scholarly journals Novel Cellular Immunotherapy Using Allogeneic Vγ9/δ2-T Cells Gene-Modified to Express HTLV-1 P40Tax-Specific TCR for the Treatment of Adult T Cell Leukemia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3216-3216
Author(s):  
Hiroshi Fujiwara ◽  
Satoshi Okumura ◽  
Yoshihiro Miyahara ◽  
Linan Wan ◽  
Isao Tawara ◽  
...  

Background: Adult T-cell leukemia/lymphoma (ATL) is a refractory peripheral T-cell malignancy caused by human T-lymphotropic virus type 1 (HTLV-1) infection. Although only allogeneic hematopoietic stem cell transplantation (allo-HSCT) displaying the graft-vs. ATL (GvATL) can bring durable remission, allo-HSCT is largely ineligible for newly diagnosed ATL patients due to disease aggressiveness and advanced age-related conditions. Thus, a novel treatment with safety and efficacy instead of allo-HSCT still remains an unmet need, and a cellular immunotherapy using TCR or CAR gene-modified immune cells exerting GvATL could be such an option. However, to generate those effector cells from autologous T cells of heavily pre-treated ATL patients faces many obstacles. To circumvent those hurdles, an employment of unconventional allogeneic Vγ9/δ2-T cells which are potentially free from the risk of GVHD could provide greater treatment opportunity for ATL patients due to highly extended donor availability. Taking above, here, we have newly devised an adoptive immunotherapy using a novel HTLV-1 p40Tax-specific TCR gene-modified allogeneic Vγ9/δ2 T cells against ATL. Methods: After written informed conscent, we firstly established novel HLA-A24 restricted TCR-α/β genes from HTLV-1 P40Tax301-309 (SFHSLHLLF)/HLA-A24 tetramer-positive peripheral CD8+T-lymphocytes of ATL patinets in durable remission using a single cell cloning method. Then, we confirmed that T cells gene-modified with these TCR-α/β genes exerted the epitope-specific and HLA-A24-restricted responses. Next, in order to achieve highly stable expression of this TCR-α/β heterodimer on gene-modified Vγ9/δ2-T cells, we newly developed a retroviral vector co-expressing TCR-α/β and CD8 α/β genes using self-cleaving P2A and E2A peptides. Using this vector, allogeneic Vγ9/δ2-T cells from healthy donors numerously expanded with high purity in our novel culture system were subjected to gene-transfer to express relevant TCR α/β complex. Thereafter, we asssessed target-reactive cytokine production and cytocidal activity mediated by those gene-modified allogeneic Vγ9/δ2-T cells both in vitro and in vivo. Finally, we additionally assessed a potential risk of GVHD using intravenous administration of another TCR gene-modified Vγ9/δ2 T-cells in vivo. Results: To start with PBMCs from healthy donors, allogeneic Vγ9/δ2-T cells were stably multiplied greater than thousandfold with a quite high purity (≥95%) using our novel bisphosphonate derivative PTA (tetrakis-pivaloyloxymethyl2-(thiazole-2-ylamino) ethylidene-1,1-bisphosphonate) combined with both 25 ng/ml of IL-7 and IL-15 in culture for 8 to 10 days. The stable expression of introduced TCR α/β heterodimer on Vγ9/δ2-T cells were successfully achieved by co-expression of CD8 α/β molecule. Those gene-modified Vγ9/δ2-T cells successfully recognized target peptide (SFHSLHLLF) in an HLA-A24 restricted fashion, and similarly demonstrated a cytocidal activity both in vitro and in vivo against HLA-A24 positive HTLV-1 infected cell lines (TL-Su and ILT#Hod), but not HLA-A24-negtive/Tax-positive cell line ILT#37 or HLA-A24-positve/Tax-negative cell line ATN-1. Furthermore, intravenously administered those TCR gene-modified Vγ9/δ2-T cells quickly and durably eradicated luciferase-gene modified TL-Su cells, but not ATN-1 cells in xenografted immunodeficient (NOG) mice, examined by in vivo imaging system. Finally, infused HLA-A2 restricted and NY-ESO-1 specific TCR (G50) gene-modified Vγ9/δ2-T cells exerted durable antitumor activity without causing GVHD using NOG mice xenografted with HLA-A2 positive melanoma cell line cells (NW-MEL-38). Conclusions: Our preclinical observations here obviously demonstrated the potential utility of TCR-α/β gene-modified allogeneic Vγ9/δ2-T cells for the treatment of ATL without causing GVHD. Further studies regarding biological behaviors of HTLV-1 Tax specific TCR-α/β gene-modified allogeneic Vγ9/δ2-T cells following target recognition in vivo are warranted, however, based on these lines of evidence and currently conducting assessments using clinical samples, we are planning to launch a novel clinical trial, particularly focusing on the applicability of HLA partially matched relative donors, as the source of gene-modified allogeneic Vγ9/δ2-T cells, which could highly extend the donor availability. Disclosures Fujiwara: BrightPath Biotherapeutics, Co.,Ltd.: Other: member of the department endowed by BrightPath Bio. Okumura:BrightPath Biotherapeutics, Co.,Ltd.: Other: member of the department endowed by BrightPth Bio.. Miyahara:BirghtPath Biotherapeutics, Co., Ltd.: Other: member of the department endowed by BrightPath Bio.. Wan:BrightPath Biotherapeutics, Co., Ltd.: Other: member of the department endowed by BrightPath Bio.. Tawara:Astellas Pharma: Research Funding; Ono Pharmaceutical: Research Funding; Kyowa Hakko Kirin: Honoraria, Research Funding. Shiku:BrightPath Biotherapeutics, Co., Ltd.: Other: Chair of the department endowed by BrightPath Bio..

