Efficacy and safety of pyrotinib and radiotherapy vs. pyrotinib-based therapy in patients with HER2+ breast cancer with brain metastasis: a retrospective cohort study.

Background: At present, local therapy, such as surgery and radiotherapy, is the mainstay treatment for brain metastasis and anti-human epidermal growth factor receptor type 2 (HER2)-targeted therapy has been shown to be efficacious for HER2+ breast cancer (BC) patients with brain metastasis. However, Clinical studies comparing the combined effects of the two treatments are lacking. This study sought to investigate the efficacy and safety of pyrotinib and radiotherapy versus pyrotinib-based therapy in treating HER2+ BC patients with brain metastasis. Methods: This retrospective, observational study collected data from 79 HER2+ BC patients with brain metastasis who received pyrotinib-based therapy from May 2018 to December 2021. Among these patients, 35 received pyrotinib-based therapy concurrently with, or within 3 months before or after, brain radiotherapy (Group A), and 44 received pyrotinib-based therapy as the primary regimen (with no restriction as to whether they had received brain radiotherapy previously or not, the interval between receiving radiotherapy and receiving pyrotinib was >3 months) (Group B). Patient information was collected by the Electronic Medical Records System. The primary endpoints were progression-free survival (PFS) and overall survival (OS). The secondary endpoints were the objective response rate (ORR), the clinical benefit rate (CBR), and safety. The assessment of adverse effects was based on CTCAE5.0. Results: The intracranial ORRs were 48.6% in Group A and 20.5% (9/44) in Group B (P=0.015). The intracranial CBRs were 80.0% in Group A and 65.9% in Group B. The median intracranial PFS times (IC-PFS) were 15.0 months and 9.0 months in Group A and Group B, respectively (P=0.385). There was no statistically significant difference in OS between the 2 groups (95.0 vs. 98.0 months, P=0.872). The subgroup analysis showed that patients with active brain metastasis who received pyrotinib and radiotherapy had a longer IC-PFS time than those who received pyrotinib-based therapy(P=0.056). No serious adverse reactions (e.g., acute brain edema, cognitive dysfunction, or treatment-related death events) were observed. Conclusions: Pyrotinib combined with radiotherapy is recommended for HER2+ breast cancer active brain metastasis patients who can tolerate radiotherapy and pyrotinib. Pyrotinib-based therapy may be considered for patients who cannot tolerate radiotherapy and pyrotinib.