NEWTON, MA, October 15, 2025 – ClearB Therapeutics, Inc., a clinical-stage biotechnology company committed to developing therapies to drive functional cure in patients with chronic hepatitis B (CHB) infection, announced that review of the safety data from the sentinel subject supported enrollment for the remainder of the cohort in their Phase 1b clinical study evaluating the therapeutic vaccine CLB-4000 (ACTRN12625000250437 and ACTRN12625000204448).

CLB-4000 is a bivalent subunit therapeutic vaccine comprised of CLB-405 and CLB-505 proteins, adjuvanted with TQL-1055. CLB-405 and CLB-505 are variants of HBsAg designed to over-represent clearance profile epitopes identified from functional cure patients. TQL-1055 is a novel, rationally designed, semi-synthetic saponin adjuvant licensed from Adjuvance Technologies, Inc. The CLB-4000-1-001 Phase 1b is an open label multicenter, multiple-dose study designed to assess the safety and tolerability of repeated intramuscular (IM) administration of CLB-4000 (fixed antigen amounts of 250 μg CLB-405 and 250 μg CLB-505, adjuvanted with multiple dose levels of TQL-1055), in noncirrhotic adults with CHB taking a stable dose of a standard of care NUC for viral suppression. To further boost the immune and antiviral responses, additional cohorts will evaluate CLB-4000 with Peg-IFNα-2a. The objectives of the study are safety and tolerability of CLB-4000 with or without Peg-IFNα-2a. Additional objectives include evaluation of antiviral activities and immunological responses. Results are expected on a rolling basis starting 2H 2026.

“It is very exciting to evaluate our promising therapeutic vaccine, CLB-4000 in first in human trials in CHB patients. We look forward to sharing emerging clinical data with the Hepatitis B community as it becomes available” said Aileen Rubio, PhD, CEO for the company. “CHB infection remains a substantial global health care problem with a continued need for safe and effective therapies. We believe that CLB-4000 could become an important component of evolving CHB treatment regimens.”