scholarly journals Tumor-specific cytolytic CD4 T cells mediate immunity against human cancer

2021 ◽  
Vol 7 (9) ◽  
pp. eabe3348
Author(s):  
Amélie Cachot ◽  
Mariia Bilous ◽  
Yen-Cheng Liu ◽  
Xiaokang Li ◽  
Margaux Saillard ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cytotoxic Activity ◽  
Single Cell ◽  
Cd4 T Cells ◽  
Ex Vivo ◽  
Human Cancer ◽  
Functional Characterization ◽  
Cytotoxic Lymphocytes ◽  
Mediate Immunity

CD4 T cells have been implicated in cancer immunity for their helper functions. Moreover, their direct cytotoxic potential has been shown in some patients with cancer. Here, by mining single-cell RNA-seq datasets, we identified CD4 T cell clusters displaying cytotoxic phenotypes in different human cancers, resembling CD8 T cell profiles. Using the peptide-MHCII-multimer technology, we confirmed ex vivo the presence of cytolytic tumor-specific CD4 T cells. We performed an integrated phenotypic and functional characterization of these cells, down to the single-cell level, through a high-throughput nanobiochip consisting of massive arrays of picowells and machine learning. We demonstrated a direct, contact-, and granzyme-dependent cytotoxic activity against tumors, with delayed kinetics compared to classical cytotoxic lymphocytes. Last, we found that this cytotoxic activity was in part dependent on SLAMF7. Agonistic engagement of SLAMF7 enhanced cytotoxicity of tumor-specific CD4 T cells, suggesting that targeting these cells might prove synergistic with other cancer immunotherapies.

scholarly journals 545 Tumor-specific cytolytic CD4 T cells mediate protective immunity against human cancer

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A581-A581
Author(s):  
Amélie Cachot ◽  
Mariia Bilous ◽  
Yen-Cheng Liu ◽  
Xiaokang Li ◽  
Alexander Rockinger ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cytotoxic Activity ◽  
Single Cell ◽  
Cancer Patients ◽  
Mhc Class Ii ◽  
High Throughput ◽  
Cd4 T Cells ◽  
Functional Characterization

BackgroundCD4 T cells have been implicated in cancer immunity for their helper functions. However, their direct cytotoxic potential remains elusive in cancer patients. Here, we aimed at assessing the presence, rate and cytotoxic function of tumor-specific Th-CTX directly in cancer patients.MethodsWe capitalized on published single cell transcriptomic analyses of patient samples, integrated with the direct phenotypic and functional characterization of clonal, tumor-specific CD4 T cell populations, using peptide-MHC class II multimers and a novel high-throughput single-cell cytotoxicity assay in picowell arrays. The direct tumor cell killing by cytolytic tumor-specific CD4 T cells in the arrays was monitored in a high-throughput manner by combining multi-channel time-lapse microscopy with deep neural networks.ResultsBy mining single-cell RNA-seq datasets of tumor infiltrating lymphocytes, we identified CD4 T cells displaying cytotoxic phenotypes in different human tumors. The cytolytic CD4 T cells formed a distinct cluster and expressed genes related to classical cytotoxic functions, largely resembling CD8 T cell gene profiles. Using the peptide MHC class II multimer technology, we confirmed directly ex vivo the presence of cytolytic tumor antigen-specific CD4 T cells, both in the circulation and in the tumors of patients. We performed an integrated phenotypic and functional characterization of cytolytic tumor-specific CD4 T cells, down to the single cell level, through a high-throughput nanobiochip consisting of massive arrays of picowells with sub-nanoliter volumes and machine learning. We demonstrated a direct, contact-dependent, granzyme-dependent cytotoxic activity against tumor cells, with delayed kinetics compared to classical cytotoxic lymphocytes. Lastly, we discovered that this cytotoxic activity was at least in part dependent on the expression of SLAMF7, a homophylic receptor known to regulate NK cell activity.ConclusionsOur work provides a deep characterization of human Th-CTX in cancer and supports their role in tumor immunity. Moreover, our results showing that agonistic engagement of SLAMF7 enhances the cytolytic capacity of tumor-specific CD4 T cells, suggests that targeting these cells might prove synergistic with the use of other immunotherapies in cancer patients.

scholarly journals Single-cell transcriptomics reveals expansion of cytotoxic CD4 T cells in supercentenarians

