An adverse event (AE) is defined as any untoward medical occurrence in a participants administered a pharmaceutical product; the untoward medical occurrence does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product whether or not it is related to the medicinal product. A TEAE is defined as any AE either reported for the first time or worsening of a pre-existing event after first dose of study drug and within 30 days of the last administration of study drug.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573.

DLTs were evaluated as per National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 5.0. Nonhematologic TEAEs of NCI CTCAE Grade ≥3 clearly unrelated to the underlying disease and occurring during the first cycle were considered DLTs.

The DLT-evaluable Analysis Set included participants who received all Cycle 1 doses of modakafusp alfa or experienced a DLT in Cycle 1 in the Part 1 Dose Escalation portion of the study.

An AE is defined as any untoward medical occurrence in a participants administered a pharmaceutical product; the untoward medical occurrence does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product whether or not it is related to the medicinal product. TEAEs grades were evaluated as per NCI CTCAE, Version 5.0. Grade 1 scaled as mild; Grade 2 scaled as moderate; Grade 3 scaled as severe or medically significant but not immediately life-threatening; Grade 4 scaled as life-threatening consequences; and Grade 5 scaled as death related to AE. Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573.

AE: any untoward medical occurrence in participants administered a pharmaceutical product; untoward medical occurrence does not necessarily have causal relationship with this treatment. AE can therefore be any unfavorable & unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with use of medicinal (investigational) product whether or not it is related to medicinal product. TEAE: any AE either reported for first time or worsening of pre-existing event after first dose of study drug & within 30 days of last administration of study drug. Serious TEAEs: any untoward medical occurrence that: 1)results in death, 2) is life-threatening, 3) requires inpatient hospitalization or prolongation of existing hospitalization, 4) results in persistent or significant disability/incapacity, 5) leads to a congenital anomaly/birth defect in the offspring of the participant or 6) is medically important event. Percentages were rounded off to nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573.

An AE is defined as any untoward medical occurrence in a participants administered a pharmaceutical product; the untoward medical occurrence does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product whether or not it is related to the medicinal product. A TEAE is defined as any AE either reported for the first time or worsening of a pre-existing event after first dose of study drug and within 30 days of the last administration of study drug. Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573.

Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573.

Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573.

Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573.

Laboratory values included hematology, chemistry, and urinalysis and were assessed per investigator's interpretation.

SAS:all participants who took ≥1 dose,even if incomplete,of TAK-573.However,clinically significant laboratory values data were not collected & will never be available to present due to an issue with report form used for data collection(identified after trial completion).Assessments of clinical significance were not included in the report form,making data collection impossible.This issue did not impact participant safety or reliability of study data,particularly primary endpoint.

Vital signs included temperature, pulse, respiratory rate, oxygen saturation, and blood pressure.

SAS:all participants who took ≥1 dose,even if incomplete,of TAK-573.However,clinically significant vital signs measurements data were not collected & will never be available to present due to an issue with report form used for data collection(identified after trial completion).Assessments of clinical significance were not included in the report form,making data collection impossible.This issue did not impact participant safety or reliability of study data,particularly primary endpoint.

ORR was defined as the percentage of participants who achieved a partial response (PR) rate or better (stringent complete response [sCR] + complete response [CR] + very good partial response [VGPR] + PR) during the study as defined by international myeloma working group (IMWG) uniform response criteria. PR: ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR: negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal free light chain (FLC) ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR:serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573 and with measurable disease at baseline.

ORR was defined as the percentage of participants who achieved a PR rate or better (sCR + CR + VGPR + PR) during the study as defined by IMWG uniform response criteria. PR :≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR:negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. Scr: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR:serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts. Due to early termination, IRC was disbanded prior to completing its evaluation and could not be utilized for the assessment, therefore the data for this outcome measure is not available.

