Benzinga | Sep 15, 2020 07:46AM EDT

Arbutus Reports AB-729 90mg Single-Dose Week 12 Data In Chronic Hep C Subjects Showed Significant, Continuous Reductions In HBsAg

Arbutus Biopharma Corporation (NASDAQ:ABUS), a clinical-stage biopharmaceutical company primarily focused on developing a cure for people with chronic hepatitis B virus (HBV) infection as well as therapies to treat coronaviruses (including COVID-19), today reports continued positive data from an ongoing Phase 1a/1b clinical trial (AB-729-001) with AB-729, its proprietary GalNAc delivered RNAi compound. These new data demonstrate that in chronic HBV subjects, a single subcutaneous injection of 90 mg of AB-729 resulted in a mean HBsAg reduction of 1.23 log10 IU/mL at week 12.

William Collier, President and Chief Executive Officer of Arbutus, stated, "The 90 mg single-dose 12-week data coupled with our previously disclosed 60 mg single-dose 12-week data mean that we now have two doses which have demonstrated meaningful reductions in HBsAg with a favorable safety and tolerability profile. We are currently dosing chronic HBV subjects in four multi-dose cohorts using both the 60 mg (every 4- and 8-weeks) and 90 mg (every 8- and 12-weeks) doses to determine the optimal dosing regimen for AB-729. We believe AB-729 will potentially offer people with chronic HBV a well-tolerated low dose treatment with a minimum of injections."

Arbutus expects to present initial results from its ongoing Phase 1a/1b clinical trial for the 60 mg multi-dose cohorts, the 90 mg single-dose cohort in HBV DNA positive subjects, as well as longer-term follow up of the 60 and 90 mg single-dose cohorts, at an upcoming scientific meeting later this year. In addition to the ongoing 60 mg multi-dose cohorts with subjects dosed at 4- and 8-weeks, the Company has also initiated 90 mg multi-dose cohorts with subjects dosed at 8- and 12-week intervals.

Mean HBsAg changes from baseline

60 mg Single-Dose 90 mg Single-Dose Cohort (B) Cohort (C) (N=6) (N=6)Week 12 (day 84) mean log10 IU/mL -0.99 (0.24) -1.23 (0.18)(Standard Error of the Mean)

Dr. Gaston Picchio, Chief Development Officer of Arbutus, stated, "The mean HBsAg decline seen in the 90 mg single-dose cohort is consistent with that seen in prior single-dose cohorts. Importantly, the data demonstrate consistent efficacy and a favorable safety profile at this intermediate dose. These findings support the continued evaluation of the 90 mg dose in the multi-dose portion of our ongoing clinical trial."

Summary of clinical trial design

AB-729-001 is an ongoing first-in-human clinical trial consisting of three parts:

In Part 1, three cohorts of healthy subjects were randomized 4:2 to receive single-doses (60 mg, 180 mg or 360 mg) of AB-729 or placebo.

In Part 2, non-cirrhotic, HBeAg positive or negative, chronic HBV subjects (N=6) on a background of nucleos(t)ide therapy with HBV DNA below the limit of quantitation received single-doses (60 mg to 180 mg) of AB-729. An additional cohort in Part 2 included 90 mg single-dose of AB-729 in HBV DNA positive chronic HBV subjects.

In Part 3, chronic HBV subjects, HBV DNA negative first and HBV DNA positive later, are receiving multi-doses of AB-729 for up to six months.