Sun Y, Chen B, Li J, et al. - Chinese patients with HER2(human epidermal growth factor receptor 2)-positive metastatic breast cancer (mBC) were highly benefited with treatment using pyrotinib. This holds true even for those with previous lapatinib exposure. Pyrotinib affords a feasible substitute of lapatinib in combination with chemotherapeutic drugs or as a monotherapy. Tolerable and easily manageable adverse effects were reported.

• Pyrotinib is a novel irreversible pan-ErbB inhibitor recently approved in China.

• This study included 64 Chinese patients treated with pyrotinib for HER2-positive mBC; 11 (17.2%) had been exposed to lapatinib.

• Objective response rate (ORR) was 73.4%, disease control rate was 98.4%, clinical benefit rate was 87.5%.

• Good response to pyrotinib-based treatment but significantly lower ORR was noted in patients exposed to lapatinib vs those without such exposure (44.1% vs 77.5%).

• In cases with previous lapatinib exposure and those with visceral metastasis, median progression-free survival was 299 days and 359 days, respectively.

• Most common grade 3 adverse events included diarrhea (28.1%), hand-foot syndrome (17.2%), and neutropenia (9.4%).