Adoptive transfer of costimulated T cells induces lymphocytosis in patients with relapsed/refractory non-Hodgkin lymphoma following CD34+-selected hematopoietic cell transplantation

Pilot study of prophylactic ex vivo costimulated donor leukocyte infusion after reduced-intensity conditioned allogeneic stem cell transplantation

Donor leukocyte infusion (DLI) can induce potent graft-versus-leukemia (GVL) activity in patients with relapsed hematologic malignancies after allogeneic hematopoietic stem cell transplantation (HSCT). Unfortunately, except in patients with chronic-phase chronic myelogenous leukemia, responses to DLI have been disappointing. GVL induction is likely to be most effective in the setting of minimal residual disease. Prevention of relapse through the provision of prophylactic DLI to high-risk patients may improve the outcome of allogeneic HSCT. We previously reported that ex vivo costimulated T cell infusion of activated DLI (aDLI) as treatment for relapse is safe and has potent GVL effects. We hypothesized that prophylactic aDLI can be given safely and prevent relapse in high-risk patients after allogeneic HSCT. Eighteen patients with acute myeolgenous leukemia (n = 14), acute lymphoblastic leukemia (n = 3), or myelodysplastic syndrome (n = 1) underwent allogeneic HSCT after a reduced-intensity conditioning (RIC) regimen with alemtuzumab, fludarabine, and busulfan. Graft-versus-host-disease (GVHD) prophylaxis consisted of tacrolimus and methotrexate with a planned early and rapid taper of tacrolimus. Patients without GVHD, off immune suppression, and in remission received aDLI at a dose of 1 × 10(7) CD3(+) cells/kg (aDLI 1) at day +120, followed by a second infusion of 1 × 10(8) CD3 cells/kg (aDLI 2) at day +180. At a median follow-up of 58 months, 5 of the 18 patients (28%) were alive, and 4 patients were in remission. Eleven patients (65%) relapsed, at a median time of 191 days. Twelve of the 18 patients received at least one aDLI, and 6 of these 12 patients also received aDLI 2. Six patients did not receive any aDLI owing to early relapse (n = 2), protocol ineligibility (n = 1), or GVHD (n = 3). Only 2 of the 12 patients who received aDLI 1 developed GVHD. Two out of the 12 patients remain in remission at the time of this report. Disease recurrence was the cause of death in 10 of the 13 patients (77%) who died. Our data indicate that prophylactic ex vivo costimulated CD3/CD28 DLI is safe, feasible, and not associated with significant GVHD. Relapse remains the major cause of treatment failure after RIC HSCT even with rapid withdrawal of immune suppression and the use of prophylactic aDLI, and better strategies to prevent relapse are needed.

Innovation and opportunity for chimeric antigen receptor targeted T cells

Adoptive cell therapy truly began with the introduction of hematopoietic stem cell transplantation. The ability to manipulate genes through cloning and expression methodologies have allowed for the development of novel chimeric receptors to selectively target cancer when introduced into immune cells. Over the past decade, gene engineered cells have been tested in clinical trials throughout the world. Recent data and striking clinical responses demonstrate the power of this new type of therapy. Current challenges include managing a potent therapy that is a dividing, rather than a static drug, safeguarding against potential toxicity, and further development to enable access to a greater number of patients.

Efficient clinical scale gene modification via zinc finger nuclease-targeted disruption of the HIV co-receptor CCR5

Since HIV requires CD4 and a co-receptor, most commonly C-C chemokine receptor 5 (CCR5), for cellular entry, targeting CCR5 expression is an attractive approach for therapy of HIV infection. Treatment of CD4(+) T cells with zinc-finger protein nucleases (ZFNs) specifically disrupting chemokine receptor CCR5 coding sequences induces resistance to HIV infection in vitro and in vivo. A chimeric Ad5/F35 adenoviral vector encoding CCR5-ZFNs permitted efficient delivery and transient expression following anti-CD3/anti-CD28 costimulation of T lymphocytes. We present data showing CD3/CD28 costimulation substantially improved transduction efficiency over reported methods for Ad5/F35 transduction of T lymphocytes. Modifications to the laboratory scale process, incorporating clinically compatible reagents and methods, resulted in a robust ex vivo manufacturing process capable of generating >10(10) CCR5 gene-edited CD4+ T cells from healthy and HIV+ donors. CD4+ T-cell phenotype, cytokine production, and repertoire were comparable between ZFN-modified and control cells. Following consultation with regulatory authorities, we conducted in vivo toxicity studies that showed no detectable ZFN-specific toxicity or T-cell transformation. Based on these findings, we initiated a clinical trial testing the safety and feasibility of CCR5 gene-edited CD4+ T-cell transfer in study subjects with HIV-1 infection.

Adoptive cellular therapy using cells enriched for NKG2D+CD3+CD8+T cells after autologous transplantation for myeloma

The number of circulating lymphocytes on day 15 after transplantation correlates with improved survival in patients with myeloma, but the lymphocyte subset responsible is unknown. NKG2D is a natural killer (NK) cell activating receptor that mediates non-MHC restricted and TCR-independent cell lysis. Our preliminary results indicate that CD3(+)CD8(+) T cells expressing NKG2D may be a critical lymphocyte population. A phase II trial examined the feasibility of infusing ex vivo-expanded cells enriched for NKG2D(+)CD3(+)CD8(+) T cells at weeks 1, 2, 4, and 8 after an autologous transplantation. In addition, low-dose IL-2 (6 × 10(5) IU/m(2)/day) was administered for 4 weeks, beginning on the day of transplantation. Twenty-three patients were accrued and 19 patients are evaluable. There were no treatment-related deaths. All patients completed their course of IL-2 and demonstrated normal engraftment. When compared with patients with myeloma who underwent transplantation not receiving posttransplantation immune therapy, the treated patients demonstrated an increase in the number of circulating NKG2D(+)CD3(+)CD8(+) T cells/μL (P < .004), CD3(+)CD8(+) T cells/μL (P < .04), CD3(+)CD8(+)CD56(+) T cells/μL (P < .004), and NKG2D(+)CD3(-)CD56(+) T cells/μL (P < .003). Myeloma cell-directed cytotoxicity by the circulating mononuclear cells increased after transplantation (P < .002). When compared to posttransplantation IL-2 therapy alone in this patient population, the addition of cells enriched for NKG2D(+)CD3(+)CD8(+) T cells increased tumor-specific immunity, as demonstrated by enhanced lysis of autologous myeloma cells (P = .02). We postulate that this regimen that increased the number and function of the NKG2D(+)CD3(+)CD8(+) T cells after transplantation may improve clinical outcomes by eliminating residual malignant cells in vivo.

Adoptive transfer of autologous T cells improves T-cell repertoire diversity and long-term B-cell function in pediatric patients with neuroblastoma

PURPOSE

Children with high-risk neuroblastoma have a poor prognosis with chemotherapy alone, and hematopoietic stem cell transplantation offers improved survival. As a dose-escalation strategy, tandem transplants have been used, but are associated with persistent immunocompromise. This study evaluated the provision of an autologous costimulated, activated T-cell product to support immunologic function.

