Atea Pharma Reports Positive Phase 2 Results for Hepatitis C Treatment

Atea Pharmaceuticals, Inc. (Nasdaq: AVIR), a clinical-phase biopharmaceutical firm focused on creating oral antiviral treatments for serious viral diseases, announced positive results from its Phase 2 study of a treatment regimen for hepatitis C virus (HCV). The regimen includes bemnifosbuvir, a nucleotide analog polymerase inhibitor, and ruzasvir, an NS5A inhibitor. The study achieved its primary endpoints, showing a 98% sustained virologic response at 12 weeks post-treatment (SVR12) in patients who adhered to the treatment protocol.

The study involved 275 treatment-naïve patients, both with and without compensated cirrhosis. An impressive 95% of the efficacy evaluable population, which included non-adherent patients, reached SVR12. This underlines the regimen's strong potency and forgiveness. The study also found the treatment to be generally safe, with no serious adverse events or treatment discontinuations.

Jean-Pierre Sommadossi, PhD, CEO and Founder of Atea, commented on the results, expressing excitement over the eight-week treatment's high SVR12 rates. Sommadossi emphasized the importance of advancing to Phase 3 development, planned for early 2025. He noted that the HCV market remains underserved, with diagnosis rates in the U.S. outpacing treatment rates each year. The new regimen, combining convenience, a low risk for drug interactions, and a short treatment duration, holds potential as a significant tool in eradicating HCV in the U.S.

In the Phase 2 study, treatment adherent patients without cirrhosis infected with HCV genotypes 1-4 achieved a 99% SVR12 rate. Those with cirrhosis had an 88% SVR12 rate, although all cirrhotic patients showed a 100% end-of-treatment response. To optimize efficacy, the Phase 3 program will extend the treatment duration to 12 weeks for patients with cirrhosis. It is estimated that less than 10% of the HCV patient population in the U.S. has cirrhosis, influenced by the high infection rates among people aged 20-49 and the declining incidence of cirrhosis in newly infected patients.

Dr. Eric Lawitz from The Texas Liver Institute, noted that the changing demographic of HCV patients and the need for shorter treatment durations make the Phase 2 results particularly promising. He highlighted that contemporary HCV patients are younger and often require concurrent medications for comorbidities, with fewer presenting with cirrhosis.

Atea is gearing up for the Phase 3 program, which will proceed following an anticipated End of Phase 2 meeting with the U.S. Food and Drug Administration (FDA) in early 2025. The Phase 3 program aims to use a fixed-dose combination (FDC) tablet to reduce the daily pill count from four to two, improving patient convenience with no food effect.

The global Phase 2 study's design focused on evaluating the safety and efficacy of an eight-week treatment regimen of daily bemnifosbuvir 550 mg and ruzasvir 180 mg. Secondary and other endpoints included SVR12 regardless of treatment adherence, virologic failure, and resistance.

Bemnifosbuvir has shown approximately 10-fold more activity than sofosbuvir (SOF) in vitro, maintaining effectiveness against SOF resistance-associated substitutions with up to 58-fold more potency. It supports once-daily dosing and has a low risk for drug interactions. Bemnifosbuvir has been well-tolerated in over 2,200 subjects at doses up to 550 mg for 12 weeks. Ruzasvir has also demonstrated potent pan-genotypic antiviral activity in preclinical and clinical studies, with a favorable safety profile in over 1,500 HCV-infected patients at doses up to 180 mg for 12 weeks.

Hepatitis C virus (HCV), a blood-borne RNA virus, primarily infects liver cells and is a leading cause of chronic liver disease and liver transplants. With an estimated 50 million people globally living with chronic HCV infection, the virus causes significant morbidity and mortality, particularly due to liver cirrhosis and cancer. The U.S. sees between 2-4 million people infected with HCV, with a lower percentage presenting with cirrhosis.

Atea Pharmaceuticals continues to focus on its lead program involving bemnifosbuvir and ruzasvir for HCV, leveraging its expertise in antiviral drug development and nucleos(t)ide chemistry to address unmet medical needs in viral infections.