Skyhawk Therapeutics Inc, a clinical-stage biotechnology company developing novel small molecule therapies designed to modulate RNA targets, announced on Tuesday the final 15-month results from its Phase 1/2 clinical trial evaluating SKY-0515, an investigational oral treatment for Huntington's disease (HD).

The randomised, double-blind, placebo-controlled parallel-group study is evaluating two dose levels of SKY-0515 in patients over 12 weeks, followed by a 12-month blinded extension period during which all participants receive active treatment at either a low or high dose (4mg or 9mg), with the majority of patients on the 9mg dose.

At the Month 15 primary timepoint, SKY-0515-treated patients showed a +1.59-point difference in Composite Unified Huntington's Disease Rating Scale (cUHDRS) change from baseline versus overlap-weighted external natural history control.

According to Skyhawk, differences favouring SKY-0515 were statistically significant across all four cUHDRS components -- Total Functional Capacity, Total Motor Score, Symbol Digit Modalities Test and Stroop Word Reading Test -- and cUHDRS differences favoured SKY-0515 at every prespecified timepoint in the study.

SKY-0515 has shown consistent average reductions in mutant huntingtin protein (mHTT) throughout the study of more than 60% at the 9 mg dose, as well as consistent average reductions in PMS1 mRNA of more than 25% at the 9 mg dose.

Additionally, SKY-0515 has demonstrated excellent central nervous system exposure and has been generally well tolerated across all dose levels studied through 15 months of treatment, with no treatment-related SAEs, Skyhawk said.