Introduction Inspired by the successful experience of CAR-T therapy in B-cell malignancies, its introduction to T-cell tumors is being studied. CD7, highly expressed on T-cell tumors, provides a potential target for CAR-T therapy. However, it is also present on normal T and NK cells, leading to possible fratricide of CAR-T during the production and elimination of T and NK cells after infusion. Moreover, CD7 was suggested to express on parts of hematopoietic stem cells (HSC). Thus, apart from the clinical efficacy and safety, the manufacture and hematopoietic toxicity (HPT) are essential topics related with anti-CD7 CAR-T therapies. Here, we reported the preliminary results of phase I clinical trial of anti-CD7 CAR-T (SENL101, dual CD7-nanobodies with 4-1BB co-stimulation domain and CD7 gene unmodified) to address these issues in CD7 + T-cell acute leukemia and lymphoblastic lymphoma (T-ALL and T-LBL) patients.