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 21-21
Author(s):  
Gisele Olinto Libanio Rodrigues ◽  
Julie Hixon ◽  
Hila Winer ◽  
Erica Matich ◽  
Caroline Andrews ◽  
...  

Mutations of the IL-7Rα chain occur in approximately 10% of pediatric T-cell acute lymphoblastic leukemia cases. While we have shown that mutant IL7Ra is sufficient to transform an immortalized thymocyte cell line, mutation of IL7Ra alone was insufficient to cause transformation of primary T cells, suggesting that additional genetic lesions may be present contributing to initiate leukemia. Studies addressing the combinations of mutant IL7Ra plus TLX3 overexpression indicates in vitro growth advantage, suggesting this gene as potential collaborative candidate. Furthermore, patients with mutated IL7R were more likely to have TLX3 or HOXA subgroup leukemia. We sought to determine whether combination of mutant hIL7Ra plus TLX3 overexpression is sufficient to generate T-cell leukemia in vivo. Double negative thymocytes were isolated from C57BL/6J mice and transduced with retroviral vectors containing mutant hIL7R plus hTLX3, or the genes alone. The combination mutant hIL7R wild type and hTLX3 was also tested. Transduced thymocytes were cultured on the OP9-DL4 bone marrow stromal cell line for 5-13 days and accessed for expression of transduced constructs and then injected into sublethally irradiated Rag-/- mice. Mice were euthanized at onset of clinical signs, and cells were immunophenotyped by flow cytometry. Thymocytes transduced with muthIL-7R-hTLX3 transformed to cytokine-independent growth and expanded over 30 days in the absence of all cytokines. Mice injected with muthIL7R-hTLX3 cells, but not the controls (wthIL7R-hTLX3or mutIL7R alone) developed leukemia approximately 3 weeks post injection, characterized by GFP expressing T-cells in blood, spleen, liver, lymph nodes and bone marrow. Furthermore, leukemic mice had increased white blood cell counts and presented with splenomegaly. Phenotypic analysis revealed a higher CD4-CD8- T cell population in the blood, bone marrow, liver and spleen compared in the mutant hIL7R + hTLX3 mice compared with mice injected with mutant IL7R alone indicating that the resulting leukemia from the combination mutant hIL7R plus hTLX3 shows early arrest in T-cell development. Taken together, these data show that oncogenic IL7R activation is sufficient for cooperation with hTLX3 in ex vivo thymocyte cell transformation, and that cells expressing the combination muthIL7R-hTLX3 is sufficient to trigger T-cell leukemia in vivo. Figure Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3720-3720
Author(s):  
Yasuhiro Nagate ◽  
Sachiko Ezoe ◽  
Jiro Fujita ◽  
Takafumi Yokota ◽  
Michiko Ichii ◽  
...  

