scholarly journals IMMU-25. MAGNETIC PARTICLE IMAGING FOR NON-INVASIVE TRACKING OF ADOPTIVE CELL TRANSFER IN CANCER IMMUNOTHERAPY

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi124-vi124
Author(s):  
Angelie Rivera-Rodriguez ◽  
Lan Hoang-Minh ◽  
Leyda Marrero-Morales ◽  
Duane Mitchell ◽  
Carlos Rinaldi
Keyword(s):  
T Cells ◽  
Ex Vivo ◽  
Cell Transfer ◽  
Cell Therapies ◽  
Non Invasive ◽  
Magnetic Particle Imaging ◽  
Particle Imaging ◽  
T Cell Transfer ◽  
Cytotoxic Function

Abstract BACKGROUND Adoptive cell therapies (ACT) are strategies being explored to boost the immune response against cancer. ACT cancer immunotherapies are effective against metastatic melanoma, leukemia, and lymphoma, but face challenges in treating other solid tumors, such as in the brain. A critical step for the success of ACT in solid cancers is achieving trafficking and persistence of T-cells at tumor sites. Glioblastoma (GBM) is the most common and aggressive cancer of the central nervous system in adults, with a prognosis of 15-18-month average patient survival after diagnosis. Biomedical imaging is often used to track cell therapies. Magnetic Particle Imaging (MPI) is a novel biomedical imaging modality enabling non-invasive visualization of the distribution of biocompatible superparamagnetic iron oxide (SPIO) tracers. OBJECTIVE Label T-cells with SPIO to non-invasively track adoptive T cell transfer immunotherapy with MPI in the context of brain cancer. METHODS Murine pmel-DsRed T-cells were isolated from the spleen of a transgenic C57BL/6 mouse, and were exposed to different SPIO concentrations ex vivo. Cell viability, phenotype, and cytotoxic function were analyzed to determine if T-cells were affected by the SPIO labeling. Moreover, in vivo experiments were performed in a murine GBM model, and labeled T-cells were injected intravenously and tracked using MPI. RESULTS The SPIO-labeling of T-cells did not affected cell viability, phenotype, or cell cytotoxic function at all tested incubation conditions. The internalized SPIO can be quantified and spatially detected using MPI both in vitro and in vivo. In addition, MPI in vivo tracking shows T-cells accumulation in liver and lungs, as well in the spleen and brain, as showed ex vivo. CONCLUSIONS SPIO-labeling of T-cells did not affected its cytotoxic function and MPI allows for in vivo tracking of adoptively T-cell transfer. MPI will provide better understanding of ACT dynamics to accelerate development of novel treatments.

scholarly journals Tracking Adoptive T Cell Therapy Using Magnetic Particle Imaging

2020 ◽  
Author(s):  
Angelie Rivera-Rodriguez ◽  
Lan B. Hoang-Minh ◽  
Andreina Chiu-Lam ◽  
Nicole Sarna ◽  
Leyda Marrero-Morales ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Solid Tumors ◽  
Magnetic Particle ◽  
Ex Vivo ◽  
Intraventricular Administration ◽  
Magnetic Particle Imaging ◽  
Particle Imaging ◽  
The Brain

ABSTRACTAdoptive cellular therapy (ACT) is a potent strategy to boost the immune response against cancer. ACT is an effective treatment for blood cancers, such as leukemias and lymphomas, but faces challenges treating solid tumors and cancers in locations like the brain. A critical step for success of ACT immunotherapy is achieving efficient trafficking of T cells to solid tumors, and the non-invasive and quantitative tracking of adoptively transferred T cell biodistribution would accelerate its development. Here, we demonstrate the use of Magnetic Particle Imaging (MPI) to non-invasively track ACT T cells in vivo. Labeling T cells with the superparamagnetic iron oxide nanoparticle tracer ferucarbotran did not affect T cell viability, phenotype, or cytotoxic function in vitro. Following ACT, ferucarbotran-labeled T cells were detected and quantified using MPI ex vivo and in vivo, in a mouse model of invasive brain cancer. Proof-of-principle in vivo MPI demonstrated its capacity to detect labeled T cells in lungs and liver after intravenous administration and to monitor T cell localization in the brain after intraventricular administration. Ex vivo imaging using MPI and optical imaging suggests accumulation of systemically administered ferucarbotran-labeled T cells in the brain, where MPI signal from ferucarbotran tracers and fluorescently tagged T cells were observed. Ex vivo imaging also suggest differential accumulation of nanoparticles and viable T cells in other organs like the spleen and liver. These results support the use of MPI to track adoptively transferred T cells and accelerate the development of ACT treatments for brain tumors and other cancers.

