This is an open-label, multicenter, dose-escalating study to determine the MTD and dose limiting toxicities (DLTs) of CEP 18770, a novel proteasome inhibitor. The study will also characterize the pharmacokinetics and the pharmacokinetic/pharmacodynamic relationship of CEP 18770, and assess the safety and tolerability of CEP-18770 treatment as well as any effect on tumour response whenever possible.