Abstract Background: Adult T-cell leukemia/lymphoma (ATLL) is a mature T-cell neoplasm, linked to the human T-cell lymphotropic virus, HTLV-1. Patients with ATLL are often at the risk of opportunistic infections. Some studies suggested that ATLL cells originate from HTLV-1-infected regulatory T cells (Tregs). It could be possible that this immunocompromised state is caused by the function of ATLL cells having similar phenotypes with Tregs. In this study, we examined the expression of immunosuppressive molecules associated with Tregs in ATLL cells, and analyzed their roles in the function of ATLL cells. Methods: The protocol of this study was approved by the Investigational Review Board of Osaka University Hospital. Peripheral blood mononuclear cells (PBMCs) were collected from 10 asymptomatic HTLV-1 carriers and 22 ATLL patients (1 with smoldering type, 5 with chronic type, 2 with lymphoma type, and 14 with acute type) after getting informed consent. PBMCs from 3 ATLL patients were separated into CD4+ CD7- CADM1+ATLL cells and adjacent CD4+CD7+ CADM1-normal T cells using Fluorescence-activated Cell Sorter (FACS), and cells in each fraction were subjected to total RNA sequencing experiments. Based on the results, we examined the expression patterns of CD39 and CD73 in HTLV-1 carriers or each type of ATLL patients, and also analyzed the immune functions of these molecules in ATLL tumor cells. Results: We compared whole transcriptome of ATLL cells and normal CD4+cells. Bioinformatic analyses showed that many genes associated with immunosuppressive functions were elevated or downregulated in ATLL cells. Among these genes we focused on CD39, CD73 and CD26, because they have recently been reported to be strongly associated with the functions of Tregs. CD39, expressed on normal Tregs, and extrinsic CD73 have immunosuppressive potential by catalyzing adenosine from extracellular ATP, and CD26 has opposite potential by resolving adenosine, which have a strong anti-inflammatory function and plays major role in Treg-mediated immunosuppression. We found that all of 4 ATLL cell lines (MJ, MT1, MT2, MT4) expressed CD39, but not CD73 just as human effector Tregs. Tumor cells from 12 acute ATLL patients (86%) and 2 chronic ATLL patients (40%) expressed CD39, but the expressions of CD73 were various. Also in asymptomatic carriers, we could detect CD39 and/or CD73 positive in CD7- CADM1+ abnormal fraction of CD4+cells. On the other hand, CD26, normally expressed on human CD4+Th cells other than effector Tregs, was negative in ATLL cell lines and primary ATLL cells except for cells in abnormal fraction of one asymptomatic carrier. CD39 negative cases in chronic/smoldering type tended to show slower disease progression after the blood collection. Next, the role of CD39 and/or CD73 in ATLL cells was assessed in vitro and in vivo. As expected, CD39+ ATLL cells converted significantly more extracellular ATP than CD39- ATLL cells, and mass spectrometry analysis of AMP/adenosine concentration identified the AMPase activity of CD73+ ATLL cells. Furthermore, we established CD39 knockout (KO) cells from ATL cell-line MJ using CRISPR/Cas9 system, and performed in vitro suppression assays for assessment of immunosuppressive function. Although wild type MJ suppressed the growth of normal CD4+ and CD8+ T cells, KO MJ did little. Next, we analyzed the role of CD39 in the progression of tumor cells in vivo. We transplanted mouse T-cell lymphoma cell-line EG7-OVA artificially expressing CD39 or mock into mice subcutaneously. The coinjection of immunoadjuvant poly(I:C) significantly suppressed the tumor growth of mock cells, but the tumor sizes of CD39 expressing cells were almost the same as those of mock cells without poly(I:C) injection (Figure). Conclusion: In this study, we reported that most of ATLL cells in acute type patients express CD39+ CD26- just as Tregs, and that CD39- KO of ATLL cell line cancelled its immunosuppressive effects, and forcibly expressed CD39 on tumor cells rejected the anti-tumor immunity in vivo. From these data, we clarified the pathological mechanism of immunosuppressive function in ATLL cells, and also showed that CD39 expression could be used as a prognostic clue and be a new therapeutic target of ATLL. Disclosures Ezoe: TAIHO Phamaceutical Co., Ltd.: Research Funding. Yokota:Celgene: Research Funding; Bristol-Myers Squibb: Research Funding; Pfizer Inc.: Research Funding; CHUGAI PHARMACEUTICAL CO., LTD.: Research Funding; MSD K.K.: Research Funding. Ichii:Novartis Pharma K.K.: Speakers Bureau; Kowa Pharmaceutical Co.,LTD.: Speakers Bureau; Celgene K.K.: Speakers Bureau. Shibayama:Novartis Pharma K.K.: Honoraria, Research Funding; Celgene K.K.: Honoraria, Research Funding; Takeda Pharmaceutical Co.,LTD.: Honoraria, Research Funding; Fujimoto Pharmaceutical: Honoraria, Research Funding; Jansen Pharmaceutical K.K: Honoraria; Ono Pharmaceutical Co.,LTD: Honoraria, Research Funding; Mundipharma K.K.: Honoraria, Research Funding; Bristol-Meyer Squibb K.K: Honoraria, Research Funding. Oritani:Novartis Pharma: Speakers Bureau. Kanakura:Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 307-307
Author(s):  
Kazushi Tanimoto ◽  
Hiroshi Fujiwara ◽  
Hiroki Tanaka ◽  
Fumihiro Ochi ◽  
Hiroaki Asai ◽  
...  

