Adoptive T cell therapy using chimeric antigen receptor (CAR)-modified T cells is a promising cancer immunotherapy. We previously developed a non-viral method of gene transfer into T cells using a piggyBac transposon system to improve the cost-effectiveness of CAR-T cell therapy. Here, we have further improved our technology by a novel culture strategy to increase the transfection efficiency and to reduce the time of T cell manufacturing. Using a CH2CH3-free CD19-specific CAR transposon vector and combining irradiated activated T cells (ATCs) as feeder cells and virus-specific T cell receptor (TCR) stimulation, we achieved 51.4% ± 14% CAR+ T cells and 2.8-fold expansion after 14 culture days. Expanded CD19.CAR-T cells maintained a significant fraction of CD45RA+CCR7+ T cells and demonstrated potent antitumor activity against CD19+ leukemic cells both in vitro and in vivo. Therefore, piggyBac-based gene transfer may provide an alternative to viral gene transfer for CAR-T cell therapy.

Insertional mutagenesis is an important risk with all genetically modified cell therapies, including chimeric antigen receptor (CAR)-T cell therapy used for hematological malignancies. Here we describe a new tagmentation-assisted PCR (tag-PCR) system that can determine the integration sites of transgenes without using restriction enzyme digestion (which can potentially bias the detection) and allows library preparation in fewer steps than with other methods. Using this system, we compared the integration sites of CD19-specific CAR genes in final T cell products generated by retrovirus-based and lentivirus-based gene transfer and by the piggyBac transposon system. The piggyBac system demonstrated lower preference than the retroviral system for integration near transcriptional start sites and CpG islands and higher preference than the lentiviral system for integration into genomic safe harbors. Integration into or near proto-oncogenes was similar in all three systems. Tag-PCR mapping is a useful technique for assessing the risk of insertional mutagenesis.

Genome-wide association studies (GWAS) performed mostly in populations of

We describe successful treatment of 3 cases of human herpesvirus 6 (HHV-6) encephalitis/myelitis following cord blood transplantation (CBT). Ganciclovir (GCV) (10 mg/kg/day) reduced HHV-6 load to undetectable levels in cerebrospinal fluid (CSF). Early dose reduction in the presence of HHV-6 detectable in CSF resulted in an increased HHV-6 load. GCV was capably shifted to valganciclovir (VGCV) with an almost equivalent concentration. GCV/VGCV may be effective for HHV-6 encephalitis/myelitis after CBT, although HHV-6 load in CSF should be monitored.

Particularly regarding the root abnormality, treatment at elder age may be a risk factor for root developmental disturbances. Risk evaluation, appropriate follow-up, and early detection of dental issues are required for all CCS.

BACKGROUND: Leukoreduced blood components have been widely implemented to prevent transfusiontransmitted cytomegalovirus (TT-CMV) in transplantation. Recent progress in leukoreduction technology has helped reduce the risk of TT-CMV in hematopoietic stem cell transplantation; however, its efficacy in umbilical cord blood transplantation (CBT) has not been systematically studied. STUDY DESIGN AND METHODS:We retrospectively analyzed the incidence of CMV infection in patients treated with CBT who received prestorage leukoreduced, CMV-unselected blood components between 2007 and 2017 in a single Japanese pediatric center. Patients were monitored for CMV antigenemia at least once weekly. RESULTS:In total, 71 patients treated with CBT were identified. Two patients were excluded because of unknown CMV serostatus or early death after CBT. Of the remaining 69 patients, 24 developed CMV antigenemia. Among them, 3 received granulocyte transfusions (3 of 3; 100%), 2 were infants with severe combined immunodeficiency who had been infected with CMV before CBT (2 of 2; 100%), and 19 were CMVseropositive patients (19 of 23, 82.6%). Conversely, of the remaining 45 patients in whom CMV antigenemia did not develop, 41 were seronegative (0 of 41; 0%) and were transfused with a total of 925 leukoreduced, CMVunselected blood components. Among the 41 patients, 9 (22%) received in vivo T-cell depletion with antithymocyte globulin. None of the patients in the seronegative group has subsequently shown evidence of CMV infection or developed CMV disease. CONCLUSION: Using prestorage leukoreduction, nocases of CMV infection were detected in seronegative CBT patients. Our findings showed the safety of leukoreduction in preventing TT-CMV in this patient group. ABBREVIATIONS: CB = cord blood; CBT = cord blood transplantation; CLIA = chemiluminescent immunoassay; CMV = cytomegalovirus; GTXs = granulocyte transfusions; GVHD = graftversus-host disease; HHV = human herpes virus; HLA = human leukocyte antigen; HSCT = hematopoietic stem cell transplantation; LR = leukoreduction; PCR = polymerase chain reaction; SCID = severe combined immunodeficiency; TT-CMV = transfusiontransmitted cytomegalovirus.From the

