Article Text

Download PDFPDF

375 In vivo generation of universal CAR T cells that mediate durable anti-tumor immunity through combinatorial targeting with bispecific small molecule adapters
  1. Kristen Mittelsteadt,
  2. Isabel Leung,
  3. Kelsey Lynch,
  4. Haiyan Chu,
  5. Chang-Chih Wu,
  6. Seungjin Shin,
  7. Ryan Larson,
  8. Andrew Scharenberg,
  9. Byoung Ryu and
  10. Laurie Beitz
  1. Umoja Biopharma, Seattle, WA, USA


Background Chimeric antigen receptor (CAR) T cell therapies have demonstrated limited efficacy against solid tumors, in part due to challenges overcoming solid tumor heterogeneity and CAR T cell exhaustion associated with the immunosuppressive tumor microenvironment (TME). Our integrated platform aims to overcome these roadblocks by engineering T cells in vivo to express a universal TagCAR which binds to a common tag on bispecific adaptor TumorTags, bridging TagCAR T cells to TumorTag-bound tumor- and TME-associated antigens, including folate receptor (FR) which is upregulated on many tumor types as well as immunosuppressive tumor-associated macrophages. Additionally, our TagCAR T cells are engineered to express a rapamycin-activated cytokine receptor (RACR) which selectively provides survival signals to TagCAR T cells in the presence of rapamycin. Here, we identify a universal TagCAR that demonstrates potent in vitro and in vivo anti-tumor polyfunctionality against FR+ target cells with a folate receptor-targeting TumorTag (UB-TT170).

Methods PBMCs from healthy donors were transduced in vitro with surface-engineered lentiviral vectors with TagCAR/RACR payloads. Resultant TagCAR T cell anti-tumor activity and persistence was assessed using a co-culture approach with FR-expressing tumor cells and titrated doses of UB-TT170. To assess in vivo anti-tumor activity, lentiviral particles containing TagCAR/RACR payloads were administered to PBMC-humanized NSG mice with established FR+ xenograft solid tumors to generate TagCAR T cells in vivo. Mice were treated with UB-TT170 and efficacy was determined by assessing tumor regression and UB-TT170-mediated TagCAR T cell expansion.

Results TagCAR T cells containing a CD8α hinge/transmembrane domain and 41bbζ endodomain were superior to other construct candidates in eliminating FR+ target cells in the presence of UB-TT170 in vitro. These TagCAR T cells demonstrated UB-TT170-mediated expansion and proinflammatory cytokine production in the presence of FR+ target cells, and repeated elimination of target cells and enhanced persistence properties with serial antigen-exposure. Cells transduced with this vector exhibited RACR-mediated expansion and improved function in the presence of rapamycin. Administration of TagCAR/RACR payload-containing lentiviral particles to PBMC-humanized NSG mice resulted in generation of TagCAR T cells in vivo, which expanded and mediated clearance of FR+ solid tumors with UB-TT170

Conclusions We have identified a universal TagCAR that displays robust anti-tumor activity and persistence qualities against FR+ target cells in vitro and in vivo with UB-TT170. These data support development of this platform as a new cellular therapy approach against solid tumors, using combinatorial targeting of tumor- and TME-associated antigens with an in vivo-generated universal TagCAR and multiple TumorTags.

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.