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Lapatinib plus trastuzumab improved OS in HER-2–positive metastatic breast cancer
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In women with HER-2–positive metastatic breast cancer, combination treatment with lapatinib plus trastuzumab demonstrated better OS compared with lapatinib alone, according to findings from a phase-3 trial.
In previous findings from the EGF104900 trial, PFS was better with lapatinib (Tykerb, GlaxoSmithKline) plus trastuzumab (Herceptin, Genentech) vs. lapatinib alone and preliminary data showed a trend in OS favoring combination treatment.
Kimberly L. Blackwell, MD, associate in medicine in the division of hematology-oncology at Duke University Medical Center, in Durham, N.C., presented updated OS findings.
In the trial, researchers randomly assigned women with HER-2–positive metastatic breast cancer progressing on prior trastuzumab-containing regimens to 1,500 mg of lapatinib once daily (n=148) or 1,000 mg of lapatinib in combination with 2 mg/kg of trastuzumab after a 4 mg/kg loading dose (n=148).
Crossover to combination therapy was allowed if objective disease progression occurred on or after four weeks with lapatinib alone therapy. Fifty-two percent of patients crossed over to combination therapy.
Median OS was 60.7 weeks with combination treatment vs. 41.4 weeks with lapatinib alone. Combination therapy also showed improvement in OS compared with lapatinib alone (HR=0.74; 95% CI, 0.57-0.97).
This improvement remained even after adjusting for prognostic factors (HR=0.71; 95% CI, 0.54-0.93). Additionally, after crossover, there was a trend toward a 25% decrease in risk for death (P=.08).
“Lapatinib in combination with trastuzumab was very well-tolerated, and there was no increase in cardiac signal observed with the combination over lapatinib alone,” Blackwell said.
“The 4.5-month improvement in survival with a combination of lapatinib and trastuzumab seen in this study in this population is similar to that seen with other biologic agents combined with chemotherapy in a first-line population of patients with metastatic breast cancer without the significant side effects associated with traditional chemotherapy,” she said.
For more information:
- Blackwell KL. #61.