Inclusion Criteria:

• Male or female patients ≥ 18 years of age.
• Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2.
• Diagnosis of relapsed, refractory multiple myeloma.
• Exposure to at least three different prior lines of therapy including exposure to at least two proteosome inhibitors (e.g. bortezomib), and at least two immunomodulatory drugs (e.g. lenalidomide) and at least one anti-CD38 monoclonal antibody agent (e.g. daratumumab) Documentation of a prior line of therapy must include at least one of the following three items: [1] medical records detailing prior treatment, best response to treatment, and date of progression; [2] myeloma markers (SPEP, UPEP, Immunoglobulin, FLC) at time of treatment and progression; or, [3] documentation by investigator/treating physician to be included in patient's medical and research record (for example, note in electronic medical record), indicating prior treatment, best response to treatment, and data of progression. To qualify as a prior line of therapy, ≥ 2 cycles of therapy must be administered unless the disease is refractory, or the regimen is not tolerated.
• Refractory status to ≥ one proteasome inhibitor AND ≥ one immunomodulatory drug. Refractory disease is defined as <25% reduction in M-protein/free light chain difference (involved vs. uninvolved) or disease progression during treatment or ≤ 60 days after treatment cessation. Patient may or may not be refractory to anti-CD38 therapy.
• Presence of secretory myeloma/measurable disease, as defined by:
  1. Serum M-protein (SPEP) ≥ 0.5 mg/dL or
  2. Urine M-protein (UPEP) ≥ 200 mg/24 hours
  3. Light chain MM: Serum free light chain (FLC) assay ≥ 10 mg/dL (100 mg/L) and abnormal serum immunoglobulin kappa/lambda FLC ratio.
• Must have a potential source of autologous T cells potentially sufficient to manufacture RAPA-201 cells, as defined by a circulating CD3+ T cell count ≥ 400 cells/µL.
• Patients must be ≥ two weeks from last myeloma therapy, major surgery, radiation therapy and participation in investigational trials.
• Patients must have recovered from clinical toxicities (resolution of CTCAE toxicity to a value of ≤ 2).
• Ejection fraction (EF) by MUGA or 2-D echocardiogram within institution normal limits, with an EF level of ≥ 40%.
• Serum creatinine ≤ to 2.5 mg/dL.
• Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) ≤ to 3 x upper limit of normal (ULN).
• Absolute neutrophil count (ANC) of ≥ 1000 cells/µL (independent of growth factor support for at least 7 days prior to screening).
• Platelet count of ≥ 50,000 cells/µL, with value obtained (independent of growth factor support or transfusion support for at least 7 days prior to screening).
• Hemoglobin count ≥ 8 grams/µL (independent of growth factor support or transfusion support for at least 7 days prior to screening).
• Bilirubin ≤ 1.5 (except if due to Gilbert's disease).
• Corrected DLCO ≥ 50% (Pulmonary Function Test).
• No history of abnormal bleeding tendency.
• Voluntary written consent must be given before performance of any study related procedure not part of standard medical care, with the understanding that consent may be withdrawn by the patient at any time without prejudice to future medical care.

Exclusion Criteria:

• Prior allogeneic stem cell transplantation.
• Current plasma cell leukemia (circulating myeloma > 20% of leukocytes).
• Other active malignancy (except for non-melanoma skin cancer).
• Non-secretory multiple myeloma (difficult to assess by IMWG criteria).
• Evidence of systemic AL Amyloidosis involving any vital organ. Incidental histologic demonstration of amyloid deposition in marrow/within plasmacytoma is not considered organ involvement.
• Life expectancy <4 months.
• Patients seropositive for HIV, hepatitis B, or hepatitis C.
• Uncontrolled hypertension.
• History of cerebrovascular accident within 6 months of enrollment.
• Myocardial infarction within 6 months prior to enrollment.
• NYHA class III/IV congestive heart failure.
• Uncontrolled angina/ischemic heart disease.
• Subjects with known central nervous system disease.
• Pregnant or breastfeeding patients.
• Patients of childbearing age, or males who have a partner of childbearing potential, who are unwilling to practice contraception.
• Patients may be excluded at PI discretion or if it is deemed that allowing participation would represent an unacceptable medical or psychiatric risk.
• Subjects should not receive any prior systemic therapy within 14 days of the protocol required apheresis procedure.