scholarly journals Vγ9Vδ2 T cells as a promising innovative tool for immunotherapy of hematologic malignancies

2011 ◽  
Vol 4 (4) ◽  
pp. 211
Author(s):  
Serena Meraviglia ◽  
Carmela La Mendola ◽  
Valentina Orlando ◽  
Francesco Scarpa ◽  
Giuseppe Cicero ◽  
...  
Keyword(s):  
T Cells ◽  
T Lymphocytes ◽  
Ex Vivo ◽  
Γδ T Cells ◽  
Hematologic Malignancies ◽  
Cytolytic Activity ◽  
Cell Therapies ◽  
Stressed Cells

The potent anti-tumor activities of γδ T cells, their ability to produce pro-inflammatory cytokines, and their strong cytolytic activity have prompted the development of protocols in which γδ agonists or ex vivo-expanded γδ cells are administered to tumor patients. γδ T cells can be selectively activated by either synthetic phosphoantigens or by drugs that enhance their accumulation into stressed cells as aminobisphosphonates, thus offering new avenues for the development of γδ T cell-based immunotherapies. The recent development of small drugs selectively activating Vγ9Vδ2 T lymphocytes, which upregulate the endogenous phosphoantigens, has enabled the investigators to design the experimental approaches of cancer immunotherapies; several ongoing phase I and II clinical trials are focused on the role of the direct bioactivity of drugs and of adoptive cell therapies involving phosphoantigen- or aminobisphosphonate-activated Vγ9Vδ2 T lymphocytes in humans. In this review, we focus on the recent advances in the activation/expansion of γδ T cells in vitro and in vivo that may represent a promising target for the design of novel and highly innovative immunotherapy in patients with hematologic malignancies.<br />

Adoptive Transfer of Adenovirus Specific T-Cells in Children with Systemic Adenovirus Infection after Allogeneic Stem Cell Transplantation.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 80-80
Author(s):  
Tobias F. Feuchtinger ◽  
Susanne Matthes-Martin ◽  
Celine Richard ◽  
Thomas Lion ◽  
Klaus Hamprecht ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Stem Cell Transplantation ◽  
Adoptive Transfer ◽  
Cell Transfer ◽  
New Treatment ◽  
T Cell Transfer

Abstract Allogeneic stem cell transplantation (SCT) has become an increasing treatment option for a variety of malignant and non-malignant disease. During immune reconstitution the host is at significant risk for viral infections. Human adenovirus (HAdV) infection is especially in children an important and serious complication. Virus-specific T-cells are essential for the clearance of HAdV, since antiviral chemotherapy has been insufficient to date. We present a new treatment option using virus-specific donor T-cells for adoptive transfer of immunity to patients with systemic HAdV-infection. We isolated in 6 patients with systemic HAdV-infection after SCT virus-specific T-cells of the donor, according to INF-γ secretion after short in vitro stimulation with viral antigen, resulting in a combination of CD4+ and CD8+ T-cells. Between 5-50x103/kg T-cells were infused for adoptive transfer. For follow-up, the infection and the in-vivo expansion of infused T-cells were evaluated. Isolated cells showed high specificity and markedly reduced but residual alloreactivity in-vitro. In three of four evaluable patients the infused T-cells underwent an in-vivo expansion and in these three patients the viral load decreased in peripheral blood after adoptive T-cell transfer. In-vivo expansion of specific T-cells was dose-independent. T-cell infusion was well tolerated. One patient experienced GvHD°II of the skin after T-cell transfer. In conclusion specific T-cell immunotherapy as a new treatment approach for children was performed in 6 cases of systemic HAdV-infection after allogeneic SCT. Induction of a specific T-cell response through adoptive transfer has been shown feasible and effective to protect from HAdV-related complications.

