Differential Role of Th1 and Th2 Cytokines in Autotoxicity Driven by CD19-Specific Second-Generation Chimeric Antigen Receptor T Cells in a Mouse Model

Abstract

T cells engrafted with chimeric AgRs (CAR) are showing exciting potential for targeting B cell malignancies in early-phase clinical trials. To determine whether the second-generation CAR was essential for optimal antitumor activity, two CD28-based CAR constructs targeting CD19 were tested for their ability to redirect mouse T cell function against established B cell lymphoma in a BALB/c syngeneic model system. T cells armed with either CAR eliminated A20 B cell lymphoma in vivo; however, one construct induced a T cell dose-dependent acute toxicity associated with a raised serum Th1 type cytokine profile on transfer into preconditioned mice. Moreover, a chronic toxicity manifested as granuloma-like formation in spleen, liver, and lymph nodes was observed in animals receiving T cells bearing either CD28 CAR, albeit with different kinetics dependent upon the specific receptor used. This phenotype was associated with an expansion of CD4+CAR+ T cells and CD11b+Gr-1+ myeloid cells and increased serum Th2-type cytokines, including IL-10 and IL-13. Mouse T cells engrafted with a first-generation CAR failed to develop such autotoxicity, whereas toxicity was not apparent when T cells bearing the same receptors were transferred into C57BL/6 or C3H animals. In summary, the adoptive transfer of second-generation CD19-specific CAR T cells can result in a cell dose–dependent acute toxicity, whereas the prolonged secretion of high levels of Th2 cytokines from these CAR T cells in vivo drives a granulomatous reaction resulting in chronic toxicity. Strategies that prevent a prolonged Th2-cytokine biased CAR T cell response are clearly warranted.

CAR T-cell Therapy: Toxicity and The Relevance of Preclinical Models

“…However, a recent study from our group has reported short-term Th1-biased cytokine driven toxicity in mice receiving mouse CD19 targeted, second-generation CAR T cells and also reported a chronic toxicity resulting from the specific expansion of myeloid cells in response to Th2-biased cytokine production arising from chronic CD4 + CAR T-cell activity [41]. In this system, acute toxicity manifested as rapid weight loss and cachexia with death occurring 1-5 days after adoptive T-cell transfer.…”

“…This third potential mechanism of CAR T-cell toxicity has arisen in experimental models of CAR T-cell therapy recently and relates to the response of non-CAR T cells to the therapy [41]. Prolonged, potentially low level, CAR T-cell activity may indirectly impact upon the local environment resulting in skewing of normal homeostatic cellular responses, that in turn develop into toxicities.…”

“…Interestingly, affected animals were essentially devoid of CD8 + CAR T cells and B cells. Together, this suggests that chronic stimulation of resident CD4 + CAR T cells, most likely due to B cells emerging from hematopoietic progenitor cells, caused production of Th2 cytokines that mediated the expanfuture science group CAR T-cell therapy: toxicity & the relevance of preclinical models Review sion of the myeloid cell compartment resulting in a lethal granulomatous reaction [41].…”

Hurdles of CAR-T cell-based cancer immunotherapy directed against solid tumors

“…A case reported by Morgan et al showed that activation of anti-ErbB2 CAR-T cells against healthy epithelial tissues that included the lung and heart resulted in the patient's death soon after adoptive transfer . The third potential mechanism of CAR-T cell toxicity may relate to the response of non-CAR-T cells to the therapy (Cheadle et al, 2014). Integrating vectors based upon retroviral and lentiviral backbones may pose a potential risk of oncogenic events.…”

Adoptive T-Cell Therapy for Cancer in the United Kingdom: A Review of Activity for the British Society of Gene and Cell Therapy Annual Meeting 2015

“…However, the Gilham/Hawkins group at the University of Manchester is actively investigating CAR T-cell-mediated toxicity and, in particular, attempting to understand chronic toxicity associated with certain CD19-specific second-generation CARs in syngeneic lymphoma model systems 62 while also working upon improving the in vitro culture conditions used to generate engineered T-cells to improve in vivo functionality. 63 Additionally, the recent arrival of Prof. Mark Exley to Manchester is stimulating work to investigate the efficacy and potency of CARs in iNKT cells.…”