Feasibility and Safety of Outpatient Model for Administration of Bispecific Antibodies: Proceedings from an International Myeloma Society 21st Annual Meeting Oral Abstract.

Background: Teclistamab, elranatamab, and taqluetamab are T-cell redirecting bispecific antibodies (BsAbs) that gained accelerated approval for the treatment of patients with relapsed/refractory multiple myeloma (RRMM). All 3 FDA labels suggest hospitalization for the step-up doses (SUDs) to monitor for CRS and ICANS.

Methods: We implemented an institutional protocol to deliver SUD and target doses in the outpatient (OP) setting to minimize hospitalization and reimbursement burdens. Patient disease and social factors were evaluated for OP protocol eligibility. SUDs were administered on days 1, 4 and 8 preceded by acetaminophen, diphenhydramine, and dexamethasone. All patients received prophylactic tocilizumab per institutional protocol. From initiation of SUD #1 until 48-hours after the target dose, patients self-monitored temperature every 8 hours or in the setting of new signs or symptoms suggestive of CRS/ICANS. If fever or neurologic change should occur, patients were educated to take medications (acetaminophen 650 mg, diphenhydramine 50 mg and dexamethasone 20 mg) and present to the Immediate Care Center for assessment and management.

Results: From 9/1/2023 to 8/31/2024, 52 patients received OP BsAb SUD. CRS occurred in 10 patients (19.2%, 9/10 events grade 1/2) and ICANS occurred in 3 patients (5.8%, grade 1). Four patients (7.7%) required hospitalization for toxicity management. All patients recovered from CRS and ICANS without additional toxicity.

Conclusion: Implementation of this OP BsAb SUD protocol is feasible with acceptable risk of CRS/ICANS and hospitalization without compromising on safety. The low incidence of CRS/ ICANS with prophylactic tocilizumab and premedication and low hospitalization rates make this appealing for selected RRMM patients.