EXPERIMENTAL DESIGN

Nineteen subjects with high-risk neuroblastoma were enrolled in a pilot phase and 23 subjects were entered in to the randomized study. Immunologic reconstitution was defined by flow cytometric and functional assays. Next-generation sequencing was conducted to identify changes to the T-cell repertoire. Twenty-two patients were vaccinated to define effects on antibody responses.

RESULTS

Subjects who received their autologous costimulated T-cell product on day 2 had significantly superior T-cell counts and T-cell proliferation compared with those who received T cells on day 90. Early administration of autologous T cells suppressed oligoclonality and enhanced repertoire diversity. The subjects who received the day 2 T-cell product also had better responses to the pneumococcal vaccine.

CONCLUSIONS

The infusion of activated T cells can improve immunologic function especially when given early after transplant. This study showed the benefit of providing cell therapies during periods of maximum lymphopenia.

Trial Watch: Adoptive cell transfer immunotherapy

During the last two decades, several approaches for the activation of the immune system against cancer have been developed. These include rather unselective maneuvers such as the systemic administration of immunostimulatory agents (e.g., interleukin-2) as well as targeted interventions, encompassing highly specific monoclonal antibodies, vaccines and cell-based therapies. Among the latter, adoptive cell transfer (ACT) involves the selection of autologous lymphocytes with antitumor activity, their expansion/activation ex vivo, and their reinfusion into the patient, often in the context of lymphodepleting regimens (to minimize endogenous immunosuppression). Such autologous cells can be isolated from tumor-infiltrating lymphocytes or generated by manipulating circulating lymphocytes for the expression of tumor-specific T-cell receptors. In addition, autologous lymphocytes can be genetically engineered to prolong their in vivo persistence, to boost antitumor responses and/or to minimize side effects. ACT has recently been shown to be associated with a consistent rate of durable regressions in melanoma and renal cell carcinoma patients and holds great promises in several other oncological settings. In this Trial Watch, we will briefly review the scientific rationale behind ACT and discuss the progress of recent clinical trials evaluating the safety and effectiveness of adoptive cell transfer as an anticancer therapy.

Cellular immunotherapy for high-grade glioma

The outcome for patients with the most common primary brain tumor, glioblastoma multiforme (GBM), remains poor. Several immunotherapeutic approaches are actively being pursued including antibodies and cell-based therapies. While the blood-brain barrier protects brain tumor cells from therapeutic antibodies, immune cells have the ability to traverse the blood-brain barrier and migrate into GBM tumors to exert their therapeutic function. Results of Phase I clinical studies with vaccines to induce GBM-specific T cells are encouraging and Phase II clinical trials are in progress. Nonvaccine-based cell therapy for GBM has been actively explored over the last four decades. Here we will review past clinical experience with adoptive cell therapies for GBM and summarize current strategies on how to improve these approaches.

T cells with chimeric antigen receptors have potent antitumor effects and can establish memory in patients with advanced leukemia

Tumor immunotherapy with T lymphocytes, which can recognize and destroy malignant cells, has been limited by the ability to isolate and expand T cells restricted to tumor-associated antigens. Chimeric antigen receptors (CARs) composed of antibody binding domains connected to domains that activate T cells could overcome tolerance by allowing T cells to respond to cell surface antigens; however, to date, lymphocytes engineered to express CARs have demonstrated minimal in vivo expansion and antitumor effects in clinical trials. We report that CAR T cells that target CD19 and contain a costimulatory domain from CD137 and the T cell receptor ζ chain have potent non-cross-resistant clinical activity after infusion in three of three patients treated with advanced chronic lymphocytic leukemia (CLL). The engineered T cells expanded >1000-fold in vivo, trafficked to bone marrow, and continued to express functional CARs at high levels for at least 6 months. Evidence for on-target toxicity included B cell aplasia as well as decreased numbers of plasma cells and hypogammaglobulinemia. On average, each infused CAR-expressing T cell was calculated to eradicate at least 1000 CLL cells. Furthermore, a CD19-specific immune response was demonstrated in the blood and bone marrow, accompanied by complete remission, in two of three patients. Moreover, a portion of these cells persisted as memory CAR(+) T cells and retained anti-CD19 effector functionality, indicating the potential of this major histocompatibility complex-independent approach for the effective treatment of B cell malignancies.

T cells with chimeric antigen receptors have potent antitumor effects and can establish memory in patients with advanced leukemia

Tumor immunotherapy with T lymphocytes, which can recognize and destroy malignant cells, has been limited by the ability to isolate and expand T cells restricted to tumor-associated antigens. Chimeric antigen receptors (CARs) composed of antibody binding domains connected to domains that activate T cells could overcome tolerance by allowing T cells to respond to cell surface antigens; however, to date, lymphocytes engineered to express CARs have demonstrated minimal in vivo expansion and antitumor effects in clinical trials. We report that CAR T cells that target CD19 and contain a costimulatory domain from CD137 and the T cell receptor ζ chain have potent non-cross-resistant clinical activity after infusion in three of three patients treated with advanced chronic lymphocytic leukemia (CLL). The engineered T cells expanded >1000-fold in vivo, trafficked to bone marrow, and continued to express functional CARs at high levels for at least 6 months. Evidence for on-target toxicity included B cell aplasia as well as decreased numbers of plasma cells and hypogammaglobulinemia. On average, each infused CAR-expressing T cell was calculated to eradicate at least 1000 CLL cells. Furthermore, a CD19-specific immune response was demonstrated in the blood and bone marrow, accompanied by complete remission, in two of three patients. Moreover, a portion of these cells persisted as memory CAR(+) T cells and retained anti-CD19 effector functionality, indicating the potential of this major histocompatibility complex-independent approach for the effective treatment of B cell malignancies.

T-lymphocyte recovery and function after cord blood transplantation

The Szabolcs laboratory is focused on understanding the biology of donor-derived cellular immunity in recipients of allogeneic hematopoietic cell transplantation that can be translated into new immunotherapy strategies. To this end, we are focused on developing novel laboratory approaches to analyze and augment immune recovery for high risk patient cohorts without increasing graft-versus-host disease. Much of our work has focused on unrelated cord blood transplantation as the dominant clinical scenario and laboratory model. Our overarching goal is to minimize transplant-related mortality and morbidity and render HLA-mismatched unrelated cord blood transplant, a widely accepted safe cellular therapy. Donor leukocyte infusions in the allogeneic hematopoietic transplant setting can provide a clinically relevant boost of immunity to reduce opportunistic infections and to increase graft-versus-leukemia activity. Our laboratory has a major focus toward ex vivo expansion of cord blood T cells with anti-apoptotic cytokines and CD3/CD28 co-stimulatory beads. Expanded lymphocytes lack alloreactivity against recipient and other allogeneic cells indicating a favorable safety profile from graft-versus-host disease. Nevertheless, expanded T cells can be primed subsequently against lymphoid and myeloid leukemia cells to generate tumor-specific cytotoxic T cells. These findings offer a major step in fulfilling critical biological requirements to quickly generate a cellular product ex vivo, using a negligible fraction of a cord blood graft that provides a flexible adoptive immunotherapy platform for both children and adults.

