Outpatient step-up dosing of bispecific antibodies in relapsed or refractory multiple myeloma: an oncology nursing framework for monitoring and supportive care

Bispecific antibodies have expanded treatment options for relapsed or refractory multiple myeloma, but treatment initiation remains operationally challenging because product-specific step-up dosing concentrates the highest risk of early immune-mediated toxicity. This structured narrative review synthesizes current prescribing information, clinical safety reports, expert guidance, implementation literature, and nursing-relevant supportive-care evidence for ambulatory step-up dosing. We revised the framework to move beyond a label-based summary and conceptualize outpatient initiation as a biologically informed, resource-stratified, and failure-aware model. Approved agents differ in target antigen, route of administration, step-up schedule, premedication, cytokine release syndrome (CRS) timing, monitoring requirements, and long-term toxicity patterns; these differences should translate into different observation windows, home-surveillance instructions, and escalation thresholds. Patient selection should integrate clinical stability, disease burden, immune reserve, baseline neurologic status, caregiver reliability, geography, communication capacity, and institutional rescue capability. The bone marrow microenvironment, T-cell fitness, tumor adaptation, antigen heterogeneity, and cumulative immune injury from prior therapies may influence both response and toxicity, supporting a translational approach to outpatient risk assessment. We propose practical decision matrices for product-specific monitoring, candidate assessment, CRS-infection dual-track fever evaluation, neurotoxicity detection, failure-mode mitigation, and continuous program evaluation. Outpatient step-up dosing should therefore be considered a selective high-acuity care model rather than a routine efficiency strategy. Prospective validation of eligibility criteria, remote monitoring, nursing-sensitive outcomes, and resource-stratified pathways is urgently needed.