Antios Therapeutics is going full throttle in pursuit of a curative hepatitis B therapy, raising $75 million just months after its previous round to accelerate phase 2b development of its lead prospect.
The drug candidate, ATI-2173, is a twist on clevudine, an antiviral that Pharmasset took into phase 3 more than a decade ago. Pharmasset stopped the program in response to cases of muscle weakness in long-term users of clevudine, prompting it to pivot to the hepatitis C work that landed it an $11 billion takeover by Gilead and spawned a mega-blockbuster franchise spearheaded by Sovaldi.
While Pharmasset moved on, other research groups retained an interest in clevudine, leading to the development of a liver-targeted prodrug version of the antiviral. The prodrug, now called ATI-2173, was designed to reduce peripheral exposure to clevudine without sacrificing efficacy.
Antios is still fairly early in the process of showing whether ATI-2173 lives up to that billing, moving into a phase 2a that is testing the prodrug in combination with Viread earlier this year, but interest in the candidate is ramping up. This year, Antios has raised a $96 million series B and inked separate deals with Arbutus Biopharma and Assembly Biosciences to run combination clinical trials.
The new series B-1 financing adds a further $75 million to Antios’ coffers to fund further clinical development. “This round of investment enables us to accelerate the phase 2b clinical development of ATI-2173, which has already demonstrated potent on-treatment and durable off-treatment effects, while being generally well-tolerated, in our Phase 1b study in patients with HBV,” Antios CEO Greg Mayes said in a statement. GordonMD Global Investments and EPIQ Capital Group co-led the round.
Antios is one of a number of biotechs working on drugs designed to cure hepatitis B, either as single agents or as part of combination therapies. The biotechs are deploying a range of modalities including RNAi and antibodies, but Antios’ reworking of an older antiviral stands apart from the competition.