Adoptive immunotherapy with antigen-specific T cells in myeloma: a model of tumor-specific donor lymphocyte infusion

Agonistic antibody to CD40 boosts the antitumor activity of adoptively transferred T cells in vivo

CD40, a member of the tumor necrosis factor receptor superfamily, is broadly expressed on antigen-presenting cells and other cells, including fibroblasts and endothelial cells. Binding of CD40 and its natural ligand CD40L (CD154) triggers cytokine secretion, and increased expression of costimulatory molecules is required for T-cell activation and proliferation. However, to our knowledge, the use of agonistic antibodies to CD40 to boost adoptively transferred T cells in vivo has not been investigated. The purpose of this study was to determine whether anti-CD40 monoclonal antibody (mAb) in combination with interleukin (IL)-2 could improve the efficacy of in vitro-activated T cells to enhance antitumor activity. Mice bearing B16 melanoma tumors expressing the gp100 tumor antigen were treated with cultured, activated T cells transgenic for a T-cell receptor specifically recognizing gp100, with or without anti-CD40 mAb. In this model, the combination of anti-CD40 mAb with IL-2 led to expansion of adoptively transferred T cells and induced a more robust antitumor response. Furthermore, the expression of CD40 on bone marrow-derived cells and the presence of CD80/CD86 in the host were required for the expansion of adoptively transferred T cells. The use of neutralizing mAb to IL-12 provided direct evidence that enhanced IL-12 secretion induced by anti-CD40 mAb was crucial for the expansion of adoptively transferred T cells. Collectively, these findings provide a rationale to evaluate the potential application of anti-CD40 mAb in adoptive T-cell therapy for cancer.

Neoantigen and tumor antigen-specific immunity transferred from immunized donors is detectable early after allogeneic transplantation in myeloma patients

To enhance the therapeutic index of allogeneic hematopoietic SCT (HSCT), we immunized 10 HLA-matched sibling donors before stem cell collection with recipient-derived clonal myeloma Ig, idiotype (Id), as a tumor antigen, conjugated with keyhole limpet hemocyanin (KLH). Vaccinations were safe in donors and recipients. Donor-derived KLH- and Id-specific humoral and central and effector memory T-cell responses were detectable by day 30 after HSCT and were boosted by post-transplant vaccinations at 3 months in most recipients. One patient died before booster vaccinations. Specifically, after completing treatment, 8/9 myeloma recipients had persistent Id-specific immune responses and 5/9 had improvement in disease status. Although regulatory T cells increased after vaccination, they did not impact immune responses. At a median potential follow-up period of 74 months, 6 patients are alive, the 10 patients have a median PFS of 28.5 months and median OS has not been reached. Our results provide proof of principle that neoantigen and tumor antigen-specific humoral and cellular immunity could be safely induced in HSCT donors and passively transferred to recipients. This general strategy may be used to reduce relapse of malignancies and augment protection against infections after allogeneic HSCT.

To ablate or not to ablate? HSCs in the T cell driver's seat

The combination of the induction of lymphopenia and vaccination and/or T cell transfer is garnering much attention for cancer treatment. Preclinical studies have shown that the induction of lymphopenia by chemotherapy or radiation can enhance the antitumor efficacy of several distinct, cell-based immunotherapeutic approaches. The mechanism(s) by which such enhancement is achieved are being intensively studied, yet there is much opportunity for improvement. The animal studies reported by Wrzesinski and colleagues in this issue of the JCI are a promising and timely step in this direction (see the related article beginning on page 492). The authors have evaluated both the effect of increasing the intensity of lymphodepletion and the influence of HSC transfer on the in vivo function of adoptively transferred CD8(+) T cells. We discuss their results in light of the evolving field and their implications for advancing cell-based immunotherapies for cancer.

Risk factors for relapse after complete remission with high-dose therapy for multiple myeloma

Complete remission (CR) is an important surrogate for long-term survival for patients with multiple myeloma. However, most patients achieving CR eventually relapse and die from their disease. To better define the predictors of relapse, we conducted a retrospective review of outcomes for patients who achieved CR after autografting at our institution. From January 1990 to December 2002, among >400 patients transplanted, 81 (54 males and 27 females) achieved CR. With a median follow up of 58 months for all surviving patients, the 5-year progression-free survival (PFS) was 33% [95% confidence interval (CI) = 23 - 44] and 5-year overall survival (OS) was 67% (95% CI = 54 - 77). Median PFS was 37 months and median OS has not yet been reached. On multivariate analysis, high tumor mass at diagnosis emerged as a predictor of poor outcome. We conclude that high tumor mass at diagnosis predicts a significantly shorter remission duration for myeloma patients undergoing autografting.

Novel approaches in allogeneic stem cell transplantation

Allogeneic transplantation remains an integral part of the management of hematologic malignancies. However, transplant-related mortality, graft-versus-host disease, and disease recurrence continue to be major limitations to successful transplant outcomes and challenges to investigators in the field. Newer approaches have focused on reduction of the intensity of the conditioning regimens, harnessing the antitumor effects of the allograft, and development of adoptive immunotherapy strategies to circumvent the limitations. These developments provide physicians with the ability to tailor transplants to specific patients and their diseases.

