To improve clinical outcomes and shorten the vein-to-vein time of chimeric antigen receptor T (CAR-T) cells, we developed the FasT CAR-T (F-CAR-T) next-day manufacturing platform. We report the preclinical and first-in-human clinical studies evaluating the safety, feasibility, and preliminary efficacy of CD19 F-CAR-T in B-cell acute lymphoblastic leukemia (B-ALL). CD19 F-CAR-T cells demonstrated excellent proliferation with a younger cellular phenotype, less exhaustion, and more effective tumor elimination compared to conventional CAR-T cells in the preclinical study. In our phase I study (NCT03825718), F-CAR-T cells were successfully manufactured and infused in all of the 25 enrolled pediatric and adult patients with B-ALL. CD19 F-CAR-T safety profile was manageable with 24% grade 3 cytokine release syndrome (CRS) and 28% grade 3/4 neurotoxicity occurring predominantly in pediatric patients. On day 14, 23/25 patients achieved minimal residual disease (MRD)-negative complete remission (CR), and 20 subsequently underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) within 3 months post F-CAR-T therapy. Fifteen of 20 patients were disease-free with a median remission duration of 734 days. One patient relapsed and 4/20 died from transplant-related mortality. Of the three patients who did not undergo allo-HSCT, two remained in CR until 10 months post-F-CAR-T. Our data indicate that anti-CD19 FasT CAR-T shows promising early efficacy for B-ALL. Further evaluations in larger clinical studies are needed.

We developed a T-cell-receptor (TCR) complex-based chimeric antigen receptor (CAR) named Synthetic TCR and Antigen Receptor (STAR). Here, we report preclinical and phase I clinical trial data (NCT03953599) of this T-cell therapy for refractory and relapsed (R/R) B-cell acute lymphoblastic leukemia (B-ALL) patients. STAR consists of two protein modules each containing an antibody light or heavy chain variable region and TCR α or β chain constant region fused to the co-stimulatory domain of OX40. T-cells were transduced with a STAR-OX40 lentiviral vector. A leukemia xenograft mouse model was used to assess the STAR/STAR-OX40 T cell antitumor activity. Eighteen patients with R/R B-ALL were enrolled into the clinical trial. In a xenograft mouse model, STAR-T-cells exhibited superior tumor-specific cytotoxicity compared with conventional CAR-T cells. Incorporating OX40 into STAR further improved the proliferation and persistence of tumor-targeting T-cells. In our clinical trial, 100% of patients achieved complete remission 4 weeks post-STAR-OX40 T-cell infusion and 16/18 (88.9%) patients pursued consolidative allogeneic hematopoietic stem cell transplantation (allo-HSCT). Twelve of 16 patients (75%) remained leukemia-free after a median follow-up of 545 (433-665) days. The two patients without consolidative allo-HSCT relapsed on Day 58 and Day 186. Mild cytokine release syndrome occurred in 10/18 (55.6%) patients, and 2 patients experienced grade III neurotoxicity. Our preclinical studies demonstrate super anti-tumor potency of STAR-OX40 T-cells compared with conventional CAR-T cells. The first-in-human clinical trial shows that STAR-OX40 T-cells are tolerable and an effective therapeutic platform for treating R/R B-ALL. | INTRODUCTIONOver the past decades, several chimeric antigen receptor (CAR) T-cell therapies targeting distinct cancer types have received regulatory approvals. [1][2][3][4] While early CAR-T approaches were associated with relatively severe cytokine release syndrome (CRS), CAR-T-related neurotoxicity, and infectious complications, 5,6 second-generation CARs composed of a target-specific single-chain variable fragment (scFv), a flexible hinge region, a transmembrane domain, a costimulatory domain and a CD3ζ intracellular signaling domain have shown remarkable efficacy in patients with B-cell malignancies. 7,8 However, many studies have demonstrated that strengthening the Jiasheng Wang, Xian Zhang, and Zhixiao Zhou contributed equally to this work.

Cytomegalovirus (CMV) infection remains a major cause of mortality after hematopoietic stem cell transplantation (HSCT). Current treatments, including antiviral drugs and adoptive cell therapy with CMV-specific cytotoxic T lymphocytes (CTLs), only show limited benefits in patients. T-cell receptor (TCR)-T cell therapy offers a promising option to treat CMV infections. Here, using tetramer-based screening and single-cell TCR cloning technologies, we identified various CMV antigen-specific TCRs from healthy donors, and generated TCR-T cells targeting multiple pp65 epitopes corresponding to three major HLA-A alleles. The TCR-T cells showed efficient cytotoxicity toward epitope-expressing target cells in vitro. After transfer into immune-deficient mice bearing pp65 + HLA + tumor cells, TCR-T cells induced dramatic tumor regression and exhibited long-term persistence. In a phase I clinical trial (NCT04153279), CMV TCR-T cells were applied to treat patients with CMV reactivation after HSCT. Except one patient who withdrew at early treatment stage, all other six patients were well-tolerated and achieved complete response (CR), no more than grade 2 cytokine release syndrome (CRS) and other adverse events were observed. CMV TCR-T cells persisted up to 3 months. Among them, two patients have survived for more than 1 year. This study demonstrates the great potential in the treatment and prevention of CMV infection following HSCT or other organ transplantation.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective therapy for B-cell acute lymphoblastic leukemia (B-ALL). Although allo-HSCT can be curative for some B-ALL patients, relapse still occurs in some patients following allo-HSCT. Conventional chemotherapies show poor efficacy in B-ALL patients who have relapsed following allo-HSCT. In the past decade, chimeric antigen receptor T-cell (CAR-T) therapy has shown to be efficacious for B-ALL patients. In particular, autologous CD19 CAR-T therapy results in a high remission rate. However, there are challenges in the use of CD19 CAR-T therapy for B-ALL patients who have relapsed following allo-HSCT, including the selection of CAR-T cell source for manufacturing, post-CAR-T graft-versus-host disease (GVHD) risk, maintenance of long-term efficacy after remission through CAR-T therapy, and whether a consolidative second transplant is needed. In this review, we describe the current status of CAR-T therapy for B-ALL patients who have relapsed following allo-HSCT, the advantages and disadvantages of various CAR-T cell sources, the characteristics and management of GVHD following CAR-T therapy, and the risk factors that may affect long-term efficacy. Keywords Allogeneic hematopoietic stem cell transplantation • CD19 chimeric antigen receptor T-cell therapy • B-cell acute lymphoblastic leukemia • Relapse Prevention and management of relapse after allogeneic hematopoietic cell transplantation in hematological malignanciesPei-hua Lu and Kai-yan Liu have contributed equally to this work.