CAR T cell therapy has shown dramatic clinical success in relapsed or refractory B-ALL and other hematological malignancies. However, the loss of specific antigens, cell fratricide, T cell aplasia, and normal T cell separation are challenges in treating T cell leukemia/lymphoma with CAR T therapy. CD99 is a promising antigen to target T-ALL and AML as it is strongly expressed on the majority of T-ALL and AML. Here, we isolated a low-affinity CD99 (12E7) antibody, which specifically recognizes leukemia cells over normal blood cells. Moreover, T cells transduced with an anti-CD99-specific CAR that contained the 12E7 scFv expanded with minor fratricide and without normal blood cells toxicity. We observed that our anti-CD99 CAR T cells showed robust cytotoxicity specifically against CD99+ T-ALL cell lines and primary tumor cells in vitro and significantly prolonged cell line-derived xenografts (CDXs) or patient-derived xenografts (PDXs) models survival in vivo. Together, our results demonstrate that anti-CD99 CAR T cells could specifically recognize and efficiently eliminate CD99+ leukemia cells.

CAR T cell therapy has shown dramatic clinical success in relapsed or refractory (r/r) B-ALL and other haematological malignancies. However, the loss of specific antigens, cell fratricide, T cell aplasia, and normal T cell separation are challenges in treating T cell leukemia/lymphoma with CAR T therapy. CD99 is a promising antigen to target T-ALL and AML as it is expressed on the majority of T-ALL and AML. Here, we isolated a low-affinity CD99 (12E7) antibody, which specifically recognizes leukemia cells over normal bone marrow cells. T cells transduced with an anti-CD99-specific CAR that contained the 12E7 scFv expanded with minor fratricide, maintained their cytotoxic function and mediated powerful antitumour effects. Subsequently, we conducted a pilot clinical study to evaluate the safety and feasibility of therapy with anti-CD99 CAR T cells in 4 patients with r/r T-LBL (n=1), AML (n=2) or myeloid sarcoma (MS) (n=1). The clinical overall response rate (ORR) was 50% (2/4 patients), and 1 patients (25%) achieved complete remission (CR) for 2 month. Mild cytokine release syndrome (CRS) occurred in 2 patients and the CRS no more than grade 2. Together, our results demonstrate that anti-CD99 CAR T cells specifically recognize and efficiently eliminate CD99+ leukemia cells.

Abstract:Cr-Si-O-N coatings with different oxygen contents were deposited by multi-arc ion plating, where various O 2 /(N 2 + O 2 ) reactive gas rates were adopted. The XRD and XPS results showed that the CrN crystals disappeared with the increasing of the oxygen flux ratio to 10 at.%. The microhardness of all the Cr-Si-O-N coatings was approximately 2000 Hv 0.05 , which were dramatically plummeted compared to that of the Cr-Si-N coatings (≈3300 Hv 0.05 ). The Cr-Si-O-N coatings were annealed under 800 • C and 1200 • C in the air atmosphere for 2 h to study the high-temperature oxidation resistance of the coatings. Meanwhile, Cr-Si-O-N coatings with different O 2 /(N 2 + O 2 ) rates were also used to carry out the corrosion resistance testing using the electrochemical working station in 3.5% NaCl solution under free air condition at room temperature. The results indicated that the coatings containing oxygen were more vulnerable to the high-temperature destruction and more easily corroded in the NaCl electrolyte.

293T suspensions cells were first cultured in a big bubble-stirred bioreactors for large-scale lentivirus vectors (LV) production in the study. Direct domesticated approaches were utilized for 293 suspensions cells. We validated of the ability to LV package and drew a growth curve in shake flask. The results show 293T suspension culture was successful, and also retained the capacity for LV production. After facile optimization of the viral package and cryopreservation conditions, 293T suspension cells were inoculated in a 5.5 L bioreactor. Packaged CAR-CD30 lentivirus yield was close to that from the original shake flask culture. Cultivation for 4 days in the bioreactor enabled production of 1.5±0.3×107 TU/mL coarse LV and the lentiviral infection efficiency was 48.6±2.8% in T Cells. The process has merits of low cost as well as more effective, and expected to be highly competitive compared to other bioreactors.