Based on potent anti-tumor effects observed in preclinical studies using mRNA electroporation [32], an initial study focusing on toxicity assessment was conducted (NCT01355965) at the University of Pennsylvania, US, using T cells that only transiently expressed the second-generation murine anti-mesothelin CAR that contained the CD3ζ and 41BB signalling domains [24,33]. The gene discussed is CD247; the disease is neoplasm.