This is a phase I study to estimate the maximum tolerated dose and the dose limiting toxicities of the intravenous formulation of irinotecan given orally in combination with a fixed dose of oral gefitinib. This trial will use the EWOC method, which is an adaptive dose escalation scheme. The method is fully adaptive and makes use of all the information available at the time of each dose assignment, and directly addresses the ethical need to control the probability of overdosing. It is designed to approach the maximum tolerated dose (MTD) as fast as possible.