A Phase II Study to Evaluate the Efficacy and Safety of HLX43 in Patients With Hormone Receptor Positive, HER2 Negative Locally Advanced or Metastatic Breast Cancer

March 5, 2026 updated by: Shanghai Henlius Biotech

A Phase II Study to Evaluate the Efficacy and Safety of HLX43 (Anti-PD-L1 ADC) in Patients With Hormone Receptor Positive, HER2 Negative Locally Advanced or Metastatic Breast Cancer

This is a Phase II Study of HLX43 in Hormone Receptor Positive，HER-2 negative Locally Advanced or Metastatic Breast Cancer Patients with Disease Progression on Standard of Care. Eligible subjects will be treated with the study drug until the loss of clinical benefit, death, intolerable toxicity, withdrawal of informed consent, or other reasons specified by the protocol (whichever occurs first)

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Male/female who are at least 18 years of age and and no more than 75 years old on the day of signing the informed consent.
  2. With histologically confirmed diagnosis of HER2-negative, Hormone Receptor Positive Locally Advanced or Metastatic Breast Cancer.
  3. Must have experienced disease progression after receiving at least one line of endocrine therapy for advanced or metastatic disease.
  4. Had measurable disease according to the RECIST v1.1, the target lesion must not be a bone metastatic lesion only.
  5. ECOG PS: 0-1.
  6. Expected survival ≥ 6 months.
  7. Had adequate organ function

Exclusion Criteria:

  1. Patients with other malignant tumors within 3 years before the randomization
  2. Prior documented interstitial lung disease (ILD)/ pneumonitis that required steroids, current ILD/ pneumonitis, or suspected ILD/pneumonitis
  3. Lung-specific intercurrent clinically significant illnesses
  4. Uncontrolled or significant cardiovascular disease or infection
  5. Prior adverse events leading to permanent discontinuation of immunotherapy; or prior immune-related pneumonia or immune-related myocarditis of grade ≥2.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: HLX43 DOSE1
Patients with good tolerability and well controlled disease will receive the treatment once every 3 weeks (Q3W), until disease progression and loss of benifit, initiation of a new anti-tumor therapy, death,emergence of intolerable toxicity, or withdrawal of informed consent (whichever occurs first).
Drug: HLX43
HLX43 is an anti-PD-L1 monoclonal antibody conjugated with a novel high potency DNA topoisomerase I (topo I) inhibitor, with a drug-antibodyratio (DAR) of 8.
Experimental: HLX43 DOSE2
Patients with good tolerability and well controlled disease will receive the treatment once every 3 weeks (Q3W), until disease progression and loss of benifit, initiation of a new anti-tumor therapy, death,emergence of intolerable toxicity, or withdrawal of informed consent (whichever occurs first).
Drug: HLX43
HLX43 is an anti-PD-L1 monoclonal antibody conjugated with a novel high potency DNA topoisomerase I (topo I) inhibitor, with a drug-antibodyratio (DAR) of 8.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
ORR
Time Frame: Up to 24WEEK
Objective response rate (ORR) assessed by IRRC (Independent Radiology Review Committee) per RECIST 1.1
Up to 24WEEK
PFS
Time Frame: Up to 5 years
Progression-Free Survival (PFS) assessed by IRRC (Independent Radiology Review Committee) per RECIST 1.1
Up to 5 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Shanghai Henlius Biotech

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

April 1, 2026

Primary Completion (Estimated)

December 30, 2026

Study Completion (Estimated)

December 30, 2027

Study Registration Dates

First Submitted

March 5, 2026

First Submitted That Met QC Criteria

March 5, 2026

First Posted (Actual)

March 10, 2026

Study Record Updates

Last Update Posted (Actual)

March 10, 2026

Last Update Submitted That Met QC Criteria

March 5, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • HLX43-BC201

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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