CAR-based Cellular Therapy: clinical ePoster

A101 - EMERGING CYTOKINE RELEASE SYNDROME IS ASSOCIATED WITH REDUCTION OF CD4+CD25HIGH127DIM T REGULATORY CELLS IN PATIENTS AFTER CAR T CELL THERAPY (ID 432)

Authors
  • C. Schultze-Florey
  • V. Panagiota
  • I. Odak
  • S. Bektas
  • T. Froehlich
  • A. Gladysz
  • Z. Li
  • G. Beutel
  • M. Eder
  • I. Prinz
  • R. Foerster
  • A. Ganser
  • C. Koenecke

Abstract

Background:
Chimeric antigen receptor (CAR) T cell therapy is often accompanied by potentially life-threatening cytokine release syndrome (CRS). The role of T regulatory cells (Tregs) during CRS remains to be elucidated. Here we prospectively investigated the Tregs population in patients with and without CRS after anti-CD19-CAR T Infusion.

Methods:
The cohort consisted of 11 patients with relapsed or refractory transformed follicular lymphoma and diffuse large B cell lymphoma (DLBCL). All received anti-CD19-CAR T infusion (Tisagenlecleucel) after lymphodepletion with fludarabine and cyclophosphamide. All patients gave written informed consent to participate in the study. Patients were grouped based on emergence of CRS. Tregs were detected from peripheral blood via flow cytometry by staining for CD4+CD25+CD127dim- lymphocytes. To determine the absolute frequencies BD Trucount_ tubes were employed. Three time points were selected for analysis: baseline (d-1 - d+2 from Tisagenlecleucel infusion); 1 day prior or at the day of CRS diagnosis before start of CRS treatment (TP1, d+1 - d+6); after CRS clearance (TP2, d+3 - d+10). As control group served patients without CRS using comparable time points.

Results:
Four patients met CRS criteria (Grade 1-4). On 3/4 CRS patients blood samples were available at all three time points and these were thus selected for analysis. Upon emergence of CRS (TP1) Tregs (measured in frequency of lymphocytes) showed a mean reduction of -46.91% compared to the baseline time point while the no-CRS controls increased their frequency by on average +10.57% (Figure 1A). Inter-group comparison at TP1 revealed differences of Tregs levels (0.87 vs. 3.10 % of lymphocytes) as well as in absolute Tregs count (1.79 Tregs/µl vs. 8.84 Tregs/µl, Figure 1B). Tregs frequencies in patients after CRS clearance (TP2) increased on average by 3.05-fold compared to TP1 while Tregs frequencies stayed stable in controls (Figure 1A). Based on this increase, Tregs frequencies at TP2 were similar to values of no-CRS patients. These findings are limited by the small patient number and in general low frequencies of Tregs early after CAR T infusion. Therefore, these pilot data need validation in a larger cohort.

Conclusions:
In this prospective single center pilot study, blood samples of emerging CRS showed a reduction of Tregs frequencies and absolute numbers compared to no-CRS patients. After clearance of CRS, Tregs frequencies increased to values of no-CRS patients. Therefore, investigation of Treg frequencies as a predictive marker for CRS should be further investigated. However, future studies are needed to validate these findings in a larger cohort.



[Figure 1: Tregs frequencies in CRS vs no CRS patients.]

 

Disclosure:
Nothing to declare.

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