Genetic modification of T cells

Adoptively transferred T cells have shown activity in treating viral infections after hemopoietic transplantation and anti-tumor activity against some malignancies such as melanoma and lymphoma. Current research focuses on defining the optimum type of cell for transfer to improve persistence and genetically modifying infused T cells to augment function, overcome tumor evasion strategies and allow ablation should adverse effects occur.

Active and passive immunotherapy for lymphoma: proving principles and improving results

Conventional chemotherapy for lymphoma has advanced greatly over the past 50 years, changing some lymphoma subtypes from uniformly lethal to curable; however, the majority of lymphomas in patients remain incurable, and there is a need for novel therapies with less toxicity and more specific targeting of tumor cells. The vertebrate immune system has evolved the capacity for such specific targeting through the B-cell and T-cell receptors; passive immunotherapies utilizing these receptors, such as monoclonal antibodies (mAbs) or T cells, have shown efficacy in treating lymphomas. The first generation of mAb-based therapies has transformed the standard of care for lymphoma, and newer antibodies may improve on this approach. Clinical activity has been shown by T cells bearing receptors that target viral antigens as well as T cells bearing re-engineered receptors that target antigens recognized by antibodies. Active immunotherapies, such as vaccines and immune checkpoint blockades, have prolonged survival in certain solid tumors and are being actively pursued to treat lymphoma. A variety of vaccines (eg, protein- and cell-based vaccines) are being tested in ongoing trials, and the most recent iterations show therapeutic activity. Newer trials are addressing the problem of tumor-induced immunosuppression by the use of antibodies against immunologic checkpoints or by the reinfusion of primed T cells after lymphodepletion, a process we refer to as immunotransplantation. Herein, we discuss results of the various immunotherapy strategies applied to lymphoma and the ongoing approaches for their improvement.

Induction of TLR4-dependent CD8+ T cell immunity by murine β-defensin2 fusion protein vaccines

Our laboratory previously described the strategy of fusing chemokine receptor ligands to antigens in order to generate immunogenic DNA vaccines. In the present study, we produced mouse β-2 defensin (mBD2) fusion proteins using both ovalbumin (OVA) and gp100 as model antigens. Superior cross-presentation by dendritic cells (DC) was observed for mBD2 fused antigens over unfused antigens in vitro. In vivo, we observed significant increases in the expansion of adoptively transferred antigen-specific MHC class I, but not class II-restricted T cells after immunization with mBD2 fused antigen over antigen alone. This enhanced expansion of class I restricted T cells was Toll-like receptor 4 (TLR4) dependent, but CC chemokine receptor 6 (CCR6) independent. Superior tumor resistance was observed for mBD2-fusion protein vaccines, compared to unfused antigen, in both B16-OVA and B16 tumor models. These data suggest that production of mBD2 fusion proteins is feasible and that the vaccines facilitate in vivo expansion of adoptively transferred T cells through a TLR4-dependent mechanism.

The immunobiology of cord blood transplantation

Despite significant recent advances in the applicability and outcome following unrelated cord blood transplantation (UCBT), infections remain a major cause of mortality associated with poor immune recovery in the first 6 months after UCBT. Enhanced immune reconstitution not only could improve survival by reduced transplant related mortality, but may also favorably impact on relapse incidence by improved graft-versus-leukemia effects. This review will summarize our current understanding of the biology of immune recovery post-UCBT with an emphasis on adaptive T cell dependent immunity. New efforts to boost immunity will be also highlighted including our own laboratory, where ex vivo T cell expansion is pursued towards adoptive immunotherapy.

Adoptive therapy using antigen-specific T-cell clones

T-cell therapy involves the ex vivo isolation and expansion of antigen-specific T cells for adoptive transfer. The use of T-cell clones represents one embodiment of this approach and provides a uniform population of effector cells, so that parameters contributing to an effective response can be rigorously evaluated. T cells of defined specificity, phenotype, and function are isolated and expanded; when infused into patients, these intrinsic factors can be considered in light of extrinsic factors such as the type of conditioning regimen, cytokine support, and immunomodulatory reagents. In this chapter, 2 topics related to the use of antigen-specific T-cell clones are discussed: first, advances enabling the isolation and expansion of antigen-specific T-cell clones for human trials of adoptive therapy, and second, a contextual framework of advantages and limitations in which the use of adoptively transferred T-cell clones can be judiciously applied as a means to dissect the requirements for effective therapy.

Artificial antigen-presenting cells for use in adoptive immunotherapy

The observation that T cells can recognize and specifically eliminate cancer cells has spurred interest in the development of efficient methods to generate large numbers of T cells with specificity for tumor antigens that can be harnessed for use in cancer therapy. Recent studies have demonstrated that during encounter with tumor antigen, the signals delivered to T cells by professional antigen-presenting cells can affect T-cell programming and their subsequent therapeutic efficacy. This has stimulated efforts to develop artificial antigen-presenting cells that allow optimal control over the signals provided to T cells. In this review, we will discuss the advantages and disadvantages of cellular and acellular artificial antigen-presenting cell systems and their use in T-cell adoptive immunotherapy for cancer.

Comparison of anti-CD3 and anti-CD28-coated beads with soluble anti-CD3 for expanding human T cells: differing impact on CD8 T cell phenotype and responsiveness to restimulation

Background

The ability to expand virus- or tumor-specific T cells without damaging their functional capabilities is critical for success adoptive transfer immunotherapy of patients with opportunistic infection or tumor. Careful comparisons can help identify expansion methods better suited for particular clinical settings and identify recurrent deficiencies requiring new innovation.

Methods

We compared the efficacy of magnetic beads coated with anti-CD3 and anti-CD28 (anti-CD3/CD28 beads), and soluble anti-CD3 plus mixed mononuclear cells (designated a rapid expansion protocol or REP) in expanding normal human T cells.

Results

Both anti-CD3/CD28 beads and soluble anti-CD3 promoted extensive expansion. Beads stimulated greater CD4 cell growth (geometric mean of 56- versus 27-fold (p < 0.01) at day 21) but both stimulated similar CD8 expansion (189- versus 186-fold). Phenotypically, bead-treated CD4 and CD8 T cells and anti-CD3-treated CD4 cells typically assumed an effector/effector memory phenotype by day 14. By comparison, a subset of anti-CD3-treated CD8 cells, derived from naïve cells, retained much greater expression of CD45RA, CD27 and CCR7, than matched bead-treated cells despite comparable expansion. These cells were clearly distinguishable from CD45RA+ terminally differentiated effector cells by the presence of CD27, the absence of CD57 and their inability to produce cytokines after stimulation. When used to expand previously stimulated cells, anti-CD3 plus autologous MNCs produced much less antigen-induced cell death of CD8 cells and significantly more CD8 expansion than beads.

