This is an open label, single-arm, multicenter, Phase 2 study to evaluate the efficacy and safety of bb2121 in subjects with relapsed and refractory multiple myeloma. A leukapheresis procedure will be performed to manufacture bb2121 chimeric antigen receptor (CAR) modified T cells. Prior to bb2121 infusion subjects will receive lymphodepleting therapy with fludarabine and cyclophosphamide.

Anti-myeloma bridging treatment is allowed for disease control while bb2121 is being
manufactured.

Three sites in Japan will be activated in 2019 and will be open for enrollment to patients in
Japan.

Inclusion Criteria:

Eligibility is determined prior to leukapheresis. Subjects must satisfy the following criteria to be enrolled in the study:

1. Subject is ≥ 18 years of age at the time of signing the informed consent form (ICF).

2. Documented diagnosis of multiple myeloma

- Must have received at least 3 prior MM treatment regimens. Note: induction with or without hematopoietic stem cell transplant and with or without maintenance therapy is considered a single regimen.

- Must have undergone at least 2 consecutive cycles of treatment for each regimen, unless PD was the best response to the regimen.

- Must have received a proteasome inhibitor, an immunomodulatory agent and an anti-CD38 antibody.

- Must be refractory to the last treatment regimen.

3. Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1.

4. Subjects must have measurable disease, including at least one of the criteria below:

- Serum M-protein greater or equal to 1.0 g/dL

- Urine M-protein greater or equal to 200 mg/24 h

- Serum free light chain (FLC) assay: involved FLC level greater or equal to 10 mg/dL (100 mg/L) provided serum FLC ratio is abnormal

Exclusion Criteria:

The presence of any of the following will exclude a subject from enrollment:

1. Subjects with known central nervous system involvement with myeloma.

2. History or presence of clinically relevant central nervous system (CNS) pathology.

3. Subjects with active or history of plasma cell leukemia.

4. Subjects with solitary plasmacytomas or non-secretory myeloma without other evidence of measurable disease

5. Inadequate organ function

6. Ongoing treatment with chronic immunosuppressants

7. Previous history of an allogeneic hematopoietic stem cell transplantation or treatment with any gene therapy-based therapeutic for cancer or investigational cellular therapy for cancer or BCMA targeted therapy

8. Evidence of human immunodeficiency virus (HIV) infection.

9. Seropositive for and with evidence of active viral infection with hepatitis B virus (HBV)

10. Seropositive for and with evidence of active viral infection with hepatitis B virus (HBV) and Hepatitis C virus (HCV)

11. Subjects with a history of class III or IV congestive heart failure (CHF) or severe non-ischemic cardiomyopathy, history of stroke, unstable angina, myocardial infarction, or ventricular arrhythmia within the previous 6 months.

12. Subjects with second malignancies in addition to myeloma if the second malignancy has required therapy in the last 3 years or is not in complete remission

13. Pregnant or lactating women.

14. Subject with known hypersensitivity to any component of bb2121 productThe presence of any of the following will exclude a subject from enrollment:

1. Subjects with known central nervous system involvement with myeloma. 2. History or presence of clinically relevant central nervous system (CNS) pathology.

3. Subjects with active or history of plasma cell leukemia. 4. Subjects with solitary plasmacytomas or non-secretory myeloma without other evidence of measurable disease 5. Inadequate organ function 6. Ongoing treatment with chronic immunosuppressants 7. Previous history of an allogeneic hematopoietic stem cell transplantation or treatment with any gene therapy-based therapeutic for cancer or investigational cellular therapy for cancer or BCMA targeted therapy 8. Evidence of human immunodeficiency virus (HIV) infection. 9. Seropositive for and with evidence of active viral infection with hepatitis B virus (HBV) and Hepatitis C virus (HCV) 10. Subjects with a history of class III or IV congestive heart failure (CHF) or severe non-ischemic cardiomyopathy, history of stroke, unstable angina, myocardial infarction, or ventricular arrhythmia within the previous 6 months. 11. Subjects with second malignancies in addition to myeloma if the second malignancy has required therapy in the last 3 years or is not in complete remission 12. Pregnant or lactating women. 13 Subject with known hypersensitivity to any component of bb2121 product, cyclophosphamide, fludarabine, or tocilizumab.

Raje N, Berdeja J, Lin Y, Siegel D, Jagannath S, Madduri D, Liedtke M, Rosenblatt J, Maus MV, Turka A, Lam LP, Morgan RA, Friedman K, Massaro M, Wang J, Russotti G, Yang Z, Campbell T, Hege K, Petrocca F, Quigley MT, Munshi N, Kochenderfer JN. Anti-BCMA CAR T-Cell Therapy bb2121 in Relapsed or Refractory Multiple Myeloma. N Engl J Med. 2019 May 2;380(18):1726-1737. doi: 10.1056/NEJMoa1817226.