Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) is triggered by BCR/ABL kinase. Recent efforts focused on the development of more potent tyrosine kinase inhibitors (TKIs) that also inhibit mutant tyrosine kinases such as nilotinib and dasatinib. Although major advances in the treatment of this aggressive disease with potent inhibitors of the BCR/ABL kinases, patients in remission frequently relapse due to drug resistance possibly mediated, at least in part, by compensatory activation of growth-signaling pathways and protective feedback signaling of leukemia cells in response to TKI treatment. Continuous activation of AKT/mTOR signaling and inactivation of p53 pathway were two mechanisms of TKI resistance. Here, we reported that nutlin-3 plus tanshinone IIA significantly potentiated the cytotoxic and apoptotic induction effects of imatinib by down-regulation of the AKT/mTOR pathway and reactivating the p53 pathway deeply in Ph+ ALL cell line. In primary samples from Ph+ ALL patients, nutlin-3 plus tanshinone IIA also exhibited synergetic cytotoxic effects with imatinib. Of note, three samples from Ph+ ALL patients harboring T315I mutation also showed sensitivity to the combined treatment of imatinib, nutlin-3 plus tanshinone IIA. In Ph+ ALL mouse models, imatinib combined with nutlin-3 plus tanshinone IIA also exhibited synergetic effects on reduction in leukemia burden. These results demonstrated that nutlin-3 plus tanshinone IIA combined TKI might be a promising treatment strategy for Ph+ ALL patients.
CD7 has been found to be a promising chimeric antigen receptor (CAR)-T cell target in several clinical trials. However, its expression on normal T cells poses additional challenges in CD7-directed CAR, such as complete fratricide, contamination with malignant cells, and immune suppression due to T-cell aplasia. By taking advantage of evolved affinity between ligand and receptor, we constructed a CD7-directed CAR with the extracellular domain of SECTM1, a natural ligand of CD7, as the recognition domain. SECTM1 CAR-T cells killed the majority of T cells with high CD7 expression in vitro. However, SECTM1 CAR-T cells with low or negative CD7 expression survived, expanded, and showed strong cytotoxicity to CD7-positive malignant cell lines and primary leukemic blasts from T-ALL and AML patients in vitro. It also exhibited efficacy in inhibiting xenograft tumor growth in vivo. More exploration is needed for clinical efficacy potential to CD7 positive patients.
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