Background: The prognosis of relapsed/refractory (R/R) acute myeloid leukemia (AML) remains poor; therefore, novel treatment strategies are required urgently. Meanwhile, recent clinical trials have demonstrated that CAR-T cells for AML have been less successful than those targeting CD19 for B cell malignancies. Recently, we developed piggyBac-modified ligand-based CAR-T cells that target CD116, also called granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor (GMR) α chain, for treating juvenile myelomonocytic leukemia (Nakazawa, et al. J Hematol Oncol. 2016). Since CD116 is overexpressed in 60%-80% of AML cases, the present study aimed to develop a novel therapeutic method for R/R AML using GMR CAR-T cells. Methods: CD116 expression in AML cell lines or primary leukemia cells were examined using flow cytometry. The original piggyBac transposon plasmid for GMR CAR comprises GM-CSF as an antigen recognition site, IgG1 CH2CH3 hinge region, CD28 costimulatory domain, and CD3ζ chain. To improve the in vivo persistency and anti-tumor effects, two types of spacer (∆CH2H3 and G4S) that lack CH2CH3 lesion were newly constructed. In order to modulate the antigen recognition ability, mutated ligand-based GMR CAR vectors were constructed with a mutation at residue 21 of GM-CSF that is reported to play a critical role in its biological activity (Lopez, et al. Embo j. 1992). All the GMR CAR-T cells were generated with piggyBac gene modification. To investigate the in vitro anti-tumor activity, GMR CAR-T cells were co-cultured with AML cell lines. In order to evaluate the in vivo anti-tumor effects, NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice were intravenously injected with THP-1, THP1-ffLuc, or MV4-11 and then treated with GMR CAR-T cells. To characterize the safety profile of GMR CAR-T cells, peripheral blood mononuclear cells or polymorphonuclear cells were co-cultured with GMR CAR-T cells at an effector:target ratio of 1:1 for 3 days. Thereafter, B cells, NK cells, neutrophils, and monocytes were quantified using flow cytometry using counting beads. Results: Approximately 80% of the AML cells predominant in myelomonocytic leukemia expressed CD116. PiggyBac-modified GMR CAR-T cells displayed a favorable CD45RA+CCR7+-dominant phenotype, consistent with our previous findings. GMR CAR-T cells exhibited potent cytotoxic activities against CD116+ AML cells in vitro. GMR CAR-T cells incorporating a G4S spacer significantly improved the long-term in vitro and in vivo anti-tumor effects as compared to those incorporating a ∆CH2CH3 spacer. Furthermore, by employing a mutated GM-CSF at residue 21 (E21K and E21R) as an antigen recognition site, the in vivo anti-tumor effects were also substantially improved along with prolonged survival (Figure 1) over controls (PBS or CD19.CAR-T cells) (all, p < 0.01) as well as over GMR CAR-T cells with a wild-type GM-CSF ligand (E21R: p < 0.01; E21K: p = 0.02), with 4 out of 5 mice surviving for > 150 days. Safety tests revealed that the toxicity of GMR CAR-T cells was restricted to normal monocytes. It is noteworthy that the cytotoxic effects of GMR CAR-T cells on normal neutrophils, T cells, B cells, and NK cells were minimal. Conclusions: GMR CAR-T cell therapy appears to be a potentially useful strategy for CD116+ R/R AML. Based on the promising results, we plan to perform the first-in-human clinical trial of GMR CAR-T cells. Disclosures Saito: Toshiba Corporation: Research Funding. Hasegawa:Toshiba Corporation: Research Funding. Inada:Kissei Pharmaceuticals: Ended employment in the past 24 months. Nakashima:Toshiba Corporation: Research Funding. Yagyu:Toshiba Corporation: Research Funding. Nakazawa:Toshiba Corporation: Research Funding.

Objectives As the prognosis of relapsed/refractory (R/R) acute myeloid leukaemia (AML) remains poor, novel treatment strategies are urgently needed. Clinical trials have shown that chimeric antigen receptor (CAR)‐T cells for AML are more challenging than those targeting CD19 in B‐cell malignancies. We recently developed piggyBac ‐modified ligand‐based CAR‐T cells that target CD116/CD131 complexes, also known as the GM‐CSF receptor (GMR), for the treatment of juvenile myelomonocytic leukaemia. This study therefore aimed to develop a novel therapeutic method for R/R AML using GMR CAR‐T cells. Methods To further improve the efficacy of the original GMR CAR‐T cells, we have developed novel GMR CAR vectors incorporating a mutated GM‐CSF for the antigen‐binding domain and G4S spacer. All GMR CAR‐T cells were generated using a piggyBac ‐based gene transfer system. The anti‐tumor effect of GMR CAR‐T cells was tested in mouse AML xenograft models. Results Nearly 80% of the AML cells predominant in myelomonocytic leukaemia were found to express CD116. GMR CAR‐T cells exhibited potent cytotoxic activities against CD116 + AML cells in vitro . Furthermore, GMR CAR‐T cells incorporating a G4S spacer significantly improved long‐term in vitro and in vivo anti‐tumor effects. By employing a mutated GM‐CSF at residue 21 (E21K), the anti‐tumor effects of GMR CAR‐T cells were also improved especially in long‐term in vitro settings. Although GMR CAR‐T cells exerted cytotoxic effects on normal monocytes, their lethality on normal neutrophils, T cells, B cells and NK cells was minimal. Conclusions GMR CAR‐T cell therapy represents a promising strategy for CD116 + R/R AML.