Gated targeting with a novel switchable CAR platform technology


Gated targeting with a novel switchable CAR platform technology

Feldmann, A.; Hoffmann, A.; Kittel-Boselli, E.; Bergmann, R.; Koristka, S.; Arndt, C.; Loureiro, L.; Berndt, N.; Bachmann, M.

T-cells armed with conventional CARs (cCARs) are highly effective especially in hematological malignancies. However, they often fail against solid tumors, induce tumor escape variants and cause life-threatening side effects. The safety of cCAR therapy should be improved by on/off-switchable CARs. Additionally, gated targeting strategies could increase the CAR specificity, minimize on-target/off-tumor toxicities and reduce tumor escape variants. For AND gate targeting, the signaling and costimulatory motifs are split from one onto two separate CARs of different specificities. Dual-CAR-T-cells, expressing both CARs, get activated only after recognizing both antigens. However, the application of such pairs of cCARs is very challenging as the affinity and signal strength of both CARs have to be adapted accordingly. Furthermore, the cCAR size limits the number of specificities that can be simultaneously transduced into a T-cell.
Therefore, our idea was to replace the extracellular scFv domain of cCARs with a small peptide epitope. Resulting RevCARs have a small size, avoid unspecific binding and tonic signaling caused by scFv dimerization. RevCAR-T-cells can be redirected against tumors only via bispecific target modules. Such RevTMs can be used as on/off-switch of RevCAR-T-cells and flexibly replaced for targeting of any antigens. For proof of concept, two RevCARs with different peptide epitopes and a series of respective RevTMs were constructed and functionally proven for targeting of leukemic as well as solid cancers. Moreover, for gated targeting, two RevCARs were expressed in the same T-cell that differ in their extracellular peptide epitope, transmembrane and intracellular signaling domains to separately transmit isolated activation and costimulatory signals. For efficient activation of Dual-RevCAR-T-cells, both RevCARs must be engaged by respective RevTMs recognizing different epitopes and antigens.
In summary, we established a novel switchable, modular and adaptable RevCAR system characterized by small size, improved safety, easy controllability, and high flexibility allowing gated targeting strategies.

  • Lecture (Conference)
    International Conference on Lymphocyte Engineering (ICLE) 2019, 13.-15.09.2019, London, England
  • Abstract in refereed journal
    Human Gene Therapy 30(2019)12
    DOI: 10.1089/hum.2019.29091.abstracts

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Permalink: https://www.hzdr.de/publications/Publ-29298
Publ.-Id: 29298