An AE is any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE is defined as any untoward medical occurrence that, at any dose, meets 1 or more of the criteria listed below: Results in death, requires inpatient hospitalization or prolongation of existing hospitalization, life-threatening, congenital anomaly/birth defect etc. A treatment-related AE was any untoward medical occurrence attributed to the study drug in a participant who received study drug. Relatedness to study drug was assessed by the investigator.

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. A treatment-related AE was any untoward medical occurrence attributed to the study drug in a participant who received study drug. Relatedness to study drug was assessed by the investigator. AEs were graded according to NCI CTCAE version 5.0 as Grade 1 indicates Mild AE, Grade 2 indicates Moderate AE, Grade 3 indicates severe AE, and grade 4 indicates life-threatening consequences; urgent intervention indicated. Grade 5 indicates death related to AE.

CRS and ICANS were assessed according to ASTCT criteria. ASTCT for ICANS: Grade 1 [immune effector cell-associated encephalopathy (ICE, overall score range 0-10, higher score = better condition) score 7-9, awakens spontaneously]; Grade 2 [ICE score 3-6, awakens to voice]; Grade 3 [ICE score 0-2, awakens only to tactile stimulus, any clinical seizure that resolves rapidly or non-convulsive seizures on EEG that resolve with intervention, focal/local oedema on neuroimaging]; Grade 4 [ICE 0 (unarousable and unable to perform ICE), Unarousable or requires vigorous or repetitive tactile stimuli to arouse. Stupor or coma, Life-threatening prolonged seizure (>5 min); or repetitive clinical or electrical seizures without return to baseline in between, deep focal motor weakness such as hemiparesis or paraparesis, Diffuse cerebral oedema on neuroimaging; decerebrate or decorticate posturing; or cranial nerve VI (abducens nerve) palsy; or papilledema; or Cushing's triad].

Hematology results were graded according to the NCI CTCAE version 5.0 for relevant parameters, Grade 1 indicates Mild AE, Grade 2 indicates Moderate AE, Grade 3 indicates severe AE, and grade 4 indicates life-threatening consequences; urgent intervention indicated, Grade 5 indicates death related to AE. Hematological measures included Hemoglobin, Platelet count, WBC count, Plasma cell count. Absolute: Neutrophils, Eosinophils, Monocytes, Basophils, Lymphocytes, Plasma cells etc.

Clinical chemistry data included BUN (Blood urea nitrogen), Creatinine, Glucose (non-fasting), Total Calcium, Sodium, Potassium, Chloride, Magnesium, Phosphorus or Phosphates, Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Total bilirubin, Alkaline phosphatase, Albumin, Chloride, Total CO2 (bicarbonate), Total protein, Lactate dehydrogenase (LDH), Uric acid, Serum beta-2 microglobulin.

Alanine aminotransferase, aspartate aminotransferase, Alkaline Phosphatase, and total bilirubin (TBILI) were used to assess possible drug induced liver toxicity.

ORR: % of participants with objective response. stringent complete response (sCR):CR; ii) normal serum free light chain (FLC) ratio; absence of clonal cells in bone marrow biopsy (BMB)/ bone marrow aspirate (BMA) by immunohistochemistry or immunofluorescence. CR: negative immunofixation on serum and urine, disappearance of any soft tissue plasmacytomas and <5% plasma cells in BMA. If the only measurable disease is by serum FLC levels, CR was normal serum FLC ratio of 0.26-1.65. VGPR:Serum and urine M-protein detectable by immunofixation but not on electrophoresis;>=90% reduction in serum M-protein plus urine M-protein level <100 mg/24 h; if only measurable disease is by serum FLC levels, VGPR:>=90% decrease in difference between involved and uninvolved serum FLC levels; in addition if present at baseline, >90% reduction compared to baseline in size of soft tissue plasmacytomas. PR:≥50% reduction of serum M-protein and reduction in 24 hours urinary M-protein by ≥90% or to <200 mg/24 h.

