Sample size will depend on the number of patients recruited during dose escalation. Three patients must be recruited in each dose level. If one out of three experiences a dose-limiting toxicity (DLT), 3 more patients must be recruited in the same dose level. Considering that there are 4 dose levels to be tested, the estimated number of patients is 9 to 24. Patients receiving the recommended dose (RD) will be incorporated into phase II of the study.