Importantly, the first two published pediatric clinical trials of CD19 CARs in B-ALL illustrate both the impressive clinical efficacy of these therapeutics and the fact that not every CAR molecule is created equally, with a major divergence in long-term persistence seen between different CAR architectures (Lee et al. 2015, Maude et al. 2014). The gene discussed is CD19; the disease is acute lymphoblastic leukemia.