CRR was defined as the percentage of participants with a BOR of confirmed sCR/CR per IMWG response criteria as determined by investigator. sCR: i) CR; ii) normal serum FLC ratio and absence of clonal cells in BMB/BMA by immunohistochemistry or immunofluorescence (κ/λ ratio <=4:1 or >=1:2 for κ and λ participants, respectively, after counting >=100 plasma cells; iii) if the only measurable disease was by serum FLC levels, sCR was defined as normal serum FLC ratio of 0.26 to 1.65 plus absence of clonal cells in BMB/BMA b by immunohistochemistry or immunofluorescence (κ/λ ratio <=4:1 or >=1:2 for κ and λ participants, respectively, after counting >=100 plasma cells). CR: i) negative immunofixation on serum and urine, disappearance of any soft tissue plasmacytomas and <5% plasma cells in BMA; ii) if the only measurable disease was by serum FLC levels, CR was defined as normal serum FLC ratio of 0.26 to 1.65 plus criteria (i).

Time to response was defined for participants with an objective response per IMWG criteria, as the time from the date of first dose to the first documentation of objective response that was subsequently confirmed.

DOR: time from the first documentation of objective response, until confirmed PD, or death due to any cause, whichever occurred first. PD: Increase of >=25% from lowest confirmed response value in any 1 or more of following: serum M-component (absolute increase must be >=0.5 g/dL); serum M-protein increase >=1 g/dL, if lowest M component was >=5 g/dL; urine M-protein (absolute increase must be >=200 mg/24 h). In participants without measurable serum and urine M-protein levels, difference between involved and uninvolved serum FLC levels (absolute increase must be >10 mg/dL). In participants without measurable serum, urine M-protein levels and involved serum FLC levels, BM plasma-cell % irrespective of baseline status (must be >=10%). Appearance of a new lesion, >=50% increase from nadir in SPD of >1 lesion, or >=50% increase in longest diameter of a previous lesion >1 cm in short axis. >=50% increase in circulating plasma cells (minimum of 200 cells per mcL) if only measure of disease.

DOCR was defined as the time from the first documentation of sCR or CR that was subsequently confirmed, until confirmed PD per IMWG criteria, or death due to any cause, whichever occurred first. sCR: i) CR; ii) normal serum FLC ratio and absence of clonal cells in BMB/BMA by immunohistochemistry or immunofluorescence (κ/λ ratio <=4:1 or >=1:2 for κ and λ participants, respectively, after counting >=100 plasma cells; iii) if the only measurable disease was by serum FLC levels, sCR was defined as normal serum FLC ratio of 0.26 to 1.65 plus absence of clonal cells in BMB/BMA b by immunohistochemistry or immunofluorescence (κ/λ ratio <=4:1 or >=1:2 for κ and λ participants, respectively, after counting >=100 plasma cells). CR: i) negative immunofixation on serum and urine, disappearance of any soft tissue plasmacytomas and <5% plasma cells in BMA; ii) if the only measurable disease was by serum FLC levels, CR was defined as normal serum FLC ratio of 0.26 to 1.65 plus criteria (i).

PFS was defined as the time from the date of first dose until confirmed PD per IMWG criteria, or death due to any cause, whichever occurred first. Analysis was performed using Kaplan-Meier method. Participants with no PD event or death or who started a new anticancer therapy prior to an event or with an event after a gap of 2 or more missing disease assessments were censored on the date of last adequate disease assessment. Participants who did not have an adequate post-baseline disease assessment were censored on the date of first dose of study intervention unless death occurred on or before the time of the second planned disease assessment (<=8 weeks after the date of first dose) in which case the death was considered an event.

OS was defined as the time from the date of first dose until death due to any cause. If a participant was not known to have died, survival was censored at the date of last contact. Analysis was performed using Kaplan-Meier method.

