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

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)

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Key information

Conditions

Hormone Receptor Positive HER-2 Negative Breast Cancer Breast Diseases Breast Neoplasms Neoplasms Neoplasms by Site Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year–75 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

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.
With histologically confirmed diagnosis of HER2-negative, Hormone Receptor Positive Locally Advanced or Metastatic Breast Cancer.
Must have experienced disease progression after receiving at least one line of endocrine therapy for advanced or metastatic disease.
Had measurable disease according to the RECIST v1.1, the target lesion must not be a bone metastatic lesion only.
ECOG PS: 0-1.
Expected survival ≥ 6 months.
Had adequate organ function

Exclusion criteria

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

Treatment and study plan

HLX43

Drug

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.

Primary outcomes

ORR

Time frame: Up to 24WEEK

Objective response rate (ORR) assessed by IRRC (Independent Radiology Review Committee) per RECIST 1.1
PFS

Time frame: Up to 5 years

Progression-Free Survival (PFS) assessed by IRRC (Independent Radiology Review Committee) per RECIST 1.1

Study contacts

Contact information is provided by the study sponsor or research team.

Liman Zhang

CONTACT

[email protected]

18501255848

Sponsors and collaborators

Lead sponsor

Shanghai Henlius Biotech

Industry

Registry information

Official study title

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

Important dates

Study start: 2026
Primary completion: 2026
Study completion: 2027
First posted: Mar 10, 2026
Registry last updated: Mar 10, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

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