The efficacy and safety of Lapatinib in combination with capecitabine in breast cancer patients with good performance status was evaluated in a randomised, phase III study. Patients eligible for enrolment had HER2-overexpressing, locally advanced or metastatic breast cancer, progressing after prior treatment that included taxanes, anthracyclines and trastuzumab. LVEF was evaluated in all patients (using echocardiogram [Echo] or multi gated acquisition scan [MUGA]) prior to initiation of treatment with Lapatinib to ensure baseline LVEF was within the institutions normal limits. In the clinical study LVEF was monitored at approximately eight week intervals during treatment with Lapatinib to ensure it did not decline to below the institutions lower limit of normal. The majority of LVEF decreases (greater than 60 % of events) were observed during the first nine weeks of treatment, however limited data was available for long term exposure.
Patients were randomised to receive either Lapatinib 1250 mg once daily (continuously) plus capecitabine (2000 mg/m2/day on days 1-14 every 21 days), or to receive capecitabine alone (2500 mg/m2/day on days 1-14 every 21 days). The primary endpoint was time to progression (TTP). Assessments were undertaken by the study investigators and by an independent review panel, blinded to treatment. The study was halted based on the results of a pre-specified interim analysis that showed an improvement in TTP for patients receiving Lapatinib plus capecitabine. An additional 75 patients were enrolled in the study between the time of the interim analysis and the end of the enrolment.
