Adoptive Therapy with T-Cell Precursors for Immune Reconstitution After Allogeneic Hematopoietic Stem Cell Transplantation.

Abstract Abstract 3525 Poster Board III-462 Recipients of allogeneic hematopoietic transplantation experience a slow reconstitution of donor-derived B and T cell number and function. This post-transplant period of immunodeficiency is associated with an increased risk of infection and malignant relapse. The developement of these complications notably correlates with the recovery of CD4+T cell subset. We proposed a strategy to enhances in vivo reconstitution by promoting donor-derived T cell development in the recipient's thymus. Recently Notch1-based ex-vivo system have been established to mature cord blood- or bone marrow-derived human HSCs into committed T-cell precursors. We used this system for the generation of T-cell precursors starting from G-CSF mobilized human HSCs. We cultured mobilized human CD34+ hematopoietic stem cells (HSCs) (2.5 × 105) in vitro on OP9 mouse stromal cells expressing the Notch 1 ligand Delta-like-1 (OP9-DL1) in the presence of rhFLT3-ligand (5ng/ml) and rhIL7 (5 ng/ml). After 6 weeks of co-culture we obtained a 3 log increase of human T-linage precursors of CD45RA+CD7high phenotype. Further co-colture (7-9 weeks) leed to the generation of CD4+ and CD8+ double-positive (DP) T cells and even mature CD4+ and CD8+ single positive (SP) ab-TCR lymphocytes. Experiments were designed in order to evaluate whether human CD45RA+CD7high T cell precursors could 1) engraft into NOD-SCID IL2 rg-/− mice 2) leed to in vivo expansion and maturation along T cell developmental pathway. Control mice were irradiated and transplanted with G-CSF-mobilized human CD34+ (dose 5×106 i.v.). 4 weeks after transplant more than 20% human CD45 positive cells engrafted in the bone marrow. Thymic engraftment occured at 8 weeks after transplant, with 80% human CD45 positive cells (thymic cellularity: 2.7×105 cells), mostly with T cell-immature phenotype of CD3-CD4-CD8 triple negative (95%) (TN) and CD4+CD8+double positive (5%) (DP). Co-transplant of CD45RA+CD7high T cell precursors (106 cells i.v.) along with CD34+HSC leed to an accelerated thymic engraftment (95% human CD45 positive cells; thymic cellularity 2.5 × 106 cells) already at 6 wks after transplant. Thymocytes were CD3-CD4-CD8 triple negative (51%) (TN) and CD4+CD8+double positive (DP) (42%) cells and at 8 weeks after transplant matured into CD3+CD4+ and CD3+CD8+ single positive (SP) T cells. Spectratyping analyses revealed a broad diversity of the T-cell receptor (TCR) repertoire. This occured in the complete absence of Graft versus Host Disease (GvHD) suggesting that adoptively transferred ex vivo-generated T-cell precursors developed into host-tolerant mature T cells. Ongonig experiment are needed to clarify the beneficial effect of adoptive immunotherapy with human T cell precursors on peripheral T cell reconstitution and control of infection in the humanized mouse system. We conclude that ex-vivo generation of human T-linage precursors is feasible from the G-CSF-mobilized HSCs and that can be succesfully tranfered in-vivo as a new strategie to enhance T-cell reconstitution after allogeneic HSCT with no risk of GvHD. Disclosures: No relevant conflicts of interest to declare.

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Naive and Ex Vivo Activated Human T Cells Generate Consistent Engraftment and Lethal Graft-Versus-Host Disease (GvHD) in NOD SCID β 2M Null Mice: A New Xenogeneic Model for GvHD.

Blood ◽

10.1182/blood.v106.11.3106.3106 ◽

2005 ◽

Vol 106 (11) ◽

pp. 3106-3106

Author(s):

