Addition of lapatinib to trastuzumab improves responses in women with newly diagnosed, HER2-positive breast cancer who receive the combination prior to undergoing surgery, suggests research.
The findings of the EPHOS-B trial were presented at the 10th European Breast Cancer Conference (EBCC-10) in Amsterdam, the Netherlands, by Judith Bliss, from The Institute of Cancer Research in London, UK.
Participants were randomly assigned to receive trastuzumab either with lapatinib 1000 mg/day (n=66) or alone (n=32) or no treatment (n=29) in the 10 to 12 days prior to undergoing surgery.
Among women with available pre- and post-surgery biopsy samples, the primary endpoint of a minimum 30% decrease in levels of the proliferation marker Ki67 was met by significantly more patients in the combination arm than in the trastuzumab alone or no treatment arms, at 75.6% versus 43.3% and 7.1%, respectively.
A central review of pathology reports showed that 10.6% of patients in the combination group had a pathological complete response compared with none of the patients in the trastuzumab alone or control groups.
And a higher proportion of women given lapatinib plus trastuzumab had minimal residual disease, defined as residual tumour less than 5 mm, than did those who received trastuzumab alone, at 16.7% versus 3.1%, while no control patient achieved this outcome.
"The early reduction or absence of invasive disease in approximately quarter of patients after only 11 days' preoperative combination HER2 therapy identifies cancers addicted to the HER2 pathway", say the researchers. "Using preoperative anti-HER2 therapy offers potential to personalise therapy for these patients."
Speaking to the press, Judith Bliss commented: "Clearly these results need further confirmation, but I suspect the excitement from seeing the speed of disappearance of the tumours will mean that several trials will attempt to confirm these results."
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