Lapatinib:

A specified dose of lapatinib will be orally taken once daily, at least one hour before or one hour after the morning meal. Lapatinib should be taken at the same time of day wherever possible.

The starting dose of lapatinib should be 750 mg/day, which will be increased to 1000 mg/day (dose escalation group) according to the dose escalation criteria.

Trastuzumab:

Trastuzumab (4 mg/kg/day in the first week and 2 mg/kg/day for the 2nd and subsequent weeks) will be administered by intravenous infusion over at least 90 minutes immediately after administration of lapatinib. The fifth (Day 36) and subsequent doses may be administered up to 3 days after the scheduled date. In this case, however, the all following doses should be administered at one-week intervals.

Tablets contain 405mg of lapatinib ditosylate monohydrate, equivalent to 250mg lapatinib free base per tablet. Oval, orange, film-coated tablets.

To confirm the safety and tolerability of the recommended dose of lapatinib in combination with trastuzumab which was determined in a preceding overseas study, and to determine the recommended dose in Japan.