Easix and Modified-Easix Are Early Predictors of Severe Cytokine Release Syndrome and Neurotoxicity in Patients Treated with Chimeric Antigen Receptor T Cells

Introduction

Chimeric Antigen Receptor (CAR) T cells are associated with unique toxicities, including cytokine release syndrome (CRS) and immune effector cells-associated neurotoxicity syndrome (ICANS). Patients (pts) with severe CRS and ICANS exhibit hemodynamic instability and coagulopathy with evidence of endothelial activation and increased blood brain barrier permeability. Increases in inflammatory cytokines and biomarkers of endothelial activation in serum and CSF have been associated with severe CRS and ICANS. The EASIX (Endothelial Activation and Stress Index) score [lactate dehydrogenase (LDH) (U/L) × creatinine (mg/dl) / platelets (PLT) (10⁹ cells/L)] correlates with severe fluid overload and survival in allogeneic transplant pts. Elevated LDH and low PLT levels have been associated with severe ICANS development, and high IL-6 levels are seen in severe CRS and ICANS. We hypothesized that the EASIX and a newly proposed version of it, the modified-EASIX (mEASIX), in which creatinine is replaced by CRP (mg/dL) as an easily available surrogate for IL6, would be associated with CRS and ICANS in CAR T cells pts.

Methods

We analyzed 2 different populations of adult CAR T cells pts treated at our institution: 1) B-cell acute lymphoblastic leukemia (B-ALL) pts treated with CD1928z CAR T cells from 2010 to 2016 (NCT01044069), and 2) aggressive diffuse large B-cell lymphoma (DLBCL) pts treated with axicabtagene ciloleucel (axi-cel) or tisagenlecleucel (tisa-cel) after FDA approval starting from 2018. EASIX and mEASIX scores were calculated for each patient daily from start of lymphodepletion conditioning to day +14. A log transformation using base 2 (log2) was applied to all EASIX/mEASIX variables to reduce skew. CRS and ICANS were graded according to the ASTCT grading system.

Results

87 pts, B-ALL (n=53) and DLBCL (n=34), were analyzed. According to ASTCT grading, 83% (72/87) experienced CRS and 54% (47/87) developed ICANS, grade ≥3 in 23% (20/87) and 40% (35/87) of pts, respectively. When analyzed by disease, CRS and ICANS rates were 87% (46/53) and 55% (29/53) for B-ALL and 76% (26/34) and 53% (18/34) for DLBCL, respectively. CRS and ICANS were grade ≥3 in 28% (15/53) and 45% (24/53) of B-ALL pts and in 15% (5/34) and 32% (11/34) of DLBCL pts, respectively. Median time of onset of CRS after CAR T cell infusion was day +2 and median onset of ICANS was day +6 for the overall population and the subgroups. High EASIX and mEASIX scores at start of conditioning were both associated with development of any grade CRS [OR=1.81 (95% CI 1.09-3.36) p=0.038 and OR=1.94 (95% CI 1.32-3.38) p=0.005] and grade ≥3 CRS [OR=1.47 (95% CI 1.05-2.29) p=0.049 and OR=1.34 (95% CI 1.07-1.80) p=0.024], respectively (Table). Following CAR T cell infusion, high scores of both EASIX [OR=1.60 (95% CI 1.12-2.43) p=0.017] and mEASIX [OR=1.32 (95% CI 1.07-1.69) p=0.014] on day +1 were associated with development of grade ≥3 CRS. Moreover, both high EASIX [OR=1.43 (95% CI 1.08-1.96) p=0.018] and mEASIX [OR=1.29 (95% CI 1.07-1.60) p=0.010] scores on day +3 were associated with grade ≥3 ICANS. When analyzed by disease, results were confirmed for severe CRS and ICANS in B-ALL patients, while in the DLBCL group only mEASIX at start of conditioning and at day +1 was associated with development of any grade CRS. EASIX and mEASIX scores were not associated with response rates to CAR T cells therapy.

Conclusions

EASIX and mEASIX scores calculated at baseline (before lymphodepletion) are associated with development of CRS and severe CRS. Moreover, both high EASIX and mEASIX scores on day +1 and day +3 are associated with occurrence of grade ≥3 CRS and grade ≥3 ICANS, respectively. We conclude that EASIX and mEASIX, as markers of endothelial damage and inflammation, could be useful as early predictors in guiding treatment decisions before the onset of severe symptoms.

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