Safety Study of Lenalidomide Maintenance Therapy Post Allogeneic HCT for High-risk Multiple Myeloma

Inclusion Criteria: * One prior allograft from an 8/8 or 7/8 allele matched related or unrelated donor, received 60 to 90 days prior to initiation of lenalidomide * Meet the diagnostic criteria of symptomatic myeloma at anytime prior to allogeneic HCT * Have high-risk multiple myeloma * Received ≤ three (3) prior lines of therapy. Prior therapies may include: combination chemotherapy, monotherapy, lenalidomide and autologous HCT. Localized radiation therapy does not count as a single line of therapy. Previous progression on lenalidomide does not exclude participation in the study. * Received a reduced intensity conditioning regimen * Received or are receiving a GVHD prophylaxis regimen of a calcineurin inhibitor in combination with either methotrexate, mycophenolate mofetil (MMF) or sirolimus * Karnofsky performance score ≥ 80 or ECOG ≤ 2 * There must be at least 50% donor chimerism and no evidence of falling donor chimerism within 1 month of enrollment * Laboratory test results within range, within 14 days prior to initiation of lenalidomide * All study participants must be registered into the mandatory RevAssist® program, and be willing and able to comply with the requirements of RevAssist®. Exclusion Criteria: * Disease progression at time of study entry * Patients with any grade III-IV GVHD at the time of study entry * Patients requiring additional immunosuppressive therapy to control acute GVHD other than corticosteroids and immunosuppressive agents used for prophylaxis. * Concomitant use of other investigational agents * Patients who have received donor lymphocyte infusions * Active CNS malignancy * Uncontrolled bacterial, viral, or fungal infections * Prior malignancies except resected basal cell carcinoma or treated cervical carcinoma in situ \< 5 years from study entry. * Known hypersensitivity or desquamating rash to either thalidomide or lenalidomide. * Known positive for HIV or active infectious hepatitis. * Women who are pregnant or breastfeeding. * New York Heart Association (NYHA) Class III or IV heart failure, uncontrolled angina, severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence of acute ischemia or active conduction system abnormalities.