Bruno Nervi ◽

Michael P. Rettig ◽

Julie K. Ritchey ◽

Gerhard Bauer ◽

Jon Walker ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Ex Vivo ◽

Conditioning Regimen ◽

Activation Markers ◽

In Vivo Models ◽

Hematopoietic Stem ◽

Human T Cells ◽

The Impact

Abstract GvHD remains a major cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation and donor lymphocyte infusion. The human GvHD pathophysiology includes recipient tissue destruction and proinflammatory cytokine production associated with the conditioning regimen; donor T cells become allo-activated, proliferate, and mediate tissue injury in various organs, including the liver, skin, and gut. Modern therapeutic strategies to control GvHD while maintaining the beneficial graft-versus-leukemia effects require ex vivo T cell stimulation and expansion. Multiple studies have demonstrated that these ex vivo expanded T cells exhibit decreased survival and function in vivo, including reduced alloreactivity and GvHD potential. Unfortunately no in vivo models exist to consistently examine the impact of ex vivo manipulation of human T cells (HuT) on T cell function. Naive HuT were compared to HuT activated using CD3/28 beads (XcyteTMDynabeads) with 50 U/ml IL-2 for 4 days (Act). We initially evaluated the HuT engraftment and GvHD potential of naive and Act in RAG2γ null mice (n=22) conditioned with clodronate liposomes on day −1 and 350cGy on day 0, as previously described by others. We injected 107 and 1.5x107 naive or Act HuT intravenously (iv). All mice exhibited low HuT engraftment and no lethal GvHD. NOD SCIDβ 2M null mice (β 2M) were next conditioned with 250cGy on day −1 (n=34), or 300cGy on day 0 (n=21). 107 naive vs Act HuT were injected retroorbitaly (ro). Lower HuT doses or iv injection resulted in no expansion or GvHD. Engraftment of HuT in peripheral blood of recipient mice was evaluated weekly by FACS and euthanasia was performed if mice lost > 20% body weight. 60% of the mice conditioned with 250cGy that received naive HuT developed lethal GvHD, in comparison to 75% of mice that received 300cGy and nave HuT, and 100% of mice that received 300cGy and Act HuT. Table 1 250cGy 300cGy Naive (n=34) Naive (n=8) Activated (n=13) *p<0.02 PB engraftment (%HuT) 20%±15 33%±21 59%±19 Lethal GvHD 60% 75% 100% All mice receiving 300cGy had well preserved CD4/CD8 ratios (1–1.5). Tissue infiltration was greatest in mice that had received 300cGy and Act HuT (spleen, liver, lung, kidney: 50–70%). Of interest, serum levels of hu IFNγ dramatically increased over time in all mice who went on to develop lethal GvHD (day 3=270 ug/ml and day 15=36,000 ug/ml) compared to mice that did not develop lethal GvHD (day 10=40 ug/ml and day 17=1,020 ug/ml)(p<0.05). Interestingly, the up-regulation of the activation markers CD25 and CD30 in HuT, and IFNγ production predicted lethal GvHD in β 2M null mice. In summary, we developed a xenogeneic model of lethal GvHD where naive or ex vivo Act HuT injected ro in sublethaly irradiated β 2M not only engraft, expand in vivo, but also infiltrate and damage different mouse target organs. HuT are allo-activated against mouse antigens and damage the target tissues, sharing the major characteristics of human GvHD and causing the death of mice. This model will allow us to study the effects of specific ex vivo T cell manipulation including transduction, selection, expansion, and the depletion or addition of various T cells and other cellular subsets on the outcome of GvHD, to determine improved therapeutic interventions.

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Functional Comparison of Freshly Isolated and Ex-Vivo Expanded CD4+CD25+Foxp3+ Regulatory T Cells in Suppressing Murine Acute GvHD

Blood ◽

10.1182/blood.v112.11.812.812 ◽

2008 ◽

Vol 112 (11) ◽

pp. 812-812 ◽

Cited By ~ 1

Author(s):

Emanuela I Sega ◽

Dennis Leveson-Gower ◽

Vu H. Nguyen ◽

Robert Negrin

Keyword(s):

