Easix Indices Predict CRS and Overall Survival in Adult CAR-T Cell Recipients

Background: Immunotherapy with Chimeric Antigen Receptor T cells (CAR-Τ) is worldwide commercially available for refractory B cell malignancies, with continuously expanding indications.Given that cytokine release syndrome (CRS) and neurotoxicity (ICANS) are encountered in many CAR-T recipients both in trials and real-world setting, novel predictive and prognostic markers are highly needed.

Aim: To this end, we hypothesized that EASIX (Endothelial Activation and Stress Index) and the most recently described modified EASIX (mEASIX) would be associated with severe CRS, ICANS and/or Overall Survival (OS) in the real-world setting.

Methods: We collected data from consecutive adult patients (pts) from six transplant centers in Greece. Tisagenlecleucel and axicabtagene ciloleucel were administered since 2020, and brexucabtagene autoleucel since 2022. All pts received lymphodepleting therapy before CAR-T cell infusion with combination of cyclophosphamide and fludarabine. For patient monitoring as well as for prophylaxis and treatment of side effects, the EBMT and MD Anderson guidelines were adopted. EASIX (lactate dehydrogenase [LDH; U/L] x creatinine [mg/dL]/platelet [PLT] count; 10 ⁹/L]) and mEASIX (which replaces creatinine with CRP [mg/dL]) were calculated before lymphodepletion (baseline), at day of infusion (0), and day 14 (14). The following variables were analyzed: age, gender, disease type and phase, product type, time from collection to product arrival and to infusion, progression-free (PFS) and overall survival (OS), laboratory markers at pre-specified time-points (LDH, creatinine, platelets, ferritin, CRP). Data cut-off date was end of June 2023, with at least 1 month of follow-up post infusion. Multivariate models were not performed due to multicollinearity issues.

Results:

Ninety pts, aged 49 (18-75) years, received commercial CAR-T cell products (33 tisagenlecleucel, 37 axicabtagene ciloleucel, 11 brexucabtagene autoleucel) for refractory/relapsed DLBCL (56), PMBCL (5), TFL (8), B-ALL (10), or MCL (11) after a median of 3 (1-9) previous lines of treatment including autologous (n=13) or allogeneic (n=7) transplantation.

Severe (grade 3-4) CRS and ICANS were noted in 21% and 39%, respectively. Severe CRS was associated with mEASIXbaseline (p=0.025), and CRPbaseline (p=0.001), EASIX14 and m-EASIX14 (p<0.001). Both mEASIXbaseline and m-EASIX14 were able to predict severe CRS in ROC curve (AUC=0.768, p=0.032 and AUC=0.712, p=0.027). Severe ICANS did not correlate with EASIX indices, except for a trend towards statistically significant association with EASIX14 (p=0.054). On the other hand, severe ICANS was associated with increased LDH at baseline (p=0.001).

With a median follow-up of 6.6 (1-42) months, 1-year PFS and OS were 33.2% and 62.5% respectively. Baseline values of ferritin and LDH, CRP values at all time-points, EASIX14 and mEASIX14 were associated with OS. Both EASIX indices predicted death in ROC curves. Similarly, EASIX14 was associated with PFS.

Conclusions: This multicenter study, based on real-world experience with CAR-T cell therapy, confirms the predictive value of EASIX and mEASIX not only for life-threatening complications but also for survival outcomes. The implementation of EASIX may therefore aid in the selection of patients who are candidates for interventions to mitigate untoward sequelae of CAR-T therapy.