Adoptive T-Cell Therapy of Cancer

Adoptive therapy involves the transfer of ex vivo expanded immune effector cells to patients as a means of augmenting the antitumor immune response. In general, this transfer is accomplished by harvesting cells from the peripheral blood, tumor sites, or draining lymph nodes and expanding effector cells in a specific or nonspecific fashion for adoptive transfer. This article describes the rationale for adoptive T-cell therapy, the developments that have led to the translational application of this strategy for the treatment of cancer, the challenges that have been addressed, and future approaches to the development of adoptive therapy as a treatment modality.

T cell-mediated graft-versus-leukemia reactions after allogeneic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation represents the only curative approach for many hematological malignancies. During the last years the impact of the conditioning regimen has been re-assessed. With the advent of reduced-intensity conditioning the paradigm has changed from cytoreduction executed by high-dose radio-chemotherapy to immunological surveillance of leukemia by donor cells. Distinct subsets of T cells and NK cells contribute to graft-versus-leukemia reactions. So far, cytotoxic T lymphocytes are the mainstay of allogeneic immunotherapy. Here, we summarise the current knowledge of T cell-mediated graft-versus-leukemia reactions and present results from pre-clinical and clinical studies of T cell-based adoptive immunotherapy. We address the issues of feasibility and specificity of adoptive immunotransfer from a clinical point of view and discuss the prerequisites for successful clinical applications. Finally, the prospects for immunological research that have evolved with the increasing use of reduced-intensity conditioning and allogeneic stem cell transplantation are highlighted.

Cytokine signals in T-cell homeostasis

Thymic production of T cells declines rapidly with age, and therefore homeostatic cycling (HC) of mature lymphocytes plays an important role in maintaining stable numbers of mature T lymphocytes bearing sufficient repertoire diversity. Following lymphocyte depletion, HC changes in quality and magnitude, resulting in homeostatic peripheral expansion (HPE), a state of widespread T-cell cycling that serves to increase T-cell number and to maintain T-cell repertoire diversity to the greatest extent possible. Recent studies delineating the requirements for HC and HPE have shown that naive CD4+ cells and naive CD8+ cells require both IL7 and TCR engagement for survival, cycling, and homeostatic expansion, whereas CD8+ memory cells are maintained and expanded by cytokine signals alone, independent of TCR engagement. While basal levels of IL15 are sufficient for HC and HPE of CD8+ memory cells, supranormal levels of IL7 will also suffice. The requirements for memory CD4+ cells remain unclear, but current models hypothesize that either IL7 or TCR triggering may be sufficient. Thus, the changes in immune physiology that are present in lymphopenic hosts can be largely accounted for by cytokine-driven signals, especially those rendered by IL7 or IL15. As the alterations in immune physiology present in lymphopenic hosts may be conducive to stronger antitumor immune responsiveness, careful delineation of the factors responsible may be expected to give rise to approaches to augment the effectiveness of current antitumor immunotherapies.

The graft-versus-lymphoma effect: clinical review and future opportunities

Numerous lines of preclinical and clinical evidence support the existence of a graft-versus-leukemia effect, but less evidence supporting a comparable graft-versus-lymphoma effect exists. We review here current clinical data addressing the graft-versus-lymphoma effect, including comparisons of autologous, syngeneic, and allogeneic transplantation; responses to immunomodulation; and responses to nonmyeloablative stem cell transplantation. Despite several limitations of the data, we believe that there is sufficient evidence suggesting a significant graft-versus-lymphoma effect. In addition, we discuss approaches for clinical management of lymphoma patients, opportunities for mechanistic studies afforded by donor leukocyte infusions and nonmyeloablative transplantation, and suggestions for clinical studies to further define the magnitude and applicability of the graft-versus-lymphoma effect.

Therapeutic idiotype vaccines in B lymphoproliferative diseases

The recognition of the surface immunoglobulin protein of the tumour B cells as a specific tumour antigen has prompted the development of vaccination strategies aimed at the induction of humoral and cellular antitumour responses. Results obtained in preclinical models of B lymphoproliferative diseases, as well as in initial clinical trials, have shown the immunogenic potential of the idiotype (Id) when administered in association with proper adjuvants. The definitive evidence for clinical efficacy of this therapeutic approach awaits ongoing randomised Phase III studies. Research efforts at present include identification of new vaccination settings to improve the clinical benefit of vaccine treatment, the establishment of more convenient methods to produce individual Id vaccines and the development of new strategies of vaccination, including genetic vaccination.

Dendritic cells strongly boost the antitumor activity of adoptively transferred T cells in vivo

Dendritic cells (DCs) have been well characterized for their ability to initiate cell-mediated immune responses by stimulating naive T cells. However, the use of DCs to stimulate antigen-activated T cells in vivo has not been investigated. In this study, we determined whether DC vaccination could improve the efficacy of activated, adoptively transferred T cells to induce an enhanced antitumor immune response. Mice bearing B16 melanoma tumors expressing the gp100 tumor antigen were treated with cultured, activated T cells transgenic for a T-cell receptor specifically recognizing gp100, with or without concurrent peptide-pulsed DC vaccination. In this model, antigen-specific DC vaccination induced cytokine production, enhanced proliferation, and increased tumor infiltration of adoptively transferred T cells. Furthermore, the combination of DC vaccination and adoptive T-cell transfer led to a more robust antitumor response than the use of each treatment individually. Collectively, these findings illuminate a new potential application for DCs in the in vivo stimulation of adoptively transferred T cells and may be a useful approach for the immunotherapy of cancer.