Abstract [Background and purpose] Mogamulizumab, a newly developed monoclonal antibody (mAb) targeting the receptor for C-C chemokine 4 (CCR4) has initially demonstrated a promising clinical outcome for the treatment of therapy-resistant Adult T cell leukemia (ATL) of which tumor cells broadly express CCR4. However, in practice, we sometimes encounter unsuccessful cases of ATL treated with mogmulizumab, especially in the setting of combination therapy with multiple anticancer agents. In those cases, ATL tumor cells were still positive for CCR4, but the chemotherapy-induced lymphocytopenia was reproducibly noticeable. Considering the pharmacologic action of mogamulizumab, the defucosylation-enhanced antibody-dependent cellular cytotoxicity (ADCC) exerted by FcγRIIIa (CD16) expressing effector cells in vivo, as observed for Natural Killer (NK) cells, we hypothesized that adoptive transfer of ADCC effector cells might be able to regain the anti-ATL efficacy of mogamulizumab. Accordingly, we examined in vivo the feasibility of T cells gene-modified to express a newly generated chimeric CD16-CD3ζ receptor as a transferable alternative effector cell for mogamulizumab. [Methods] A novel affinity-matured chimeric CD16 with a 158V/V-CD3ζ (cCD16ζ ) gene construct was lentivirally introduced into CD3+ T cells from both healthy individuals (n=4) and patients with adult T cell leukemia (ATL) (n=3) (cCD16ζ-T cells). Using ATL or HTLV-1 infected cell lines variably expressing CCR4 on the cell surface (n=7), and primary ATL tumor cells (n=3), in the context of ADCC activity, functional properties of cCD16ζ-T cells were extensively examined both in vitro and in vivo, compared with those of NK cells from healthy donors (n=3). Next, we examined the in vivo therapeutic efficacy of concomitantly infused cCD16ζ-T cells with mogamulizumab via tail vein using a xenografted mouse model. Finally, we examined the feasibility of double gene-modified T cells to express human telomerase reverse transcriptase (hTERT)-specific TCR and cCD16ζ receptor, because we recently demonstrated that HLA-A*24:02-restricted and hTERT461-469 (VYGFVRACL)-specific TCR gene-modified CD8+ T cells displayed the cytocidal activity against ATL tumor cells (Blood, 2014). [Results] cCD16ζ-T cells were readily expandable in ex vivo culture using anti-CD2/CD3/CD28 beads and recombinant human (rh)IL-2, and they successfully displayed ADCC-mediated tumoricidal activity against CCR4+ MT-4 and ATN-1 (ATL cell lines) cells, but not CCR4- K562 cells with mogamulizumab, in a effector cell number and an antibody dose dependent manner. Pharmacological dose of 0.1μg/ml mogamulizumab could bind to ATL cell line cells expressing variable extent of CCR4 ranging from MFI 1.01 for HUT102 cell line to 12.3 for MT-2 (0.57 for K562 as a negative control), and could mediate the similar degree of ADCC activity exerted by cCD16ζ-T cells. The magnitude of ADCC activity mediated by cCD16ζ-T cells against opsonized ATN-1 with mogamulizumab was almost similar to that by activated NK cells using rhIL-2. This cytotoxicity was inhibited by anti-CD16 mAb. During ADCC, ligation of opsonized cancer cells with mogamulizumab to cCD16ζ receptor stimulated cCD16ζ-T cells to release toxic granules shown by CD107a expression. cCD16ζ-T cells generated from patients with ATL (n=3) successfully displayed ADCC activity against autologous tumor cells in vitro. Human cCD16ζ-T cells infused concomitantly with mogamulizumab synergistically inhibited the growth of disseminated luciferase gene-modified ATN-1 cells in immunodeficient mice, demonstrated using an in vivo bioluminescence assay. Additionally, this tumor suppressive effect contributed to the longer survival of treated mice. Finally, the double-gene modified CD3+ T cells could successfully recognize ATN-1 through both the mogamulizumab-opsonized CCR4 and hTERT epitope/HLA-A24*02 complex on the cell surface. Disclosures Okamoto: CDM Center, Takara Bio Inc.: Employment. Mineno:Takara Bio Inc.: Employment. Shiku:Takara Bio Inc.: Research Funding.


