BOSTON, July 14, 2026
Atea Pharmaceuticals announced the initiation of a first-in-human Phase 1 clinical trial evaluating AT-587, an investigational oral nucleotide analog being developed as a potential first-in-class treatment for hepatitis E virus (HEV) infection. The randomized, double-blind, placebo-controlled study marks an important milestone in expanding Atea’s antiviral pipeline and addresses a significant unmet medical need, as there are currently no approved therapies for chronic HEV infection.
Phase 1 Trial to Evaluate Safety, Tolerability and Pharmacokinetics
The Phase 1 study will enroll healthy volunteers and assess the safety, tolerability, and pharmacokinetics of AT-587 through both single ascending dose (SAD) and multiple ascending dose (MAD) cohorts. The trial also includes a food-effect assessment to evaluate how food influences drug exposure. Part A will evaluate single-dose administration under fasting conditions, while Part B will investigate once-daily and twice-daily dosing over seven days. Dose escalation will be guided by ongoing safety and pharmacokinetic findings throughout the study.
Preclinical Data Demonstrate Strong Antiviral Activity Against HEV
Atea highlighted encouraging preclinical findings presented at EASL Congress 2026, where AT-587 demonstrated potent antiviral activity against hepatitis E virus. In laboratory studies, the investigational therapy was reported to be 30- to 150-fold more potent than ribavirin and sofosbuvir against HEV replication while showing no observable toxicity. Additional in vivo studies using an HEV genotype 3 animal model demonstrated significant reductions in viral RNA levels. AT-587 also maintained activity against ribavirin- and sofosbuvir-resistant HEV variants, supporting its potential as a differentiated antiviral therapy.
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Addressing a Significant Unmet Need in Chronic HEV Infection
Hepatitis E virus causes an estimated 20 million acute infections globally each year, with chronic disease primarily affecting immunocompromised individuals such as organ transplant recipients and patients receiving immunosuppressive therapies. Chronic HEV infection can progress to cirrhosis and liver failure, yet current treatment options remain limited to off-label therapies with modest efficacy and tolerability. Atea plans to initially focus the clinical development of AT-587 on immunocompromised patients with chronic HEV, aiming to provide a novel antiviral option for a patient population with few available therapeutic alternatives.
Source: Atea Pharmaceuticals press release