2019 ◽  
Vol 116 (48) ◽  
pp. 24242-24251 ◽  
Author(s):  
Kosuke Hashimoto ◽  
Tsukasa Kouno ◽  
Tomokatsu Ikawa ◽  
Norihito Hayatsu ◽  
Yurina Miyajima ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Single Cell ◽  
Cd4 T Cells ◽  
Healthy Aging ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Cell Receptor ◽  
Peripheral Blood Mononuclear ◽  
Age Related

Supercentenarians, people who have reached 110 y of age, are a great model of healthy aging. Their characteristics of delayed onset of age-related diseases and compression of morbidity imply that their immune system remains functional. Here we performed single-cell transcriptome analysis of 61,202 peripheral blood mononuclear cells (PBMCs), derived from 7 supercentenarians and 5 younger controls. We identified a marked increase of cytotoxic CD4 T cells (CD4 cytotoxic T lymphocytes [CTLs]) as a signature of supercentenarians. Furthermore, single-cell T cell receptor sequencing of 2 supercentenarians revealed that CD4 CTLs had accumulated through massive clonal expansion, with the most frequent clonotypes accounting for 15 to 35% of the entire CD4 T cell population. The CD4 CTLs exhibited substantial heterogeneity in their degree of cytotoxicity as well as a nearly identical transcriptome to that of CD8 CTLs. This indicates that CD4 CTLs utilize the transcriptional program of the CD8 lineage while retaining CD4 expression. Indeed, CD4 CTLs extracted from supercentenarians produced IFN-γ and TNF-α upon ex vivo stimulation. Our study reveals that supercentenarians have unique characteristics in their circulating lymphocytes, which may represent an essential adaptation to achieve exceptional longevity by sustaining immune responses to infections and diseases.

scholarly journals CRTAM determines the CD4+ cytotoxic T lymphocyte lineage

2015 ◽  
Vol 213 (1) ◽  
pp. 123-138 ◽  
Author(s):  
Arata Takeuchi ◽  
Mohamed El Sherif Gadelhaq Badr ◽  
Kosuke Miyauchi ◽  
Chitose Ishihara ◽  
Reiko Onishi ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cytotoxic Activity ◽  
Cd4 T Cells ◽  
Intracellular Signaling ◽  
Ectopic Expression ◽  
T Cell Subsets ◽  
Naive T Cells ◽  
Naïve T Cells ◽  
Ifn Γ

Naive T cells differentiate into various effector T cells, including CD4+ helper T cell subsets and CD8+ cytotoxic T cells (CTL). Although cytotoxic CD4+ T cells (CD4+CTL) also develop from naive T cells, the mechanism of development is elusive. We found that a small fraction of CD4+ T cells that express class I–restricted T cell–associated molecule (CRTAM) upon activation possesses the characteristics of both CD4+ and CD8+ T cells. CRTAM+ CD4+ T cells secrete IFN-γ, express CTL-related genes, such as eomesodermin (Eomes), Granzyme B, and perforin, after cultivation, and exhibit cytotoxic function, suggesting that CRTAM+ T cells are the precursor of CD4+CTL. Indeed, ectopic expression of CRTAM in T cells induced the production of IFN-γ, expression of CTL-related genes, and cytotoxic activity. The induction of CD4+CTL and IFN-γ production requires CRTAM-mediated intracellular signaling. CRTAM+ T cells traffic to mucosal tissues and inflammatory sites and developed into CD4+CTL, which are involved in mediating protection against infection as well as inducing inflammatory response, depending on the circumstances, through IFN-γ secretion and cytotoxic activity. These results reveal that CRTAM is critical to instruct the differentiation of CD4+CTL through the induction of Eomes and CTL-related gene.

scholarly journals 192 Pooled T cell receptor screening (POTS) provides unbiased, high-throughput method for TCR discovery

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A204-A204
Author(s):  
Jack Reid ◽  
Shihong Zhang ◽  
Ariunaa Munkhbat ◽  
Matyas Ecsedi ◽  
Megan McAfee ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Single Cell ◽  
T Cell Receptor ◽  
High Throughput ◽  
Ex Vivo ◽  
Cell Receptor ◽  
High Avidity ◽  
Reporter System ◽  
High Throughput Method

