A Study of Combination Therapy With Venetoclax, Daratumumab and Dexamethasone (With and Without Bortezomib) in Subjects With Relapsed or Refractory Multiple Myeloma

Inclusion Criteria:

- Eastern Cooperative Oncology Group (ECOG) performance status <= 2.

- Participant has relapsed or refractory multiple myeloma with documented evidence of
progression that occurred during or after the participant's last treatment regimen
based on investigator's determination of International Myeloma Working Group (IMWG)
criteria.

- Measurable disease confirmed by central lab at Screening, defined by at least 1 of the
following:

1. Serum M-protein >= 1.0 g/dL (>= 10 g/L), OR

2. Urine M-protein >= 200 mg/24 hours, OR

3. Serum free light chain (FLC) >= 10 mg/dL, provided serum FLC ratio is abnormal in
participants who do not have measurable disease by Serum Protein Electrophoresis
(SPEP) or Urine Protein Electrophoresis (UPEP) criteria.

- Participant has received previous multiple myeloma treatment as defined in the
protocol for Part 1 and Part 2 of this study.

- Bone marrow aspirate samples have been collected.

- To qualify for Part 1, the participant must be t(11;14) positive as determined by an
analytically validated Fluorescent In Situ Hybridization (FISH) assay per central
laboratory testing.

- Participants must have adequate hematologic, renal and hepatic function.

Exclusion Criteria:

- Previous treatment with venetoclax or other B-Cell Lymphoma 2 (BCL-2) inhibitor OR
previous treatment with daratumumab or other anti-CD38 therapy.

- For participants in Part 2:

1. Participant is refractory to any proteasome inhibitor, defined as progression on
or within 60 days of the last dose of a proteasome inhibitor-containing regimen.

2. Participant has had prior treatment with proteasome inhibitor within 60 days
prior to first dose of study drug.

- Treatment with anti-myeloma chemotherapy, radiotherapy, biological, immunotherapy or
an investigational therapy, including targeted small molecule agents within 2 weeks or
5 half-lives (whichever is longer and/or applicable) before first dose.

- Treatment with anti-myeloma monoclonal antibodies within 6 weeks prior first dose.

- Recent corticosteroid therapy at a cumulative dose equivalent to >= 140 mg of
prednisone or a single dose equivalent to >= 40 mg of dexamethasone within 2 weeks
prior the first dose of study drug.

- Known meningeal involvement of multiple myeloma.

- Significant history of medical conditions as listed in the protocol.