Kidney Week

Abstract: FR-PO1238

Creatinine-Cystatin C Discordance in Chimeric Antigen Receptor-T Cell Recipients with Atypical Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS): A Case Series

Session Information

• Onconephrology: Diagnostic Dilemmas, Therapy-Related Toxicities, and Clinical Cases
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Onconephrology

• 1600 Onconephrology

Authors

• Chewcharat, Api, Brigham and Women's Hospital, Boston, Massachusetts, United States

Api Chewcharat, MD, MPH, FASN

• Kim, Ava, Brigham and Women's Hospital, Boston, Massachusetts, United States

Ava Kim

• Zargari, Kiana Melody, Brigham and Women's Hospital, Boston, Massachusetts, United States

Kiana Melody Zargari

• Anumolu, Rajesh, Brigham and Women's Hospital, Boston, Massachusetts, United States

Rajesh Anumolu, MBBS

• Kirkpatrick, Anna S., Massachusetts General Hospital, Boston, Massachusetts, United States

Anna S. Kirkpatrick

• Sise, Meghan E., Massachusetts General Hospital, Boston, Massachusetts, United States

Meghan E. Sise, MD, MS

• Gupta, Shruti, Brigham and Women's Hospital, Boston, Massachusetts, United States

Shruti Gupta, MD, MPH

Introduction

Accurate assessment of kidney function is essential for dosing renally cleared medications, some of which are associated with neurotoxicity. Estimated glomerular filtration rate (eGFR) based on serum creatinine (eGFR_Cr) may overestimate kidney function compared to cystatin C-based estimates (eGFR_cys), particularly among patients receiving chimeric antigen receptor T-cell (CAR-T). Here, we evaluated patients whether discordance contributes to medication-related neurotoxicity including fludarabine and cefepime.

Case Description

We reviewed the charts of all patients who received CAR-T between Jan 2024 and Dec 2025 at a major academic center. We examined whether eGFR discordance, defined as eGFR_cys ≥30% lower than eGFR_cr, was associated with neurologic symptoms after CAR-T therapy. Clinical and radiographic data were reviewed to assess for features suggestive of medication-related neurotoxicity. We identified 3 patients with diffuse large B-cell lymphoma and eGFR discordance who developed atypical, prolonged neurotoxicity characterized by persistent encephalopathy, poor response to corticosteroids (CS), and no evidence of inflammatory cells in cerebrospinal fluid (CSF). The first case was a 71-year-old female (eGFR_Cr 93 vs. eGFR_cys 49 mL/min/1.73m² ) who developed persistent altered mental status (AMS) with tremors, myoclonus, and aphasia refractory to CS. The second was an 81-year-old male (eGFR_Cr 72 vs. eGFR_cys 43) who presented with sustained AMS and transient CS response, followed by progressive confusion and lower extremities weakness over a month. MRI showed increasing supratentorial white matter hyperintensities (Figure 1). Finally, an 86-year-old male (eGFR_Cr 59 vs. eGFR_cys 38) developed AMS with diffuse myoclonus refractory to CS and situximab. His course was complicated by AKI, febrile neutropenia treated with cefepime. In all three cases, EEG and CSF were unrevealing.

Discussion

Prolonged, CS-refractory AMS in patients receiving CAR-T with an eGFR discordance should prompt reconsideration of the diagnosis of ICANS and evaluation of alternative, medication-related neurotoxicity.