Conclusions

Anti-CD3/CD28 beads are highly effective for expanding CD4 cells, but soluble anti-CD3 has significant potential advantages for expanding CD8 T cells, particularly where preservation of phenotypically "young" CD8 cells would be desirable, or where the T cells of interest have been antigen-stimulated in vitro or in vivo in the recent past.

Interleukin-7 permits Th1/Tc1 maturation and promotes ex vivo expansion of cord blood T cells: a critical step toward adoptive immunotherapy after cord blood transplantation

Donor leukocyte infusions (DLI) in the allogeneic hematopoietic transplant setting can provide a clinically relevant boost of immunity to reduce opportunistic infections and to increase graft-versus-leukemia activity. Despite significant advances in applicability, DLI has not been available for single-unit recipients of unrelated cord blood transplant. Ex vivo expansion of cord blood T cells can be achieved with interleukin (IL)-2 and CD3/CD28 costimulatory beads. However, significant apoptosis occurs in proliferating T cells, diminishing the yield and skewing the CD4/CD8 ratio in the T-cell population, jeopardizing the potential efficacy of DLI. In this study, we show that interleukin (IL)-7 not only reduces apoptosis of activated T lymphocytes and enhances their proliferation but also promotes functional maturation, leading to secretion of IFN-gamma and other key cytokines. Recognizing that infused T lymphocytes will need to meet microbial antigens in secondary lymphoid organs to generate effectors, we also show that expansion with IL-7 promotes the preservation of a polyclonal broad T-cell receptor repertoire and a surface phenotype that favors lymph node homing. Expanded lymphocytes lack alloreactivity against recipient and other allogeneic cells, indicating a favorable safety profile from graft-versus-host disease. Nevertheless, expanded T cells can be primed subsequently against lymphoid and myeloid leukemia cells to generate tumor-specific cytotoxic T cells. Taken together, our findings offer a major step in fulfilling critical numerical and biological requirements to quickly generate a DLI product ex vivo using a negligible fraction of a cord blood graft that provides a flexible adoptive immunotherapy platform for both children and adults.

Efficient clinical-scale enrichment of lymphocytes for use in adoptive immunotherapy using a modified counterflow centrifugal elutriation program

BACKGROUND AIMS

Clinical-scale lymphocyte enrichment from a leukapheresis product has been performed most routinely using costly magnetic bead separation systems that deplete monocytes, but this procedure may leave behind residual beads or antibodies in the enriched cell product. Counterflow centrifugal elutriation has been demonstrated previously to enrich monocytes efficiently for generation of dendritic cells. This study describes a modified elutriation procedure for efficient bead-free economical enrichment of lymphocytes from leukapheresis products from healthy donors and study subjects with human immunodeficiency virus (HIV) infection or malignancy.

METHODS

Modified program settings and conditions for the CaridianBCT Elutra device were investigated to optimize lymphocyte enrichment and recovery. Lymphocyte enrichment was measured using a novel approach utilizing cell sizing analysis on a Beckman Coulter Multisizer and confirmed by flow cytometry phenotypic analysis.

RESULTS

Efficient enrichment and recovery of lymphocytes from leukapheresis cell products was achieved using modified elutriation settings for flow rate and fraction volume. Elutriation allowed for enrichment of larger numbers of lymphocytes compared with depletion of monocytes by bead adherence, with a trend toward increased lymphocyte purity and yield via elutriation, resulting in a substantial reduction in the cost of enrichment per cell. Importantly, significant lymphocyte enrichment could be accomplished using leukapheresis samples from healthy donors (n=12) or from study subjects with HIV infection (n=15) or malignancy (n=12).

CONCLUSIONS

Clinical-scale closed-system elutriation can be performed efficiently for the selective enrichment of lymphocytes for immunotherapy protocols. This represents an improvement in cost, yield and purity over current methods that require the addition of monocyte-depleting beads.

Rapamycin generates anti-apoptotic human Th1/Tc1 cells via autophagy for induction of xenogeneic GVHD

Murine T cells exposed to rapamycin maintain flexibility towards Th1/Tc1 differentiation, thereby indicating that rapamycin promotion of regulatory T cells (Tregs) is conditional. The degree to which rapamycin might inhibit human Th1/Tc1 differentiation has not been evaluated. In the presence of rapamycin, T cell costimulation and polarization with IL-12 or IFN-α permitted human CD4+ and CD8+ T cell differentiation towards a Th1/Tc1 phenotype; activation of STAT1 and STAT4 pathways essential for Th1/Tc1 polarity was preserved during mTOR blockade but instead abrogated by PI3 kinase inhibition. Such rapamycin-resistant human Th1/Tc1 cells: (1) were generated through autophagy (increased LC3BII expression; phenotype reversion by autophagy inhibition via 3-MA or siRNA for Beclin1); (2) expressed anti-apoptotic bcl-2 family members (reduced Bax, Bak; increased phospho-Bad); (3) maintained mitochondrial membrane potentials; and (4) displayed reduced apoptosis. In vivo, type I polarized and rapamycin-resistant human T cells caused increased xenogeneic graft-versus-host disease (x-GVHD). Murine recipients of rapamycin-resistant human Th1/Tc1 cells had: (1) persistent T cell engraftment; (2) increased T cell cytokine and cytolytic effector function; and (3) T cell infiltration of skin, gut, and liver. Rapamycin therefore does not impair human T cell capacity for type I differentiation. Rather, rapamycin yields an anti-apoptotic Th1/Tc1 effector phenotype by promoting autophagy.

Unrelated umbilical cord blood transplantation and immune reconstitution

This review highlights the unique features of immune reconstitution following unrelated cord blood transplantation (UCBT) that lead to heightened risk of infection-related mortality in the early post-UCBT period. There is no evidence that innate immunity is uniquely compromised after UCBT, but the development of antigen-specific cellular immunity is affected by numerical and qualitative deficits, primarily within the first 100 days. Nevertheless, beyond the first few months after UCBT there is no evidence for reduced graft-versus-leukemia (GVL) or anti-viral immunity compared to other hematopoietic cell therapy (HCT) modalities. Novel cellular therapies that are about to enter the clinical setting in the form of natural killer (NK) cell and T-cell therapies in the form of donor lymphocyte infusion (DLI) are also discussed.

Autologous and allogeneic cellular therapies for high-risk pediatric solid tumors

Since the 1950s, the overall survival of children with cancer has gone from almost zero to approaching 80%. Although there have been notable successes in treating solid tumors such as Wilms tumor, some childhood solid tumors have continued to elude effective therapy. With the use of megatherapy techniques such as tandem transplantation, dose escalation has been pushed to the edge of dose-limiting toxicities, and any further improvements in event-free survival will have to be achieved through novel therapeutic approaches. This article reviews the status of autologous and allogeneic hematopoietic stem cell transplantation (HSCT) for many pediatric solid tumor types. Most of the clinical experience in transplant for pediatric solid tumors is in the autologous setting, so some general principles of autologous HSCT are reviewed. The article then examines HSCT for diseases such as Hodgkin disease, Ewing sarcoma, and neuroblastoma, and the future of cell-based therapies by considering some experimental approaches to cell therapies.

