Effectiveness and safety of pyrotinib‐based therapy in patients with HER2‐positive metastatic breast cancer: A real‐world retrospective study

The previous studies had demonstrated the promising effectiveness and acceptable safety of pyrotinib in patients with HER2‐positive metastatic breast cancer. We aimed to investigate the real‐world data of pyrotinib in complex clinical practice and complement the findings of clinical trials. Two hundred and eighteen patients were included for effectiveness analysis. A total of 62.0% had received two or more lines of systematic therapy, and 95.4% had been exposed to prior anti‐HER2 therapy, with 95.4% receiving trastuzumab, 5.0% receiving pertuzumab, and 40.8% receiving lapatinib. The median progression‐free survival (PFS) was 9.3 months and the objective response rate (ORR) was 44.0%. Patients treated with pyrotinib‐based therapy as first, second, or later line had a median PFS of 15.0, 10.3, and 6.8 months, respectively. Patients treated with pyrotinib and trastuzumab received significant benefit in terms of median PFS compared with pyrotinib alone (10.7 (9.1–12.3) vs. 8.8 (8.1–9.5), p = 0.016). Patients pretreated with lapatinib had a median PFS of 6.9 months. The median PFS time was 7.0 months in patients with brain metastasis. Multivariate Cox regression analyses showed that lines of pyrotinib‐based therapy (1 vs. 2 vs. ≥3), prior treatment with lapatinib, and combination treatments with trastuzumab proved to be independent predictors of PFS. Two hundred and forty‐eight patients were included in the safety analysis, and the results showed that the toxicity of pyrotinib was tolerable, with the most common grade 3/4 adverse event being diarrhea (19.8%). Pyrotinib‐based therapy demonstrated promising efficacy and tolerable toxicity in first‐, second‐, and later‐line treatments and in lapatinib‐treated patients. The combination of pyrotinib and trastuzumab showed advantages in PFS, even for patients resisting trastuzumab. Pyrotinib‐based therapy could be the preferred choice for brain metastasis patients, especially when combined with brain radiotherapy.