One group found that armoring CAR T-cells with superkine IL-2 (Super2), a variant of IL-2 that binds to the IL-2 receptor with higher affinity than the wild-type cytokine, and IL-33 significantly enhanced anti-tumor activity in vivo compared to armoring with either cytokine alone, without evidence of toxicity in the immunocompetent mouse models used (59). Here, IL33 is linked to neoplasm.