Abstract PO2-16-06: Treatment Patterns of Neoadjuvant Therapy in Chinese Patients with HR-Positive/HER2-Positive Early or Locally Advanced Breast Cancer: A Real-World Study Using NCID Data in 2019-2022

Abstract Background: With the approval of pertuzumab (P) in China in 2019, P plus trastuzumab (T) and chemotherapy has become a standard of care in the neoadjuvant setting for patients with HER2-positive (HER2+) early or locally advanced breast cancer (BC). As a unique subtype, HR-positive (HR+)/HER2+ BC is less responsive to neoadjuvant chemotherapy plus HER2 targeted therapy with lower pathologic complete response (pCR) rates compared with the HR−/HER2+ subgroup. In China, the treatment pattern of HR+/HER2+ BC patients is unclear. In this real-world study, we summarized the current treatment patterns of Chinese patients diagnosed with HR+/HER2+ BC at an early or locally advanced stage based on national-level data to drive clinical decision support. Methods: A representative sample of 51 hospitals (31 cancer centers and 20 general hospitals) covering 29 provinces from NCID (National Cancer Information Database) were generated. Anonymous individual patient data from electronic medical records (EMR) were retrieved to extract information on therapy modalities. Early or locally advanced HR+/HER2+ BC patients who were initially diagnosed between January 1, 2019 and May 31, 2022 were included. Data were analyzed both by year and in the aggregate to ensure accuracy and stability. Results: The types of hospitals and study period reflected the current treatment landscape of HR+/HER2+ early or locally advanced BC in Chinese clinical practice. From 2019 to 2022, the results were consistent by year. In the aggregate, a total of 290,626 patients were initially diagnosed with BC during the study period. 84% (243,528/290,626) were at an early or locally advanced stage, of which 50% (121,548/243,528) had a pathologic diagnosis, 24% (29,390/121,548) were identified as HER2+, 69% (20,370/29,390) were both HR+ and HER2+, and 87% (17,630/20,370) underwent surgery. After excluding those without post-operative pathologic reports or with other primary cancers, 15,368 patients were analyzed regarding treatment patterns. 30% (4,598/15,368) received neoadjuvant therapy but 69% (10,677/15,368) had no neoadjuvant therapy. Among 4,598 patients, 31% (1,434/4,598) received T as single anti-HER2 targeted therapy, 36% (1,649/4,598) received dual HER2 blockade (1,522 T plus P, 127 T plus a TKI [tyrosine kinase inhibitor]), and the rest (1,515) received treatment that not contain a targeted agent. For patients treated with T plus P, 1,465 received concurrent chemotherapy (410 anthracyclines-based, 828 platinum-based); for patients treated with T plus TKI, 123 received concurrent chemotherapy (15 anthracyclines-based, 79 platinum-based). The most frequently prescribed chemotherapies were platinum-based regimens (57% for T plus P plus chemotherapy and 64% for T plus TKI plus chemotherapy). Conclusions: Based on the largest nationwide database, strong representativeness and stability of our data sources, our findings are of great significance to clinical decision-making. The proportion of patients who underwent neoadjuvant therapy of HR+HER2+ BC is much lower than in many other countries, with T plus P in combination with chemotherapy appearing to be the most commonly used targeted regimen. We also found some distinctions between neoadjuvant patterns of early-stage BC in the real world of China and guidelines, which would be further explored in subsequent research. Citation Format: Zhenzhen Liu, Jiujun Zhu, Chengzheng Wang, Zhenduo Lu, Xiuchun Chen, Lianfang Li, Xianfu Sun, Chongjian Zhang, Jianghua Qiao, Min Yan. Treatment Patterns of Neoadjuvant Therapy in Chinese Patients with HR-Positive/HER2-Positive Early or Locally Advanced Breast Cancer: A Real-World Study Using NCID Data in 2019-2022 [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-16-06.