T Cells ◽

T Cell ◽

Regulatory T Cells ◽

Acute Gvhd ◽

Bone Marrow Cells ◽

Ex Vivo ◽

Allogeneic Bone ◽

Cell Reactivity ◽

Hematopoietic Stem

Abstract Graft versus host disease (GVHD) is a major complication of hematopoietic stem cell transplantation resulting from donor T cell reactivity against host tissue antigens. CD4+CD25+Foxp3+ regulatory T cells (Treg) are known to be important in maintaining self tolerance and preventing autoimmunity. Using murine models of acute GVHD in which allogeneic bone marrow cells are transplanted into lethally irradiated hosts, we and others have shown that donor Treg are able to suppress GVHD induced by donor allogeneic T cells and dramatically improve survival. Treg are rare and suppression of GVHD requires adequate numbers of Treg in relation to the number of conventional T cells (Tcon). To overcome this problem, expansion of Treg has been performed, however there has not been a head to head comparison of the function of expanded vs fresh Treg. Highly purified CD4+CD25+Foxp3+ T cells (>98% purity) were expanded using anti-CD3/anti-CD28 dynabeads and 1000 U/ml IL-2. Under these conditions, after five days Treg expanded up to 13 fold while maintaining high Foxp3 expression levels (85–90%). Longer expansion periods result in more T cell expansion but an overgrowth of Foxp3 negative T cells. In a mixed lymphocyte reaction assay, the ex-vivo expanded Treg efficiently suppressed the proliferation of alloreactive T cells. The expanded Treg were evaluated in an in vivo acute GVHD mouse model in direct comparison with freshly isolated Treg using a novel bioluminescent imaging assay that allowed for assessment of Tcon proliferation in addition to traditional metrics of GVHD severity including weight gain, survival and GVHD score. Initial experiments show that, similar to freshly isolated Treg, the ex-vivo expanded Treg suppress GVHD symptoms and improve survival, although a greater number of expanded Treg were required comparable to freshly isolated Treg. The mean GVHD score for the Tcon alone group was 5.8±1.02. Fresh Treg added at 1:1 ratio decreased the GVHD score to 0.75±0.25 (p=0.0036). Ex-vivo expanded Treg demonstrated a dose-dependent decrease in GVHD score, although four times more expanded Treg were needed to obtain a similar reduction in GVHD score (0.50±0.5, p=0.0036). This observed difference in potency was not due to the ex-vivo expanded Treg being short-lived when infused in mice. Bioluminescence imaging of luciferase positive (luc+) cultured Treg showed the same in vivo persistence as freshly isolated Treg. The ability to expand ex-vivo generated Treg is greater than the difference in potency, making ex-vivo expanded Treg potentially a viable option for treatment of GVHD, however, increased ratios of Treg:Tcon are likely to be required.

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Down-Modulating p18Ink4c for Ex Vivo Expansion of Hematopoietic Stem Cells.

Blood ◽

10.1182/blood.v104.11.1687.1687 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1687-1687

Author(s):

Tao Cheng ◽

Hui Yu ◽

Donna Shields ◽

Youzhong Yuan ◽

Hongmei Shen

Keyword(s):

Ex Vivo ◽

The Self ◽

Transduction Efficiency ◽

Rt Pcr ◽

Hematopoietic Stem ◽

Human Cd34 ◽

Cd34 Cells ◽

Human Hscs

Abstract Our recent study demonstrated that the cyclin-dependent kinase inhibitor (CKI) p18Ink4c (p18), also an INK4 family protein acting at early G1-phase, exerts its inhibitory role during the self-renewing division of murine hematopoietic stem cells (HSC) in vivo (Nature Cell Biology 2004). Down-modulating p18 may permit enhanced stem cell expansion in vitro, a hypothesis that is now being testing in our laboratory. To provide the proof-of-the concept, we first took advantage of the murine system by testing the in vivo reconstituting ability of cells that had been cultured under the Dexter culture condition for 19 weeks. 2–20x105 cells with non-adherent and adherent populations were transplanted into lethally irradiated hosts. 3 of 7 mice revealed long-term engraftment in the p18−/− transplanted group (0.5–33% engraftment levels) while there was no engraftment in the p18+/+ group (n=7). Moreover, a substantial level (38.6% on average) of long-term engraftments (7 months) in multilineage was achieved in secondary recipients transplanted with the p18−/− cells (n=3), demonstrating the self-renewal potential of the expanded HSCs after the extended period of long-term culture. These data strongly indicate that p18 absence is able to substantially mitigate the differentiating effect of the ex vivo culture conditions on HSCs and therefore offer a strong rationale for targeting p18 in human HSC expansion. P18 mRNA was detected by RT PCR in human CD34+ cells with a higher expression level in the more primitive subset: CD34+CD38−. To explore the possibility of targeting p18 for expanding human HSCs, we have employed the RNA interference (RNAi) technology in CD34+ cord blood cells. We screened a pool of small interfering RNA (siRNA) oligos and three of them were able to effectively reduce p18 expression by 60–80% in 48 hours as assessed by both RNA and protein analyses in human cells. Further, we tested both transient and permanent delivery methods for introducing the RNAi effect in the CD34+CD38− cells. To demonstrate whether the RNAi method would be sufficient to impact the outcome of cell division after a single or limited cell cycle(s), we chose the nucleofector technology and were able to achieve 48.30±11.66% of transduction efficiency with good viability (50.63±9.38%, n=3) in human CD34+ cells. After a single electroporation pulse, we were able to increase by 2-fold the CD34+CD38− cells associated with the same magnitude of increased colony forming activity under culture condition supplemented with SCF, TPO and Flt3. To observe the long-term effect of p18 downregulation in human HSCs, we constructed a p18 short hairpin (shRNA)-expressing lentiviral vector that was engineered to have the mouse U6 promoter upstream of a CMV-EGFP expression cassette. A transduction efficiency of 30–60% was achieved after overnight infection of the human CD34+ cells with the p18 shRNA or with control lentiviral vectors pseudotyped with the VSV-g envelope. 72–96 hours after the transduction, human p18 protein can be knocked down by the p18 siRNA lentivector at near 100% in the HeLa cell line as determined on the western blot, and at more than 50% in human primary CD34+ cells as determined by real time RT PCR. We are currently undertaking further study aimed at assessing the repopulating ability of the transduced human HSCs with lentivirus-mediated p18 shRNA in NOD/SCID mice. Together, these findings suggest that down-modulating p18 might be a feasible approach for manipulating human HSCs ex vivo.