Percentage of participants with TEAEs meeting DLT definition were reported. Toxicity was evaluated as per the NCI CTCAE, Version 5.0. The hematologic TEAEs of Grade ≥3 clearly unrelated to the underlying disease and occur during the first cycle that are considered DLTs: Grade ≥3 hemolysis; Grade 4 neutropenia for >7 consecutive days; Grade 4 thrombocytopenia for >14 consecutive days; Grade 3 thrombocytopenia with clinically significant bleeding; Any other Grade ≥4 hematologic toxicity except for Grade 4 lymphopenia. An incomplete recovery from treatment-related toxicity causing >2-week delay in the next scheduled infusion before the initiation of Cycle 2 were considered a DLT. Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573. Overall number of participants analyzed is the number of participants with data available for analysis.

As per planned analysis, data for this outcome measure was collected and reported dose-wise for each treatment schedule.

The Pharmacokinetic (PK) Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analysis. Number analyzed is the number of participants with data available for analysis during the specified time-point.

As per planned analysis, data for this outcome measure was collected and reported dose-wise for each treatment schedule.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analysis. Number analyzed is the number of participants with data available for analysis during the specified time-point.

As per planned analysis, data for this outcome measure was collected and reported dose-wise for each treatment schedule. Given the low exposure at the 0.1 mg/kg dose, there was insufficient data to characterize the terminal phase PK required for calculating this parameter. Consequently, this parameter has been marked as "Not Calculated" - and therefore not reported - for the Part 1, Schedule A, 0.1 mg/kg dose group, in accordance with non-compartmental PK analysis standards.

PK Analysis Set; Overall number analyzed: participants with data available for analysis.Number analyzed: participants with data available during specified time-point.Given low exposure at 0.01mg/kg dose,there was insufficient data to characterize terminal phase PK required for calculating this parameter.Consequently,this parameter has been marked as "Not Calculated" and therefore not reported for Part 1,Schedule A,0.01mg/kg dose group,in accordance with non-compartmental PK analysis standards.

As per planned analysis, data for this outcome measure was collected and reported dose-wise for each treatment schedule.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analysis. Number analyzed is the number of participants with data available for analysis during the specified time-point.

As per planned analysis, data for this outcome measure was collected and reported dose-wise for each treatment schedule. Given the low exposure at the 0.1 mg/kg dose, there was insufficient data to characterize the terminal phase PK required for calculating this parameter. Consequently, this parameter has been marked as "Not Calculated" - and therefore not reported - for the Part 1, Schedule A, 0.1 mg/kg dose group, in accordance with non-compartmental PK analysis standards.

PK Analysis Set; Overall number analyzed: participants with data available for analysis.Number analyzed: participants with data available during specified time-point.

As per planned analysis, data for this outcome measure was collected and reported dose-wise for each treatment schedule.

PK Analysis Set; Overall number analyzed: participants with data available for analysis.Number analyzed: participants with data available during specified time-point.Given low exposure at 0.01mg/kg dose,there was insufficient data to characterize terminal phase PK required for calculating this parameter.Consequently,this parameter has been marked as "Not Calculated" and therefore not reported for Part 1,Schedule A,0.01mg/kg dose group,in accordance with non-compartmental PK analysis standards.

Clearance is defined as a quantitative measure of the rate at which a drug substance is removed from the body. CL = dose/AUC. As per planned analysis, data for this outcome measure was collected and reported dose-wise for each treatment schedule.

PK Analysis Set; Overall number analyzed: participants with data available for analysis.Number analyzed: participants with data available during specified time-point.Given low exposure at 0.01mg/kg dose,there was insufficient data to characterize terminal phase PK required for calculating this parameter.Consequently,this parameter has been marked as "Not Calculated" and therefore not reported for Part 1,Schedule A,0.01mg/kg dose group,in accordance with non-compartmental PK analysis standards.

Volume of distribution is defined as the theoretical volume in which the total amount of drug would need to be uniformly distributed to produce the desired serum concentration of a drug. V(ss) = (dose/AUC)*MRT, where MRT is mean residence time. As per planned analysis, data for this outcome measure was collected and reported dose-wise for each treatment schedule.

