This was a real-world study that included cases of metastatic
breast cancer (MBC) with
trastuzumab and
lapatinib failure. One group of patients received
pyrotinib monotherapy or combination
therapy, whereas the other group received T-DM1 monotherapy. The primary study endpoint was progression-free survival (PFS); secondary endpoints were the objective response rate (ORR), clinical benefit rate (CBR) and safety.
RESULTS: Between January 2013 and November 2019, 105 patients were enrolled in the
pyrotinib group (n=55) or T-DM1 group (n=50). The median PFS was 6.0 months (95% CI, 4.7 to 7.3 months) with
pyrotinib and 4.2 months (95% CI, 3.6 to 4.8 months) with T-DM1 (P=0.044). ORR values were 16.3% and 20.0% in the
pyrotinib and T-DM1 groups, respectively (P=0.629); CBR values were 45.5% and 40.0% in the
pyrotinib and T-DM1 groups, respectively (P=0.573). Subgroup analysis of those benefitting from
lapatinib revealed a median PFS of 8.1 months (95% CI, 4.8 to 11.4 months) in the
pyrotinib group, whereas that of the T-DM1 group was 4.4 months (95% CI, 3.8 to 5.0 months, P=0.013). Moreover, the median PFS of patients without liver
metastases was 6.9 months (95% CI, 3.7 to 10.1 months) in the
pyrotinib group and 4.1 months (95% CI, 3.1 to 5.1 months) in the T-DM1 group (P=0.010). The main common adverse events (AEs) were
diarrhea (98.2%) and
nausea (49.1%) in the
pyrotinib group and
thrombocytopenia (42.0%) and
nausea (40.0%) in the T-DM1 group. The percentages of grade 3 to 4 AEs in the
pyrotinib and T-DM1 groups were 34.5% and 40.0%, respectively.
CONCLUSIONS: The results of this study suggest that patients with HER2-positive MBC with
trastuzumab and
lapatinib failure can benefit from subsequent
pyrotinib treatment and tolerate this treatment well, especially those who have benefited from previous
lapatinib treatment or those who have no liver
metastasis.