Peginterferon-alpha-2a add-on to treatment with siRNA JNJ-73763989 in virologically suppressed chronic hepatitis B: The phase II PENGUIN study.

Background & Aims: Previous studies showed that combination treatment with short interfering RNA JNJ-73763989 (JNJ-3989) ± capsid assembly modulator bersacapavir (JNJ-56136379) and nucleos(t)ide analogs (NAs) was well tolerated by patients with chronic HBV (CHB), with JNJ-3989 dose-dependent reductions in viral markers, including HBsAg. The open-label, single-arm phase IIa PENGUIN study (NCT04667104) evaluated this regimen plus pegylated interferon alpha-2a (PegIFN-α2a) in patients with virologically suppressed CHB.

Methods: Patients who were either HBeAg-positive or -negative virologically suppressed and taking NAs were included; all received JNJ-3989 ± bersacapavir for 24 weeks (some either did not start or discontinued bersacapavir as a result of protocol amendment) with PegIFN-α2a added during the final 12 weeks of treatment. The primary endpoint was the proportion of patients with ≥2 log IU/ml HBsAg reduction from baseline at week 24 (W24). Safety, tolerability, and proportion of patients meeting predefined NA stopping criteria were assessed. After 24 weeks of treatment, NA was stopped when stopping criteria were met; all patients were followed for 48 weeks. Efficacy and safety endpoints were summarized using descriptive statistics.

Results: In total, 48 patients (HBeAg positive, n = 11; HBeAg negative, n = 37) were enrolled; 47 reached follow-up week 48 (FUW48). Of the 48 patients, 31 (64.6%) achieved the primary endpoint; one achieved HBsAg seroclearance (<0.05 IU/ml) at both W24 and FUW48 after stopping NA. Mean HBsAg changes from baseline were -1.43, -2.18, and -0.71 logIU/ml at W12, W24, and FUW48, respectively. At W24, 15/48 (31.3%) patients met NA stopping criteria; 11/15 (73.3%) remained off NA by FUW48. One patient achieved functional cure at FUW48. Adverse events were consistent with known PegIFN-α2a safety profiles.

Conclusions: Treatment with JNJ-3989 ± bersacapavir + NA and PegIFN-α2a was generally well tolerated. Most patients had pronounced HBsAg reductions from baseline, no additional benefit from PegIFN-α2a, and did not achieve functional cure.

Clinical Trials Registration: The study is registered at ClinicalTrials.gov (NCT04667104).

Impact And Implications: Previous studies with JNJ-73763989 (JNJ-3989) ± bersacapavir (JNJ-56136379) and nucleos(t)ide analogs (NAs) in patients with chronic hepatitis B (CHB) have demonstrated JNJ-3989 dose-dependent and robust reductions in viral markers; however, functional cure was only rarely achieved. The current study assessed whether the addition of pegylated interferon alpha-2a (PegIFN-α2a) to a JNJ-3989-based regimen after HBsAg levels were reduced would lead to further HBsAg declines and improved outcomes during off-treatment follow-up. Study results confirmed pronounced HBsAg reductions from baseline in virologically suppressed patients with HBeAg-positive or -negative CHB. However, the addition of PegIFN-α2a to JNJ-3989 ± bersacapavir and NA for the final 12 weeks of a 24-week treatment period did not appear to improve antiviral activity in the studied population. Studies in other CHB groups, including treatment-naïve, HBeAg-positive patients, could help elucidate whether this or other treatment regimens including JNJ-3989 and NA can lead to functional cure in a larger proportion of patients.