Study of bb21217 in Multiple Myeloma

Part A of the study will be Dose Escalation followed by Part B, an expansion cohort.

Following consent, enrolled subjects will undergo a leukapheresis procedure to collect
autologous mononuclear cells for manufacture of investigational drug product (bb21217).
Following manufacture of the drug product, subjects will receive lymphodepletion prior to
bb21217 infusion. All subjects will then be followed for up to 60 months in Study CRB-402.

All subjects who complete the study, as well as those who withdraw from the study after
receiving bb21217 for reasons other than death or meeting the early termination criteria,
will be asked to continue to undergo long-term follow-up in a companion study.

Inclusion Criteria:

- ≥18 years of age at the time of signing informed consent

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

- Diagnosis of MM with relapsed or refractory disease and have had at least 3 different
prior lines of therapy including proteasome inhibitor (e.g., bortezomib or
carfilzomib) and immunomodulatory therapy (IMiD; e.g., lenalidomide or pomalidomide),
or have double refractory disease to a proteasome inhibitor and IMiD, defined as
progression on or within 60 days of treatment with these agents.

- Subjects must have measurable disease

Exclusion Criteria:

- Subjects with known central nervous system disease

- Inadequate hepatic function

- Inadequate renal function

- Inadequate bone marrow function

- Presence of active infection within 72 hours

- Subjects with a history of stroke, unstable angina, myocardial infarction, or
ventricular arrhythmia requiring medication or mechanical control

- Significant co-morbid condition or disease which in the judgment of the Investigator
would place the subject at undue risk or interfere with the study; examples include,
but are not limited to, cirrhotic liver disease, sepsis, recent significant traumatic
injury, and other conditions

- Known human immunodeficiency virus (HIV) positivity

- Known hepatitis A virus (HAV), hepatitis B virus (HBV) or hepatitis C virus (HCV)
positivity with evidence of ongoing infection.

- Subjects with a history of stroke, unstable angina, myocardial infarction, or
ventricular arrhythmia requiring medication or mechanical control

- Pregnant or lactating women