2026 Southeastern Residency Conference

Comparative Safety of Inpatient versus Outpatient Step‑Up Dosing for Bispecific T‑Cell Engagers in Multiple Myeloma
Saumyaa Patel; Chynna Bambico; Jon Shaffer
AdventHealth Orlando, Orlando, FL, USA
BACKGROUND
Bispecific T-Cell Engagers (BiTEs) for relapsed/refractory multiple myeloma were approved with recommended inpatient step-up dosing and post-dose observation to mitigate early toxicities, primarily cytokine release syndrome (CRS) and immune effector cell–associated neurotoxicity syndrome (ICANS). Emerging literature suggests outpatient step-up dosing may be feasible with standardized monitoring and prophylaxis, but real-world data on patient safety outcomes remains limited. The objective of this study is to compare whether inpatient versus outpatient step-up dosing for teclistamab, talquetamab, and elranatamab affects the incidence and grade of CRS and ICANS.
METHODS
This single-center, retrospective chart review included adults with multiple myeloma initiated on teclistamab, talquetamab, or elranatamab at a tertiary academic hospital between June 1, 2023, and February 30, 2026. Patients were identified from the electronic health records after Institutional Review Board (IRB) approval. They were grouped according to care setting during step-up dosing: inpatient observation as recommended by Food and Drug Administration (FDA) label versus outpatient monitoring. Inclusion criteria included age ≥18 years and first step-up dose administered with follow-up per institutional protocol. Exclusion criteria included initial step-up performed elsewhere, concurrent enrollment in an interventional trial, or clinical instability at step-up initiation (for example, active infection or hemodynamic instability). Baseline variables included age, gender, Eastern Cooperative Oncology Group (ECOG) performance status, and number of prior therapy lines. Primary outcomes included incidence and grade of CRS and ICANS per the American Society for Transplantation and Cellular Therapy (ASTCT) criteria. Secondary outcomes included tocilizumab use, corticosteroid use, fluid bolus use, vasopressor use, supplemental oxygen use, emergency department visit or readmission, and readmission length of stay. Descriptive statistics will summarize baseline characteristics. Categorical outcomes will be compared using chi-squared or Fisher’s exact tests while continuous outcomes will be compared using Mann-Whitney U or student’s t-tests.
RESULTS A total of 41 patients were included, with 11 (27%) receiving outpatient and 30 (73%) receiving inpatient step-up dosing. Baseline characteristics were generally comparable, including age, gender, and prior lines of therapy. CRS occurred less frequently in the outpatient group vs. the inpatient group (9% vs. 47%). All outpatient CRS events were grade 2, while inpatient events were grade 1 (17%) and grade 2 (30%). ICANS was uncommon and occurred in 9% of outpatients vs. 20% of inpatients. All outpatient ICANS events were grade 2, while inpatient events were grade 1 (13%) and grade 2 (7%).
Supportive care interventions were similar overall. Tocilizumab use occurred in 9% of outpatients vs. 13% of inpatients, and fluid boluses were administered only in the inpatient group (23%). Off day corticosteroid use was more common in the outpatient group (91% vs. 30%). Lastly, no patients required vasopressors or intensive care unit admission, and thirty-day hospitalization rates were identical (27% vs. 27%).
CONCLUSIONS Outpatient step-up dosing of bispecific T cell engagers was not associated with increased incidence or severity of CRS or ICANS vs. inpatient initiation. Although CRS rates were lower in the outpatient cohort, escalation of care and healthcare utilization were similar. These findings support the feasibility and safety of outpatient BiTE initiation in appropriately selected patients with standardized monitoring and prophylactic strategies.