Finally, in a prior trial using mRNA CAR T cells targeting mesothelin, the CAR provoked an anaphylaxis response in a patient after a prolonged break of 49 days between doses.41 Subsequently, anaphylaxis on the trial was prevented by ensuring all doses were delivered no longer than 10 days apart, thus it will be important to ensure similar timing in translation of the mRNA GD2-directed CAR T cell strategy. Here, MSLN is linked to anaphylaxis.