Partly MHC Matched Allogeneic Tumor Specific T Cells Mediate Tumor Regression without Inducing GVHD in Immunosuppressed Host.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5210-5210
Author(s):  
Andrea Boni ◽  
Pawel Muranski ◽  
Claudia Wrzesinski ◽  
Andrew Kaiser ◽  
Chrystal Paulos ◽  
...  
Keyword(s):  
T Cells ◽  
Tumor Regression ◽  
Marrow Transplant ◽  
Adoptive Cell Transfer ◽  
Autologous Tumor ◽  
Cell Transfer ◽  
Tumor Treatment ◽  
Transgenic Cells ◽  
T Cell Transfer

Abstract Adoptive cell transfer (ACT) immunotherapy following lymphodepleting conditioning is a promising strategy for the treatment of metastatic solid tumors, however the difficulties in generating autologous tumor specific lymphocytes for every patient has significantly limited its applications. Allogeneic partly matched tumor specific T cells could be used for patients in whom autologous cells are not available, however their rapid rejection by the host restricts this approach. When CD8+ pmel-1 T cells from B6-BALB-C F1 (b/d) were transferred into B16 tumor-bearing B6 mice (b/b) or into a different F1 (b/k), these tumor-specific T cells were rapidly rejected, and had no impact on the tumor regression. Here we show that following myeloablative conditioning, the adoptive transfer of allogeneic, major histocompatibility mismatched tumor-specific T lymphocytes resulted in the regression of large vascularized tumors. The ability of adoptively transferred allogeneic T cells to mediate tumor regression was directly proportional to the dose of irradiation given prior T cell transfer which also correlated with the in vivo survival of the transferred cells. At the highest irradiation dose used (i.e. 11 Gy) allogeneic T cells could survive for as long as 4 weeks and their efficacy was comparable to syngeneic tumor-reactive T cells. In addition we found that the risk of inducing a graft versus host (GVH) reaction was minor when the specificity of transferred TCR is confined. In fact co-transfer of transgenic cells and small amounts of open repertoire T cells (2*10e4) able to react with the host did not result in any measurable toxicity whereas co transfer of greater quantities (2*10e5 or more) could cause fatal GVHD effect. Interestingly GVH reaction was associated with an improved tumor treatment, though this effect was transient as most of the animals succumbed to GVHD. Here we demonstrate that allogeneic T cells might represent an important tool in cancer immunotherapy allowing treatment of patients for whom it is not possible to obtain autologous cells. Furthermore the possible synergy between tumor specific allogeneic T cells and GVH effect could be exploited in bone marrow transplant protocols.

scholarly journals Development of Magnetic Particle Imaging (MPI) for Cell Tracking and Detection

2020 ◽  
Author(s):  
Kierstin P Melo ◽  
Ashley V Makela ◽  
Natasha N Knier ◽  
Amanda M Hamilton ◽  
Paula J Foster
Keyword(s):  
Iron Content ◽  
Cell Tracking ◽  
Magnetic Particle ◽  
Ex Vivo ◽  
Imaging Modality ◽  
Superparamagnetic Iron Oxide ◽  
Cell Injection ◽  
Magnetic Particle Imaging ◽  
Particle Imaging