MRD negativity rate was defined as the percentage of participants with negative MRD (assessed by central laboratory) per IMWG sequencing criteria at any time from the date of first dose until the first documentation of confirmed PD, death or start of new anticancer therapy, whichever occurred first. Sequencing MRD negative included: 1) CR: negative immunofixation on serum and urine, disappearance of any soft tissue plasmacytomas and <5% plasma cells in BMA. If the only measurable disease is by serum FLC levels, CR was defined as normal serum FLC ratio of 0.26 to 1.65; 2) Absence of clonal plasma cells by next generation sequencing (NGS) on BMA in which presence of a clone was defined as <2 identical sequencing reads obtained after DNA sequencing of BMA using the LymphoSIGHT platform (or validated equivalent method) with a minimum sensitivity of 1 in 10^5 nucleated cells.

Participants received elranatamab 4 mg on C1D1 and 20 mg on C1D4 and then 76 mg QW for 1 cycle. Thereafter, in dose level 1 received 116 mg Q2W for C2 to C6 and 116 mg Q4W from C7 and onwards (participants with PR or better response persisting for >= 2 months on Q2W). One cycle =28 days. Treatment continued until confirmed disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

Participants received elranatamab 4 mg on C1D1 and 20 mg on C1D4 and then 76 mg QW for 1 cycle. Thereafter, in dose level 2 participants received 152 mg Q2W for C2 to C6 and 152 mg Q4W from C7 and onwards (participants with PR or better response persisting for >= 2 months on Q2W). One cycle =28 days. Treatment continued until confirmed disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

Participants received elranatamab 4 mg on C1D1 and 20 mg on C1D4 and then 76 mg QW for 1 cycle. Thereafter, participants were received 116 or 152 mg Q2W for C2 to 6 and 116 mg or 152 mg Q4W from C7 and onwards (participants with PR or better response persisting for >=2 months on Q2W). One cycle =28 days. Treatment continued until confirmed disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

Participants received elranatamab 4 mg on C1D1 and 20 mg on C1D4 and then 76 mg QW for 1 cycle. Thereafter, in dose level 2 participants received 152 mg Q2W for C2 to C6 and 152 mg Q4W from C7 and onwards (participants with PR or better response persisting for >= 2 months on Q2W). One cycle =28 days. Treatment continued until confirmed disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

Participants received elranatamab 4 mg on C1D1 and 20 mg on C1D4 and then 76 mg QW for 1 cycle. Thereafter, in dose level 2 participants received 152 mg Q2W for C2 to C6 and 152 mg Q4W from C7 and onwards (participants with PR or better response persisting for >= 2 months on Q2W). One cycle =28 days. Treatment continued until confirmed disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

Participants received elranatamab 4 mg on C1D1 and 20 mg on C1D4 and then 76 mg QW for 1 cycle. Thereafter, participants were received 116 or 152 mg Q2W for C2 to 6 and 116 mg or 152 mg Q4W from C7 and onwards (participants with PR or better response persisting for >=2 months on Q2W). One cycle =28 days. Treatment continued until confirmed disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

Participants received elranatamab 4 mg on C1D1 and 20 mg on C1D4 and then 76 mg QW for 1 cycle. Thereafter, in dose level 2 participants received 152 mg Q2W for C2 to C6 and 152 mg Q4W from C7 and onwards (participants with PR or better response persisting for >= 2 months on Q2W). One cycle =28 days. Treatment continued until confirmed disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

Participants received elranatamab 4 mg on C1D1 and 20 mg on C1D4 and then 76 mg QW for 1 cycle. Thereafter, participants were received 116 or 152 mg Q2W for C2 to 6 and 116 mg or 152 mg Q4W from C7 and onwards (participants with PR or better response persisting for >=2 months on Q2W). One cycle =28 days. Treatment continued until confirmed disease progression, unacceptable toxicity, withdrawal of consent, or study termination.