Given the activity of carfilzomib seen in selected solid tumors, and unpublished data to suggest weekly dosing may result in a similar pharmacokinetic profile including AUC, the investigators propose to study the safety, tolerability, pharmacokinetics, and anti-tumor activity of carfilzomib monotherapy given on a weekly dosing schedule. Weekly dosing has the advantage of patient convenience, and if acceptable toxicity and pharmacokinetics, it allows for easier integration of this schedule into subsequent combination therapy clinical trials.