AbstractIntroductionMagnetic particle imaging (MPI) is a new imaging modality that sensitively and specifically detects superparamagnetic iron oxide nanoparticles (SPIONs) within a sample. SPION-based MRI cell tracking has very high sensitivity, but low specificity and quantification of iron labeled cells is difficult. MPI cell tracking could overcome these challenges.MethodsMDM-AB-231BR cells labeled with MPIO, mice were intracardially injected with either 2.5 × 105 or 5.0 × 105 cells. MRI was performed in vivo the same day at 3T using a bSSFP sequence. After mice were imaged ex vivo with MPI. In a second experiment Mice received an intracardiac injection of either 2.5 × 10 5 or 5 × 10 4 MPIO-labeled 231BR cells. In a third experiment, mice were injected with 5 × 10 4 4T1BR cells, labelled with either MPIO or the SPION Vivotrax. MRI and MPI was performed in vivo.ResultsSignal from MPI and signal voids from MRI both showed more iron content in mice receiving an injection of 5.0 × 105 cells than the 2.5 × 105 injection. In the second experiment, Day 0 MRI showed signal voids and MPI signal was detected in all mouse brains. The MPI signal and iron content measured in the brains of mice that were injected with 2.5 × 10 5 cells were approximately four times greater than in brains injected with 5 × 10 4 cells. In the third experiment, in vivo MRI was able to detect signal voids in the brains of mice injected with Vivotrax and MPIO, although voids were fainter in Vivotrax labeled cells. In vivo MPI signal was only detectable in mice injected with MPIO-labeled cells.ConclusionThis is the first example of the use of MPIO for cell tracking with MPI. With an intracardiac cell injection, approximately 15% of the injected cells are expected to arrest in the brain vasculature. For our lowest cell injection of 5.0 × 104 cells this is ∼10000 cells.

Adoptive Transfer of Hexon-Specific T-Cells as a Treatment of Adenovirus Reactivation Following Allogeneic Stem Cell Transplantation.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 796-796
Author(s):  
Kathrin Opherk ◽  
Friedhelm R Schuster ◽  
Wolfgang Andreas Bethge ◽  
Peter Bader ◽  
Johann Greil ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Adoptive Immunotherapy ◽  
Therapeutic Option ◽  
T Cell Responses ◽  
Cell Transfer ◽  
Adoptive T Cell Transfer ◽  
Cell Responses ◽  
T Cell Transfer

Abstract Abstract 796 In pediatric patients human adenovirus (HAdV) was identified as a common viral pathogen responsible for significant morbidity and mortality post allo SCT. Antiviral chemotherapy is often insufficient. Given that T-cell immunity is crucial for protection against adenoviral infection/reactivation, cellular immunotherapy is a promising therapeutic option. The capsid protein Hexon has been shown to contain immunodominant T-cell epitopes, with T-cell responses in the majority of the healthy population. Therefore a prospective phase I/II clinical study was performed analysing safety and feasibility of adoptive Hexon-specific T-cell transfer in patients after allogeneic SCT and HAdV infection refractory to Cidofovir treatment. Hexon-specific T-cells were isolated from the SCT-donor by using the IFNγ secretion system and small T-cell populations were immediately infused, without in vitro expansion steps. Fourty pediatric and adult patients with a mean age of 15 years were treated according to the study protocol after haploidentical, matched unrelated and matched sibling donor SCT between day 11 and 327 post SCT. The T-cell dose varied from 300-25000 T-cells/kg. No acute toxicitiy was observed. In two patients GvHD °I-°II of the skin occured within two weeks after administration of specific T-cells, one patient also developed GvHD of the gut. In vivo T-cell responses were absent in all patients before adoptive T-cell transfer and detectable in 70% of evaluable patients within the first weeks after adoptive transfer, associated with a clinical and/or virological response to the adoptive T-cell transfer. However, in patients with adenoviral disease response rate was lower and 6 of 14 evaluable patients succumbed with the infection within few days, in spite of adoptive immunotherapy. This lead to the assumption, that adoptive treatment in patients with severe infection related morbidity was to late during the course of infection. In conclusion we could show that adoptive immunotherapy is safe, feasible and a promising therapeutic option in patients with HAdV infection. Infusion of small IFNγ producing Hexon-specific T-cells populations resulted in an in vivo expansion of specific T-cells in the majority of cases. Emergence of in vivo T-cell responses was closely associated with a clearance or reduction of the viral load. Disclosures: No relevant conflicts of interest to declare.

