Advanced engineering strategies. Combining CAR transfer with genome editing offers the prospect of enhanced CAR T cells. Viral vector CAR transduction has been combined with co-expressed guide RNAs and electroporation of mRNA coding for Cas9 or base editor (BE). Alternatively, Cas9/guide RNP complexes offer efficient editing, and a route to site-specific transgene insertion by homologous recombination if a suitable CAR template is provided. Other advances include the ability to remove shared antigens such as CD7 that would otherwise result in T-cell fratricide during manufacture, and simultaneous manipulation of checkpoint pathways to address exhaustion and promote activity.