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Second-Generation Chimeric Antigen Receptors Successfully Modify Hematopoietic Stem Cells for Immunotherapy of B-Lineage Malignancies

Blood ◽

10.1182/blood.v124.21.655.655 ◽

2014 ◽

Vol 124 (21) ◽

pp. 655-655

Author(s):

Roy L. Kao ◽

Tulika Tyagi ◽

Sarah M. Larson ◽

Andy Tu ◽

Shantha Senadheera ◽

...

Keyword(s):

T Cells ◽

Second Generation ◽

Ex Vivo ◽

Antigen Receptors ◽

Antigen Specificity ◽

Hematopoietic Stem ◽

Cd34 Cells ◽

Human Hscs ◽

B Lineage

Abstract Patients with refractory or recurrent B-lineage hematological malignancies have less than 50% of chance of cure, despite intensive therapy. Chimeric Antigen Receptors (CARs) successfully engineer antigen specificity in immune cells, with clinical trials currently being conducted using ex vivo expanded gene-modified mature T cells. Results from preclinical studies and clinical trials show that effector cells usually have transient in vivo persistence that could significantly limit clinical efficacy and allow tumor recurrence. Our main hypothesis is that modification of hematopoietic stem cells (HSCs) with CARs will lead to persistent in vivo production of target-specific immune cells in multiple lineages, enhancing graft-versus-tumor activity and development of immunological memory. Using CD19 as target, we have generated first-generation and CD28- and 4-1BB-containing-second-generation CAR lentiviral constructs for modification of human HSCs, for assessment in vitro and in vivo. Gene modification with anti-CD19 CAR of CD34+cells isolated from human umbilical cord blood (UCB) did not impair normal differentiation and proliferation, with fully functional CAR-expressing cell progeny. Transduction with lentiviral vectors consistently achieved 40-50% efficiency at the clinically relevant vector copy number of 1-2 copies/cell. While first- and second-generation CARs triggered antigen-dependent cytotoxicity by myeloid and T cells in a similar fashion, only second-generation constructs successfully activated NK cells for antigen-dependent elimination of cell targets. In vivo studies using humanized NSG engrafted with CAR-modified human UCB CD34+ cells demonstrated similar levels of engraftment of human cells as compared to non-modified UCB CD34+ cells, with CAR-expressing cells in multiple lineages (myeloid, NK, T) successfully engrafted into bone marrow, spleen, peripheral blood and thymus detectable by flow cytometry and qPCR, in stable levels up to 35 weeks of life, with gene modification with first- or second-generation anti-CD19 CARs. No animals engrafted with CAR-modified HSCs presented signs of autoimmunity or chronic inflammation. Cells presented ex vivo antigen-dependent cytotoxicity against cell targets. Mice successfully engrafted with CAR-modified HSCs harbored decreased CD19+populations, and only HSCs modified with second-generation CARs successfully led to tumor growth inhibition and survival advantage at tumor challenge. CAR-modified HSCs led to development of T cell effector memory and T cell central memory subsets, confirming the expectation of development of long-lasting phenotypes due to directed antigen specificity. Longer survival of mice with developing tumors was also significantly correlated to higher number of CAR-expressing cells infiltrating subcutaneous tumors. Our results demonstrate feasibility of CAR modification of human HSCs for cancer immunotherapy. This approach can be applied to different cancers just by adjusting the target specificity. Furthermore, it could be easily employed in the context of HSC transplantation to augment the anti-leukemic activity, with CAR-expressing myeloid and NK cells to ensure tumor-specific immunity until de novo production of T cells from CAR-modified HSCs. It also bears the possibility of decreased morbidity and mortality, being desirable for vulnerable populations such as children and elderly patients, and offers alternative treatment for patients with no available HLA-matched sources for bone marrow transplantation, benefiting ethnic minorities. Disclosures Larson: Millenium Pharmaceuticals, Inc.: Speakers Bureau.

