CD19 and congenital rubella syndrome: These data could support the development of allogeneic CAR T cells from healthy donors, in whom the activity and cytotoxicity of T cells are not modified by the tumor clone (see section Alternative Sources) or the association with immunomodulatory agents, as discussed supra. Recent results of a pilot study evaluating CD19 CAR T cells concomitantly to ibrutinib in CLL (n = 19) showed a good tolerability, with robust CAR T-cell expansion and decreased CRS severity as compared to CLL patients treated with CAR T cells without ibrutinib, and similar response rates and long-term outcomes (184).