Dr. Zefei Jiang from The Fifth Medical Center of Chinese PLA General Hospital, along with his colleagues, published the groundbreaking article titled "Neoadjuvant-adjuvant pertuzumab in HER2-positive early breast cancer: final analysis of the randomized phase III PEONY trial" in Nature Communications on March 9, 2024. This pivotal research examines the long-term efficacy and safety of incorporating pertuzumab, a monoclonal antibody, into the treatment regimen for HER2-positive early and locally advanced breast cancer. HER2-positive breast cancer is characterized by the overexpression of the human epidermal growth factor receptor 2 (HER2), which promotes the growth of cancer cells. Pertuzumab targets the HER2 receptor, working synergistically with trastuzumab, another HER2-targeted therapy, to provide a more effective treatment approach.The PEONY trial, a pivotal, large-scale, multicenter, double-blind, placebo-controlled phase III study, was designed to address the critical need for improved treatment strategies in patients with HER2-positive early and locally advanced breast cancer. Involving 329 female patients, the trial aimed to fill the gap in long-term data on the combined neoadjuvant and adjuvant use of pertuzumab in conjunction with trastuzumab. Participants were treated with neoadjuvant pertuzumab or placebo, along with trastuzumab and docetaxel, followed by adjuvant chemotherapy consisting of 5-fluorouracil, epirubicin, and cyclophosphamide. They continued with pertuzumab or placebo and trastuzumab until disease recurrence or unacceptable toxicity for up to one year.
The study provided comprehensive long-term results, including event-free survival (EFS), disease-free survival (DFS), overall survival (OS), and safety data over a median follow-up period of 62.9 months, demonstrating the potential of dual HER2 blockade with pertuzumab and trastuzumab to significantly enhance treatment outcomes.
Table 1 . Site of first EFS event
Patients who had an additional event within 60 days of their first event are reported in the category according to the following hierarchy: distant recurrence, locoregional recurrence, contralateral breast cancer, second primary non-breast cancer, and death without previous event.
CNS central nervous system, EFS event-free survival.
（Nat Commun. 2024 Mar 09;15(1): 2153. doi:10.1038/s41467-024-45591-7.）
Results
The trial’s results underscore the efficacy and safety of the neoadjuvant-adjuvant pertuzumab regimen:
- Event-Free Survival (EFS): At the 5-year mark, patients in the pertuzumab group had an EFS rate of 84.8%, compared to 73.7% in the placebo group. The hazard ratio (HR) was 0.53 (95% confidence interval [CI], 0.32–0.89), indicating a 47% reduction in the risk of an event occurring in the pertuzumab group.
- Disease-Free Survival (DFS): The 5-year DFS rates were 86.0% for the pertuzumab group and 75.0% for the placebo group. The HR was 0.52 (95% CI, 0.30–0.88), showing a significant benefit for patients receiving pertuzumab.
- Overall Survival (OS): While OS events were fewer, a positive trend was observed, with the 5-year OS rates being 93.9% for the pertuzumab group and 90.0% for the placebo group, indicating a trend towards improved survival with pertuzumab (HR 0.53; 95% CI, 0.23–1.19).
- Safety: The safety profile was consistent with previous studies, with no new safety signals identified. The primary side effect observed was diarrhea,
- which was more frequent in the pertuzumab group but manageable.
Key findings from the study include:
- A significant improvement in the 5-year event-free survival (EFS) rate: 84.8% in the pertuzumab group versus 73.7% in the placebo group.
- Enhanced 5-year disease-free survival (DFS) rates: 86.0% in the pertuzumab group compared to 75.0% in the placebo group.
- The safety profile of pertuzumab was consistent with known data, with the main side effect being diarrhea, and no new safety concerns were identified.
The study’s significance lies in its demonstration that dual HER2 blockade with pertuzumab and trastuzumab considerably improves long-term outcomes for patients with HER2-positive early or locally advanced breast cancer. This research confirms the positive benefit-risk ratio of adding pertuzumab to the treatment regimen, supporting its continued use to enhance survival rates and reduce disease recurrence in this patient population.
Conclusion
The final analysis of the PEONY trial provides robust evidence supporting the addition of pertuzumab to the standard neoadjuvant and adjuvant treatment regimens for HER2-positive early breast cancer. The significant improvements in event-free and disease-free survival rates highlight the importance of dual HER2 blockade in optimizing treatment outcomes. This study reinforces the clinical value of pertuzumab in improving patient prognoses and shaping future breast cancer treatment protocols.
