Abstract P1-19-40: Apatinib in the treatment of HER-2 negative advanced breast cancer with chest wall metastasis multicenter phase II clinical study

Background: Angiogenesis is a key mechanism of tumour growth. Apatinib is an oral tyrosine kinase inhibitor that selectively inhibits vascular endothelial growth factor receptor 2 (VEGFR-2) and blocks downstream signalling and inhibiting tumour angiogenesis. It was approved in China to treat gastric cancer in October 2014. However, as breast cancer with a chest wall metastasis (CWM) has rich vascular distribution, whether Apatinib is also effective for breast cancer with a chest wall metastasis remains unknown. Therefore, we designed this clinical study to address this question. Method: The trial involved four centres in China from September 2016 to July 2019. It enrolled patients (pts) who were diagnosed of HER2 negative breast cancer with CWM and experienced first line or could not afford standard treatment. The patients were given Apatinib 500mg/day (single or combined with endocrine therapy if hormone receptor positive (HR+)) until progression or side effect not tolerated. Each patient had at least one measurable lesion according to Response Evaluation Criteria in Solid Tumours (RECIST), version 1.1.This study was approved by ethics committee at the Ethics Committee of Beijing Cancer Hospital, and all participants provided written informed consent. The trial was also Register to clinicaltrial.gov ( NCT02878057). Results: 30 pts were enrolled in the study with a median age of 50 (range 35-69) years old. Among the 30 pts, there were 23 ER positive pts (76.7%). 17 pts (56.7%) had more than 2 sites of metastasis, and 5 pts had invasive metastasis (16.6%). 15 pts (50%) were multi pre-treated. The response of 19 pts (63.3%) could be evaluated, and the overall response rate was 57.9% (no CR, 11 cases reached PR, 2 in HR-, 9 in HR+). and the median PFS was 8.6 months (range 0.5-29.5; 95% CI 0.0-18.7). The tumour in chest wall shrunk obviously. Side effects also existed. 15 pts (50%) had hypertension (grade 3: 6.7%); 10 pts (33.3%) had proteinuria (grade 3: 20%); 4 pts (13.3%) had fatigue (grade 3: 3.3%); 3 pts (10%) had bilirubin increase (grade 3: 6.7%). 8 pts discontinued the treatment due to side effects and 3 due to personal reasons. The Apatinib dose was reduced from 500mg to 250mg for most pts 18/30 (60%), and some pts took 500 mg and 250 mg every other day 10/30 (33.3). Conclusion: Apatinib was effective for pts with chest wall metastasis and pts could benefit from longer PFS. However, the side effects should be pay more attention from start on apatinib treatment. Citation Format: Huiping Li, Cuizhi Geng, Guohong Song, Hanfang Jiang, Zhongshen Tong, Junlan Yang, Ran Ran, Ruyan Zhang, Yaxin Liu, Xinyu Gui, Maorong Wei, Lu Xue. Apatinib in the treatment of HER-2 negative advanced breast cancer with chest wall metastasis multicenter phase II clinical study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-19-40.