Inclusion Criteria:

• Diagnosis of multiple myeloma with documented relapsed or refractory disease according to International Myeloma Working Group (IMWG) criteria, or relapsed/refractory plasma cell leukemia
• Collection of a bone marrow, fluid or tissue sample that is expected to have enough cells to run the assay
• Measurable disease defined by one of the following:
  • Serum monoclonal protein >= 0.5 g/dL by serum protein electrophoresis (SPEP)
  • >= 200 mg/monoclonal protein in urine on 24 hr urine protein electrophoresis (UPEP)
  • Involved serum free light chain (FLC) >= 10 mg/dL and abnormal involved:uninvolved ratio
  • Plasma cytomas that are palpable per exam or measurable per standard radiologic review
  • Circulating plasma cells >= 2,000 if diagnosis of plasma cell leukemia
• Minimum of 3 prior lines of therapy including an immunomodulatory drug (IMiD) and a proteasome inhibitor (PI)
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-3
• Female patients of child bearing potential and non-vasectomized male patients agree to practice appropriate methods of birth control
• Ability to understand purpose and risks of the study and provide signed and dated informed consent, and authorization to use protected health information
• Expected survival is > 100 days
• Adequate organ function as determined by the investigator

Exclusion Criteria:

• Mucosal or internal bleeding, or platelet transfusion refractory
• Any medical conditions that would impose excessive risk to the patient, or would adversely affect his/her participation in the study
• Known active infection requiring antibiotics within 7 days of initiation of study treatment, unless considered controlled in the opinion of the investigator
• Other malignancy with life expectancy < 1 year due to the other malignancy
• Pregnant or breast feeding women
• Serious psychiatric illness, alcoholism, or drug addiction
• Human immunodeficiency virus (HIV), or active hepatitis B or C infection
• Previous treatments for multiple myeloma (MM) within 2 weeks of initiation of study treatment
• Prior autologous or allogeneic stem cell transplantation (SCT) within 12 weeks of initiation of study treatment
• Prior allogeneic hematopoietic cell transplantation (HCT) with active graft versus host disease (GVHD) on therapeutic dosing of immunosuppression or prednisone > 20 mg daily equivalent
• Prior major surgical procedure or radiation treatment within 2 weeks of initiation of study treatment (not including limited radiation used for palliation of bone pain)