Abstract
BACKGROUND & AIMS: JNJ-73763989 (JNJ-3989) is a small-interfering RNA composed of two triggers targeting the HBsAg and HBx protein open reading frame, designed to target all HBV RNAs for degradation. JNJ-3989 + nucleos(t)ide analogue (NA) treatment dose-dependently reduced chronic hepatitis B (CHB) viral antigens. Viral sequence changes in the JNJ-3989 S-/X-trigger target regions were evaluated at baseline, on-treatment, and in patients with virologic relapse (VR) after discontinuation of all treatment in REEF-1 (NCT03982186) and REEF-2 (NCT0412954) studies. METHODS: HBV DNA/RNA was extracted from plasma samples, and the HBV genome was sequenced using next-generation sequencing. Nucleotide variants were defined as changes vs. the universal HBV reference sequence (read frequency >15%). RESULTS: Baseline polymorphisms in the JNJ-3989 target region complementary to positions 2-18 of the S-/X-trigger were present in 10.1% and 2.4% of not currently treated patients, respectively, with no relevant impact on JNJ-3989-induced HBsAg decline. Variants at X-trigger target region positions of interest (POI) were more frequently observed off treatment in JNJ-3989-treated virologically suppressed (VS) patients with VR vs. NA-control arm VS patients with VR (55.8% vs. 5.7%, respectively). Variants at S-trigger POI were observed off treatment in 32.1% and 19.4% of JNJ-3989- and NA-control treated VS patients with VR, respectively. Off-treatment HBsAg kinetics did not differ between JNJ-3989-treated patients with and without variants in S-/X-trigger target POI during VR. CONCLUSION: Baseline sequence polymorphisms did not impact JNJ-3989 treatment response. JNJ-3989-treated patients who experienced VR post-treatment had variants in the X-trigger target region during VR, but not at baseline or on-treatment, suggesting that X-trigger variants developed off treatment in JNJ-3989-treated patients. The presence of these variants did not impact off-treatment HBsAg kinetics. CLINICALTRIALGOV IDENTIFIERS: NCT03982186 and NCT0412954. IMPACT AND IMPLICATIONS: Small-interfering RNA (siRNA) therapy with JNJ-3989 in patients with chronic hepatitis B induces potent, dose-dependent reductions in viral antigens, though the magnitude of decline varies among individuals. Baseline nucleotide polymorphisms in JNJ-3989 trigger target regions did not account for variability in HBsAg or HBeAg responses. Substitutions in siRNA trigger target regions were frequently detected during and after virologic relapse in JNJ-3989-treated patients, confirming antiviral target engagement. However, the emergence of these variants did not affect off-treatment HBsAg or HBV DNA kinetics. This study provides the first comprehensive clinical virology analysis of siRNA-based therapy in HBV infection, offering insights relevant to the broader development of antiviral siRNA therapeutics. The clinical significance of X-trigger substitutions for potential re-treatment with JNJ-3989 or other HBV-targeting siRNAs remains to be determined.ClinicalTrial.gov Identifiers: NCT03982186 and NCT0412954.