Lenalidomide and Rituximab in Treating Patients With Recurrent and/or Refractory Multiple Myeloma

RATIONALE: Lenalidomide may stop the growth of multiple myeloma by blocking blood flow to the cancer. Monoclonal antibodies, such as rituximab, can block cancer growth in different ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and help kill them or carry cancer-killing substances to them. Giving lenalidomide together with rituximab may be an effective treatment for multiple myeloma. PURPOSE: This phase II trial is studying the side effects of giving lenalidomide together with rituximab and to see how well it works in treating patients with recurrent or refractory multiple myeloma.