participants with Stage 2 and early Stage 3 HD. The trial includes multiple sites across Australia and New Zealand. The initial dosing took place at Flinders Medical Centre in Adelaide, Australia.

“We are pleased to participate in this important clinical trial and to have dosed the first patient here at Flinders,” said Dr. Karyn Boundy, FRACP, Neurologist, Principal Investigator at Flinders Medical Centre. “Given the lack of approved disease-modifying treatments for Huntington’s disease, we are hopeful that SKY-0515 could offer a new therapeutic option for patients.”

“As Skyhawk kicks off their Phase 2/3 FALCON-HD trial in Australia and New Zealand, the international Huntington’s community looks forward to expansion worldwide,” said Ed Wild, professor of neurology at the University College London. “SKY-0515’s unique ability to reduce both HTT and PMS1 could meaningfully enhance therapeutic impact beyond that of lowering HTT alone.”