Sac-TMT plus KL-A167 for PD-L1–positive, hormone receptor–positive/HER2–negative metastatic breast cancer after CDK4/6 inhibitors

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This is a prospective, single-arm Phase II trial enrolling 35 patients with PD-L1–positive, HR+/HER2– metastatic breast cancer previously treated with CDK4/6 inhibitors. Patients receive intravenous Sac-TMT (5 mg/kg) plus KL-A167 (900 mg) every two weeks until disease progression or unacceptable toxicity. The primary endpoint is the 6-month progression-free survival rate by investigator assessment using RECIST v1.1, with secondary endpoints including PFS, ORR, DCR, DoR, OS, and safety. Tumor assessments are every 6 weeks for the first 6 months then every 12 weeks, and an exploratory analysis will correlate TROP2 and PD-L1 expression with outcomes.

Why it matters

Who can join: the full rules

Inclusion Criteria:

1. 18-75 years old.
2. HR+/HER2- breast cancer (BC), meeting the following conditions:

   1. HR+/HER2-; HER2-(IHC 0 or 1+); IHC 2+(FISH negative); HR+ (ER and/or PR IHC showed ≥1%);
   2. Tumor stage: Locally advanced, recurrent, or metastatic HR+/HER2- breast cancer; 3) Disease progression during or within 12 months after completion of adjuvant endocrine therapy based on a CDK4/6 inhibitor, or disease progression on CDK4/6 inhibitor treatment for metastatic disease; 4) PD-L1 positive (CPS ≥ 1); 5) At least one measurable target lesion as assessed by the investigator per RECIST 1.1; 6) Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1; Life expectancy more than 12 weeks; 7) Adequate organ function, defined as:

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   1. Complete blood count: Neutrophil count ≥ 1.5×10\^9/L; platelets ≥ 100×10\^9/L; hemoglobin ≥ 9 g/dL.
   2. Liver function: AST, ALT, and ALP ≤ 2.5× ULN; total bilirubin ≤ 1.5× ULN; ALT and AST ≤ 5× ULN, TBIL ≤ 2× ULN for patients with liver metastases; ALP ≤ 5× ULN for patients with liver or bone metastases.
   3. Renal function: Creatinine clearance ≥ 60 ml/min (Cockcroft-Gault formula).
   4. Coagulation function: INR, APTT, and PT ≤ 1.5× ULN.
   5. Cardiac function: ECHO or MUGA scan indicating LVEF ≥ 50%. 8) For female participants of childbearing potential and male participants with reproductive potential, effective medical contraceptive measures must be implemented from the time of signing the informed consent until six months after the last administration; 9) Voluntary participation in the study with signed informed consent, demonstrated good compliance, and willingness to follow up as required.

Exclusion Criteria:

1. Received any of the following treatments during the advanced stage:

   1. .Chemotherapy;
   2. .any targeted therapy against topoisomerase I including antibody-drug conjugates (ADCs);
   3. . immune checkpoint agonists (e.g., anti-PD-1/L1antibodies, anti-CTLA-4 antibodies), or any immune cell therapy;
2. Recurrence or metastasis within 12 months of the last chemotherapy in the early stage;
3. Subjects with central nervous system (CNS) metastases. For subjects with brain metastases who have previously received local therapy,
4. Other malignancies within 5 years prior to dosing (excluding locally treated and cured tumors such as basal cell carcinoma, squamous cell carcinoma of the skin, or cervical carcinoma in situ);

Where it's running

• Sun Yat-sen University Cancer Center
  Guangzhou, Guangdong, China Recruiting

Study contacts

• Principal investigator: Fei Xu, MD — Sun Yat-sen University
• Study coordinator: Fei Xu, MD
• Email: xufei@sysucc.org.cn
• Phone: +86-13711277870

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.