Safety and Efficacy of Nucleic Acid Polymers in Monotherapy and Combined with Immunotherapy in Treatment-Naive Bangladeshi Patients with HBeAg+ Chronic Hepatitis B Infection

Abstract

Previous in vivo studies have suggested that nucleic acid polymers (NAPs) may reduce circulating levels of HBsAg in the blood by blocking its release from infected hepatocytes and that this effect may have clinical benefit. NAP treatment, was evaluated in two clinical studies in patients with HBeAg positive chronic HBV infection. The REP 101 study examined REP 2055 monotherapy in 8 patients and the REP 102 study examined REP 2139-Ca, in monotherapy in 12 patients, 9 of which transitioned to short term combined treatment with pegylated interferon alpha 2a or thymosin alpha 1. In both studies NAP monotherapy was accompanied by 2-7 log reductions of serum HBsAg, 3-9 log reductions in serum HBV DNA and the appearance of serum anti-HBsAg antibodies (10-1712 mIU / ml). Eight of the 9 patients transitioning to combined treatment with immunotherapy (pegylated interferon or thymosin alpha 1) in the REP 102 study experienced HBsAg loss and all 9 patients experienced substantial increases in serum anti-HBsAg antibody titers before withdrawal of therapy. For 52 weeks after removal of REP 2055 therapy, rebound of serum viremia (HBV DNA > 1000 copies / ml, HBsAg > 1IU / ml) was not observed in 3 / 8 patients. Suppression of serum virema was further maintained for 290 and 231 weeks in 2 of these patients. After withdrawal of all therapy in the 9 patients that transitioned to combination therapy in the REP 102 study, 8 patients achieved HBV DNA < 116 copies / ml after treatment withdrawal. Viral rebound occurred over a period of 12 to 123 weeks in 7 patients but was still absent in two patients at 135 and 137 weeks of follow-up. Administration tolerability issues observed with REP 2055 were rare with REP 2139-Ca but REP 2139-Ca therapy was accompanied by hair loss, dysphagia and dysgeusia which were considered related to heavy metal exposure endemic at the trial site. These preliminary studies suggest that NAP can elicit important antiviral responses during treatment which may improve the effect of immunotherapy. NAPs may be a potentially useful component of future combination therapies for the treatment of chronic hepatitis B.

Trial registration: ClinicalTrials.gov NCT02646163 and NCT02646189.

Conflict of interest statement

Competing Interests: The authors of this manuscript have the following competing interests: MB and AV are employees of and shareholders in Replicor Inc.

Figures

Fig 1

Flow diagrams for the REP 101 study (A) and REP 102 study (B) indicating enrollment, assignment and allocation to treatment, entry into follow-up and analysis. * received 28 weeks of REP 2055 + ETV after REP 2055 monotherapy (patient 8, see methods and results).

Fig 2

Chemical structures of REP 2055 (A) and REP 2139 (B).

Fig 3. On-treatment antiviral response to REP 2055 monotherapy in patients admitted to the REP 101 protocol.

Individual patient, colour coded antiviral responses to NAP monotherapy are shown for serum HBsAg (A), serum anti-HBs (B) and serum HBV DNA (C). LLOQ = lower limit of quantitation. Protective immunity = 10mIU / ml (as defined by the Architect® Assay). *serum HBsAg clearance in these patients until the end of REP 2055 treatment was established via the onsite qualitative HBsAg assay (see methods). ** = transient depression in serum HBsAg associated with increased frequency REP 2055 dosing. Dotted portion of lines for patient 8 in A, B and C indicate an additional 28 weeks of combination therapy with REP 2055 and ETV (see Results and Table 2).

Fig 4

On-treatment serum ALT (A) and AST (B) observations in all patients treated with REP 2055 in the REP 101 study. Individual patient, colour coded test results are provided.

Fig 5. On-treatment antiviral response to REP 2139-Ca monotherapy therapy in patients admitted to the REP 102 protocol.

Individual patient, colour coded antiviral responses to NAP monotherapy are shown for serum HBsAg (A), serum anti-HBs (B) and serum HBV DNA (C). LLOQ = lower limit of quantitation. Protective immunity = 10mIU / ml (as defined by the Architect® Assay).

Fig 6. On-treatment antiviral response in the nine REP 2139-Ca patients in the REP 102 protocol who responded to monotherapy and proceeded to combination therapy with REP 2139-Ca and pegylated interferon alpha 2a or thymosin alpha 1.

Individual patient, colour coded antiviral responses to total therapy are shown for serum HBsAg (A), serum anti-HBs (B), serum anti-HBs normalized to the start of combination therapy (C) and serum HBV DNA (D). In A, B and D the colour coded arrows indicate the start of immunotherapy for each respective patient. In (C), negative numbers indicate REP 2139-Ca monotherapy and positive numbers from 0 onward indicate combination therapy. Immunotherapy exposure for each patient (see methods) are indicated in the figure legend as follows: Z = thymosin alpha 1, P = pegylated interferon alpha 2a, ½ P = extended pegylated interferon exposure at ½ dose (with REP 2139-Ca at ½ dose). Dotted coloured lines in (D) indicate initial serum HBV DNA responses off-treatment.* = patients with inadvertent exposure to 1–3 weeks of peg-IFN at the end of treatment.

Fig 7

On-treatment serum ALT (A) and AST (B) observations in all patients treated with REP 2139-Ca and immunotherapy in the REP 102 study. Individual patient, colour coded test results are provided. The immunotherapy present at the time of ALT flare is indicated with arrows: Z = thymosin alpha 1, P = pegylated interferon alpha 2a, ½ P = pegylated interferon exposure at ½ dose (with REP 2139-Ca at ½ dose).