Safety, tolerability, pharmacokinetics, and antiviral activity of the novel core protein allosteric modulator ZM-H1505R (Canocapavir) in chronic hepatitis B patients: a randomized multiple-dose escalation trial

BACKGROUND: Hepatitis B virus (HBV) core protein-targeting antivirals (CpTAs) are promising therapeutic agents for treating chronic hepatitis B (CHB). In this study, the antiviral activity, pharmacokinetics (PK), and tolerability of ZM-H1505R (Canocapavir), a chemically unique HBV CpTA, were evaluated in patients with CHB. METHODS: This study was a double-blind, randomized, placebo-controlled phase 1b trial in Chinese CHB patients. Noncirrhotic and treatment-naive CHB patients were divided into three cohorts (10 patients per cohort) and randomized within each cohort in a ratio of 4:1 to receive a single dose of 50, 100, or 200 mg of Canocapavir or placebo once a day for 28 consecutive days. RESULTS: Canocapavir was well tolerated, with the majority of adverse reactions being grade I or II in severity. There were no serious adverse events, and no patients withdrew from the study. Corresponding to 50, 100, and 200 mg doses of Canocapavir, the mean plasma trough concentrations of the drug were 2.7-, 7.0-, and 14.6-fold of its protein-binding adjusted HBV DNA EC(50) (135 ng/mL), respectively, with linear PK and a low-to-mild accumulation rate (1.26–1.99). After 28 days of treatment, the mean maximum HBV DNA declines from baseline were -1.54, -2.50, -2.75, and -0.47 log(10) IU/mL for the 50, 100, and 200 mg of Canocapavir or placebo groups, respectively; and the mean maximum pregenomic RNA declines from baseline were -1.53, -2.35, -2.34, and -0.17 log(10) copies/mL, respectively. CONCLUSIONS: Canocapavir treatment is tolerated with efficacious antiviral activity in CHB patients, supporting its further development in treating HBV infection. TRIAL REGISTRATION: ClinicalTrials.gov, number NCT05470829). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12916-023-02814-w.