Elotuzumab Plus Lenalidomide (Elo/Rev) for Serologic Relapse/Progression While on Lenalidomide

Inclusion Criteria: * Patients with multiple myeloma who demonstrate evidence of serologic relapse/progression while on lenalidomide maintenance given as part of first line therapy (including upfront high-dose chemotherapy followed by autologous hematopoietic cell transplantation (HCT)) without symptomatic relapse/progression. Lenalidomide maintenance is defined as single agent lenalidomide therapy of any doses up to 10 mg PO daily for up to 28 days (28-day cycle). * Male or female patients aged ≥ 18 years old * Ability to provide written informed consent obtained prior to participation in the study and any related procedures being performed * Measurable disease as outlined in protocol guidelines * Participants must meet laboratory criteria as outlined in protocol guidelines Exclusion Criteria: * Prior Elotuzumab * Patients with clinical relapse/progression as per the International Myeloma Working Group (IMWG) Uniform Response Criteria for Multiple Myeloma defined as one or more of the following criteria: * Development of new soft tissue plasmacytomas or bone lesions (osteoporotic fractures do not constitute progression) * Definite increase in the size of existing plasmacytomas or bone lesions. A definite increase is defined as a 50% (and ≥1 cm) increase as measured serially of the measurable lesion * Hypercalcemia (\>11 mg/dL); * Decrease in hemoglobin of ≥2 g/dL not related to therapy or other non-myeloma-related conditions; * Rise in serum creatinine by 2 mg/dL or more from the start of the therapy and attributable to myeloma * Hyperviscosity related to serum paraprotein * Women who are pregnant or breast feeding or women of childbearing potential (WOCBP) not using an effective method of birth control. Women of childbearing potential must have a negative serum pregnancy testing within 7 days prior to the administration of drug. * Male patients whose sexual partners are WOCBP not using effective birth control * Patients with a prior malignancy with in the last 5 years (except for basal or squamous cell carcinoma, or in situ cancer of the cervix) * Patients with known positivity for human immunodeficiency virus (HIV)) or hepatitis C; baseline testing for HIV and hepatitis C is not required * Patients with a diagnosis of POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes) or plasma cell leukemia (\> 2.0 × 10\^9/L circulating plasma cells by standard differential)