Rationale: Giving colony-stimulating factors, such as G-CSF and plerixafor helps stem cells move from the patient's bone marrow to the blood so they can be collected and stored. Purpose: This phase II trial is studying how well plerixafor works in patients with multiple myeloma previously treated with lenalidomide and planning to undergo autologous stem cell transplant.

Primary Objective: I. To determine the proportion of patients reaching a stem cell yield of 3 million CD34 cells/kg by second day of apheresis with intravenously administered AMD3100 among patients receiving primary therapy for myeloma with lenalidomide. Secondary Objectives: I. Safety and tolerability of intravenously administered AMD3100. II. Rate of failure to mobilize. Outline: Patients receive plerixafor IV on days 5-8 and filgrastim subcutaneously on days 1-8 in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed at 30 days.

Inclusion - Absolute neutrophil count >= 1000/uL - Platelet >= 75000/uL - Hemoglobin >= 8.0 g/dL - Serum aspartate aminotransferase (AST)/serum glutamic oxaloacetic transaminase (SGOT), serum alanine aminotransferase (ALT)/serum glutamic pyruvic transaminase (SGPT) and total bilirubin < 2 x upper limit of normal (ULN) - Confirmed diagnosis of multiple myeloma, requiring therapy - Initial treatment for symptomatic myeloma using a lenalidomide based treatment regimen, started =< 12 months prior to registration - Received at least 2 cycles of treatment with the lenalidomide regimen - Last dose of lenalidomide > 2 weeks prior to registration - Eligible to undergo autologous transplantation - ECOG performance status (PS) 0 or 1 - Willingness to return for follow-up - Provide informed written consent - Adequate cardiopulmonary function: ejection fraction >= 45%, corrected pulmonary diffusion capacity of >= 50%, FEV1 >= 50%, FVC >= 50% - Negative serum or urine pregnancy test done =< 7 days prior to registration, for women of childbearing potential only Exclusion - A co-morbid condition which, in the view of the Investigators, renders the patient at high risk from treatment complications - Active malignancy with the exception of non melanoma skin cancer or in situ cervical or breast cancer - Other co-morbidity which would interfere with patient's ability to participate in the trial, e.g. uncontrolled infection, uncompensated heart or lung disease - Other concurrent chemotherapy, radiotherapy, or any ancillary therapy considered investigational - Use of cyclophosphamide as part of stem cell mobilization - Use of more than one regimen for treatment of symptomatic myeloma - Dialysis dependent renal failure - Pregnant women or women of reproductive ability who are unwilling to use effective contraception - Nursing women - Men who are unwilling to use a condom (even if they have undergone a prior vasectomy) while having intercourse with any woman, while taking the drug and for 4 weeks after stopping treatment - Acute infection, active HIV infection