PANKU-Breast01: Phase III Data in Previously Treated HR-Positive/HER2-Negative Disease
PANKU-Breast01 (NCT06343948) is a randomized, open-label Phase III study conducted at 72 centers in China, evaluating iza-bren against treatment of physician’s choice (TPC) chemotherapy in patients with unresectable locally advanced or metastatic HR+/HER2-negative breast cancer. Eligible patients had disease progression after at least one line of endocrine therapy and one or two lines of chemotherapy, with prior CDK4/6 inhibitor and taxane exposure required. A total of 383 patients were randomized to receive iza-bren at 2.5 mg/kg on Days 1 and 8 of each 21-day cycle (n=190) or investigator-selected chemotherapy—eribulin, capecitabine, gemcitabine or vinorelbine (n=193). The primary endpoint was PFS assessed by blinded independent central review (BICR), with OS as a key secondary endpoint.
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Key Efficacy and Safety Highlights | |||
|
Category |
Parameter |
Iza-bren (n=190) |
Physician’s Choice Chemotherapy (n=193) |
|
Efficacy |
Median PFS follow-up |
15.2 months |
15.2 months |
|
Median PFS by BICR |
8.2 months |
4.0 months | |
|
PFS hazard ratio |
0.41 |
Comparator arm | |
|
PFS statistical significance |
p<0.0001 |
— | |
|
PFS rate at 12 months |
26.5% |
9.2% | |
|
Confirmed ORR |
40.5% |
20.2% | |
|
Disease control rate |
86.3% |
63.7% | |
|
Median duration of response |
6.9 months |
4.2 months | |
|
Safety |
Grade ≥3 treatment-related adverse events |
85.3% |
65.8% |
|
Serious treatment-related adverse events |
41.6% |
11.4% | |
|
Dose reduction due to treatment-related adverse events |
64.7% |
28.5% | |
|
Treatment discontinuation due to treatment-related adverse events |
1.6% |
1.0% | |
Conclusion
The Phase III PANKU-Breast01 results position iza-bren as a promising investigational option for previously treated HR+/HER2-negative advanced breast cancer. The significant improvement in PFS, higher response rate and longer response duration suggest meaningful antitumor activity compared with physician’s choice chemotherapy in a population with limited later-line options. However, the substantial incidence of high-grade hematologic toxicity and immature OS data remain important considerations. As the evidence matures, the balance between efficacy, toxicity management and longer-term outcomes will determine the potential role of this EGFR×HER3-targeting ADC in the treatment landscape. The study’s conduct in China also makes assessment of generalizability to broader populations an important consideration.