2014 ◽  
Vol 38 (5) ◽  
pp. 608-612 ◽  
Author(s):  
Dai Chihara ◽  
Yoshitoyo Kagami ◽  
Harumi Kato ◽  
Noriaki Yoshida ◽  
Tohru Kiyono ◽  
...  

2003 ◽  
Vol 77 (14) ◽  
pp. 7728-7735 ◽  
Author(s):  
Jianxin Ye ◽  
Li Xie ◽  
Patrick L. Green

ABSTRACT Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are distinct oncogenic retroviruses that infect several cell types but display their biological and pathogenic activity only in T cells. Previous studies have indicated that in vivo HTLV-1 has a preferential tropism for CD4+ T cells, whereas HTLV-2 in vivo tropism is less clear but appears to favor CD8+ T cells. Both CD4+ and CD8+ T cells are susceptible to HTLV-1 and HTLV-2 infection in vitro, and HTLV-1 has a preferential immortalization and transformation tropism of CD4+ T cells, whereas HTLV-2 immortalizes and transforms primarily CD8+ T cells. The molecular mechanism that determines this tropism of HTLV-1 and HTLV-2 has not been determined. HTLV-1 and HTLV-2 carry the tax and rex transregulatory genes in separate but partially overlapping reading frames. Since Tax has been shown to be critical for cellular transformation in vitro and interacts with numerous cellular processes, we hypothesized that the viral determinant of transformation tropism is encoded by tax. Using molecular clones of HTLV-1 (Ach) and HTLV-2 (pH6neo), we constructed recombinants in which tax and overlapping rex genes of the two viruses were exchanged. p19 Gag expression from proviral clones transfected into 293T cells indicated that both recombinants contained functional Tax and Rex but with significantly altered activity compared to the wild-type clones. Stable transfectants expressing recombinant viruses were established, irradiated, and cocultured with peripheral blood mononuclear cells. Both recombinants were competent to transform T lymphocytes with an efficiency similar to that of the parental viruses. Flow cytometry analysis indicated that HTLV-1 and HTLV-1/TR2 had a preferential tropism for CD4+ T cells and that HTLV-2 and HTLV-2/TR1 had a preferential tropism for CD8+ T cells. Our results indicate that tax/rex in different genetic backgrounds display altered functional activity but ultimately do not contribute to the different in vitro transformation tropisms. This first study with recombinants between HTLV-1 and HTLV-2 is the initial step in elucidating the different pathobiologies of HTLV-1 and HTLV-2.


