NEWTON, Mass. — ClearB Therapeutics, Inc., a clinical-stage biotechnology company developing therapies aimed at achieving a functional cure for chronic hepatitis B (CHB), announced that the safety review of the sentinel subject in its ongoing Phase 1b clinical trial has supported enrollment of the remainder of the study cohort evaluating CLB-4000, the company’s first-in-human therapeutic vaccine (ACTRN12625000250437 and ACTRN12625000204448).
CLB-4000 is a bivalent subunit therapeutic vaccine composed of the CLB-405 and CLB-505 proteins, adjuvanted with TQL-1055. The CLB-405 and CLB-505 antigens are engineered variants of hepatitis B surface antigen (HBsAg) designed to emphasize epitopes associated with viral clearance observed in functionally cured patients. TQL-1055, a novel semi-synthetic saponin adjuvant licensed from Adjuvance Technologies, enhances the immune response to vaccination.
The Phase 1b study (CLB-4000-1-001) is an open-label, multicenter, multiple-dose trial assessing the safety and tolerability of repeated intramuscular doses of CLB-4000 in noncirrhotic adults with CHB who are receiving stable nucleos(t)ide analogue (NUC) therapy for viral suppression. The study includes fixed antigen doses of 250 µg each of CLB-405 and CLB-505 combined with varying levels of TQL-1055. Additional cohorts will evaluate the vaccine in combination with Peg-IFNα-2a to further enhance antiviral and immune responses.
The primary objectives of the study are to evaluate safety and tolerability, while secondary objectives include assessing antiviral activity and immunological responses. Results are expected to be released on a rolling basis beginning in the second half of 2026.
“It is very exciting to evaluate our promising therapeutic vaccine, CLB-4000, in first-in-human trials in CHB patients,” said Aileen Rubio, Ph.D., Chief Executive Officer of ClearB Therapeutics. “CHB infection remains a substantial global health problem with an urgent need for safe and effective therapies. We believe CLB-4000 could become an important component of evolving treatment regimens designed to achieve functional cure.”
According to the World Health Organization, hepatitis B is a potentially life-threatening liver infection that affects roughly two billion people worldwide, with about 250 million living with chronic infection. Viral hepatitis ranks as the seventh leading cause of death globally, and liver cancer — a common consequence of chronic HBV infection — is the third most frequent cause of cancer-related mortality.
