Chimeric Receptors Containing CD137 Signal Transduction Domains Mediate Enhanced Survival of T Cells and Increased Antileukemic Efficacy In Vivo

Abstract

Persistence of T cells engineered with chimeric antigen receptors (CARs) has been a major barrier to use of these cells for molecularly targeted adoptive immunotherapy. To address this issue, we created a series of CARs that contain the TCR-ζ signal transduction domain with the CD28 and/or CD137 (4-1BB) intracellular domains in tandem. After short-term expansion, primary human T cells were subjected to lentiviral gene transfer, resulting in large numbers of cells with >85% CAR expression. In an immunodeficient mouse xenograft model of primary human pre-B-cell acute lymphoblastic leukemia, human T cells expressing anti-CD19 CARs containing CD137 exhibited the greatest anti-leukemic efficacy and prolonged (>6 months) survival in vivo, and were significantly more effective than cells expressing CARs containing TCR-ζ alone or CD28-ζ signaling receptors. We uncovered a previously unrecognized, antigen-independent effect of CARs expressing the CD137 cytoplasmic domain that likely contributes to the enhanced antileukemic efficacy and survival in tumor bearing mice. Furthermore, our studies revealed significant discrepancies between in vitro and in vivo surrogate measures of CAR efficacy. Together these results suggest that incorporation of the CD137 signaling domain in CARs should improve the persistence of CARs in the tumor microenvironment and hence maximize their antitumor activity.

Engineering HIV-Resistant, Anti-HIV Chimeric Antigen Receptor T Cells

“…scFvs from the previously reported human anti-HIV bNAbs PGT145, PGT128, 10E8, and VRC07-523 [51][52][53] were gene-synthesized by GenScript ( Figure S3). Synthesized scFvs included additional sequences for cloning into BamHI and NheI sites of pRRL-MND-CD19CAR-BFP while maintaining the reading frame with upstream human CD8 signal peptide and downstream CAR domains (including CD8a hinge and transmembrane domains and 4-1BB and CD3z intracellular signaling domains 64 ). The AAV6-CCR5-HIVCAR plasmid is as described previously, 48 except that RQR8 was replaced by BFP.…”

Intrinsic Functional Potential of NK-Cell Subsets Constrains Retargeting Driven by Chimeric Antigen Receptors

“…The first construct additionally comprises an IgG1-CH2CH3 spacer region and costimulatory domains from CD28 and OX40, and the second consists of CD8 spacer region and 4-1BB costimulatory domain. This CAR was originally described in (24) and cloned into a retroviral SFG vector by M. Pule and colleagues. For the purpose of this study both constructs were recloned from the retrovirus vector SFG into the mRNA expression vector pCIpA102 as described in (25).…”

CART‐cells merge into the fast lane of cancer care

“…To overcome this limitation, several groups developed "2nd generation CARs" which include an additional CD28 or CD137(4-1BB) derived co-stimulatory domain in addition to the CD3f domain. The strong pre-clinical suggestion that 2nd generation CARs would translate into a more potent anti-tumor product [13,14] has now been proven by dramatic clinical outcomes for patients with relapsed and refractory CD191 malignancies (see Table I) [1][2][3][4]6]. The optimal co-stimulatory domain for 2nd generation CARs is not known but pre-clinical studies suggest 4-1BB CARs may yield improved in vivo expansion and persistence and 4-1BB CARs have been shown to have prolonged persistence in CLL and ALL recipients, which may correlate with sustained remissions [4,6,14].…”