The 4th International Workshop on CAR-T (iwCAR-T) was held in Tampa, FL, with the aims of bringing together leading international clinical and translational research minds in CAR-T together in an in-person forum to discuss the current state of affairs in clinical care and research in CAR-T and to set the agenda for clinical and translational research priorities in collaboration with relevant stakeholder Day 1 of iwCAR-T featured discussions on emerging CARs and future challenges in solid tumors.