Tumor responses and early onset cytokine release syndrome in synovial sarcoma patients treated with a novel affinity-enhanced NY-ESO-1-targeting TCR-redirected T cell transfer.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. 2530-2530 ◽  
Author(s):  
Mikiya Ishihara ◽  
Shigehisa Kitano ◽  
Hiroyoshi Hattori ◽  
Yoshihiro Miyahara ◽  
Hidefumi Kato ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Synovial Sarcoma ◽  
Early Onset ◽  
Cell Kinetics ◽  
Cell Transfer ◽  
Cytokine Release ◽  
Clinical Responses ◽  
T Cell Transfer

2530 Background: Adoptive transfer of TCR-redirected T cells has been reported to exhibit efficacy in some of melanoma and sarcoma patients. However, there have not been well known about cytokine release syndrome (CRS) or its relations to tumor responses. This study evaluates clinical responses in association with the cell kinetics and CRSs after transfer of high-affinity NY-ESO-1 TCR-gene transduced T cells in NY-ESO-1-expressiong cancer patients (NCT02366546). Methods: We developed a novel-type affinity-enhanced NY-ESO-1-specific TCR and an originally-developed retrovirus vector that encodes siRNA to silence endogenous TCR creation. The NY-ESO-1/TCR sequence is mutated for high affinity with replacements of G50A and A51E in CDR2 region. This is a first-in-man clinical trial of the novel NY-ESO-1-specfic TCR-T cell transfer to evaluate the safety, in vivo cell kinetics and clinical responses. It was designed as a cell-dose escalation from 5 x108 to 5 x109 cells. NY-ESO-1-expressing refractory cancer patients were enrolled, with 3+3 cohort design. Cyclophosphamide (1,500mg/m2) were administered prior to the TCR-T cell transfer as pre-conditioning. Results: 9 patients were treated with the NY-ESO-1/TCR-T cell transfer. The TCR-T cells expanded in peripheral blood with a dose-dependent manner, associated with rapid proliferation within 5 days after the cell transfer. 3 patients receiving 5x109 cells developed early-onset CRSs, with elevations of serum IL-6, IFN-γ. The CRSs developed on day1 or 2 after the cell transfer. They were well managed with tocilizumab treatment. 3 synovial sarcoma patients exhibited tumor shrinkages of partial responses, and they all had high-expression of NY-ESO-1 in the tumor samples, namely, 75% or more. Exploratory analysis revealed that multiple chemotactic cytokines including CCL2 and CCL7, and IL-3 increased in the serum from the patients with CRS. The proportions of effector-memory phenotype T cells in the infused cell-product were significantly associated with CRS development. Conclusions: The affinity-enhanced NY-ESO-1/TCR-T cell transfer exhibited early-onset CRS in association with in vivo cell proliferation and sequential tumor responses in the patients with high-NY-ESO-1-expressing synovial sarcoma. Clinical trial information: NCT02366546.

scholarly journals A New Hope in Immunotherapy for Malignant Gliomas: Adoptive T Cell Transfer Therapy

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Dong-Sup Chung ◽  
Hye-Jin Shin ◽  
Yong-Kil Hong
Keyword(s):  
T Cells ◽  
T Cell ◽  
Ex Vivo ◽  
Malignant Gliomas ◽  
Adoptive T Cell Therapy ◽  
Cell Transfer ◽  
Adoptive T Cell Transfer ◽  
T Cell Therapy ◽  
Promising Therapeutic Approach ◽  
T Cell Transfer

