This is a phase II study of HLX22 in combination with trastuzumab and chemotherapy versus placebo in combination with trastuzumab and chemotherapy in locally advanced and/or metastatic HER2-Positive breast cancer previously treated with HER2 ADC. Eligible participants will be treated with the study drug until the loss of clinical benefit, intolerable toxicity, initiation of new anti-tumor therapy, voluntary withdrawal from the study by the patient, loss to follow-up, death, or when the investigator determines that the patient should be withdrawn from the study (whichever occurs first).
Experimental group: HLX22 + trastuzumab + investigator's choice of chemotherapy, once every 3 weeks (Q3W).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
90
15 mg/kg, intravenous infusion (IV) on Day 1 (D1) of Q3W
Loading dose 8 mg/kg, maintenance dose 6 mg/kg, IV, Q3W, D1.
1000 mg/m2, oral (po), twice daily (BID), D1-14, Q3W
175 mg/m2, D1; or 80-90 mg/m2, D1 D8 D15, Q3W, IV
75-100 mg/m2, D1, Q3W, IV
1.4 mg/m2, D1 and D8, Q3W, IV
25-30 mg/m2, D1 and D8, Q3W, IV
Objective response rate (ORR) assessed by the blinded independent central review (BICR) as per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1
ORR is defined as the percentage of participants who have a Complete Response (\[CR\], disappearance of all evidence of disease) or Partial Response (\[PR\], regression of measurable disease and no new sites) per RECIST 1.1
Time frame: Up to 2 years
Progression-free survival (PFS) assessed by the BICR as per RECIST 1.1
PFS is defined as the time from randomization to the first documented disease progression per RECIST 1.1 or death due to any cause, whichever occurs first.
Time frame: up to 5 years
ORR assessed by the investigator as per RECIST 1.1
Time frame: up to 2 years
PFS assessed by the investigator as per RECIST 1.1
Time frame: up to 5 years
Duration of response (DoR) assessed by the BICR and the investigator as per RECIST 1.1
DoR is defined as the time from the date of first achievement of CR or PR (whichever is documented first) to the date of the first documentation of PD or death (whichever occurs first)
Time frame: up to 2 years
Overall survival (OS)
OS is defined as the time from randomization to death due to any cause.
Time frame: up to 5 years
Adverse Events (AEs)
Incidence and severity of AEs graded according to Common Terminology Criteria for Adverse Events (CTCAE) v6.0.
Time frame: time from the date of the first dose of study drug until 90 days after last dose, assessed up to 5 years
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