ContraVir Pharmaceuticals, Inc., a biopharmaceutical company focused on the development and commercialization of targeted antiviral therapies, announced that following a positive recommendation from an independent Data Safety Monitoring Board (DSMB), the company has begun screening patients with chronic hepatitis B (HBV) for enrollment in a head-to-head phase 2a study comparing ContraVir's CMX157 to tenofovir DF (TDF, marketed by Gilead Sciences as Viread).  The study will compare sequentially escalating doses of CMX157, beginning at a 5 mg daily CMX157 dose compared to 300 mg daily dose of TDF which is the standard daily dose of Viread.  The study is expected to conclude in the fourth quarter of 2016.

The DSMB conducted an independent review of the safety, tolerability and pharmacokinetic profile of CMX157 from the three completed dosing groups of ContraVir's ongoing phase 1b safety study in healthy volunteers.  In addition to recommending initiation of the phase 2a study, the DSMB also recommended continuation of the phase 1b, which is now past its midpoint with the final two dosing groups (50 and 100 mg) remaining.

"This is a significant inflection point for ContraVir, as the phase 2a study we've just commenced will be the first evaluation of the antiviral activity of CMX157 compared to Viread in hepatitis B patients," said James Sapirstein, CEO of ContraVir. "We're highly encouraged by the pharmacokinetic profile demonstrated so far in the Phase 1b study, which showed detectable CMX157 levels at 5 mg once daily, the lowest dose tested. Considering our animal data showing a high degree of liver targeting and laboratory data showing superior potency of CMX157 against HBV in vitro, these preliminary results suggest the potential of CMX157 to be dosed lower than Viread, and at the same or lower dose than tenofovir alafenamide, Gilead's 'TAF'.  We look forward to dosing the first HBV patients in this study and to reporting the data as we advance through the different dosing groups."

The phase 2a trial will enroll 60 treatment-naïve patients with chronic HBV infection.  This study will consist of a sequential dose escalation, with 10 patients per cohort receiving four weeks of a once-daily dose of either 5, 10, 25, 50 or 100 mg of CMX157, plus two patients per cohort receiving 300 mg of TDF, the standard dose of Viread.  As in the Phase 1b study, initiation of each higher dose cohort will follow review of the data from the previous cohort, and there will be another DSMB review between the 25 mg and 50 mg CMX157 cohorts. Final results from this study are expected in the fourth quarter of 2016.