How ContraVir Pharma Won Big on Its HBV Interim Results

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ContraVir Pharmaceuticals Inc. (NASDAQ: CTRV) is watching its shares climb on Thursday after the company reported positive interim data from its ongoing Hepatitis B (HBV) mid-stage trial. Specifically, the company announced data for CMX157, its highly potent prodrug of tenofovir.

Overall the study is the first evaluation of CMX157 in HBV patients, and directly compares CMX157 to tenofovir disoproxil fumarate (TDF, Gilead’s Viread) in chronically infected HBV patients.

The CMX157 treated patients showed an average 99% reduction in HBV viral load compared to baseline.  What was significant here was that the observed antiviral activity for CMX157 is comparable to that observed in TDF-treated patients, but at less than 10% of the dose.

A key goal of this study was to monitor levels of active tenofovir in the blood, exposure to which is a key predictor of off-target side effects. Following oral dosing, levels of CMX157 and active tenofovir in the bloodstream are roughly dose proportional and similar both in chronic HBV patients as well as in an earlier healthy volunteer study. Notably, CMX157 does not appear to break down readily into active tenofovir in the blood in contrast to patients taking Viread.

Active tenofovir levels observed in blood following oral dosing of CMX157 are significantly below levels seen for Viread-treated patients, regardless of dose used, which is consistent with CMX157 targeting the liver followed by activation of CMX157 specifically within the liver. This is further supported by the observation that viral load reductions with CMX157 are comparable to Viread despite a significantly lower dose.

James Sapirstein, CEO of ContraVir, commented:

We are pleased and excited with these clinical results, as they demonstrate CMX157’s great potential in our ongoing effort to develop a cure for HBV. The significant viral load reduction and favorable safety at this low dose of CMX157 speaks to the unique liver-targeting mechanism of our drug, which concentrates the antiviral activity of tenofovir in the liver, enabling anti-HBV efficacy at lower doses and minimal drug exposure to other tissues. We believe, based on the data that are being generated, that CMX157 has great potential as a safe and highly potent backbone of combination therapy against HBV.

Shares of ContraVir Pharma were last trading up 23% at $1.38, with a consensus analyst price target of $5.00 and a 52-week trading range of $0.76 to $2.48.

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