In patients with human epidermal growth factor receptor 2–positive advanced breast cancer, the combination of lapatinib plus taxane resulted in poorer progression-free survival and more toxicity than trastuzumab plus taxane, according to final clinical trial results reported online March 16 in the Journal of Clinical Oncology.

“Our results support the use of trastuzumab over lapatinib in the HER2 treatment-naive first-line metastatic setting,” wrote Dr. Karen A. Gelmon of the BC Cancer Agency, Vancouver, and her colleagues (J. Clin. Oncol. 2015 Mar. 16 doi:10.1200/JCO.2014.56.9590]).

For patients taking lapatinib plus taxane, the median progression-free survival was 9.0 months vs. 11.3 months for those taking trastuzumab plus taxane (hazard ratio, 1.37; 95% CI, 1.13-1.65; P = .001). Among patients with centrally confirmed HER2-positive disease, those receiving lapatinib had worse overall survival (HR, 1.47; 95% CI, 1.03-2.09; P = .03), the investigators reported.

From 2008 to 2011 the NCIC Clinical Trials Group MA.31 enrolled patients in 21 countries, and evaluated 537 patients with centrally confirmed HER2-postive disease; 61% had an Eastern Cooperative Oncology Group performance status of 0, 82% had no prior anti-HER2 therapy, 70% had no prior taxane therapy, 65% were estrogen-receptor positive, and 42% had metastatic disease at diagnosis. The median follow up was 21.5 months.

Treatment discontinuation because of toxicity was more frequent with lapatinib (15%) than trastuzumab (8%). Grade 3 or 4 rash occurred in 8% of patients in the lapatinib arm, compared with 0% in the trastuzumab group (P < .001). Grade 3 or 4 diarrhea occurred in 19% vs. 1% of the lapatinib and trastuzumab arms, respectively (P < .001).

The authors noted that these results “have implications for the treatment of patients with advanced HER2-positive breast cancer, where dual therapy or newer agents are not available but where the older agents or biosimilars may be available and affordable.”