Dyax Corp. has announced positive safety, pharmacokinetic, biomarker, and efficacy results from the Phase 1b clinical study of their investigational product, DX-2930. Discovered by Dyax, DX-2930 is a fully human monoclonal antibody inhibitor of plasma kallikrein being developed for the prevention of HAE attacks.

The ongoing Phase 1b study is a multi-center, randomized, double-blind, placebo-controlled, multiple-ascending dose study designed to assess the safety, tolerability and pharmacokinetics of DX-2930 in HAE patients. An analysis of HAE attack rate was also conducted following a pre-specified statistical analysis plan. A total of 37 subjects were randomized to active drug or placebo in a 2:1 ratio across 4 dosing groups of 30, 100, 300, or 400 mg. Each subject received two doses of DX-2930 or placebo, separated by 14 days, and was followed for 15 weeks after the second dose. DX-2930 was well tolerated at all dose levels. There were no deaths or subject discontinuations due to an adverse event. There were no serious adverse events in subjects treated with DX-2930 and no evidence of dose-limiting toxicity. There was no safety signal in treatment-emergent adverse events, clinical laboratory results, vital signs, or electrocardiograms. Subcutaneous injection was well tolerated. Pharmacokinetic results demonstrated that DX-2930 has linear, dose-dependent exposure and a mean elimination half-life of approximately 14 days across all dose groups studied. Pharmacodynamic results from two different exploratory biomarker assays confirmed ex vivo plasma kallikrein inhibition in a dose- and time-dependent manner. Primary proof-of-concept efficacy analyses were based on subjects in the 300 mg, 400 mg, and placebo dose groups who reported having at least 2 attacks in the 3 months prior to study entry. During the pre-specified, primary efficacy interval of 6 weeks (from days 8 to 50; corresponding to peak drug level), the HAE attack rate (adjusted for baseline attacks) was 0 in the 300 mg group and 0.045 attacks per week in the 400 mg group, compared to 0.37 attacks per week in the placebo group. This resulted in a 100% reduction for the 300 mg dose group as compared to placebo (P < 0.0001), and an 88% reduction for the 400 mg dose group as compared to placebo (P=0.005). During this primary efficacy interval, 100% of subjects in the 300 mg group (P=0.026) and 82% of subjects in the 400 mg group (P=0.030) were attack-free compared with 27% of subjects in the placebo group.

The study will be complete when all subjects in the 400 mg dose group finish the final safety assessments on study day 120.

Dyax also announced receipt of Fast Track designation from the U.S. Food and Drug Administration (FDA) for the investigation of DX-2930 for HAE.

“These data provide important clinical proof-of-concept, dose response and safety information in the target patient population,” said Burt Adelman, M.D., Executive Vice President of Research and Development and Chief Medical Officer at Dyax. “The study met all of its primary objectives, and notably, DX-2930 also demonstrated statistically significant reductions in attack rate compared to placebo, an important characteristic for a prophylactic treatment. We look forward to communicating these results to the FDA to ensure that our product development plan is supportive of drug approval. We plan to take full advantage of the opportunities that Fast Track designation allows in order to maximize the possibility of a more rapid path to approval.”

“The positive results from this trial are a significant milestone for Dyax and will be integral in guiding the future clinical development of DX-2930,” said Gustav Christensen, President and CEO of Dyax. “If approved, we believe that DX-2930, with its unique profile, is well positioned as a potential preventive treatment option for patients suffering from HAE.”

(Source: Dyax Corp.)