New York based biotech startup Contravir just stunned the community with interim results from its Phase 2a study on CMX157, a prodrug of tenofovir. Contravir is run by Gilead veteran James Sapirstein how knows the anti-viral space inside out, having helped the pharma giant turning Viread into the blockbuster it is. And now he is taking a shot at Hepatitis B with CMX157.
Interim results of the head-to-head study of CMX157 in HBV patients which compares CMX157 to tenofovir disoproxil fumarate in chronically infected hepatitis B (HBV) patients showed impressive results:
“Patients successfully completed 5 mg and 10 mg cohorts, and interim data reported below are from 10 HBV-infected patients who completed 14 days of once-a-day oral dosing of 25 mg of CMX157, and two HBV patients treated for 14 days of oral dosing with 300 mg TDF. The CMX157 treated patients showed an average 99% reduction in HBV viral load compared to baseline. Significantly, the observed antiviral activity for CMX157 is comparable to that observed in TDF-treated patients, but at 1/12th the dose (25 mg CMX157 vs. standard 300 mg TDF).”
The big plus of CMX157 is that it does not break down into active tenofovir in the blood but is activated in the liver. That means that systemic tenofovir exposure can be reduced markedly while still targeting the liver in an effective way:
“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.”
The best news is that Contravir is confident that dose escalations to 50 mg and 100 mg levels will be well safe and tolerated. So we can probably expect even better results from the CMX157 trial in the near future.
Despite the recent progress in anti-viral research, WHO estimates that there are still 240 million people suffering from chronic HBV. Better treatment options to fight this worldwide epidemic are very good news indeed.