BackgroundT Cell Receptor (TCR)-T cell therapies have shown some promising results in cancer clinical trials, however the efficacy of treatment remains suboptimal. Outcomes could potentially be improved by utilizing highly functional TCRs for future trials. Current TCR discovery methods are relatively low throughput and rely on synthesis and screening of individual TCRs based on tetramer binding and peptide specificity, which is costly and labor intensive. We have developed and validated a pooled approach relying on directly cloned TCRs transduced into a fluorescent Jurkat reporter system (figure 1). This approach provides an unbiased, high-throughput method for TCR discovery.MethodsAs a model for POTS, T cells specific for a peptide derived adenovirus structural protein were sorted on tetramer and subjected to 10x single cell VDJ analysis. Pools of randomly paired TCR alpha and beta chains were cloned from the 10x cDNA into a lentiviral vector and transduced into a Jurkat reporter cells. Consecutive stimulations with cognate antigen followed by cell sorts were performed to enrich for functional TCRs. Full length TCRab pools were sequenced by Oxford Nanopore Technologies (ONT) and compared to a 10x dataset to find naturally paired TCRs.ResultsComparison between the ex vivo single cell VDJ sequencing and ONT sequencing of the transduced antigen specific TCRs showed more than 99% of the TCR pairs found in reporter positive Jurkat cells were naturally paired TCRs. The functionality of 8 TCR clonotypes discovered using POTS were compared and clone #2 showed the strongest response. Of the selected clonotypes, clone #2 showed a low frequency of 0.9% in the ex vivo single cell VDJ sequencing. After the first round of stimulation and sequencing, clone #2 takes up of 5% of all reporter-positive clones. The abundance of clone #2 further increased to 17% after another round of stimulation, sorting and sequencing, suggesting this method can retrieve and enrich for highly functional antigen specific TCRs.Abstract 192 Figure 1Outline of the POTS workflow.ConclusionsPOTS provides a high-throughput method for discovery of naturally paired, high-avidity T cell receptors. This method mitigates bias introduced by T cell differentiation state by screening TCRs in a clonal reporter system. Additionally, POTS allows for screening of low abundance clones when compared with traditional TCR discovery techniques. Pooled TCRs could also be screened in vivo with primary T cells in a mouse model to screen for the most functional and physiologically fit TCR for cancer treatment.

scholarly journals Inconsistent Reversal of HIV-1 Latency Ex Vivo by Antigens of HIV-1, CMV, and Other Infectious Agents

2020 ◽  
Author(s):  
Thomas Vollbrecht ◽  
Aaron O. Angerstein ◽  
Bryson Menke ◽  
Nikesh M. Kumar ◽  
Michelli Faria Oliveira ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Ex Vivo ◽  
Latent Reservoir ◽  
Antigen Specificity ◽  
Pcr Assay ◽  
Hiv 1

Abstract BackgroundA reservoir of replication-competent but latent virus is the main obstacle to a cure for HIV-infection. Much of this reservoir resides in memory CD4 T cells. We hypothesized that these cells can be reactivated with antigens from HIV and other common pathogens to reverse latency. ResultsWe obtained mononuclear cells from the peripheral blood of antiretroviral-treated patients with suppressed viremia. We tested pools of peptides and proteins derived from HIV and from other pathogens including CMV for their ability to reverse latency ex vivo by activation of memory responses. We assessed activation of the CD4 T cells by measuring the up-regulation of cell-surface CD69. We assessed HIV-expression using two assays: a real-time PCR assay for virion-associated viral RNA and a droplet digital PCR assay for cell-associated, multiply spliced viral mRNA. Reversal of latency occurred in a minority of cells from some participants, but no single antigen induced HIV-expression ex vivo consistently. When reversal of latency was induced by a specific peptide pool or protein, the extent was proportionally greater than that of T cell activation. ConclusionsIn this group of patients in whom antiretroviral therapy was started during chronic infection, the latent reservoir does not appear to consistently reside in CD4 T cells of a predominant antigen-specificity. Peptide-antigens reversed HIV-latency ex vivo with modest and variable activity. When latency was reversed by specific peptides or proteins, it was proportionally greater than the extent of T cell activation, suggesting partial enrichment of the latent reservoir in cells of specific antigen-reactivity.

scholarly journals Dual T cell– and B cell–intrinsic deficiency in humans with biallelic RLTPR mutations

2016 ◽  
Vol 213 (11) ◽  
pp. 2413-2435 ◽  
Author(s):  
Yi Wang ◽  
Cindy S. Ma ◽  
Yun Ling ◽  
Aziz Bousfiha ◽  
Yildiz Camcioglu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cd4 T Cells ◽  
Ex Vivo ◽  
Cell Phenotype ◽  
Loss Of Function ◽  
Inborn Errors