PK Analysis Set; Overall number analyzed: participants with data available for analysis.Number analyzed: participants with data available during specified time-point.Given low exposure at 0.01mg/kg dose,there was insufficient data to characterize terminal phase PK required for calculating this parameter.Consequently,this parameter has been marked as "Not Calculated" and therefore not reported for Part 1,Schedule A,0.01mg/kg dose group,in accordance with non-compartmental PK analysis standards.

ADA samples scoring equal to or above the cut-point (titer of 75) were defined as ADA positive. Percentages were rounded off to the nearest decimal.

The Immunogenicity-evaluable Analysis Set included participants from the SAS with a baseline assessment and at least 1 postbaseline immunogenicity assessment. Overall number of participants analyzed is the number of participants with data available for analyses.

ORR was defined as the percentage of participants who achieved a PR rate or better (sCR + CR + VGPR + PR) during the study as defined by IMWG uniform response criteria. PR: ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR: negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR: serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours. Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573 and with measurable disease at baseline. Overall number of participants analyzed is the number of participants with data available for analyses.

The CBR was defined as the percentage of participants with a confirmed response of sCR, CR, VGPR, PR, or minimal response (MR) during the study per investigator assessment as defined by IMWG Uniform Response Criteria. PR: ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR: negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR: serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours. MR: ≥25% but ≤49% reduction of serum M-protein and reduction in 24-hour urine M-protein by 50% to 89%. Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573 and with measurable disease at baseline. Overall number of participants analyzed is the number of participants with data available for analysis.

The DCR was defined as the proportion of participants with a confirmed response of sCR, CR, VGPR, PR, MR, or stable disease (SD) during the study per investigator assessment as defined by IMWG Uniform Response Criteria. PR: ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR: negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR: serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours. MR: ≥25% but ≤49% reduction of serum M-protein and reduction in 24-hour urine M-protein by 50% to 89%. SD: no known evidence of progressive or new bone lesions if radiographic studies were performed. Percentages were rounded off to the nearest decimal.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573 and with measurable disease at baseline. Overall number of participants analyzed is the number of participants with data available for analysis.

DOR was defined as the time from the date of first documentation of response PR or better (sCR + CR + VGPR + PR) to the time of disease progression or death, whichever occurs first. PR: ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR: negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR: serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573. Overall number of participants analyzed is the number of participants with data available for analyses.

Time to response was defined as the time from first dose to the date of first documentation of response (PR or better [sCR + CR + VGPR + PR]) PR: ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR: negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR: serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573. Overall number of participants analyzed is the number of participants with data available for analyses.

PFS was defined as the time from the date of enrollment until the date of progressive disease (PD) or death due to any cause, whichever occurs first as defined by IMWG Criteria. Per IMWG criteria, PD: serum M-component increase ≥0.5 g/dl or urine M-component increase ≥ 200 mg/24-hour/ difference between involved and uninvolved FLC levels increase >10 mg/dl or bone marrow plasma cell ≥10%/ development of new/ increase in size of existing bone lesions or soft tissue plasmacytoma or development of hypercalcemia.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573. The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts. Overall number of participants analyzed is the number of participants with data available for analysis.

The OS was defined as the time from the date of first dose to the date of death due to any cause.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573. The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts. Overall number of participants analyzed is the number of participants with data available for analyses.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analysis. Number analyzed is the number of participants with data available for analysis during the specified time-point.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analysis. Number analyzed is the number of participants with data available for analysis during the specified time-point.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analysis. Number analyzed is the number of participants with data available for analysis during the specified time-point.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analyses. Number analyzed is the number of participants with data available for analysis during the specified time-point.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analyses. Number analyzed is the number of participants with data available for analysis during the specified time-point.

Clearance is defined as a quantitative measure of the rate at which a drug substance is removed from the body. CL = dose/AUC.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analyses. Number analyzed is the number of participants with data available for analysis during the specified time-point.

Volume of distribution is defined as the theoretical volume in which the total amount of drug would need to be uniformly distributed to produce the desired serum concentration of a drug. V(ss) = (dose/AUC)*MRT, where MRT is mean residence time.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analysis. Number analyzed is the number of participants with data available for analysis during the specified time-point.

