Two autologous chimeric antigen receptor (CAR) T cell therapies (KymriahTM and YescartaTM) were recently approved by the FDA. KymriahTM is for the treatment of pediatric patients and young adults with refractory or relapse (R/R) B cell precursor acute lymphoblastic leukemia and YescartaTM is for the treatment of adult patients with R/R large B cell lymphoma. In common, both are CD19-specific CAR T cell therapies lysing CD19-positive targets. Their dramatic efficacy in the short term has been highlighted by many media reports. By contrast, their glaring safety gaps behind the miracles remain much less addressed. Here, we focus on addressing the crucial challenges in relation to the gaps.