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Interleukin 4 expressed in situ selectively alters thymocyte development.

Journal of Experimental Medicine ◽

10.1084/jem.173.1.89 ◽

1991 ◽

Vol 173 (1) ◽

pp. 89-100 ◽

Cited By ~ 63

Author(s):

D B Lewis ◽

C C Yu ◽

K A Forbush ◽

J Carpenter ◽

T A Sato ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cell Receptor ◽

Interleukin 4 ◽

Thymocyte Development ◽

Double Positive ◽

Peripheral T Cells ◽

Single Positive ◽

And Control

Using a transgenic mouse model we show that increased intrathymic expression of interleukin 4 (IL-4) significantly perturbs the development of thymocytes. Transgenic double-positive (CD4+CD8+) thymocytes, which are present in dramatically reduced numbers, exhibit increased T cell receptor (TCR) expression and increased mobilization of calcium mediated by these receptors. In contrast, transgenic single-positive (CD4+CD8- and CD4-CD8+) thymocytes and peripheral T cells exhibit decreased TCR-mediated calcium mobilization. The development of CD4-CD8+ thymocytes is significantly perturbed by IL-4 expressed in vivo; only peripheral CD4+ T cells are found in significant numbers in transgenic mice, while CD4-CD8+ thymocytes are present in increased numbers, apparently because of their failure to emigrate to the periphery. In contrast to these selective effects on T cell development, no significant differences in the numbers of B cells or mast cells, or in the plasma levels of IgE and IgG1 are observed between transgenic and control mice. These observations suggest that IL-4 in vivo exerts its major effects locally rather than systemically, even when its expression is constitutively increased.

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Robust Therapeutic Expression of the Common Gamma Chain with the Human Pgk Promoter Using Foamy Virus in Vivo Gene Therapy in a Canine Model of Severe Combined Immunodeficiency

Blood ◽

10.1182/blood.v124.21.4794.4794 ◽

2014 ◽

Vol 124 (21) ◽

pp. 4794-4794

Author(s):

Christopher R Burtner ◽

Olivier Humbert ◽

Patricia O'Donnell ◽

Nicholas Hubbard ◽

Daniel Humphrys ◽

...

Keyword(s):