The PK Analysis Set included participants from the SAS who had sufficient data to calculate at least 1 PK parameter for modakafusp alfa. Overall number of participants analyzed is the number of participants with data available for analyses. Number analyzed is the number of participants with data available for analysis during the specified time-point.

ORR was defined as the percentage of participants who achieved a PR rate or better (sCR + CR + VGPR + PR) during the study as defined by IMWG uniform response criteria. PR :≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR:negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR:serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours. Percentages were rounded off to the nearest decimal.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts.

The CBR was defined as the percentage of participants with a confirmed response of sCR, CR, VGPR, PR, or minimal response (MR) during the study per investigator assessment as defined by IMWG Uniform Response Criteria. PR: ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR: negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR: serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours. MR: ≥25% but ≤49% reduction of serum M-protein and reduction in 24-hour urine M-protein by 50% to 89%. Percentages were rounded off to the nearest decimal.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts.

Duration of clinical benefit was defined as the time from first documented evidence of confirmed MR or better until the earliest date of a confirmed PD per IMWG, or death among participants who achieve a confirmed MR or better. MR: ≥25% but ≤49% reduction of serum M-protein and reduction in 24-hour urine M-protein by 50% to 89%. Per IMWG criteria, PD: serum M-component increase ≥0.5 g/dl or urine M-component increase ≥ 200 mg/24-hour/ difference between involved and uninvolved FLC levels increase >10 mg/dl or bone marrow plasma cell ≥10%/ development of new/ increase in size of existing bone lesions or soft tissue plasmacytoma or development of hypercalcemia.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts. Overall number of participants analyzed is the number of participants with events. Participants with no post baseline response assessment were censored.

The DCR was defined as the proportion of participants with a confirmed response of sCR, CR, VGPR, PR, MR, or stable disease (SD) during the study per investigator assessment as defined by IMWG Uniform Response Criteria. PR: ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to <200 mg/24 hours. CR: negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow. sCR: CR+normal FLC ratio and absence of clonal cells in bone marrow biopsy by immunohistochemistry. VGPR: serum and urine M-protein detectable by immunofixation but not on electrophoresis, or ≥90% reduction in serum M-protein plus urine M-protein <100 mg/24 hours. MR: ≥25% but ≤49% reduction of serum M-protein and reduction in 24-hour urine M-protein by 50% to 89%. SD: no known evidence of progressive or new bone lesions if radiographic studies were performed. Percentages were rounded off to the nearest decimal.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts.

Duration of disease control was defined as the time from first documented evidence of SD or better until the earliest date of a confirmed PD per IMWG, or death among participants who achieved a SD or better. SD: no known evidence of progressive or new bone lesions if radiographic studies were performed. Per IMWG criteria, PD: serum M-component increase ≥0.5 g/dl or urine M-component increase ≥200 mg/24-hour/ difference between involved and uninvolved FLC levels increase >10 mg/dl or bone marrow plasma cell ≥10%/ development of new/ increase in size of existing bone lesions or soft tissue plasmacytoma or development of hypercalcemia.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts. Overall number of participants analyzed is the number of participants with data available for analyses.

TTP was defined as the time from the date of the first dose until the earliest date of confirmed PD per IMWG, or death due to PD. Per IMWG criteria, PD: serum M-component increase ≥0.5 g/dl or urine M-component increase ≥200 mg/24-hour/ difference between involved and uninvolved FLC levels increase >10 mg/dl or bone marrow plasma cell ≥10%/ development of new/ increase in size of existing bone lesions or soft tissue plasmacytoma or development of hypercalcemia.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts. Overall number of participants analyzed is the number of participants with data available for analyses.

MRD negativity rate at a sensitivity of 10^-5 was defined as participants who were MRD negative at a sensitivity of 10^-5 in participants achieving suspected complete response (CR). CR was defined as negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow; in participants for whom only measurable disease is by serum FLC level, normal FLC ratio of 0.26 to 1.65 in addition to CR criteria was required.