Gut ◽  
2015 ◽  
Vol 66 (3) ◽  
pp. 454-463 ◽  
Author(s):  
Daniele Mennonna ◽  
Cristina Maccalli ◽  
Michele C Romano ◽  
Claudio Garavaglia ◽  
Filippo Capocefalo ◽  
...  

ObjectivePatient-specific (unique) tumour antigens, encoded by somatically mutated cancer genes, generate neoepitopes that are implicated in the induction of tumour-controlling T cell responses. Recent advancements in massive DNA sequencing combined with robust T cell epitope predictions have allowed their systematic identification in several malignancies.DesignWe undertook the identification of unique neoepitopes in colorectal cancers (CRCs) by using high-throughput sequencing of cDNAs expressed by standard cancer cell cultures, and by related cancer stem/initiating cells (CSCs) cultures, coupled with a reverse immunology approach not requiring human leukocyte antigen (HLA) allele-specific epitope predictions.ResultsSeveral unique mutated antigens of CRC, shared by standard cancer and related CSC cultures, were identified by this strategy. CD8+and CD4+T cells, either autologous to the patient or derived from HLA-matched healthy donors, were readily expanded in vitro by peptides spanning different cancer mutations and specifically recognised differentiated cancer cells and CSC cultures, expressing the mutations. Neoepitope-specific CD8+T cell frequency was also increased in a patient, compared with healthy donors, supporting the occurrence of clonal expansion in vivo.ConclusionsThese results provide a proof-of-concept approach for the identification of unique neoepitopes that are immunogenic in patients with CRC and can also target T cells against the most aggressive CSC component.


Blood ◽  
2008 ◽  
Vol 112 (6) ◽  
pp. 2484-2488 ◽  
Author(s):  
Julie H. Lin ◽  
Ellen J. Kim ◽  
Anand Bansal ◽  
John Seykora ◽  
Stephen K. Richardson ◽  
...  

Abstract The oral rexinoid bexarotene (Targretin) is widely used for treatment of cutaneous T-cell lymphomas (CTCL). We recently reported the first case of adult T-cell leukemia/lymphoma (ATLL) that responded rapidly to combination therapy of bexarotene and interferon (IFN)-α2b with complete clinical response. We demonstrated that bexarotene induced apoptosis of the patient's malignant peripheral blood T-cells in vitro. However, our patient developed skin and nodal relapse 180 days after starting treatment. We now demonstrate that his peripheral blood malignant T cells became resistant to bexarotene-induced apoptosis. We investigated potential mechanisms that may cause aberrations in the retinoid X receptor (RXR) subunits, RXR-α and RXR-β, to account for these findings. Sequence analysis did not reveal acquisition of mutations in the genes encoding RXR-α and RXR-β by resistant cells. We assessed RXR-α and RXR-β expression by Western blot analysis and found that resistant cells had significantly decreased RXR-α expression compared with pretherapy bexarotene-sensitive cells. Our findings indicate that reduced expression of the RXR-α receptor subunit may represent a mechanism for resistance to bexarotene in T-cell malignancies.


