Adverse events

Participants received either PVd or DPd as standard therapy. In pomalidomide, bortezomib and dexamethasone (PVd) treatment, participants received pomalidomide 4 milligrams (mg) orally (PO) on Days 1 to 14 in each treatment cycle; bortezomib 1.3 mg/meter square (m\^2) subcutaneous (SC) injection on Days 1, 4, 8 and 11 (Cycles 1 to 8) and on Days 1 and 8 (Cycle 9 onwards); and dexamethasone 20 mg (or 10 mg for participants aged greater than \[\>\] 75 years) PO on Days 1, 2, 4, 5, 8, 9, 11 and 12 (Cycles 1 to 8) and Days 1, 2, 8 and 9 (Cycle 9 onwards). Each treatment cycle of 21 days. In daratumumab, pomalidomide and dexamethasone (DPd) treatment, participants received daratumumab 1800 mg SC injection weekly on Days 1, 8, 15 and 22 (Cycle 1 and 2), every 2 weeks on Days 1 and 15 (Cycle 3 to 6) and every 4 weeks on Day 1 (Cycle 7 onwards); pomalidomide 4 mg PO on Days 1 to 21 (Cycle 1 onwards); dexamethasone 40 mg (or 20 mg for participants aged \>75 years) PO or intravenous(IV) weekly during Cycle 1-2 on Days 1, 8, 15, and 22 or split with 20 mg on Days 1, 2, 8, 9, 15, 16, 22, and 23. Each treatment cycle of 28 days. Participants continued to receive PVd or DPd until confirmed progressive disease (PD), death, intolerable toxicity, withdrawal of consent, or end of study, whichever occurred earlier.

Participants received at least one cycle of bridging therapy, that is PVd: pomalidomide 4 mg PO on Days 1 to 14, bortezomib 1.3 mg/m\^2 SC injection on Days 1, 4, 8, and 11, and dexamethasone 20 mg (or 10 mg for participants aged \>75 years) PO on Days 1, 2, 4, 5, 8, 9, 11, and 12; each treatment cycle of 21 days. DPd: daratumumab SC 1800 mg (co-formulated with rHuPH20) weekly on Days 1, 8, 15, and 22, pomalidomide 4 mg PO on Days 1 to 21, and dexamethasone PO or IV 40 mg (or 20 mg for participants aged \>75 years) weekly during Cycle 1-2 on Days 1, 8, 15, and 22 or split with 20 mg on Days 1, 2, 8, 9, 15, 16, 22, and 23. Each treatment cycle of 28 days. Additional cycles of bridging therapy was considered based on participant's clinical status and timing of availability of JNJ-68284528 (cilta-cel). Followed by bridging therapy, participants received conditioning regimen: cyclophosphamide 300 mg/m\^2 IV and fludarabine 30 mg/m\^2 IV daily, for 3 days on chimeric antigen receptor T cells (CAR-T) Day -5, -4, -3 (prior to JNJ-68284528 infusion), followed by JNJ-68284528 (cilta-cel) infusion 0.75\*10\^6 chimeric antigen receptor (CAR)-positive viable T cells per kilogram (kg) 5 to 7 days after the start of conditioning regimen.