A real-world study published in the Asian Journal of Surgery indicates that a trastuzumab biosimilar (Zercepac) combined with pertuzumab (Perjeta) and chemotherapy is effective and safe for treating HER2-positive breast cancer. The study highlights the potential for a more affordable treatment option with comparable efficacy to the originator drugs.
Study Details and Findings
The single-arm study evaluated the efficacy and safety of a trastuzumab biosimilar and pertuzumab combined with chemotherapy in 22 female patients with HER2-positive early or locally advanced breast cancer. Patients received neoadjuvant therapy for 4 to 8 cycles, followed by surgery. The primary endpoint was the total pathological complete response (CR), with secondary endpoints including breast pathological CR, objective response rate (ORR), and disease control rate (DCR).
Key findings from the study include:
- A total pathological CR of 68.2%.
- A breast pathological CR of 81.8%.
- A 100% ORR and DCR, indicating that all patients achieved these efficacy endpoints.
- A breast retention rate of 40.9%.
Notably, 3 patients achieved CR in the primary breast lesion but had residual tumor cells in lymph nodes. The combination of trastuzumab biosimilar and pertuzumab showed comparable efficacy to the originator trastuzumab drug (Herceptin) at a 440 mg dose.
Treatment Regimens and Administration
Most patients received the TCbHP regimen, which includes 75 mg/m2 docetaxel and 6 mg/mL/min carboplatin. Other patients received the THP regimen (docetaxel, trastuzumab, and pertuzumab) or EC sequential THP (epirubicin and cyclophosphamide combined with THP). The trastuzumab biosimilar is administered intravenously over 90 minutes, either weekly or every three weeks. Pertuzumab is initially infused at 840 mg over 60 minutes, followed by 420 mg every three weeks, each dose administered over 30 minutes to 1 hour.
Context and Clinical Significance
HER2-positive breast cancer accounts for 15% to 25% of all breast cancer subtypes. Neoadjuvant therapy, combining targeted medications with chemotherapy, is a common approach. The EMA approved the trastuzumab biosimilar in 2020, based on comparative studies demonstrating similar efficacy and safety to the reference product. Pertuzumab was approved for combination use with trastuzumab and docetaxel in 2013 for HER2-positive metastatic or locally recurrent unresectable breast cancer.
Limitations and Future Directions
The study's primary limitation is its small sample size. However, the results suggest that trastuzumab biosimilar and pertuzumab offer an effective and safe treatment option for patients with HER2-positive breast cancer, potentially at a lower cost. Further research with larger cohorts is needed to validate these findings and support the broader adoption of trastuzumab biosimilars in clinical practice.
