AKI Following Bispecific Antibody (bsAb) Therapy for Hematologic Malignancies: Incidence, Imaging-Based Structural Changes, and Association with Comorbidities

Background: Acute kidney injury (AKI) is a sudden decline in kidney function. The renal effects of bispecific antibody (bsAb) therapy in hematologic malignancies are poorly understood. We retrospectively assessed AKI incidence, progression, need for RRT, and imaging changes in bsAb-treated patients. Methods: We reviewed charts of 48 adults who received outpatient bsAb therapy for hematologic malignancies between July 2023 and March 2025 at the Stephenson Cancer Center. AKI was defined per KDIGO criteria. Patients were followed up to 100 days after the last bsAb infusion. Results: AKI occurred in 22 of 48 patients (45.8%), with 13 cases occurring within 7 days of any bsAb dose and 7 within 7 days of the first dose. Six patients experienced recurrent AKI episodes. The AKI cohort had a mean baseline serum creatinine of 1.15 mg/dL (SD 0.49) and a peak of 2.35 mg/dL (SD 1.25). Renal function returned to baseline in 68.2% within an average of 8.1 days (SD 9.9). Three patients (13.6%) required temporary RRT, and two required ICU admission. Urinalysis was performed in 50% of AKI patients; 18.2% had urine protein-creatinine ratio, and 13.6% had albumin-creatinine ratio testing. Nephrotoxic exposure was identified in 8 patients. Pre-existing CKD and ESRD were more common in the AKI group (40.9%) versus non-AKI (11.5%). Hypertension (72.7% vs 57.6%), heart disease (40.9% vs 34.6%), and hyperlipidemia (54.5% vs 19.2%) were also more prevalent in the AKI cohort. Diabetes prevalence was similar between groups (22.7% vs 23.1%). Ten patients with AKI (45%) had both pre- and post-treatment renal imaging. Ultrasound was most commonly used. Five patients (50%) showed kidney size reduction post-AKI, four (40%) had stable dimensions, and one (10%) had relative enlargement, suggestive of inflammation or edema. Conclusion: AKI is a frequent and often transient complication of bsAb therapy. Half of those with paired imaging showed structural renal changes, highlighting the importance of renal monitoring. These findings underscore the need for prospective studies with standardized imaging to better characterize bsAb-related nephrotoxicity.