Patients will be treated until disease progression but for a maximum of 6 cycles. Patients having completed the treatment phase (24 weeks) and showing complete or partial response as well as stable disease will enter the observation phase of the study. This phase will end 12 months after the last patient has been included. At any time during treatment phase or observation phase, patients with signs of disease progression according to RECIST criteria for reporting results of cancer treatment or having discontinued treatment due to unacceptable toxicity will go off study and be treated at the investigator's discretion.