Eligibility required relapsed/refractory MM after ≥3 prior lines (including PI+IMiD), measurable disease per IMWG, and adequate hematologic/organ function (ANC ≥1.0×10^9/L, platelets ≥50-75×10^9/L, LVEF >50%). Excluded: plasma cell leukemia/POMS/Waldenström's, recent SCT (<90 days), QTc >470ms, active CHF (NYHA class III/IV), or anti-tumor therapy within 28 days. Concurrent prednisone ≤30mg/day was permitted.

Dose-limiting toxicities (DLTs) were assessed during the first 28 days using CTCAE v4.0, defining hematologic DLTs as prolonged grade 4 cytopenias (neutropenia >7 days, thrombocytopenia >7 days) or grade 3+ cytopenias with complications (fever/hemorrhage), and non-hematologic DLTs as grade 3+ organ toxicities (liver/kidney), persistent GI toxicity >3 days despite therapy, or cases meeting Hy's Law criteria. Treatment-emergent AEs were monitored through Cycle 4 (12 weeks) including vital signs, labs, and neurologic assessments.

PK parameters (Cmax, Cmin, AUC, clearance, t1/2) of AMG 224's antibody-drug conjugate (anti-BCMA-MCC-DM1) components were assessed in Cycles 1-2. Efficacy outcomes included best overall response per IMWG-URC (CR/sCR/VGPR/PR), time-to-progression, duration of response (Kaplan-Meier), MRD-negativity rate (sensitivity <1:10^5), and immunogenicity (anti-drug antibodies) over 6 years. Intensive PK sampling occurred pre/post-infusion through 336 hours.

Eligibility required relapsed/refractory MM after ≥3 prior lines (including PI+IMiD), measurable disease per IMWG, and adequate hematologic/organ function (ANC ≥1.0×10^9/L, platelets ≥50-75×10^9/L, LVEF >50%). Excluded: plasma cell leukemia/POMS/Waldenström's, recent SCT (<90 days), QTc >470ms, active CHF (NYHA class III/IV), or anti-tumor therapy within 28 days. Concurrent prednisone ≤30mg/day was permitted.

Dose-limiting toxicities (DLTs) were assessed during the first 28 days using CTCAE v4.0, defining hematologic DLTs as prolonged grade 4 cytopenias (neutropenia >7 days, thrombocytopenia >7 days) or grade 3+ cytopenias with complications (fever/hemorrhage), and non-hematologic DLTs as grade 3+ organ toxicities (liver/kidney), persistent GI toxicity >3 days despite therapy, or cases meeting Hy's Law criteria. Treatment-emergent AEs were monitored through Cycle 4 (12 weeks) including vital signs, labs, and neurologic assessments.

PK parameters (Cmax, Cmin, AUC, clearance, t1/2) of AMG 224's antibody-drug conjugate (anti-BCMA-MCC-DM1) components were assessed in Cycles 1-2. Efficacy outcomes included best overall response per IMWG-URC (CR/sCR/VGPR/PR), time-to-progression, duration of response (Kaplan-Meier), MRD-negativity rate (sensitivity <1:10^5), and immunogenicity (anti-drug antibodies) over 6 years. Intensive PK sampling occurred pre/post-infusion through 336 hours.

Eligibility required relapsed/refractory MM after ≥3 prior lines (including PI+IMiD), measurable disease per IMWG, and adequate hematologic/organ function (ANC ≥1.0×10^9/L, platelets ≥50-75×10^9/L, LVEF >50%). Excluded: plasma cell leukemia/POMS/Waldenström's, recent SCT (<90 days), QTc >470ms, active CHF (NYHA class III/IV), or anti-tumor therapy within 28 days. Concurrent prednisone ≤30mg/day was permitted.

Dose-limiting toxicities (DLTs) were assessed during the first 28 days using CTCAE v4.0, defining hematologic DLTs as prolonged grade 4 cytopenias (neutropenia >7 days, thrombocytopenia >7 days) or grade 3+ cytopenias with complications (fever/hemorrhage), and non-hematologic DLTs as grade 3+ organ toxicities (liver/kidney), persistent GI toxicity >3 days despite therapy, or cases meeting Hy's Law criteria. Treatment-emergent AEs were monitored through Cycle 4 (12 weeks) including vital signs, labs, and neurologic assessments.

PK parameters (Cmax, Cmin, AUC, clearance, t1/2) of AMG 224's antibody-drug conjugate (anti-BCMA-MCC-DM1) components were assessed in Cycles 1-2. Efficacy outcomes included best overall response per IMWG-URC (CR/sCR/VGPR/PR), time-to-progression, duration of response (Kaplan-Meier), MRD-negativity rate (sensitivity <1:10^5), and immunogenicity (anti-drug antibodies) over 6 years. Intensive PK sampling occurred pre/post-infusion through 336 hours.

Eligibility required relapsed/refractory MM after ≥3 prior lines (including PI+IMiD), measurable disease per IMWG, and adequate hematologic/organ function (ANC ≥1.0×10^9/L, platelets ≥50-75×10^9/L, LVEF >50%). Excluded: plasma cell leukemia/POMS/Waldenström's, recent SCT (<90 days), QTc >470ms, active CHF (NYHA class III/IV), or anti-tumor therapy within 28 days. Concurrent prednisone ≤30mg/day was permitted.

Dose-limiting toxicities (DLTs) were assessed during the first 28 days using CTCAE v4.0, defining hematologic DLTs as prolonged grade 4 cytopenias (neutropenia >7 days, thrombocytopenia >7 days) or grade 3+ cytopenias with complications (fever/hemorrhage), and non-hematologic DLTs as grade 3+ organ toxicities (liver/kidney), persistent GI toxicity >3 days despite therapy, or cases meeting Hy's Law criteria. Treatment-emergent AEs were monitored through Cycle 4 (12 weeks) including vital signs, labs, and neurologic assessments.

PK parameters (Cmax, Cmin, AUC, clearance, t1/2) of AMG 224's antibody-drug conjugate (anti-BCMA-MCC-DM1) components were assessed in Cycles 1-2. Efficacy outcomes included best overall response per IMWG-URC (CR/sCR/VGPR/PR), time-to-progression, duration of response (Kaplan-Meier), MRD-negativity rate (sensitivity <1:10^5), and immunogenicity (anti-drug antibodies) over 6 years. Intensive PK sampling occurred pre/post-infusion through 336 hours.