Rituximab, Bendamustine Hydrochloride, and Lenalidomide in Treating Patients With Refractory or Relapsed Indolent Non-Hodgkin Lymphoma

RATIONALE: Monoclonal antibodies, such as rituximab, can block cancer growth in different ways. Some find cancer cells and help kill them or carry cancer-killing substances to them. Others interfere with the ability of cancer cells to grow and spread. Drugs used in chemotherapy, such as bendamustine hydrochloride, also work in different ways to kill cancer cells or stop them from dividing. Lenalidomide may stop the growth of non-Hodgkin lymphoma by blocking blood flow to the cancer. Giving lenalidomide together with rituximab and bendamustine hydrochloride may kill more cancer cells. PURPOSE: This phase I trial studies the side effects and the best dose of giving lenalidomide together with rituximab and bendamustine hydrochloride in treating patients with refractory or relapsed indolent non-Hodgkin lymphoma.