Antigen presentation on artificial acellular substrates: modular systems for flexible, adaptable immunotherapy

BACKGROUND

Recent findings on T cells and dendritic cells have elucidated principles that can be used for a bottom-up approach to engineering artificial antigen presentation on synthetic substrates.

OBJECTIVE/METHODS

To compare the latest artificial antigen-presenting cell (aAPC) technology, focussing on acellular systems because they offer advantages such as easy tunability and rapid point-of-care application compared with cellular systems. We review acellular aAPC performance and discuss their promise for clinical applications.

RESULTS/CONCLUSION

Acellular aAPCs are a powerful alternative to natural-cell-based therapies, offering flexibility and modularity for incorporation oSf a variety of stimuli, hence increasing precision. Current technologies should adapt physiologically important signals within safe materials to more closely approximate their cellular counterparts. These constructs could be administered parenterally as APC replacements for active vaccines or used ex vivo for adoptive immunotherapy.

Non-MHC-dependent redirected T cells against tumor cells

Adoptive transfer of T cells with restricted tumor specificity provides a promising approach to immunotherapy of cancers. However, the isolation of autologous cytotoxic T cells that recognize tumor-associated antigens is time consuming and fails in many instances. Alternatively, gene modification with tumor antigen-specific T-cell receptors (TCR) or chimeric antigen receptors (CARs) can be used to redirect the specificity of large numbers of immune cells toward the malignant cells. Chimeric antigen receptors are composed of the single-chain variable fragment (scFv) of a tumor-recognizing antibody cloned in frame with human T-cell signaling domains (e.g., CD3zeta, CD28, OX40, 4-1BB), thus combining the specificity of antibodies with the effector functions of cytotoxic T cells. Upon antigen binding, the intracellular signaling domains of the CAR initiate cellular activation mechanisms including cytokine secretion and cytolysis of the antigen-positive target cell.In this chapter, we provide detailed protocols for large-scale ex vivo expansion of T cells and manufacturing of medium-scale batches of CAR-expressing T cells for translational research by mRNA electroporation. An anti-CD19 chimeric receptor for the targeting of leukemias and lymphomas was used as a model system. We are currently scaling up the protocols to adapt them to cGMP production of a large number of redirected T cells for clinical applications.

Adoptive cellular therapy

Cell-based therapies with various lymphocytes and antigen-presenting cells are promising approaches for cancer immunotherapy. The transfusion of T lymphocytes, also called adoptive cell therapy (ACT), is an effective treatment for viral infections, has induced regression of cancer in early stage clinical trials, and may be a particularly important and efficacious modality in the period following hematopoietic stem cell transplantation (HSCT). Immune reconstitution post-SCT is often slow and incomplete, which in turn leads to an increased risk of infection and may impact relapse risk in patients with malignant disease. Immunization post-HSCT is frequently unsuccessful, due to the prolonged lymphopenia, especially of CD4 T cells, seen following transplant. ACT has the potential to enhance antitumor and overall immunity, and augment vaccine efficacy in the post-transplant setting. The ability to genetically engineer lymphocyte subsets has the further potential to improve the natural immune response, correct impaired immunity, and redirect T cells to an antitumor effector response. This chapter focuses on various applications of ACT for cancer immunotherapy, and we discuss some of the latest progress and hurdles in translating these technologies to the clinic.

Increased plasma-immune cytokines throughout the high-dose melphalan-induced lymphodepletion in patients with multiple myeloma: a window for adoptive immunotherapy

High-dose melphalan (HDM) followed by autologous stem cell transplantation (ASCT) is a standard treatment for patients with multiple myeloma. However, lymphocyte reconstitution is impaired after HDM. Recent work has suggested that the lymphopenia period occurring after various immunosuppressive or chemotherapy treatments may provide an interesting opportunity for adoptive antitumor immunotherapy. The objective of this study was to determine an immunotherapy window after HDM and ASCT, evaluating T cell lymphopenia, and measuring circulating immune cytokine concentrations in patients with multiple myeloma. The counts of T cell subpopulations reached a nadir at day 8 post-ASCT (day 10 post-HDM) and recovered by day 30. IL-6, IL-7, and IL-15 plasma levels increased on a median day 8 post-ASCT, respectively, 35-fold, 8-fold, and 10-fold compared with pre-HDM levels (p < or = 0.05). The increases in IL-7 and IL-15 levels were inversely correlated to the absolute lymphocyte count, unlike monocyte or myeloid counts. Furthermore, we have shown that CD3 T cells present in the ASC graft are activated, die rapidly when they are cultured without cytokine in vitro, and that addition of IL-7 or IL-15 could induce their survival and proliferation. In conclusion, the early lymphodepletion period, occurring 4-11 d post-HDM and ASCT, is associated with an increase of circulating immune cytokines and could be an optimal window to enhance the survival and proliferation of polyclonal T cells present in the ASC autograft and also of specific antimyeloma T cells previously expanded in vitro.

Combining conventional therapies with intratumoral injection of autologous dendritic cells and activated T cells to treat patients with advanced cancers

Dendritic cells (DCs) are potent antigen-presenting cells that have been used in cancer immunotherapy. To take advantage of the ability of DCs to acquire antigenic materials from their environment and generate primary as well as recall immune responses, 37 patients with advanced cancers were enrolled in a series of protocols based on direct intratumoral injection of immature DCs. To augment antigen uptake and antitumor immune response, DC injection was combined with radiotherapy or chemotherapy and/or injection of activated T cells. Treatments were well tolerated with no adverse reactions. Clinical responses were based on Response Evaluation Criteria in Solid Tumors, with the majority of patients showing stable disease. One of two patients who also received local radiation achieved a sustained complete response at injected and metastatic sites. The clinical responses observed in cancer patients with advanced disease suggest potential effectiveness of combination strategies and establish the basis for the current treatment protocol that is underway.

Lymphoma immunotherapy: vaccines, adoptive cell transfer and immunotransplant

Therapy for non-Hodgkin lymphoma has benefited greatly from basic science and clinical research such that chemotherapy and monoclonal antibody therapy have changed some lymphoma subtypes from uniformly lethal to curable, but the majority of lymphoma patients remain incurable. Novel therapies with less toxicity and more specific targeting of tumor cells are needed and immunotherapy is among the most promising of these. Recently completed randomized trials of idiotype vaccines and earlier-phase trials of other vaccine types have shown the ability to induce antitumor T cells and some clinical responses. More recently, trials of adoptive transfer of antitumor T cells have demonstrated techniques to increase the persistence and antitumor effect of these cells. Herein, we discuss lymphoma immunotherapy clinical trial results and what lessons can be taken to improve their effect, including the combination of vaccination and adoptive transfer in an approach we have dubbed 'immunotransplant'.

