Antiviral activity and safety of the hepatitis B core inhibitor ABI-H0731 administered with a nucleos(t)ide reverse transcriptase inhibitor in patients with HBeAg-negative chronic hepatitis B infection

Abstract

Background and Aims: Nucleos(t)ide reverse transcriptase inhibitors (NrtI) are the standard of care for the treatment of chronic HBV (CHB) infection. While these agents achieve viral suppression in most patients (pts), sustained response is rarely achieved following cessation of treatment. The HBV core inhibitor ABI-H0731 (731) in combination with a NrtI is currently being evaluated in Phase 2 clinical studies. Method: ABI-H0731-201 is a double-blind, placebo (Pbo)-controlled study in NrtI-suppressed pts with CHB. Patients were randomized 3:2 to receive 731 (300 mg QD) +NrtI or Pbo+NrtI for 24 wks. Eligible pts had HBV DNA ≤LLOQ for ≥ 6 mos, HBsAg >1000 IU/mL, ALT ≤5× ULN and Metavir F0-F2. HBV DNA was measured by COBAS TaqMan 2.0 (LLOQ = 20 IU/mL) and an in-house (ASMB) semi-quantitative PCR assay (LLOQ = 5 IU/mL). HBV pgRNA was measured by an ASMB RTqPCR assay (LLOQ = 35 IU/mL). Safety was assessed through reporting of adverse events (AE) and laboratory abnormalities. This report summarizes the antiviral activity and safety for the HBeAg-negative pts only. Results: Of the 26 HBeAg-negative pts enrolled in the study, 16 received 731+NrtI and 10 received Pbo+NrtI. Overall, the mean (range) age was 48 (34–64) years, 16 (62%) were male, 21 (81%) were Asian. Results are shown in the table. Treatment with 731+NrtI resulted in a higher proportion of pts achieving TND by the ASMB HBV DNA assay compared with Pbo+NrtI. At baseline and throughout the study, the pgRNA and HBcrAg levels were low and the HBsAg levels did not change. The safety profile of 731+NrtI was similar to Pbo +NrtI. Both treatments were well-tolerated, with no serious adverse events or discontinuations due to AEs. All AEs and lab abnormalities were mild or moderate in severity. Only one pt receiving 731+NrtI reported a Grade 1 rash that resolved on study without treatment interruption. No Grade 3 ALT elevations were observed. Conclusion: In 24 weeks of treatment, a higher proportion of HBeAgnegative pts receiving 731+NrtI achieved HBV DNA TND by highly sensitive PCR methodology compared to Pbo+NrtI. 731 has a favorable safety and tolerability profile. These data suggest the contribution of 731 to the standard of care in achieving deeper viral suppression and support continued treatment with 731+NrtI in the open-label Phase 2 study ABI-H0731-211.