Outpatient administration of cycle 1 of bispecific antibody therapy in hematologic malignancies: A real-world experience.

Abstract

e19510 Background: Bispecific antibodies are increasingly used in hematologic malignancies but are commonly administered inpatient during ramp-up dosing of cycle 1 due to concerns for cytokine release syndrome (CRS) and immune effector cell–associated neurotoxicity syndrome (ICANS). Inpatient administration increases healthcare utilization and may impact patient experience negatively. Real-world data supporting outpatient administration during cycle 1 are limited. Methods: At the Brown Cancer Center, we conducted a retrospective study of adult patients who initiated cycle 1 of bispecific antibody therapy as outpatient in the time period between January 2023 and December 2025. Agents included glofitamab, blinatumomab, teclistamab, and talquetamab. Outcomes included CRS, ICANS, hospitalization, treatment completion, mortality, and length of stay (LOS). Results: Of 70 patients screened, 18 received outpatient cycle 1 bispecific antibody therapy. Cytokine release syndrome occurred in 4/18 patients, all requiring hospitalization with a length of stay of 2 to 3 days. One patient developed ICANS, and one patient was hospitalized for a non– treatment-related reason. Based on manufacturer recommendations, the expected inpatient monitoring would be as follows for each drug: (teclistamab: 6 days, talquetamab: 8 days, blinatumomab: 3 days, glofitamab: 1 day). For our 18 patients, it will translate to 97 hospital days. The actual number of hospitalization days was 14, resulting in net savings of 83 hospital admission days. All patients completed cycle 1 therapy. No grade ≥3 toxicities or treatment-related deaths were observed. Conclusions: Our study showed that giving bispecific antibodies to patients in an outpatient setting during the first treatment cycle was safe and practical, with structured monitoring. Overall, the side effects from treatment were manageable. This approach can lead to cost savings, decreased hospitalization (85% reduction in LOS), and possibly higher patient satisfaction. Still, larger studies are needed to better select patients, improve predictions for side effects, and further clarify the safety of administering bispecific antibodies on an outpatient basis. Outpatient bispecific therapy. Therapy Patients (n) ICANS CRS Grade 1–2 Number of patients admitted within 30 days Recommended Inpatient Days (Cycle 1, per patient) Hospital Days Saved (Manufacturer-Recommended/Outpatient Days) Glofitamab 1 0 0 0 1 1/1 Blinatumomab 6 0 3 3 3 10/18 Teclistamab 5 1 0 2 6 27/30 Talquetamab 6 0 1 1 8 45/48 CRS: Cytokine Release Syndrome. ICANS: Immune Effector Cell-Associated Neurotoxicity Syndrome.