Real-world data of lapatinib and treatment after lapatinib in patients with previously treated HER2-positive metastatic breast cancer: A multicenter, retrospective study.

Lapatinib is widely used in the later lines treatment of HER2 positive metastatic breast cancer (MBC). EGF104900 study suggested that among patients who experienced progression on prior trastuzumab-containing regimens, lapatinib plus trastuzumab had better effects than trastuzumab alone. However, no evidence was discovered in terms of lapatinib plus capetabine compared with lapatinib plus trastuzumab plus chemotherapy, as well as a treatment after progression on lapatinib. We evaluated the medical records retrospectively of all MBC patients with HER2 positive disease who progressed on prior trastuzumab-containing regimens (advanced setting) and a taxane (any setting) and received lapatinib-based treatment from 2015 to 2018 in five institutions in China. A total of 242 patients were available for analysis. Among them, 164 (68%) patients received lapatinib plus capetabine (LX) and 78 (32%) patients received lapatinib plus trastuzumab and one chemotherapy (HLC). The median progression-free survival (PFS) of the HLC group was significantly superior to the LX group (8.8 months vs 5.0 months, P < .0000001). No significant difference in grade 3 or worse adverse events was observed in two groups (P = .57). A total of 175 patients were available for the analysis of the postlapatinib treatment. Continuation of lapatinib showed superior mPFS results compared to the non-anti-HER2 treatment (4 months vs 2 months, P = .01) and similar results compared to switch to other anti-HER2 treatments (4 months vs 4 months, P = .88). In patients who had progressed on prior trastuzumab-base therapy, HLC provided a new dual-targeting treatment option for the later lines therapy of patients with HER2 positive MBC. Moreover, evidence of cross-line use of lapatinib was provided.