Study of CC-93269, a BCMA x CD3 T Cell Engaging Antibody, in Subjects With Relapsed and Refractory Multiple Myeloma

The dose escalation part (Part A) of the study will evaluate the safety and tolerability of
escalating doses of CC-93269, administered intravenously (IV), to determine the maximum
tolerated dose (MTD) and non-tolerated dose (NTD) of both the first dose and subsequent doses
of CC-93269. The expansion part (Part B) will further evaluate the safety and efficacy of
CC-93269 administered at or below the MTD in selected expansion cohorts in order to determine
the recommended Phase 2 dose (RP2D). One or more dosing regimens may be selected for cohort
expansion. All treatments will be administered in 28-day cycles for up to 2 years until
confirmed disease progression, unacceptable toxicity, or subject/Investigator decision to
withdraw.

Inclusion Criteria:

Subjects must satisfy the following criteria to be enrolled in the study:

1. Subject must understand and voluntarily sign an informed consent form (ICF) prior to
any study-related assessments/procedures being conducted.

2. Subject (male or female) is ≥ 18 years of age the time of signing the ICF.

3. Subject has a history of Multiple Myeloma (MM) with relapsed and refractory disease,
and must have failed treatment with, are intolerant to or are not candidates for
available therapies that are known to confer clinical benefit to patients with
relapsed and refractory MM.

4. Subjects must have measurable disease (as determined by the central lab).

5. Subject consents to hospitalization for monitoring and collection of study peripheral
blood samples (Part A only).

6. Subject consents to serial bone marrow aspirations and/or biopsies during Screening,
study treatment and at the end of treatment.

7. Subject has an Eastern Cooperative Oncology Group (ECOG) PS of 0 or 1.

8. Subjects must have adequate hematologic, liver, renal, and coagulation function as
assessed by laboratory tests.

9. Females and males must practice true abstinence or agree to contraceptive methods
throughout the study, and during the safety follow-up period.

Exclusion Criteria:

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

1. Subject has received prior investigational therapy directed at B cell maturation
antigen (BCMA).

2. Subject has symptomatic central nervous system involvement of multiple myeloma.

3. Subject has non-secretory multiple myeloma, plasma cell leukemia, Waldenstrom's
macroglobulinemia, POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy,
monoclonal protein, and skin changes), or amyloidosis.

4. Subject is on chronic systemic immunosuppressive therapy or corticosteroids.

5. Subjects with clinically significant cardiac disease.

6. Subject had a prior autologous stem cell transplant ≤ 3 month prior to starting
CC-93269.

7. Subject had a prior allogeneic stem cell transplant ≤ 12 month prior to starting
CC-93269.

8. Subject had a prior systemic cancer-directed treatments or investigational modalities
≤ 5 half-lives or 4 weeks prior to starting CC-93269, whichever is shorter.

9. Subject had major surgery ≤ 2 weeks prior to starting CC-93269.

10. Subject is a pregnant or lactating female.

11. Subject has known human immunodeficiency virus (HIV) infection.

12. Subject has known history or serological evidence of prior hepatitis B or C virus
(HBV/HCV) infection.

13. Subject requires ongoing treatment with chronic, therapeutic dosing of anti-coagulants
(eg, warfarin, low molecular weight heparin, Factor Xa inhibitors)

14. Subject has a history of concurrent second cancers requiring active, ongoing systemic
treatment.

15. Subject has a history or presence of clinically relevant central nervous system (CNS)
pathology.