Gene Therapy ◽

T Cells ◽

T Cell ◽

Intravenous Injection ◽

Ex Vivo ◽

Foamy Virus ◽

Gamma Chain ◽

Hematopoietic Stem ◽

Common Gamma Chain

Abstract In vivo gene therapy has several benefits over ex vivo hematopoietic stem cell gene therapy, including the correction of progenitor cells in their native environments, the portability of the treatment to the patient, and the ability to administer serial doses of therapeutic vector. Foamy viruses (FV) are ideal vectors for in vivo gene therapy for 3 primary reasons: (1) FV are non-pathogenic in humans, (2) they exhibit enhanced serum stability as compared to lentiviruses packaged with the vesicular stomatitis virus glycoprotein (VSV-G), and (3) FV integrate into host genomes with a favorable integration pattern. We recently demonstrated that intravenous injection of a FV vector expressing the human common gamma chain (γC) under the constitutively active short elongation factor 1α (EF1α) promoter is sufficient to drive development of CD3+ lymphocytes in canine X-SCID, which undergo T cell receptor rearrangement and exhibit a functional signaling response to T cell activating mitogens (Burtner CR, Beard BC, Kennedy DR, et al. Intravenous injection of a foamy virus vector to correct canine SCID-X1. Blood. 2014;123(23):3578-84). However, retroviral integration site analysis in that study indicated that T cell reconstitution occurred through the correction of a limited number of progenitors, possibly due to sub-therapeutic expression levels from the EF1α promoter. To address this issue, we are evaluating multiple parameters of vector design for in vivo gene therapy, including different promoters, using injections of vectors marked with different fluorophores. Preliminary data indicated that ex vivo transduction of canine CD34+ cells with a FV vector expressing human γC and a fluorescent reporter under the human phosphoglycerate kinase (PGK) promoter resulted in higher transduction efficiencies and increased mean fluorescence intensity, compared to that of an identical vector containing the EF1α promoter. We therefore performed a head-to-head comparison of the two promoters by simultaneously injecting X-SCID pups with equal titers of 2 therapeutic, human γC-encoding FV vectors that differed only in the promoter used to drive human γC expression and in the fluorophore color to distinguish gene-marked cells (GFP and mCherry). Each dog received 4 x 108 infectious units of each FV vector. A significant population of gene-marked lymphocytes appeared in the PGK arm 42 days post in vivo gene therapy, which continued to expand over the next two months of follow-up (Fig 1A). By 84 days post injection, lymphocyte gene marking in the competitive PGK arm reached 60% in both dogs. For comparison, this robust level of lymphocyte gene marking was achieved in only 2 of 5 dogs after 122 and 160 days, respectively, in our previous EF1α virus treated cohort. In contrast, the EF1α arm peaked at 42 days after in vivo gene therapy and never expanded above 10% (Fig 1A). Interestingly, the expansion of T lymphocytes from gene-modified cells expressing γC under the PGK promoter appeared to preclude further development of T cells by the by the EF1α arm, suggesting competition within the expanding T cell niche. The expansion of gene-marked lymphocytes was followed by the development of CD3+ T cells, leading to a therapeutic level of CD3+ cells (1000 cells/μl of blood) in both dogs (Fig 1B). Additionally, our data indicate low but persistent gene marking in other blood cells, including granulocytes and B cells, with B cell marking in one animal exceeding 2% in the PGK arm. Our data suggest that the PGK promoter results in a robust and sustained correction of progenitor T cells in a relevant large-animal disease model for primary immunodeficiency. These data also highlight the utility of the in vivo approach to explore key parameters of vector design in competitive repopulation experiments that may be useful for other diseases. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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The Checkpoint for Agonist Selection Precedes Conventional Selection in Human Thymus

Blood ◽

10.1182/blood.v128.22.860.860 ◽

2016 ◽

Vol 128 (22) ◽

pp. 860-860

Author(s):

Greet Verstichel ◽

David Vermijlen ◽

Liesbet Martens ◽

Glenn Goetgeluk ◽

Yvan Saeys ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Conflicts Of Interest ◽

Ex Vivo ◽

Double Positive ◽

Human Thymus ◽

Tcr Signals

Abstract The thymus plays a central role in self-tolerance by preventing strongly self-reactive thymocytes from accumulating as naïve T cell receptor (TCR) αβ+ T cells in the periphery. The elimination of auto-reactive T cells from the naïve pool is in part mediated by deletion during conventional negative selection. Alternatively, self-reactive thymocytes can also be positively selected in response to strong TCR signals during agonist selection and functionally differentiate to innate TCRαβ + T cells such as the CD8αα+ double negative (DN) T cells. How thymocytes discriminate between these opposite outcomes remains unclear. We identified a novel agonist-selected PD-1+ CD8αα+ subset of mature CD8+ T cells in human thymus. Using the same markers a similar population was also identified in cord blood at about the same frequency as TCRγδ+ cells. This population expresses high levels of Helios, indicative of strong TCR engagement, and displays an effector phenotype associated with agonist selection. Indeed, PD-1+CD8αα+ T cells exhibit innate production of IFN-γ and an elevated T-bet to Eomes ratio typical of effector CD8 T cells. These cells are CD62L-, CXCR3+ and Hobit high suggesting that these cells leave the thymus and home to the tissues. Interestingly, in vitro CD3/TCR stimulation of sorted early post-β-selection thymocyte blasts uniquely gives rise to this innate subset, whereas small CD4+CD8+ double positive precursors fail to survive strong TCR signals. The generation of the innate subset seems to arise also in vivo from early post-β-selection thymocyte blasts as these two populations have an identical TCRα repertoire: ex vivo isolated PD-1+CD8αα+ thymocytes are skewed for early 3' TRAV and 5' TRAJ rearrangements compared to conventional CD8 T cells. A similar skewing was found in early post-β-selection thymocyte blasts. As TCRα rearrangements are terminated by TCR engagement of agonist selection, this is strong evidence for a precursor progeny relationship. Together, we conclude that human CD8αα+ T cells are preferentially selected by strong TCR engagement on a subset of progenitors that express a full TCRαβ early on, leading to the generation of a post-selection T cell population with innate functional capacity and a markedly distinct TCR repertoire. These findings uncover the heterogeneity among DP precursors in their potential to survive strong selection signals and suggests that the decision making in the thymus to divert immature thymocytes to the agonist selection pathway occurs early before conventional selection of DP cells. We propose that progression through the immature thymic developmental program influences the outcome of TCR engagement with early post-β-selection thymocytes triggered by strong TCR signals preferentially giving rise to innate CD8αα+ T cells in humans. Disclosures No relevant conflicts of interest to declare.

