A Study of A166 in Patients With HER2-Positive Unresectable or Metastatic Breast Cancer

NCT07299825 | Recruiting Phase 2

• 1 other identifier: KL166-II-08
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 1

Brief Summary

Evaluation of the efficacy of A166 in Patients with HER2-Positive unresectable or metastatic breast cancer previously treated with TOP1 inhibitor Antibody-Drug Conjugates

Conditions

Her 2 Positive Breast Cancer

Outcome Measures

Primary Outcomes (1)

• Objective response rate(ORR)

  ORR is defined as the percentage of patients who achieve complete response(CR) or partial response (PR), as assessed by investigator per RECIST 1.1

  Within 24 months of last patient enrolled

Secondary Outcomes (5)

• Progression-free survival (PFS)

  Within 24 months of last patient enrolled

• Overall survival (OS)

  Within 48 months of last patient enrolled

• Disease control rate(DCR)

  Within 24 months of last patient enrolled

• Duration of response(DOR)

  Within 24 months of last patient enrolled

• Clinical Benefit Rate (CBR)

  Within 24 months of last patient enrolled

Study Arms (1)

A166

EXPERIMENTAL

A166 is administered intravenously at a dose of 4.8 mg/kg every 21 (±3) days (q3w).

Drug: A166

Interventions

A166 DRUG

intravenous(IV) infusion (Q3W)

A166

Eligibility Criteria

• Age: 18 Years - 75 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Male or female patient ≥ 18 years and ≤ 75 years when signing the informed consent form.
• Breast cancer patients by histopathology and/or cytology documented.
• In the advanced or metastatic stage, having received no more than 5 lines of systemic therapy, one of which must include a HER2 ADC with a topoisomerase inhibitor payload.
• Patients must have experienced disease progression or intolerance during or after the most recent treatment prior to randomization.
• At least one measurable lesion according to RECIST 1.1 criteria.

You may not qualify if:

• Previous treatment with A166 or any HER2-targeted antibody-drug conjugate (ADC) with a microtubule inhibitor payload.
• Known history of severe hypersensitivity to other monoclonal antibodies, or allergy to A166 or their components.
• Permanent discontinuation of trastuzumab or its biosimilars due to any toxicity in prior treatments.
• Presence of severe corneal epithelial disease at baseline; or inability to perform daily activities without contact lenses.
• Presence of spinal cord compression or clinically active central nervous system (CNS) metastases.
• Other conditions considered by the investigator to make the patient unsuitable for participation in the study.

Sponsors & Collaborators

• Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd.: lead

Study Sites (1)

Henan Provincial Cancer Hospital

Zhenzhou, Henan, 450000, China

RECRUITING

Central Study Contacts

Min Yan, Professor

CONTACT

0371-65588404; ym200678@126.com

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: December 3, 2025
• First Posted: December 23, 2025
• Study Start: September 20, 2024
• Primary Completion (Estimated): September 20, 2027
• Study Completion (Estimated): December 31, 2027
• Last Updated: May 8, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)