A single-stage Phase 2 study, with an early stopping rule for excessive toxicity: the goal is to enroll 45 patients at the 25-mg dose level of lenalidomide. However, if 7 in the first 18 or fewer patients receiving lenalidomide at 25 mg develop grade 4 non-hematologic toxicity at anytime during study, no further patients will be enrolled. With respect to the stopping rule, a grade 4 hematologic toxicity will be considered if the episode has lasted for greater than or equal to 5 days. Grade 4 lymphopenia of any duration will not be counted. If less than 7 of the first 18 patients experience the above level of toxicity, accrual will continue until 45 patients have been enrolled at the 25 mg dose level of lenalidomide.