Combined immunodeficiency (CID) refers to inborn errors of human T cells that also affect B cells because of the T cell deficit or an additional B cell–intrinsic deficit. In this study, we report six patients from three unrelated families with biallelic loss-of-function mutations in RLTPR, the mouse orthologue of which is essential for CD28 signaling. The patients have cutaneous and pulmonary allergy, as well as a variety of bacterial and fungal infectious diseases, including invasive tuberculosis and mucocutaneous candidiasis. Proportions of circulating regulatory T cells and memory CD4+ T cells are reduced. Their CD4+ T cells do not respond to CD28 stimulation. Their CD4+ T cells exhibit a "Th2" cell bias ex vivo and when cultured in vitro, contrasting with the paucity of "Th1," "Th17," and T follicular helper cells. The patients also display few memory B cells and poor antibody responses. This B cell phenotype does not result solely from the T cell deficiency, as the patients’ B cells fail to activate NF-κB upon B cell receptor (BCR) stimulation. Human RLTPR deficiency is a CID affecting at least the CD28-responsive pathway in T cells and the BCR-responsive pathway in B cells.

Loss of EBV-Specific CD4+T Cells during Progression to EBV-Related AIDS Non-Hodgkin Lymphoma: Restoration by Highly Active Antiretroviral Therapy (HAART).

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3110-3110
Author(s):  
Erwan R. Piriou ◽  
Christine Jansen ◽  
Karel van Dort ◽  
Iris De Cuyper ◽  
Nening M. Nanlohy ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Response ◽  
Cd4 T Cells ◽  
Antigen Processing ◽  
Ex Vivo ◽  
T Cell Response ◽  
Cd4 T Cell ◽  
Cell Numbers

Abstract Objective: EBV-specific CD8+ T cells have been extensively studied in various settings, and appear to play a major role in the control of EBV-related malignancies. In contrast, it is still unclear whether EBV-specific CD4+ T cells play a role in vivo. To study this question, an assay was developed to measure the CD4+ T-cell response towards two EBV antigens, in both healthy (n=14) and HIV-infected subjects (n=23). In addition, both HAART-treated (n=12) and untreated HIV+ individuals (n=14) - including progressors to EBV-related lymphoma - were studied longitudinally. Methods: EBV-specific CD4+ T cells were stimulated with peptide pools from latent protein EBNA1 and lytic protein BZLF1, and detected by measurement of IFNg-production. Results: After direct ex vivo stimulation, EBNA1 or BZLF1-specific IFNg- (and/or IL2) producing CD4+ T cell numbers were low, and measurable in less than half of the subjects studied (either HIV- and HIV+). Therefore, PBMC were cultured for 12 days in the presence of peptides and IL2 (from day 3), and then restimulated with peptides, allowing specific and reproducible expansion of EBV-specific CD4+ T cells, independent of HLA type and ex vivo antigen processing. Interestingly, numbers of EBV-specific CD4+ T cells inversely correlated with EBV viral load, implying an important role for EBV-specific CD4+ T cells in the control of EBV in vivo. Untreated HIV-infected individuals had a lower CD4+ T cell response to EBNA1 and BZLF1 as compared to healthy EBV carriers and HAART-treated HIV+ subjects. In longitudinal samples, EBNA1-specific, but not BZLF1-specific T-cell numbers increased after HAART, while EBV load was not affected by treatment. In all the progressors to EBV-related lymphoma, EBV-specific CD4+ T cells were lost at least 24 months before lymphoma diagnosis. Conclusions: Both cross-sectional and longitudinal data suggest an important role for EBV-specific CD4+ T cells in the control of EBV-related malignancies. Furthermore, it seems that HAART treatment leads to recovery of EBNA1-specific, but not BZLF1-specific CD4+ T-cell responses, implying changes in the latency pattern of EBV, despite an unaltered cell-associated EBV DNA load. Thus, early HAART treatment might prevent loss of specific CD4+ T-cell help and progression to NHL.

