ContraVir’s Lead Hepatitis B Candidate Advances in Phase 2a Trial

ContraVir’s Lead Hepatitis B Candidate Advances in Phase 2a Trial

ContraVir has begun patient enrollment for the next dosing group in its Phase 2a clinical trial comparing the company’s CMX157 with Viread (tenofovir disoproxil fumarate) to treat chronic hepatitis B (HBV).

The biopharmaceutical company develops targeted antiviral therapies focused mainly on potential cures for hepatitis B. CMX157 is one of two anti-HBV compounds under development by ContraVir.

CMX157 is a highly potent drug similar to the successful antiviral drug Viread. Its novel liver-targeting structure results in decreased circulating levels of tenofovir, which lowers systemic exposure and reduces the possibility of renal side effects.

In a previous Phase 1b dose-escalation clinical trial (NCT01080820), CMX157 displayed an excellent safety, tolerability, and drug distribution profile. Based on the lead candidate’s best-in-class potential, ContraVir is hopeful that CMX157 will become the cornerstone of a curative combination therapy for HBV.

The dose-escalation Phase 2a clinical trial (NCT02710604) is designed to enroll 60 previously untreated patients with chronic HBV infection to compare the safety and effectiveness of ContraVir’s CMX157 with Gilead Science’s Viread.

Ten patients per group will receive four weeks of 5, 10, 25, 50, or 100 mg daily of CMX157. Two patients per group will get Viread in standard 300 mg doses.

Enrollment was opened after a positive recommendation from an independent data safety monitoring board (DSMB) after it reviewed the safety, tolerability, and pharmacokinetic profile of CMX157 from the completed 5, 10, and 25 mg cohorts of the Phase 2a study. Based on a favorable review, testing of higher drug doses (50 and 100 mg daily) was approved.

“Coupled with our recent demonstration of clinical proof of concept for CMX157 in HBV patients, the DSMB’s confirmation of CMX157’s  safety profile continues to build the case for this drug’s potential as a cornerstone for combination therapy to cure HBV,” James Sapirstein, ContraVir’s CEO, said in a press release.

“We look forward to reporting final Phase 2a data by year-end, and continue to believe that CMX157 has the ideal attributes needed for use as a component of a future combination drug strategy where drug-drug interactions put high demands on safety,” he said.

CMX157’s positive interim data demonstrated strong antiviral activity. Specifically, a 25 mg dose achieved a comparable HBV result in reduced viral load to the standard 300 mg dose of Viread, but with significantly less systemic side effects. Results from the completed Phase 1b and the ongoing Phase 2a trials suggest that CMX157 might mitigate kidney and bone toxicities that are linked to Viread.


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