Current Chimeric Antigen Receptor (CAR) T cell treatments can be profoundly successful in treating cancers, but there are challenges in developing new treatments to benefit more patients. We aim to improve safety and efficacy through improved control over the strength and quality of receptor signalling. We have developed a series of synthetic TM domains that adopt specific oligomeric states (monomers, dimers, trimers, tetramers), and when inserted into CARs to make programmable CARs (proCARs) they drive tuneable biochemical signalling and functional outputs.
Future developments may involve expressing multiple Chimeric Antigen Receptors that can be independently tuned in the same cell. To measure the pairwise interactions of proCARs with different TM domains, we used FRET (Forster Resonance Energy Transfer) and a novel assay we call “pull-sideways” in live mammalian cell membranes. We found that some of our synthetic TM domains oligomerised separately without cross-assembly, but others did not. These results determine which pairs of TM domains we can use for future CAR-T cell therapies using independently tuneable insulated signalling pathways.