The effect of absolute lymphocyte count recovery kinetics on survival after autologous stem cell transplantation for non-Hodgkin's lymphoma

Absolute lymphocyte count (ALC) >or=500 cells/microl at day 15 after autologous stem cell transplantation (ASCT) is a powerful independent, prognostic indicator for survival in multiple hematological malignancies. A limitation in these studies was the selection of a single time point (day 15 post-ASCT) as the only discriminator of clinical outcome in relation to ALC recovery. We hypothesized there is a continuous and not discrete relationship between ALC recovery and clinical outcome post-ASCT in NHL. Therefore, we analyzed 274 consecutive patients who underwent ASCT for NHL between 1987 and 2001. The primary end point was to assess the impact of the kinetics of post-ASCT lymphocyte recovery>or=500 cells/microl (K-ALC) on overall survival (OS) and progression-free survival (PFS). K-ALC was a predictor of OS and PFS when the Cox proportional hazards model was used with K-ALC entered as a continuous variable (p<0.0001). Multivariate analysis demonstrated K-ALC recovery post-ASCT to be an independent prognostic indicator for OS and PFS. These data support our hypothesis that the K-ALC post-ASCT is associated with clinical outcome in NHL.

Programming tumor-reactive effector memory CD8+ T cells in vitro obviates the requirement for in vivo vaccination

Naive and memory CD8(+) T cells can undergo programmed activation and expansion in response to a short T-cell receptor stimulus, but the extent to which in vitro programming can qualitatively substitute for an in vivo antigen stimulation remains unknown. We show that self-/tumor-reactive effector memory CD8(+) T cells (T(EM)) programmed in vitro either with peptide-pulsed antigen-presenting cells or plate-bound anti-CD3/anti-CD28 embark on a highly stereotyped response of in vivo clonal expansion and tumor destruction nearly identical to that of vaccine-stimulated T(EM) cells. This programmed response was associated with an interval of antigen-independent interferon-gamma (IFN-gamma) release that facilitated the dynamic expression of the major histocompatibility complex class I restriction element H-2D(b) on responding tumor cells, leading to recognition and subsequent tumor lysis. Delaying cell transfer for more than 24 hours after stimulation or infusion of cells deficient in IFN-gamma entirely abrogated the benefit of the programmed response, whereas transfer of cells unable to respond to IFN-gamma had no detriment to antitumor immunity. These findings extend the phenomenon of a programmable effector response to memory CD8(+) T cells and have major implications for the design of current adoptive-cell transfer trials.

Immunotherapy for pediatric cancer

Improvements in adult cancer survivorship can be achieved from behavioral changes and adopting screening programs. Yet, these approaches cannot be readily applied to lower the morbidity and mortality from childhood cancers. Rather, pediatric oncologists must rely on procedures and therapies to treat, rather than prevent malignancies. The systematic application of chemotherapy, radiation therapy, and surgery has led to remarkable advances in survival but these improvements have come at a cost. Children routinely receive chemotherapy agents that were designed decades ago, and these drugs have predictable side effects that result in the loss of potential for long-term survivors. The advent of targeted applications of immune-based therapies offers children with cancer a new class of oncolytic therapies that may be used to treat disease refractory to conventional approaches and lessen the toxicity of current treatment regimens without compromising remission. This review explores how 3 components of the immune system--T cells, natural killer (NK) cells, and antibodies--can be used for therapy of pediatric malignancies.

New frontiers in cell-based immunotherapy of cancer

BACKGROUND

Cancer remains one of the leading causes of death. Over the past decade, discovery of tumor antigens, as well as new findings in basic immunology, have led to novel opportunities for developing active immunotherapeutical approaches for prevention and treatment of cancer.

OBJECTIVE/METHODS

This is a review of the literature and patents on the therapeutic potential of immune-based cell cancer therapies.

RESULTS/CONCLUSION

In this article, we discuss the different approaches at present used for immune-based cell cancer therapies, and the results obtained both in preclinical models and in clinical trials of hematological malignancies and solid tumors.

Manufacturing validation of biologically functional T cells targeted to CD19 antigen for autologous adoptive cell therapy

On the basis of promising preclinical data demonstrating the eradication of systemic B-cell malignancies by CD19-targeted T lymphocytes in vivo in severe combined immunodeficient-beige mouse models, we are launching phase I clinical trials in patients with chronic lymphocytic leukemia (CLL) and acute lymphoblastic leukemia. We present here the validation of the bioprocess which we developed for the production and expansion of clinical grade autologous T cells derived from patients with CLL. We demonstrate that T cells genetically modified with a replication-defective gammaretroviral vector derived from the Moloney murine leukemia virus encoding a chimeric antigen receptor (CAR) targeted to CD19 (1928z) can be expanded with Dynabeads CD3/CD28. This bioprocess allows us to generate clinical doses of 1928z+ T cells in approximately 2 to 3 weeks in a large-scale semiclosed culture system using the Wave Bioreactor. These 1928z+ T cells remain biologically functional not only in vitro but also in severe combined immunodeficient-beige mice bearing disseminated tumors. The validation requirements in terms of T-cell expansion, T-cell transduction with the 1928z CAR, biologic activity, quality control testing, and release criteria were met for all 4 validation runs using apheresis products from patients with CLL. Additionally, after expansion of the T cells, the diversity of the skewed Vbeta T-cell receptor repertoire was significantly restored. This validated process will be used in phase I clinical trials in patients with chemorefractory CLL and in patients with relapsed acute lymphoblastic leukemia. It can also be adapted for other clinical trials involving the expansion and transduction of patient or donor T cells using any CAR or T-cell receptor.

High CD8+ lymphocyte dose in the autograft predicts early absolute lymphocyte count recovery after peripheral hematopoietic stem cell transplantation

Early lymphocyte recovery (ELR) after autologous peripheral hematopoietic stem cell transplantation (ASCT) is an independent predictor for survival in patients with hematological and non-hematological cancers. Sixty-five ASCT for hematological cancers were retrospectively analyzed to identify the factors associated with ELR and to assess the impact of different mobilization regimens on the pre-collection absolute lymphocyte count (ALC). The CD8+ lymphocyte dose in the autograft and the pre-mobilization ALC were independently associated with ELR (P < 0.001 and P = 0.008, respectively). CD8+ lymphocyte doses higher than 0.1 x 10(9)/kg were strongly associated with ELR [P < 0.001, odds ratio 25.22, 95% confidence interval (CI) 4.98-127.69] and this cutoff may be used to predict ELR (P = 0.001, area under the curve 0.75, 95% CI 0.62-0.88). Mobilization with granulocyte colony-stimulating factor (G-CSF) alone, the pre-collection ALC and the number of apheresis sessions were independently associated with the CD8+ lymphocyte dose (P = 0.04, P = 0.001, and P < 0.001, respectively). The number of aphereses was the variable with the strongest correlation to the CD8+ lymphocyte dose (r(s) = 0.68, P < 0.001). Median pre-mobilization ALC was higher than pre-collection ALC in the subgroup of patients without ELR mobilized with chemotherapy followed by G-CSF (1090 vs. 758 lymphocytes/microL; P < 0.001). This reduction was not significant in the subgroup with ELR mobilized with chemotherapy plus G-CSF (1920 vs. 1539/microL, respectively; P = 0.23). These results suggest that the CD8+ lymphocyte dose in the autograft is critical for ELR after ASCT and also demonstrates that mobilization with chemotherapy followed by G-CSF significantly decreases the pre-collection ALC, especially in patients with low pre-mobilization ALC.

