Researchers from Mayo Clinic (FL, USA) have recently revealed results from the Phase III ALTTO study, which indicate that trastuzumab treatment in combination with standard chemotherapy has a better outcome than lapatinib for HER2-positive breast cancer. These result were recently presented at the 2014 European Society for Medical Oncology (ESMO) Congress (26–30 September, Madrid, Spain).
In total, 8381 women were enrolled in the study, which investigated the combination of both drugs, and the drugs alone, in combination with standard chemotherapy at 946 medical centers over 44 countries. When lapatinib was added to trastuzumab as part of the dual therapy, no statistically significant differences were seen in terms of disease-free or overall survival.
In June this year, the ALTTO study released results demonstrating that when trastuzumab was used as part of a dual therapy with labatinib, no additional benefit in terms of survival was seen and toxicity was increased in patients.
In this new analysis, patients were given either trastuzumab or lapatinib alone, and trastuzumab was also given as an adjuvant treatment to disease-free patients after being treated with lapatinib alone.
At a 4.5-year follow-up, 14% of patients who were taking trastuzumab alone had one disease event, which was defined as a recurrence of breast cancer anywhere in the body, a new cancer or death. In the lapatinib-only group this statistic was higher at 18% having a disease event. Cardiac safety was good in both and there were no disparities in the development of brain metastases.
Edith Perez (Mayo Clinic), who co-chaired the study, commented: “We were glad that we received early notice in August 2011 of the potential lower benefit of lapatinib versus trastuzumab, which led us to offer trastuzumab for the patients who had been assigned to lapatinib alone. This intervention speaks well to our flexibility in the conduct of clinical trials.”
“ALTTO was and is a very important global trial. All patients were carefully managed and we demonstrated better overall outcomes than anticipated,” she continued. “We demonstrated that lapatinib’s activity appeared to be lower than that of trastuzumab in the adjuvant setting, that there was a trend for additional benefit if those patients were switched to trastuzumab, that cardiac safety was better than predicted, and that the number of brain metastases appeared similar for the patients who received either lapatinib or trastuzumab.”
The patients are continuing to be followed up and further research is being carried out for the identification of biomarkers to indicate treatment efficacy.