ContraVir’s CMX157 Outperforms Gilead’s Tenofovir AF (TAF) Against Hepatitis B Virus in Independent Head-to-Head In-Vitro Study

ContraVir Pharmaceuticals, Inc. (NASDAQ: CTRV) reported positive results from a third-party in vitro study that further validates CMX157’s profile as a highly potent anti-hepatitis B drug.  In this first head-to-head in vitro study, CMX157 compared favorably to tenofovir alafenamide fumarate (TAF), which was approved recently by the US Food and Drug Administration (FDA) as part of a four-drug combination therapy for HIV-1 (Genvoya^®), and is currently under development by Gilead Sciences Inc. (GILD) for treating chronic hepatitis B infection.  ContraVir recently initiated a Phase 1/2a clinical study of CMX157, which is currently enrolling healthy volunteers and is anticipated to begin enrolling hepatitis B patients in the second quarter 2016.
According to the news:

The study compared the anti-hepatitis B activities of CMX157 and other tenofovir prodrugs, including tenofovir DF (Viread^®), in order to profile CMX157 among this important class of antiviral therapies.  The study findings revealed that CMX157 and TAF were similarly potent against hepatitis B virus (HBV), with CMX157 trending toward higher potency (EC₅₀ = 9.3 ± 3.6 nM vs. 32.4 ± 17.1 nM for CMX157 and TAF, respectively; and EC₉₀ = 186 ± 53 nM vs 474 ± 261 nM for CMX157 and TAF, respectively).  Furthermore, viral rebound studies showed that CMX157 demonstrates best-in-class duration of activity.  Nine days following incubation with HBV, using two different experimental conditions, one at equimolar and one at EC₉₀ concentrations, CMX157 showed two- to three-fold reduced viral rebound compared to TAF.  The study also confirmed earlier results, as reported previously by ContraVir, regarding the significantly increased potency of CMX157 compared to tenofovir.