Post-transplant adoptive T-cell immunotherapy

Immune reconstitution following haematopoietic stem cell transplantation (SCT) is an often slow and incomplete process that leads to increased risk of infection and malignant disease. Immunization in SCT is frequently unsuccessful due to the prolonged lymphopenia, especially of CD4 T cells, seen following transplant. The transfusion of T cells, also called 'adoptive T-cell therapy', has the potential to enhance anti-tumour and overall immunity, and augment vaccine efficacy in the post-transplant setting. Recent advances in tissue culture, cellular immunology and tumour biology are guiding new approaches to adoptive T-cell therapy. This chapter will discuss the challenges that face the field before adoptive T-cell therapy can be translated into routine clinical practice.

Ex vivo expansion and Th1/Tc1 maturation of umbilical cord blood T cells by CD3/CD28 costimulation

One major limitation of UCBT is the lack of donor cells available for posttransplantation donor leukocyte infusions (DLI) to boost immunity or induce graft-versus-leukemia (GVL) activity. Starting from a approximately 5% fraction of a UCB graft, we report the feasibility and biological characteristics of ex vivo expansion of frozen/thawed CB T cells by anti-CD3 and anti-CD28 antibody-coated Dynal beads in the presence of interleukin (IL)-2. We postulated that while undergoing expansion, UCB T cells may mature toward a Th1/Tc1 phenotype and acquire the potential for cytotoxicity. Whereas an almost 2-log expansion also led to the acquisition of IL-12Ralpha and an increase in Th1 characteristics, postexpansion lymphocytes produced less interferon-gamma, tumor necrosis factor-alpha, and granzyme B; stored almost no perforin; and lacked cytotoxicity against allogeneic targets. Collectively, these suggest relative safety from acute/hyperacute graft-versus-host disease. CD8(+) T cells expanded preferentially, whereas a higher rate of apoptosis in CD4(+) T cells also promoted an inverted CD4/CD8 ratio. Most expanded T cells retained expression of CD27, CD28, and L-selectin but down-regulated CCR-7. In summary, UCB T cell proliferation sustained by CD3/CD28 co-stimulatory beads and IL-2 can lead to clinically relevant doses of DLI from a very small fraction of the UCB graft, although future strategies to reduce apoptosis may enhance their clinical potential.

Preparing clinical grade Ag-specific T cells for adoptive immunotherapy trials

The production of clinical-grade T cells for adoptive immunotherapy has evolved from the ex vivo numerical expansion of tumor-infiltrating lymphocytes to sophisticated bioengineering processes often requiring cell selection, genetic modification and other extensive tissue culture manipulations, to produce desired cells with improved therapeutic potential. Advancements in understanding the biology of lymphocyte signaling, activation, homing and sustained in vivo proliferative potential have redefined the strategies used to produce T cells suitable for clinical investigation. When combined with new technical methods in cell processing and culturing, the therapeutic potential of T cells manufactured in academic centers has improved dramatically. Paralleling these technical achievements in cell manufacturing is the development of broadly applied regulatory standards that define the requirements for the clinical implementation of cell products with ever-increasing complexity. In concert with academic facilities operating in compliance with current good manufacturing practice, the prescribing physician can now infuse T cells with a highly selected or endowed phenotype that has been uniformly manufactured according to standard operating procedures and that meets federal guidelines for quality of investigational cell products. In this review we address salient issues related to the technical, immunologic, practical and regulatory aspects of manufacturing these advanced T-cell products for clinical use.

Adoptive immunotherapy: good habits instilled at youth have long-term benefits

Many recent advances in basic cell biology and immunology are a harbinger of progress in adoptive cell therapy (ACT) including (1) the finding that host lymphodepletion enhances engraftment and efficacy, (2) the recognition that in vitro T cell functions may not correlate with in vivo efficacy, and (3) the development of advanced ex vivo culture methods to expand lymphocytes to therapeutically effective numbers. In this article, we focus on the development of artificial antigen presenting cells (aAPCs) in our laboratory and their applicability to augment ACT protocols. We also describe how aAPCs can be used to broaden ACT to treat patients with a wide variety of cancers, chronic infectious diseases, and autoimmune manifestations.

Umbilical cord blood xenografts in immunodeficient mice reveal that T cells enhance hematopoietic engraftment beyond overcoming immune barriers by stimulating stem cell differentiation

Clinical experience and animal models have shown that donor T cell depletion (TCD) adversely affects engraftment of hematopoietic stem cells (HSCs). Although it is known that donor T cells are acting to overcome residual host immune barriers, they may also exert effects independent of host resistance via direct or indirect interactions with donor stem cells, their microenvironment, or key differentiation events. To more precisely define the effect of T cells on engraftment, we have performed human umbilical cord blood (UCB) transplantation into immunodeficient mice under limiting dilution conditions. UCB mononuclear cells (MNC) or TCD UCB were transplanted into NOD/LtSz-scid/scid B2m(null) (NOD/SCID-beta(2)m(-/-)) mice. Cohorts of mice received UCB MNC or TCD UCB at 5 dose levels between 5 x 10(4) and 5 x 10(6) cells. At dose levels at or above 10(5) cells, engraftment was higher in the MNC recipients (n = 32) than the TCD recipients (n = 31) in a dose-dependent manner. Despite this difference, limiting dilution analysis to determine functional stem cell frequency revealed that SCID repopulating cells in TCD UCB was not significantly less than in CB MNCs, suggesting that T cells may facilitate engraftment at stages beyond the stem cell. Add-back of CD3/CD28 costimulated T cells restored and appeared to enhance engraftment, both in NOD/SCID-beta(2)m(-/-) as well as NOD/LtSz-scid IL2Rgamma(null) (NOG) recipients. These results, in a model where there are minimal host immune barriers to overcome, suggest T cells possess additional graft-facilitating properties. CD3/CD28 costimulation of UCB T cells represents a potential strategy for enhancing the engraftment of UCB.

Donor leukocyte infusions for the treatment of relapsed acute leukemia after allogeneic stem cell transplantation

Allogeneic stem cell transplantation (SCT) offers the only hope for cure for many adults with acute leukemia. Unfortunately, many patients relapse and die of their disease even after transplantation. Although in some cases, allogeneic SCT is effective because the intensive conditioning therapy eradicates all malignant cells, it has long been recognized that the adoptive transfer of donor immunity plays a critically important role in the induction and maintenance of remission. Recognition of the graft-versus-leukemia (GVL) effect of allogeneic SCT has prompted attempts at remission re-induction by adoptive immunotherapy with donor lymphocyte infusions (DLIs) in patients with relapsed disease after allogeneic SCT. In some cases, DLI-induced remissions are sustained and patients cured when no other treatment modality was effective. This review discusses the rationale, biology, complications and future applications of DLI in acute leukemia patients after allogeneic SCT.

