Relation of clinical culture method to T-cell memory status and efficacy in xenograft models of adoptive immunotherapy.
OBJECTIVE
Cytotoxic T lymphocytes modified with chimeric antigen receptors (CARs) for adoptive immunotherapy of hematologic malignancies are effective in pre-clinical models, and this efficacy has translated to success in several clinical trials. Many early trials were disappointing in large part because of the lack of proliferation and subsequent persistence of transferred cells. Recent investigations have pointed to the importance of delivering highly proliferative cells, whether of naive or early memory phenotypes.


METHODS
We investigated the influence of two common cell culturing methods used in early trials and their relationship to T-cell phenotype and pre-clinical efficacy.


RESULTS
We observed that stimulation with soluble anti-CD3 antibody OKT-3 and high-dose interleukin-2 produces more effector memory-type T cells with shorter average telomeres when compared with cells generated with the use of CD3/CD28 beads. When used in xenograft models of leukemia, bead-stimulated cells proliferated earlier and to a higher degree than those generated with the use of OKT-3/IL2 and resulted in better disease control despite no difference in distribution or migration throughout the mouse. Inclusion of the known successful clinical 4-1BB endodomain in the CAR could not rescue the function of OKT-3/IL-2-cultured cells. T cells isolated from animals that survived long-term (>120 days) retained a central memory-like phenotype and demonstrated a memory response to a large re-challenge of CD19-positive leukemia.


CONCLUSIONS
In summary, we confirm that cells with a younger phenotype or higher proliferative capacity perform better in pre-clinical models and that cell culturing influences cell phenotype seemingly independent of the 4-1BB endodomain in the CAR structure.
Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA. Electronic address: barrettd@email.chop.edu.
David M
DM
Barrett
Abramson Family Cancer Research Institute, University of Pennsylvania Cancer Center, Philadelphia, Pennsylvania, USA.
Nathan
N
Singh
Abramson Family Cancer Research Institute, University of Pennsylvania Cancer Center, Philadelphia, Pennsylvania, USA.
Xiaojun
X
Liu
Abramson Family Cancer Research Institute, University of Pennsylvania Cancer Center, Philadelphia, Pennsylvania, USA.
Shuguang
S
Jiang
Abramson Family Cancer Research Institute, University of Pennsylvania Cancer Center, Philadelphia, Pennsylvania, USA.
Carl H
CH
June
Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; Department of Pathology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
Stephan A
SA
Grupp
Abramson Family Cancer Research Institute, University of Pennsylvania Cancer Center, Philadelphia, Pennsylvania, USA.
Yangbing
Y
Zhao
D000818:Animals; D018941:Antigens, CD19 / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D064593:Heterografts; D006801:Humans; D016219:Immunotherapy, Adoptive / Q000379:methods*; D017403:In Situ Hybridization; D007938:Leukemia / Q000276:immunology / Q000628:therapy*; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology
D018941:Antigens, CD19
CD19; T lymphocytes; T-cell memory; chimeric antigen receptor; leukemia