Immunotherapy emerged as a promising therapeutic approach to highly incurable malignant gliomas due to tumor-specific cytotoxicity, minimal side effect, and a durable antitumor effect by memory T cells. But, antitumor activities of endogenously activated T cells induced by immunotherapy such as vaccination are not sufficient to control tumors because tumor-specific antigens may be self-antigens and tumors have immune evasion mechanisms to avoid immune surveillance system of host. Although recent clinical results from vaccine strategy for malignant gliomas are encouraging, these trials have some limitations, particularly their failure to expand tumor antigen-specific T cells reproducibly and effectively. An alternative strategy to overcome these limitations is adoptive T cell transfer therapy, in which tumor-specific T cells are expandedex vivorapidly and then transferred to patients. Moreover, enhanced biologic functions of T cells generated by genetic engineering and modified immunosuppressive microenvironment of host by homeostatic T cell expansion and/or elimination of immunosuppressive cells and molecules can induce more potent antitumor T cell responses and make this strategy hold promise in promoting a patient response for malignant glioma treatment. Here we will review the past and current progresses and discuss a new hope in adoptive T cell therapy for malignant gliomas.

scholarly journals Cytokine Release Syndrome and Tumor Responses in a First-in-Man Trial of a Novel Affinity-Enhanced TCR-Gene Transduced T Cell Transfer Targeting NY-ESO-1 Antigen

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 841-841
Author(s):  
Shinichi Kageyama ◽  
Mikiya Ishihara ◽  
Shigehisa Kitano ◽  
Yoshihiro Miyahara ◽  
Hidefumi Kato ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
Cell Kinetics ◽  
Cell Transfer ◽  
T Cell Therapy ◽  
Car T Cell ◽  
Car T ◽  
T Cell Transfer

Abstract Adoptive cell transfers of receptor gene-engineered T cells include chimeric antigen receptor-gene transduced T (CAR-T) cell therapy and TCR-gene transduced T (TCR-T) cell therapy. In CD19-CAR-T cell therapy, high incidence of cytokine release syndrome (CRS) is associated with in vivo CAR-T cell proliferation and its clinical efficacy. In human TCR-T cell therapies, there have not been well known about CRS and its association with in vivo T cell kinetics or tumor responses. We have been developing a novel-type affinity-enhanced NY-ESO-1-specific TCR, and an original retrovirus vector that encodes siRNA to silence endogenous TCR creation. The NY-ESO-1 TCR is mutated for high affinity with replacements of G50A and A51E in CDR2 region, which is restricted with HLA-A*02:01 and A*02:06. We extensively examined potential cross-reactivities to different antigen-peptides in preclinical studies, and the high-affinity NY-ESO-1 TCR did not recognize analogous peptides. The new generation retroviral TCR-vector provides enhanced expression of transduced tumor-specific TCRs and an inhibition effect of formations of self-reactive TCRs. This is a first-in-man clinical trial of the novel NY-ESO-1-specfic TCR-T cell transfer to evaluate the safety, in vivo cell kinetics and clinical responses. It is designed as a cell-dose escalation from 5 x108 to 5 x109 cells. NY-ESO-1-expressing refractory cancer patients were enrolled, with 3+3 cohort design. Cyclophosphamide with/without fludarabine were administered prior to the TCR-T cell transfer as pre-conditioning. Six patients were treated with the NY-ESO-1 TCR-T cell transfer, and evaluated for the safety and in vivo cell kinetics. The TCR-T cells appeared in peripheral blood with a dose-dependent manner, associated with in vivo proliferation in an early phase. In three patients given 5x108 cells, no toxicities were seen. Two patients receiving 5x109 cells developed early-phase CRS (G2), with elevations of serum IL-6 and IFN-gamma. They were managed the treatment of anti-IL-6 receptor monoclonal antibody, tocilizumab. In a patient who developed CRS, an event of lung injury (G3) occurred, which was associated with marked infiltration of the NY-ESO-1 TCR-T cells. It was successfully treated with steroid. Two synovial sarcoma patients exhibited tumor responses of PRs. In one patient, progression-free survival lasted more than 8 months. In summary, the affinity-enhanced NY-ESO-1 TCR-T cell transfer exhibited CRSs in association with in vivo cell proliferation and sequential tumor responses. Disclosures No relevant conflicts of interest to declare.

