Number of participants with anti-teclistamab antibodies will be assessed.

Objective response will be defined as partial response (PR) or better as defined by the 2016 IMWG response criteria in multiple myeloma (MM).

DOR is defined as the duration from the date of initial documentation of a response (PR or better) to the date of first documented evidence of progressive disease, as defined in the 2016 IMWG criteria, or death.

TTR is defined as the time between date of first dose of study treatment and the first efficacy evaluation that the participant has met all criteria for PR or better.

VGPR or better response rate (sCR+CR+VGPR) is defined as the percentage of participants who achieve a VGPR or better response according to the 2016 IMWG response criteria.

CR or better response rate is defined as the percentage of participants who achieve a CR or better response (sCR+CR) according to the IMWG 2016 criteria.

sCR rate is defined as the percentage of participants who achieve an sCR according to the IMWG 2016 criteria.

PFS is defined as the time from the date of first dose of study drug to the date of first documented disease progression, as defined in the 2016 IMWG response criteria, or death due to any cause, whichever occurs first.

OS is defined as the time from the date of first dose of study drug to the date of the participant's death. If the participant is alive or the vital status is unknown, then the participant's data will be censored at the date the participant was last known to be alive.

MRD-negative rate is defined as the percentage of participants who achieved MRD-negative status to a threshold of 10^-5 at any timepoint after initial dose of teclistamab and before disease progression or starting subsequent therapy.

An AE is any untoward medical occurrence in a clinical study participant administered a pharmaceutical (investigational or non investigational) product. An AE does not necessarily have a causal relationship with the treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal finding), symptom, or disease temporally associated with the use of a medicinal (investigational or non investigational) product, whether or not related to that medicinal (investigational or non investigational) product.

Severity will be graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 5.0 with the exception of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), which will be graded according to the American Society for Transplantation and Cellular Therapy (ASTCT) guidelines. Severity scale ranges from Grade 1 (Mild) to Grade 5 (Death). Grade 1= Mild, Grade 2= Moderate, Grade 3= Severe, Grade 4= Life-threatening and Grade 5= Death related to adverse event.

A SAE is any untoward medical occurrence that at any dose: results in death; is life-threatening; requires inpatient hospitalization or prolongation of existing hospitalization; results in persistent or significant disability/incapacity; is a congenital anomaly/birth defect; is a suspected transmission of any infectious agent via a medicinal product; is medically important.

Severity will be graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 5.0 with the exception of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), which will be graded according to the American Society for Transplantation and Cellular Therapy (ASTCT) guidelines. Severity scale ranges from Grade 1 (Mild) to Grade 5 (Death). Grade 1= Mild, Grade 2= Moderate, Grade 3= Severe, Grade 4= Life-threatening and Grade 5= Death related to adverse event.

Number of participants with abnormalities in clinical laboratory test values of hematology, serum chemistry, and coagulation will be reported.

Severity will be graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 5.0 with the exception of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), which will be graded according to the American Society for Transplantation and Cellular Therapy (ASTCT) guidelines. Severity scale ranges from Grade 1 (Mild) to Grade 5 (Death). Grade 1= Mild, Grade 2= Moderate, Grade 3= Severe, Grade 4= Life-threatening and Grade 5= Death related to adverse event.

Change from baseline in EORTC- QLQ-C30 score will be reported. The EORTC- QLQ-C30 Version 3 includes 30 items that make up 5 functional scales (physical, role, emotional, cognitive, and social), 1 global health status scale, 3 symptom scales (pain, fatigue, and nausea/vomiting), and 6 single symptom items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). The item and scale scores are transformed to a 0 to 100 scale. A higher score represents greater HRQoL, better functioning, and more (worse) symptoms.

Change from baseline in EQ-5D-5L scale will be reported. The EQ-5D-5L is a generic measure of health status. EQ-5D-5L is a 5 item questionnaire that assesses 5 domains including mobility, self-care, usual activities, pain/discomfort and anxiety/depression plus a visual analog scale rating "health today" with anchors ranging from 0 (worst imaginable health state) to 100 (best imaginable health state).

Change from baseline in PGIS scale will be reported. The PGIS is a single item that assesses severity of the participant's health state, on a 5-point verbal rating scale (1: None, 2: Mild, 3: Moderate, 4: Severe, 5: Very Severe) at the time of completing the PRO measure. Higher score indicate greater severity.