Ex Vivo Fludarabine Selectively Depletes Human Naive T-Cell Subsets: A Step Toward Modifying Donor Lymphocyte Infusion.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1071-1071
Author(s):  
Melody M. Smith ◽  
Cynthia R. Giver ◽  
Edmund K. Waller ◽  
Christopher R. Flowers
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Memory T Cells ◽  
Ex Vivo ◽  
T Cell Subsets ◽  
Effector Memory ◽  
Naïve T Cell ◽  
Naive T Cell

Abstract Ex vivo modification of donor lymphocytes with purine analogs (mDL) may help to minimize graft versus host disease (GvHD) while providing beneficial graft versus leukemia (GvL) effects. In a murine model system, we have shown that allogeneic donor splenocytes, treated with fludarabine ex vivo have significantly reduced GvHD activity when transferred to irradiated recipient mice, and retain anti-viral and GvL activities (Giver, 2003). This effect appears to be mediated by relative depletion of donor CD4 CD44low, “naive” T-cells. As a first step toward developing mDL for use in patients, we sought to evaluate the effects of ex vivo fludarabine exposure on human T-cell subsets, and to determine the minimum dose of fludarabine required to achieve this effect. Methods: Peripheral blood mononuclear cell samples from 6 healthy volunteers were evaluated at 0, 24, 48, and 72 hour time points after ex vivo incubation in varying dosages of fludarabine: 2, 5, and 10(n=3) mcg/ml. Fludarabine incubated samples were compared to samples that received no fludarabine (untreated). The total viable cell number was determined and the fractions and absolute numbers of viable CD4 and CD8 naïve and memory T-cells were determined using flow cytometry after incubation with 7-AAD (dead cell stain), CD4, CD8, CD45RA, CD62L, and CCR7 antibodies, and measuring the total viable cells/ml. Results: The numbers of viable CD4 and CD8 T-cells remained relatively stable in control cultures. Without fludarabine, the average viability at 72 hr of naive and memory T-cells were 92% and 77% for CD4 and 86% and 63% for CD 8 (Fig. 1A). Naive CD4 T-cells were more sensitive to fludarabine-induced death than memory CD4 cells. At 72 hr, the average viability of fludarabine-treated naive CD4 T-cells was 33% at 2 mcg/ml (8.2X the reduction observed in untreated cells) and 30% at 5 mcg/ml, while memory CD4 T-cells averaged 47% viability at 2 mcg/ml (2.3X the reduction observed in untreated cells) (Fig. 1B) and 38% at 5 mcg/ml. The average viability of naive CD8 T-cells at 72 hr was 27% at 2 mcg/ml and 20% at 5 mcg/ml, while memory CD8 T-cell viability was 22% at 2 mcg/ml and 17% at 5 mcg/ml. Analyses on central memory, effector memory, and Temra T-cells, and B-cell and dendritic cell subsets are ongoing. The 5 and 10 mcg/ml doses also yielded similar results in 3 initial subjects, suggesting that 2 mcg/ml or a lower dose of fludarabine is sufficient to achieve relative depletion of the naive T-cell subset. Conclusions: Future work will determine the minimal dose of fludarabine to achieve this effect, test the feasibility of using ex vivo nucleoside analog incubation to reduce alloreactivity in samples from patient/donor pairs, and determine the maximum tolerated dose of mDL in a phase 1 clinical trial with patients at high risk for relapse and infectious complications following allogeneic transplantation. Figure Figure

Adoptive Transfer of Treg-Depleted Donor Th1 and Th2 Cells Safely Accelerates Alloengraftment After Low-Intensity Chemotherapy

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 521-521 ◽  
Author(s):  
Daniel H. Fowler ◽  
Miriam E. Mossoba ◽  
Bazetta Blacklock Schuver ◽  
Paula Layton ◽  
Frances T Hakim ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
High Risk ◽  
Cell Therapy ◽  
Cd4 T Cells ◽  
Ex Vivo ◽  
Chronic Gvhd ◽  
Th2 Cells ◽  
Low Intensity ◽  
Ex Vivo Culture