The Intent-to-Treat (ITT) Analysis Set included all randomized participants regardless of whether they received study drug or adhered to the assigned dose. Overall number of participants analyzed is the number of participants from ITT analysis set who achieved CR.

Duration of MRD negativity (10^-5) was defined as the time from the first MRD negative status (10^-5) to the earliest date of the MRD positive status (10^-5), confirmed PD per IMWG or death.

The ITT Analysis Set included all randomized participants regardless of whether they received study drug or adhered to the assigned dose. Overall number of participants analyzed is the number of participants from ITT analysis set who achieved CR.

An AE is defined as any untoward medical occurrence in a participants administered a pharmaceutical product; the untoward medical occurrence does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product whether or not it is related to the medicinal product. A TEAE is defined as any AE either reported for the first time or worsening of a pre-existing event after first dose of study drug and within 30 days of the last administration of study drug. Percentages were rounded off to the nearest decimal.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts.

AE: any untoward medical occurrence in participants administered pharmaceutical product; untoward medical occurrence does not necessarily have causal relationship with this treatment. AE can therefore be any unfavorable & unintended sign (including abnormal laboratory finding), symptom/disease temporally associated with use of medicinal (investigational) product whether or not it is related to medicinal product. TEAE: any AE either reported for first time or worsening of pre-existing event after first dose of study drug & within 30 days of last administration of study drug. Serious TEAEs: any untoward medical occurrence that: 1) results in death, 2) is life-threatening, 3) requires inpatient hospitalization or prolongation of existing hospitalization, 4) results in persistent or significant disability/incapacity, 5) leads to a congenital anomaly/birth defect in the offspring of the participant or 6) is a medically important event. Percentages were rounded off to the nearest decimal.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts.

Laboratory values included hematology, chemistry, and urinalysis as interpreted by the investigator.

FAS:all participants who took ≥1 dose,even if incomplete,of TAK-573 in Part 3 extension cohorts.However,clinically significant laboratory values data were not collected&will never be available to present due to issue with report form used for data collection(identified after trial completion).Assessments of clinical significance were not included in report form,making data collection impossible.This issue did not impact participant safety/reliability of study data,particularly primary endpoint.

ECOG performance status was measured at baseline and over time. ECOG performance status was measured on a 6 point scale: Grade 0: Normal activity, Grade 1: Symptoms but ambulatory, Grade 2: In bed <50% of the time, Grade 3: In bed >50% of the time, Grade 4: 100% bedridden, Grade 5: Dead. Reported here is the baseline status and the worst post-baseline status measured. A decrease in grade from baseline indicates an improvement. Only categories for which there was at least 1 participant are reported.

The SAS included all enrolled participants who received at least 1 dose, even if incomplete, of TAK-573.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts. Overall number of participants analyzed is the number of participants with data available for analyses.

Percentages were rounded off to the nearest decimal.

Immunogenicity-Evaluable Set Analysis included participants with a baseline assessment and at least 1 post-baseline immunogenicity assessment. Overall number of participants analyzed is the number of participants with data available for analyses.

Medical encounters included hospitalizations, emergency room stays, or outpatient visits.

The FAS included all participants who received at least 1 dose, even an incomplete dose, of modakafusp alfa, in the Part 3 extension cohorts. Overall number of participants analyzed is the number of participants with data available for analyses.

EORTC QLQ-MY20 is a myeloma-specific module developed by the EORTC group specifically to assess quality of life in participants with multiple myeloma. It contains 20 items which can be grouped into a disease symptom subscale (6 items), side effects of treatment subscale (10 items), body image (1 item) and future perspective subscale (3 items). All transformed scale scores range from 0 to 100 with higher scores indicating worse symptoms (Disease Symptoms and Side Effects of Treatment) or better support/functioning (Future Perspective and Body Image).

The PRO Analysis Set included all participants with a baseline and at least one post-baseline measurement of any PRO measure (EORTC QLQ-MY20 or EQ-5D-5L). Overall number of participants analyzed is the number of participants with data available for analyses.