<p>Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable success in treating haematologic malignancies. However, the rise in clinical use has highlighted substantial challenges related to T cell- and tumour-intrinsic mechanisms. Additionally, the tumour microenvironment can render these treatments dysfunctional. Extensive attempts in the field are optimizing the key elements of CAR T cell products for therapy, including antigen specificity and affinity, metabolic fitness, phenotypic stability and manufacturing. Recent efforts in transcriptomic and epigenetic profiling, as well as high-throughput functional screening methods, have identified new classes of targets, binders and mechanisms to be exploited. Advances in gene editing and delivery offer opportunities to translate those strategies into clinical trials. Here we discuss the multifaceted exploration of CAR T cell engineering approaches and emerging directions, highlighting the available strategies that can be built on to create the next generation of cellular therapies.</p>