This study will employ low-dose Cyclophosphamide (administered as a single i.v. infusion at a dose of 300 mg/m2 3 days prior to the vaccination) in order to increase the immune response to IMA910 (5.78 mg i.d.). Patients will receive 7 vaccinations of IMA910 plus GM-CSF (75 μg i.d.) in the first 6 weeks of treatment (induction period) followed by 9 vaccinations at 3-week intervals for a further 27 weeks (maintenance period). The patients will receive a total of 16 vaccinations over a period of 33 weeks. An end of study visit (EOS, Visit 17) will be performed 4 weeks after the last treatment. Patients enrolled into the 2nd cohort of the study will receive the same treatment as described above and will additionally receive a topical application of 250 mg imiquimod cream (12.5 mg imiquimod) 10 minutes (up to 20 minutes) after each application of IMA910 (Visit 1-16) and from day 3 onwards 250 mg imiquimod cream (12.5 mg imiquimod) 24 hours (but up to 48 hours at the latest) after each application of IMA910 (Visit 3-16). The topical application of imiquimod additionally 24 hours (but up to 48 hours at the latest) after IMA910 application will be done by the patient at home. Imiquimod cream will be applied to a marked 5x5 cm area around the injection site of GM-CSF and IMA910.