Blood ◽  
2017 ◽  
Vol 129 (9) ◽  
pp. 1071-1081 ◽  
Author(s):  
Toshiki Watanabe

Abstract Adult T-cell leukemia (ATL) is an aggressive T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1) that develops through a multistep carcinogenesis process involving 5 or more genetic events. We provide a comprehensive overview of recently uncovered information on the molecular basis of leukemogenesis in ATL. Broadly, the landscape of genetic abnormalities in ATL that include alterations highly enriched in genes for T-cell receptor–NF-κB signaling such as PLCG1, PRKCB, and CARD11 and gain-of function mutations in CCR4 and CCR7. Conversely, the epigenetic landscape of ATL can be summarized as polycomb repressive complex 2 hyperactivation with genome-wide H3K27 me3 accumulation as the basis of the unique transcriptome of ATL cells. Expression of H3K27 methyltransferase enhancer of zeste 2 was shown to be induced by HTLV-1 Tax and NF-κB. Furthermore, provirus integration site analysis with high-throughput sequencing enabled the analysis of clonal composition and cell number of each clone in vivo, whereas multicolor flow cytometric analysis with CD7 and cell adhesion molecule 1 enabled the identification of HTLV-1–infected CD4+ T cells in vivo. Sorted immortalized but untransformed cells displayed epigenetic changes closely overlapping those observed in terminally transformed ATL cells, suggesting that epigenetic abnormalities are likely earlier events in leukemogenesis. These new findings broaden the scope of conceptualization of the molecular mechanisms of leukemogenesis, dissecting them into immortalization and clonal progression. These recent findings also open a new direction of drug development for ATL prevention and treatment because epigenetic marks can be reprogrammed. Mechanisms underlying initial immortalization and progressive accumulation of these abnormalities remain to be elucidated.


2000 ◽  
Vol 74 (20) ◽  
pp. 9610-9616 ◽  
Author(s):  
Takashi Ohashi ◽  
Shino Hanabuchi ◽  
Hirotomo Kato ◽  
Hiromi Tateno ◽  
Fumiyo Takemura ◽  
...  

ABSTRACT Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL) in infected individuals after a long incubation period. To dissect the mechanisms of the development of the disease, we have previously established a rat model of ATL-like disease which allows examination of the growth and spread of HTLV-1 infected tumor cells, as well assessment of the effects of immune T cells on the development of the disease. In the present study, we induced HTLV-1 Tax-specific cytotoxic T lymphocyte (CTL) immunity by vaccination with Tax-coding DNA and examined the effects of the DNA vaccine in our rat ATL-like disease model. Our results demonstrated that DNA vaccine with Tax effectively induced Tax-specific CTL activity in F344/N Jcl-rnu/+ (nu/+) rats and that these CTLs were able to lyse HTLV-1 infected syngeneic T cells in vitro. Adoptive transfer of these immune T cells effectively inhibited the in vivo growth of HTLV-1-transformed tumor in F344/N Jcl-rnu/rnu (nu/nu) rats inoculated with a rat HTLV-1 infected T cell line. Vaccination with mutant Tax DNA lacking transforming ability also induced efficient anti-tumor immunity in this model. Our results indicated a promising effect for DNA vaccine with HTLV-1 Tax against HTLV-1 tumor development in vivo.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2776-2776
Author(s):  
Salvatore Fiorenza ◽  
George S. Laszlo ◽  
Tinh-Doan Phi ◽  
Margaret C. Lunn ◽  
Delaney R. Kirchmeier ◽  
...  