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IMMU-31. QUANTITATIVE EVALUATION OF ROUTES OF ADMINISTRATION OF IMMUNOTHERAPEUTIC T CELLS TO ORTHOTOPIC GLIOMA

Neuro-Oncology ◽

10.1093/neuonc/noaa215.461 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii111-ii111

Author(s):

Lan Hoang-Minh ◽

Angelie Rivera-Rodriguez ◽

Fernanda Pohl-Guimarães ◽

Seth Currlin ◽

Christina Von Roemeling ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Tumor Growth ◽

Ex Vivo ◽

Adoptive T Cell Therapy ◽

Whole Body ◽

T Cell Therapy ◽

Clinical Responses

Abstract SIGNIFICANCE Adoptive T cell therapy (ACT) has emerged as the most effective treatment against advanced malignant melanoma, eliciting remarkable objective clinical responses in up to 75% of patients with refractory metastatic disease, including within the central nervous system. Immunologic surrogate endpoints correlating with treatment outcome have been identified in these patients, with clinical responses being dependent on the migration of transferred T cells to sites of tumor growth. OBJECTIVE We investigated the biodistribution of intravenously or intraventricularly administered T cells in a murine model of glioblastoma at whole body, organ, and cellular levels. METHODS gp100-specific T cells were isolated from the spleens of pmel DsRed transgenic C57BL/6 mice and injected intravenously or intraventricularly, after in vitro expansion and activation, in murine KR158B-Luc-gp100 glioma-bearing mice. To determine transferred T cell spatial distribution, the brain, lymph nodes, heart, lungs, spleen, liver, and kidneys of mice were processed for 3D imaging using light-sheet and multiphoton imaging. ACT T cell quantification in various organs was performed ex vivo using flow cytometry, 2D optical imaging (IVIS), and magnetic particle imaging (MPI) after ferucarbotran nanoparticle transfection of T cells. T cell biodistribution was also assessed in vivo using MPI. RESULTS Following T cell intravenous injection, the spleen, liver, and lungs accounted for more than 90% of transferred T cells; the proportion of DsRed T cells in the brains was found to be very low, hovering below 1%. In contrast, most ACT T cells persisted in the tumor-bearing brains following intraventricular injections. ACT T cells mostly concentrated at the periphery of tumor masses and in proximity to blood vessels. CONCLUSIONS The success of ACT immunotherapy for brain tumors requires optimization of delivery route, dosing regimen, and enhancement of tumor-specific lymphocyte trafficking and effector functions to achieve maximal penetration and persistence at sites of invasive tumor growth.

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549 Characterizing double positive T cells in the tumor microenvironment: a tale of promiscuous cell fates

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0549 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A586-A586

Author(s):

Sara Schad ◽

Andrew Chow ◽

Heng Pan ◽

Levi Mangarin ◽

Roberta Zappasodi ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Tumor Microenvironment ◽

