Neurotoxicity of Axicabtagene Ciloleucel and Long-Term Outcomes - in a Minority Rich, Ethnically Diverse Real World Cohort

Introduction

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment of B- cell malignancies leading to durable responses in patients with relapsed/refractory disease. ^1,2 One of the most severe toxicities associated with this treatment is immune effector cell-associated neurotoxicity syndrome (ICANS), which was seen in 65-75% of patients treated with axicabtagene ciloleucel (axi-cel) in initial clinical trials. ICANS can range from mild headache to coma, and can occur with or without cytokine release syndrome (CRS). Due to the recent development of CAR T-cell therapy, the long-term effects of ICANS are unknown. This study sought to determine the long-term outcomes in patients with neurotoxicity from axi-cel.

Methods

We conducted a retrospective chart review of patients who received CAR T-cell therapy with axi-cel between June 2018 and June 2021. Neurotoxicity was graded according to the American Society for Transplantation and Cellular Therapy (ASTCT) ICANS grading system. ³ The primary outcome was percentage of patients who had neurotoxicity defined as ICANS grade ≥ 1 as well as the percentage of patients with neurotoxicity lasting ≥ 1 month. We captured descriptive data such as age, sex, ethnicity, comorbidities, IPI score, stage, baseline neurologic dysfunction, performance status, and number of prior treatments. Secondary outcomes included progression free survival (PFS) and overall survival (OS).

Results

Thirty-four patients received axi-cel between June 2018 and June 2021 at our institution. Median age of patients was 65. Twenty patients (59%) were male and 14 (41%) were female. The majority of patients received axi-cel for diffuse large B-cell lymphoma (97%). Study population was predominantly hispanic (35%), white (32%), African american (29%) and asian (3%). (Sixteen patients (47%) developed neurotoxicity of any grade, with 7 patients (21%) ≥ grade 3. Of note, 4 patients (12%) died during admission for CAR T-cell therapy and 3/4 deaths were in patients with ICANS ≥ grade 3. Median follow up time was 8 months. Of the 12 patients with neurotoxicity who survived initial admission for CAR-T, 9 (75%) patients recovered from neurotoxicity and mental status was at baseline at discharge without recurrence during follow up. Three (25%) of patients had prolonged neurotoxicity lasting > 1 month. Long-term neurotoxicity included confusion, disorientation,

and mild cognitive impairment in the three patients. One patient recovered 15 months after CAR T-cell infusion. 2 patients had prolonged neurotoxicity resulting in deterioration of functional status and death in 1 patient, and 1 patient transitioning to hospice and being lost to follow up.

Conclusions

Neurotoxicity from axicabtagene ciloleucel is a common adverse event, with half of patients in our cohort having neurotoxicity of some degree, and 20% ≥ grade 3. Twenty-five percent of patients that developed neurotoxicity had long-term effects lasting > 1 month, which resulted in deterioration of functional status in 2 patients. Long-term neurotoxicity included disorientation, confusion, and memory impairment. Our study is limited by a small sample size. Larger studies with longer follow-up times are needed to further characterize the long-term outcomes of neurotoxicity associated with CAR T-cell therapy. Neurotoxicity can be confounded by other causes of neurological dysfunction in these patients such as hospital delirium, chemotherapy toxicity, encephalopathy from infection, and subtle baseline neurologic dysfunction that may not be apparent at presentation. Next steps include prospective evaluation of patients with formal neurology evaluation prior to CAR T-cell therapy and periodically after treatment, in order to objectively monitor late neurologic effects of CAR T-cell therapy.

1. Fl, L. et al. Long-term safety and activity of axicabtagene ciloleucel in refractory large B-cell lymphoma (ZUMA-1): a single-arm, multicentre, phase 1-2 trial. Lancet Oncol. 20, (2019).

2. Jacobson, C. Primary Analysis of Zuma-5: A Phase 2 Study of Axicabtagene Ciloleucel (Axi-Cel) in Patients with Relapsed/Refractory (R/R) Indolent Non-Hodgkin Lymphoma (iNHL). in (ASH, 2020).

3. Dw, L. et al. ASTCT Consensus Grading for Cytokine Release Syndrome and Neurologic Toxicity Associated with Immune Effector Cells. Biol. Blood Marrow Transplant. J. Am. Soc. Blood Marrow Transplant. 25, (2019).