“Safety and Immunotherapeutic Activity of Cemiplimab in Participants with HBV on Suppressive Antiviral Therapy: A Phase I/II Ascending Multiple Dose Study”

Brief Description: Scientists are looking at ways to cure Hepatitis B (HBV). This study will assess the safety and tolerability of cemiplimab administered in participants with HBV on suppressive antiviral therapy.

Purpose of this Study: This study is trying to find out if cemiplimab is safe and well tolerated. Participants will receive multiple dose levels (0.3, 1.0, and 3.0 mg/kg) of cemiplimab administered as two infusions at weeks 6 and 12.

Requirements to Enter Study (things that must be true for you):

  • Have chronic HBV infection (defined as HBsAg positive) and under treatment for ≥12 months with tenofovir- or entecavir-containing therapy: tenofovir disoproxil fumarate (TDF), tenofovir alanfenamide (TAF), TDF/emtricitabine (FTC), TAF/FTC, or entecavir.
  • Be willing to continue HBV antiviral therapy throughout the study.
  • Have certain tests done.
  • Agree to use contraception/birth control methods.
  • Be 18 years old or older but less than 70 years.
  • Weight ≥40 kg.
  • Had evidence of limited or no evidence of fibrosis (F0-F2) by liver biopsy or noninvasive alternative method.
  • Be willing to sign the consent after discussion with the research staff.

Exclusion Criteria (things that cannot be true about you):

  • Positive for the presence of Hepatitis C Virus.
  • Received investigational drug or device within 60 days prior to study entry.
  • Breastfeeding or pregnancy.
  • Known allergy/sensitivity or any hypersensitivity to components of study drug(s).
  • Active drug or alcohol use or dependence and other conditions that would interfere with adherence to study.
  • Acute or serious illness requiring systemic treatment and/or hospitalization within 35 days prior to study entry.
  • History of immunoglobulin IgG therapy or interferon (IFN) therapy within 12 months prior to study entry.
  • A male participant with a pregnant female partner.
  • Any vaccination within 30 days prior to entry.


  • Multiple dose levels (0.3, 1.0 and 3.0 mg/kg) of cemiplimab administered as two infusions at weeks 6 and 12.


  • Blood tests at clinic visits to check mainly hepatic and renal function.
  • Liver biopsy at study entry and at week 18 on study.
  • Leukapheresis for a group of participants.

Duration of Study: Participants will be on study for up to 90 weeks (78 weeks following the last study drug infusion) with frequent safety evaluations.