453P - Clinical outcomes of pyrotinib-based therapy after prior trastuzumab and pertuzumab in HER2-positive metastatic breast cancer

Background

At present, trastuzumab and pertuzumab has become the standard treatment for HER2-positive early breast cancer at high risk of recurrence and metastatic breast cancer who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease. There is currently no clinical trials exploring the efficacy of pyrotinib for HER2-positive advanced breast cancer after prior trastuzumab and pertuzumab. The aim of this study is to analyze the efficacy and safety of pyrotinib-based therapy in patients after prior trastuzumab and pertuzumab.

Methods

The pathological and clinical data of 77 HER2-positive advanced breast cancer patients treated with pyrotinib after prior trastuzumab and pertuzumab were retrospectively analyzed. Observation indexes included PFS, CBR, ORRand adverse events.

Results

A total of 77 patients were enrolled in this study at the Breast Oncology Department of the Fifth Medical Center of the PLA General Hospital from February 2019 to March 2023. Median age of the patients was 52 years (28-73 years), 64.9% were HR positive, 63.6% had visceral metastases, and 27.3% had brain metastases. 50(64.9%) of the patients received pyrotinib combined with capecitabine, 8(10.4%) received pyrotinib combined with vinorelbine, 3(3.9%) received pyrotinib combined with nab-paclitaxel, and 16(20.8%) received pyrotinib combined with endocrine therapy. The median line of pyrotinib was 2 (1-7), the median number of anti-HER 2 targeted therapy was 2 (2-6). Median follow-up was 17.8 months (1.6-51.4months) by the data cutoff date (May 2023). The median PFS was 13.6 months (95%CI: 8.3-18.9). The ORR was 50.0% in the 56 patients with evaluable lesions,the CBR was 54.5%, and the mPFS was 10.8 months (95%CI: 7.7-13.9). 46 patients who progressed on prior trastuzumab and pertuzumab had evaluable lesions, the ORR was 43.5%, CBR was 69.6%, and the mPFS was 9.2 months (95%CI: 6.4-12.0). The most common adverse events was diarrhea in the study.

Conclusions

This study first retrospectively analyze the value of pyrotinib in the era of dual anti-HER2 therapy, preliminarily showing good efficacy and safety of pyrotinib in patients after prior trastuzumab and pertuzumab.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.