Cd8 T Cells ◽

Human Melanoma ◽

B16 Melanoma ◽

T Cell Subsets ◽

Double Positive ◽

Cell Fates ◽

Single Positive

BackgroundCD4 and CD8 T cells are genetically and functionally distinct cell subsets of the adaptive immune system that play pivotal roles in immune surveillance and disease control. During development in the thymus, transcription factors ThPOK and Runx3 regulate the differentiation and maturation of these two lineages into single positive T cells that enter the periphery with mutually exclusive expression of either the CD4 or CD8 co-receptor.1–2 Despite our expectation that these two cell fates are fixed, mature CD4+CD8+ double positive (DP) T cells have been described in the context of numerous immunological responses, including cancer, but their molecular and functional properties and therapeutic relevance remain controversial and largely unknown.3–5MethodsOur lab has identified and characterized a heterogenous DP T cell population in murine and human melanoma tumors comprised of CD4 and CD8 T cells re-expressing the opposite co-receptor and a parallel uptake in the opposite cell type’s phenotype and function. Using CD4 (Trp1) and CD8 (Pmel) transgenic TCR T cells specific to B16 melanoma antigens gp75 and gp100 respectively, we demonstrate the re-expression of the opposite co-receptor following adoptive T cell transfer in B16 melanoma tumor bearing mice.ResultsSpecifically, up to 50% of transferred CD4 Trp1 T cells will re-express CD8 to become a DP T cell in the tumor microenvironment. Further, these CD4 derived DP T cells upregulate CD8 lineage regulator Runx3 and cytolytic genes Gzmb, Gzmk, and Prf1 to become potent cytotoxic T cells. Alternatively, a subset of CD8 Pmel T cells differentiate into DP T cells characterized by the increased expression of CD4, ThPOK, and regulatory marker FoxP3 (figure 1). In addition, we utilized 10x single cell and ATAC sequencing to further characterize these divergent DP T cell populations among open repertoire T cells isolated from murine and human melanoma tumors.ConclusionsOur findings highlight the capability of single positive T cells to differentiate in response to antigen and local stimuli into novel T cell subsets with polyfunctional characteristics. The resulting cell subsets will potentially affect the tumor microenvironment in distinct ways. Our studies may inform therapeutic approaches to identify antigen specific T cells as well as innovative signaling pathways to target when genetically engineering T cells to optimize cytotoxic function in the setting of adoptive cell therapy.Ethics ApprovalThe human biospecimen analyses were approved by Memorial Sloan Kettering Cancer Center IRB #06-107ReferencesEllmeier W, Haust L & Tschismarov R. Transcriptional control of CD4 and CD8 coreceptor expression during T cell development. Cell Mol Life Sci 2013;70:4537–4553.Luckey MA, et al. The transcription factor ThPOK suppresses Runx3 and imposes CD4+ lineage fate by inducing the SOCS suppressors of cytokine signaling. Nature Immunology 2014; 15, 638–645.Bohner P, et al. Double positive CD4(+)CD8(+) T Cells are enriched in urological cancers and favor T Helper-2 polarization. Front Immunol 2019; 10, 622.Nascimbeni M, Shin E-C, Chiriboga L, Kleiner DE & Rehermann B. Peripheral CD4(+)CD8(+) T cells are differentiated effector memory cells with antiviral functions. Blood 2004;104:478–486.Nishida K, et al. Clinical importance of the expression of CD4+CD8+ T cells in renal cell carcinoma. Int Immunol 2020;32:347–357.

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Systemic T Cell–independent Tumor Immunity after Transplantation of Universal Receptor–modified Bone Marrow into SCID Mice

Journal of Experimental Medicine ◽

10.1084/jem.184.6.2261 ◽

1996 ◽

Vol 184 (6) ◽

pp. 2261-2270 ◽

Cited By ~ 28

Author(s):

Kristen M. Hege ◽

Keegan S. Cooke ◽

Mitchell H. Finer ◽

Krisztina M. Zsebo ◽

Margo R. Roberts

Keyword(s):

T Cell ◽

Ex Vivo ◽

Lethal Dose ◽

Cell Receptor ◽

Scid Mice ◽

Human Leukemia ◽

Hematopoietic Stem ◽

Retroviral Transduction ◽

Hiv Envelope

Gene modification of hematopoietic stem cells (HSC) with antigen-specific, chimeric, or “universal” immune receptors (URs) is a novel but untested form of targeted immunotherapy. A human immunodeficiency virus (HIV) envelope–specific UR consisting of the extracellular domain of human CD4 linked to the ζ chain of the T cell receptor (CD4ζ) was introduced ex vivo into murine HSC by retroviral transduction. After transplantation into immunodeficient SCID mice, sustained high level expression of CD4ζ was observed in circulating myeloid and natural killer cells. CD4ζ-transplanted mice were protected from challenge with a lethal dose of a disseminated human leukemia expressing HIV envelope. These results demonstrate the ability of chimeric receptors bearing ζ-signaling domains to activate non–T cell effector populations in vivo and thereby mediate systemic immunity.

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