Safety, tolerability and antiviral activity of the antisense oligonucleotide bepirovirsen in patients with chronic hepatitis B: a phase 2 randomized controlled trial

Abstract

Chronic infection with hepatitis B virus (HBV) leads to an increased risk of death from cirrhosis and hepatocellular carcinoma. Functional cure rates are low with current treatment options (nucleos(t)ide analogs (NAs) and pegylated interferons). Bepirovirsen is an antisense oligonucleotide targeting all HBV messenger RNAs; in cell culture and animal models, bepirovirsen leads to reductions in HBV-derived RNAs, HBV DNA and viral proteins. This phase 2 double-blinded, randomized, placebo-controlled trial is the first evaluation of the safety and activity of an antisense oligonucleotide targeting HBV RNA in both treatment-naïve and virally suppressed individuals with chronic HBV infection. The primary objective was to assess the safety and tolerability of bepirovirsen in individuals with chronic hepatitis B (CHB) (NCT02981602). The secondary objective was to assess antiviral activity, including the change from baseline to day 29 in serum hepatitis B surface antigen (HBsAg) concentration. Participants with CHB infection ≥6 months and serum HBsAg ≥50 IU ml^-1 were enrolled from seven centers across Hong Kong and the Republic of Korea and randomized (3:1 within each dose cohort) to receive bepirovirsen or placebo via subcutaneous injection twice weekly during weeks 1 and 2 (days 1, 4, 8 and 11) and once weekly during weeks 3 and 4 (days 15 and 22). Participants were then followed for 26 weeks. Twenty-four participants were treatment-naïve and seven were receiving stable NA therapy. Treatment-emergent adverse events were mostly mild/moderate (most commonly injection site reactions). Eleven (61.1%) and three (50.0%) treatment-naïve participants experienced one or more treatment-emergent adverse event in the bepirovirsen and placebo groups, respectively. In participants receiving NA therapy, the corresponding numbers were three (60.0%) and one (50.0%). Transient, self-resolving alanine aminotransferase flares (≥2× upper limit of normal) were observed in eight treatment-naïve participants and three participants on stable NA regimens in the bepirovirsen treatment arms. HBsAg reductions were observed and were significant versus placebo for treatment-naïve participants receiving bepirovirsen 300 mg (P = 0.001), but not for the bepirovirsen 150 mg group (P = 0.245) or participants receiving stable NA therapy (P = 0.762). Two participants in each of the 300 mg dose groups achieved HBsAg levels below the lower limit of quantitation by day 29 (n = 3) or day 36 (n = 1). Bepirovirsen had a favorable safety profile. These preliminary observations warrant further investigation of the safety and activity of bepirovirsen in a larger CHB patient population.

Fig. 1. Change over time in serum HBsAg and HBV DNA.

a,b, HBsAg (a) and HBV DNA (b) at baseline, day 15, day 23, day 29 and end of study (day 211) in patients with CHB (full analysis population). Blue lines indicate HBeAg-positive patients; gray lines indicate HBeAg-negative patients; black horizontal dashed line indicates LLOQ; gray shading indicates NA administration. In HBV DNA panels for treatment-naïve patients treated with placebo and bepirovirsen 150 mg, dashed lines between day 29 and day 211 are for patients whose day 211 test failed to produce a result. The last observation for these two patients (day 113) was carried forward to day 211. Four patients reached undetectable HBsAg levels; however, only three of the four reached LLOQ by day 29, the fourth patient reached LLOQ by day 36. Comparison between bepirovirsen and pooled placebo was performed for each dose level, separately, using an analysis of covariance model with baseline as a covariate and treatment group as a factor. For each comparison, if data departed substantially from normality, the Wilcoxon rank sum test was used.

Fig. 2. Change in HBsAg, HBV RNA and HBcrAg (all time points).

a, Placebo (NA-naïve and NA-treated; n = 8). b, Bepirovirsen 150 mg (NA-naïve; n = 6). c, Bepirovirsen 300 mg (NA-naïve; n = 12). d, Bepirovirsen 300 mg (NA-treated; n = 4*) (full analysis population; HBV RNA and HBcrAg analyses were post hoc). One patient discontinued treatment on study day 8 and is not shown. This patient discontinued treatment and withdrew from the study; as such they were not assessed beyond day 8 and are not shown in this figure (exclusion not prespecified), this patient was also excluded from the per-protocol population (according to prespecified criteria). Dotted lines denote LLOQ. The data shown are descriptive, no statistical analysis was conducted.

Fig. 3. Profiles and relationships of ALT, HBsAg, HBcrAg and HBV DNA levels in treatment-naïve, NA-treated patients and healthy volunteers receiving different doses of bepirovirsen.

a,b, HBsAg and ALT (a), and HBcrAg, HBV RNA and HBV DNA (b) in a treatment-naïve patient treated with bepirovirsen 300 mg. c, HBsAg and ALT in a patient already on entecavir treated with bepirovirsen 300 mg. d, HBsAg and ALT in a treatment-naïve patient treated with bepirovirsen 150 mg (vertical lines indicate dose administration days; gray shading indicates NA dosing period for treatment-naïve patients). e, ALT results at day 29 categorized by HBsAg reduction from baseline. f, ALT AUC categorized by dose group in patients with CHB (safety population) and healthy volunteers (Study CS1 safety population; unpublished data) receiving bepirovirsen (y axis is the AUC of ALT from day 1 to day 113 that is above the AUC of baseline ALT maintained for the time period). +, positive for anti-HBsAb; –, negative for anti-HBsAb; ±, indeterminate anti-HBsAb status; anti-HBsAg, antibody to HBV surface antigen. Data shown are descriptive, no statistical analysis was conducted.