T-cell receptor gene therapy for cancer: the progress to date and future objectives

In the last decade research has begun into the use of T-cell receptor (TCR) gene therapy as a means to control and eradicate malignancies. There is now a large body of evidence to demonstrate that through the use of this technology one can redirect T-cell antigen specificity to produce both cytotoxic and helper T cells, which are functionally competent both in vitro and in vivo and show promising antitumour effects in humans. This review focuses on the means by which TCR gene transfer is achieved and the recent advances to modify the TCRs and vector delivery systems which aim to enhance the efficiency and safety of TCR gene transfer protocols.

Factors affecting human T cell engraftment, trafficking, and associated xenogeneic graft-vs-host disease in NOD/SCID beta2mnull mice

OBJECTIVE

Graft-vs-host disease (GVHD) is the major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Models of immunodeficient mice that consistently and efficiently reconstitute with xenoreactive human T cells would be a valuable tool for the in vivo study of GVHD, as well as other human immune responses.

MATERIALS AND METHODS

We developed a consistent and sensitive model of human GVHD by retro-orbitally injecting purified human T cells into sublethally irradiated nonobese diabetic/severe combined immunodeficient (NOD/SCID)-beta2m(null) recipients. In addition, we characterized for the first time the trafficking patterns and expansion profiles of xenoreactive human T cells in NOD/SCID-beta2m(null) recipients using in vivo bioluminescence imaging.

RESULTS

All NOD/SCID-beta2m(null) mice conditioned with 300 cGy total body irradiation and injected with 1 x 10(7) human T cells exhibited human T-cell engraftment, activation, and expansion, with infiltration of multiple target tissues and a subsequent >20% loss of pretransplantation body weight. Importantly, histological examination of the GVHD target tissues revealed changes consistent with human GVHD. Furthermore, we also showed by in vivo bioluminescence imaging that development of lethal GVHD in the NOD/SCID-beta2m(null) recipients was dependent upon the initial retention and early expansion of human T cells in the retro-orbital sinus cavity.

CONCLUSION

Our NOD/SCID-beta2m(null) mouse model provides a system to study the pathophysiology of acute GVHD induced by human T cells and aids in development of more effective therapies for human GVHD.

Immunomodulation against leukemias and lymphomas: a realistic future treatment?

Immunotherapy offers the potential for cure of malignancy without the side effects too commonly seen with conventional chemotherapy. The efficacy of allogenic transplantation and monoclonal antibodies in hematological malignancies illustrate this principle and are now part of routine care. Newer cell based and molecular approaches aimed at stimulating cytotoxic activity against host derived tumor associated antigens are able to 'boost' anti-tumor immunity as judged by immunological assays in vitro. Although clinically meaningful responses were originally less evident, more promising results are now being reported. Our growing understanding of tumor immunology provide rationales for further improvements in the field.

Cell isolation and expansion using Dynabeads

This chapter describes the use of Dynabeads for cell isolation and expansion. Dynabeads are uniform polystyrene spherical beads that have been made magnetisable and superparamagnetic, meaning they are only magnetic in a magnetic field. Due to this property, the beads can easily be resuspended when the magnetic field is removed. The invention of Dynabeads made, by Professor John Ugelstad, has revolutionized the separation of many biological materials. For example, the attachment of target-specific antibodies to the surface of the beads allows capture and isolation of intact cells directly from a complex suspension such as blood. This is all accomplished under the influence of a simple magnetic field without the need for column separation techniques or centrifugation. In general, magnetic beads coated with specific antibodies can be used either for isolation or depletion of various cell types. Positive or negative cell isolation can be performed depending on the nature of the starting sample, the cell surface markers and the downstream application in question. Positive cell isolation is the method of choice for unprocessed samples, such as whole blood, and for downstream molecular applications. Positive cell isolation can also be used for any downstream application after detachment and removal of the beads. Negative cell isolation is the method of choice when it is critical that cells of interest remain untouched, i.e., no antibodies have been bound to any cell surface markers on the cells of interest. Some cell populations can only be defined by multiple cell surface markers. Such populations of cells can be isolated by the combination of negative and positive cell isolation. By coupling Dynabeads with antibodies directed against cell surface activation molecules, the beads can be used both for isolation and expansion of the cells. Dynabeads are currently used in two major clinical applications: 1) In the Isolex 300i Magnetic Cell Selection System for CD34 Stem Cell Isolation--2) For ex vivo T cell isolation and expansion using Dynabeads ClinExVivo CD3/CD28 for clinical trials in novel adoptive immunotherapy.

Adoptive T cell therapy for cancer in the clinic

The transfusion of lymphocytes, referred to as adoptive T cell therapy, is being tested for the treatment of cancer and chronic infections. Adoptive T cell therapy has the potential to enhance antitumor immunity, augment vaccine efficacy, and limit graft-versus-host disease. This form of personalized medicine is now in various early- and late-stage clinical trials. These trials are currently testing strategies to infuse tumor-infiltrating lymphocytes, CTLs, Th cells, and Tregs. Improved molecular biology techniques have also increased enthusiasm and feasibility for testing genetically engineered T cells. The current status of the field and prospects for clinical translation are reviewed herein.

Principles of adoptive T cell cancer therapy

The transfusion of T cells, also called adoptive T cell therapy, is an effective treatment for viral infections and has induced regression of cancer in early-stage clinical trials. However, recent advances in cellular immunology and tumor biology are guiding new approaches to adoptive T cell therapy. For example, use of engineered T cells is being tested as a strategy to improve the functions of effector and memory T cells, and manipulation of the host to overcome immunotoxic effects in the tumor microenvironment has led to promising results in early-stage clinical trials. Challenges that face the field and must be addressed before adoptive T cell therapy can be translated into routine clinical practice are discussed.

Selection of human anti-CD28 scFvs from a T-NHL related scFv library using ribosome display

Engineered antibodies have become an invaluable source of biopharmaceuticals against a wide range of diseases. About 200 antibody-based biologicals have been tested in clinical trials. Single chain variable fragments of antibodies (scFvs) provide binding specificity and offer an increased ease of in vitro display selection. Here, we present the generation of a human scFv library from peripheral blood lymphocyte RNA of a patient with relapsed T-cell non-Hodgkin lymphoma (T-NHL) who experienced a rare case of "spontaneous" remission. Antibodies against human T-cell antigen CD28, a co-stimulatory protein that influences the immune response by amplification of the transcriptional effects of T-cell receptors, might have contributed to the patient's remission. The scFv library was panned against CD28 using ribosome display and further subjected to affinity maturation. Isolated scFv were assessed for binding specificity and affinity and may provide the basis for the development of novel immunotherapeutic strategies. This work demonstrates the selection of a fully human antibody fragment from a patient-derived gene pool by in vitro ribosome display technology.