CD19 and Miyoshi myopathy: Numerous strategies to improve outcomes and delivery of cellular immunotherapy are under investigation, including next‐generation CARs, allogeneic ‘off‐the‐shelf’ CARs and targeting of other MM antigens including G protein‐coupled receptor, class C, group 5, member D (GPRC5D), Fc receptor homologue 5 (FcRH5), cluster of differentiation (CD)19, signalling lymphocyte activation molecule family member 7 (SLAMF7) and several others.