IL-15 Administration to In-Vivo Expand Adoptively Transferred NK Cells In Rhesus Macaques

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 960-960
Author(s):  
Rebecca Lopez ◽  
Stephanie Sellers ◽  
Cynthia E. Dunbar ◽  
Richard Childs
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Nk Cells ◽  
Nk Cell ◽  
Ex Vivo ◽  
Rhesus Macaques ◽  
Cell Transfer ◽  
Regulatory Phenotype

Abstract Abstract 960 Immunotherapy using natural killer (NK) cells is currently being explored as a treatment option for patients with advanced malignant diseases. Although pilot clinical trials have shown adoptive NK cell transfer can result in tumor regression in humans with cancer, additional insight from animal models is needed to optimize methods to enhance the function and in vivo persistence of these adoptively infused lymphocytes. In contrast to mice, rhesus macaques have orthologues to most of the human MHC class I and II genes and possess NK cells expressing KIRs that are phenotypically and functionally similar to human NK cells, thus providing an excellent model to evaluate adoptive NK cell therapy. To characterize their in vivo longevity and tissue trafficking following adoptive infusion, we developed a method to expand large numbers of rhesus NK cells in vitro. NK cells enriched from peripheral blood mononuclear cells by depleting CD3+ cells using immunomagnetic beads were expanded in vitro with autologous plasma and a human EBV-LCL feeder cell line using culture conditions identical to those used for human NK cell expansion. Expanded rhesus NK cells were both phenotypically and genotypically similar to their human counterparts; NK cell cultures expanded up to 1000 fold within 2–3 weeks, were greater than 99% CD3 negative, and had a large proportion of CD16/CD56 double positive cells. In addition, expanded NK cells up-regulated receptors involved in tumor killing, including NKG2D, Granzyme B, TRAIL and Fas-ligand and were highly cytotoxic to K562 cells. Adoptive transfer of (3.2×107 – 1×108) CFSE-labeled ex vivo expanded rhesus NK cells has been well tolerated without any overt toxicities noted to date. Remarkably, despite the infusion of large cell numbers, CFSE labeled NK cells were detectable in the peripheral blood, lymph nodes, and bone marrow compartments at very low levels for only a few hours following infusion. Combining adoptive transfer of ex vivo expanded NK cells with IL-15 administration (rhesus recombinant IL-15 10 ug/kg s.c. × 5 days) resulted in only a minimal and transient 24 hour increase in the number of detectable CFSE labeled NK cells in the circulation and bone marrow. Although IL-15 administration did not substantially expand the number of circulating CFSE labeled NK cells that were adoptively transferred, it did result in a substantial increase in circulating numbers of endogenous NK and T-cells (4.74 fold and 5.2 fold increase in CD3-/CD56+ NK cells and CD3+ T-cells respectively). Surprisingly, IL-15 administration also resulted in a significant expansion of circulating T-regs (CD4-/CD25+/CD127Dim/FOXP3 +) which have previously been shown to suppress NK cell effector function in vitro and vivo; T-cells with a regulatory phenotype expanded 4.54 fold. Expansion of circulating T-regs occurred both when IL-15 was administered alone or in conjunction with adoptive NK cell transfer. Conclusions: IL-15 administration in macaques at the doses used in this study did not expand circulating numbers of adoptively transferred ex-vivo expanded NK cells, although it did significantly expand the numbers of circulating endogeneous NK cells. Remarkably, IL-15 administration was also associated with a significant expansion of T-cells with a regulatory phenotype. We are currently evaluating whether lympho-depletion followed by adoptive NK cell transfer can be used as a method to prevent the expansion of T-regs associated with IL-15 administration. Disclosures: No relevant conflicts of interest to declare.

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