ERBB2 and neoplasm: Hernandez-Lopez et al. in a recent publication offered an elegant, new approach termed “two-step recognition circuit”.1 The authors have developed a synNotch-controlled gene expression system in which low affinity HER-2 specific CAR recognizing high, but not low, levels of HER-2 expressed on tumour cells induces the expression of a high affinity HER-2-specific 2nd generation CAR on the T-cell surface (Fig. 1).