Abstract Background: There is increasing interest in targeting CD33 in malignant and non-malignant disorders, but available drugs are ineffective in many patients. As one limitation, therapeutic CD33 antibodies typically recognize the membrane-distal V-set domain. Likewise, currently tested CD33-directed chimeric antigen receptor (CAR) T cells likewise target the V-set domain and have thus far shown limited clinical activity. We have recently demonstrated that binding closer to the cell membrane enhances the effector functions of CD33 antibodies. We therefore raised antibodies against the membrane-proximal C2-set domain of CD33 and identified antibodies that bound CD33 regardless of the presence/absence of the V-set domain ("CD33 PAN antibodies"). Here, we tested their properties as targeting moiety in CD33 PAN CAR T cell constructs, using a clinically validated lentiviral backbone. Methods: To generate CAR T cells, negatively selected CD8 + T cells were transduced with an epHIV7 lentivirus encoding the scFv from a CD33 PAN antibody (clone 1H7 or 9G2) linked to either a short (IgG 4 hinge only), intermediate (hinge plus IgG 4 CH3 domain), or long (hinge plus IgG 4 CH3 domain plus IgG 4 CH2 domain) spacer, the CD28-transmembrane domain, CD3zeta and 4-1BB intracellular signaling domains, and non-functional truncated CD19 (tCD19) as transduction marker. Similar constructs using scFvs from 2 different V-set domain-targeting CD33 antibodies, including hP67.6 (My96; used in gemtuzumab ozogamicin), were generated for comparison. CAR-T cells were sorted, expanded in IL-7 and IL-15, and used in vitro or in vivo against human AML cell lines endogenously expressing CD33 and cell lines engineered to lack CD33 (via CRISPR/Cas9) with/or without forced expression of different CD33 variants. Results: CD33 V-set-directed CAR T cells exerted significantly more cytolytic activity against AML cells expressing an artificial CD33 variant lacking the C2-set domain (CD33 ΔE3-4) than cells expressing full-length CD33 at similar or higher levels, consistent with the notion that CD33 CAR T cell efficacy is enhanced when targeting an epitope that is located closer to the cell membrane. CD33 PAN CAR T cells were highly potent against human AML cells in a strictly CD33-dependent fashion, with constructs containing the short and intermediate-length spacer demonstrating robust cytokine secretion, cell proliferation, and in vitro cytolytic activity, as determined by 51Cr release cytotoxicity assays. When compared to optimized CD33 V-set CAR T cells, optimized CD33 PAN CAR T cells were significantly more potent in cytotoxicity, proliferation, and cytokine production without appreciably increased acquisition of exhaustion markers. In vivo, CD33 PAN CAR T cells extended survival in immunodeficient NOD.SCID. IL2rg -/- (NSG) mice bearing significant leukemic burdens from various cell line-derived xenografts (HL-60, KG1α and MOLM14) with efficient tumor clearance demonstrated in a dose-dependent fashion. Conclusion: Targeting the membrane proximal domain of CD33 enhances the anti-leukemic potency of CAR T cells. Our data provide the rationale for the further development of CD33 PAN CAR T cells toward clinical testing. Disclosures Fiorenza: Link Immunotherapeutics: Consultancy; Bristol Myers Squibb: Research Funding. Godwin: Pfizer: Research Funding; Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Turtle: Allogene: Consultancy; Amgen: Consultancy; Arsenal Bio: Consultancy; Asher bio: Consultancy; Astrazeneca: Consultancy, Research Funding; Caribou Biosciences: Consultancy, Current holder of individual stocks in a privately-held company; Century Therapeutics: Consultancy, Other; Eureka therapeutics: Current holder of individual stocks in a privately-held company, Other; Juno therapeutics/BMS: Patents & Royalties, Research Funding; Myeloid Therapeutics: Current holder of individual stocks in a privately-held company, Other; Nektar therapeutics: Consultancy, Research Funding; PACT Pharma: Consultancy; Precision Biosciences: Current holder of individual stocks in a privately-held company, Other; T-CURX: Other; TCR2 Therapeutics: Research Funding. Walter: Kite: Consultancy; Janssen: Consultancy; Genentech: Consultancy; BMS: Consultancy; Astellas: Consultancy; Agios: Consultancy; Amphivena: Consultancy, Other: ownership interests; Selvita: Research Funding; Pfizer: Consultancy, Research Funding; Jazz: Research Funding; Macrogenics: Consultancy, Research Funding; Immunogen: Research Funding; Celgene: Consultancy, Research Funding; Aptevo: Consultancy, Research Funding; Amgen: Research Funding.


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