Abstract Abstract 521 Ex-vivo culture of murine donor CD4+ T cells using rapamycin, co-stimulation, and IL-4 yielded a defined T cell population (T-rapa cells) that favorably modulated the balance between GVHD, graft rejection, and GVT effects. To translate these findings, we conducted a multi-center clinical trial (NCT0074490) to evaluate T-rapa cell therapy after allogeneic HCT. T-rapa cells were manufactured by ex vivo culture of donor CD4+ T cells using CD3/CD28 co-stimulation in media containing IL-4, IL-2, and rapamycin. T-rapa cells had a mixed Th2/Th1 phenotype with minimal Treg content (intra-cellular flow, n=48 products; median transcription factor expression: 11.5% [GATA-3], 5.1% [T-bet], and 0.1% [FoxP3]). Median T-rapa cell cytokine secretion (pg/ml; re-stimulation at harvest) was 1.3 [IL-4], 20.6 [IL-5], 9.7 [IL-10], 23.7 [IL-13], 34.7 [IFN-g], and 17.1 [IL-2]. Patients received an HLA-matched sibling, T cell-replete, G-CSF mobilized allograft, and GVHD prophylaxis of cyclosporine plus short-course sirolimus (to d14 post-HCT). Two protocol arms evaluated T-rapa cell therapy after induction chemotherapy and outpatient, low-intensity preparative chemotherapy (Table I). First, patients (n=25) were accrued to arm A to evaluate T-rapa infusion at d +14 post-HCT; subsequently, accrual was initiated to arm B (n=25) to evaluate T-rapa infusion on d0 of HCT. Arm A was then expanded to n=40 patients. Patients accrued to arms A and B were similar for recipient age, high-risk malignancy diagnosis, chemotherapy refractoriness, and prior regimen number (Table I). Most recipients were not in remission at the time of HCT. High-risk NHL was the most frequent diagnosis (25/65 patients), followed by non-high-risk NHL (11/65), AML/MDS (8/65), myeloma (7/65), CLL (6/65), Hodgkin's disease (5/65), and CML (3/65). Arm A and B recipients had similar mean donor myeloid cell chimerism at d +14, +28, and +100 (arm A, 43%, 74%, and 89%; arm B, 50%, 62%, and 84%). At d +14, arm A and B recipients also had mixed donor T cell chimerism (mean values, 60% in each arm; Table I). At d +28 and +100, T cell chimerism increased in arm A to 80% and 89%; in arm B, these values increased to only 67% and 69%. Four recipients on arm B had < 10% donor T cell chimerism at d +100; in contrast, the lowest donor T cell chimerism value observed at d +100 on arm A was 36%. T-rapa therapy on arm A was relatively safe as there was: no engraftment syndrome, a 10% rate of acute grade II to IV GVHD, a 67% incidence of chronic GVHD, and no transplant-related mortality (Table I). On arm A, 37.5% (15/40) of recipients are in sustained complete remission, with a median survival probability of 63.6% at 24 months post-HCT. Therefore, pre-emptive donor lymphocyte infusion with ex-vivo manufactured T-rapa cells that express a balanced Th2/Th1 effector phenotype represents a novel approach to safely accelerate alloengraftment and harness allogeneic GVT effects after low-intensity conditioning.Table IArm AArm BLow-Intensity Regimen    Induction Chemotherapy1EPOCH-FREPOCH-FR    2Terminal Chemotherapy3Flu (120 mg/m2)EPOCH-FRCy (1200 mg/m2)T-Rapa Cell TimingD +14 post-HCTD 0 of HCTPatient Characteristics    & of Patients Accrued4025    Age (median, range)55 (25–67)51 (32–66)    & of Prior Regimens3 (1–6)3 (1–8)    High-Risk Malignancy65% (26/40)52% (13/25)    Chemotherapy Refractory50% (20/40)48% (12/25)    CR (at time of HCT)25% (10/40)8% (2/25)% Donor T Cell ChimerismMean Median (Range)Mean Median (Range)Day 14 post-HCT6061(8–97)6060(4–100)Day 28 post-HCT8089(27–100)6773(10–100)Day 100 post-HCT8993(36–100)6982(0–100)Clinical Results    Engraftment Syndrome0% (0/40)0% (0/25)    Acute GVHD10% (4/40)23% (5/22)    Chronic GVHD67% (22/33)75% (15/20)    Complete Remission38% (15/40)28% (7/25)    Transplant-related Mortality0% (0/40)0% (0/25)    Percent Survival65% (26/40)40% (10/25)    Median Survival27.5 mo11.2 mo    Survival Prob. at 24 mo63.6%44.0%1EPOCH-FR, EPOCH with fludarabine (Flu) and rituximab.2Terminal (preparative) chemotherapy administered one week prior to HCT.3Flu/Cy [cyclophosphamide] doses are total doses, given over 4 days (Cy dose is 75% lower than 4800 mg/m2 “reduced-intensity” Cy dose). Disclosures: No relevant conflicts of interest to declare.

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