Preparing the ground for vaccination against multiple myeloma

Myeloma cell line-derived, pooled heat shock proteins as a universal vaccine for immunotherapy of multiple myeloma

Tumor cell-derived heat shock proteins are used as vaccines for immunotherapy of cancer patients. However, current approaches require the generation of custom-made products and are clinically ineffective. To improve the applicability of heat shock protein-based immunotherapy in cancers and to enhance clinical efficacy, we explored combinational treatments in a myeloma setting using pooled heterogeneous or allogeneic myeloma cell line-derived glycoprotein 96 (gp96) as universal vaccines, and clearly demonstrated that pooled but not single gp96 from heterogeneous or allogeneic myeloma cell lines was as effective as autologous gp96 in protecting mice from tumor challenge and rechallenge and in treating established myeloma. We showed that interferon gamma and CD4+ and CD8+ T cells were required for gp96-induced antimyeloma responses and that pooled gp96 induced broader immune responses that protected mice from developing different myeloma. Furthermore, pooled gp96 plus CpG in combination with anti-B7H1 or anti-interleukin-10 monoclonal antibodies were effective in treating mice with large tumor burdens. Thus, this study strongly suggests that pooled gp96 vaccines from myeloma cell lines can replace gp96 vaccines from autologous tumors for immunotherapy and induce immune responses against broader tumor antigens that may protect against tumor recurrence and development of unrelated tumors in vaccinated myeloma patients.

Poorex vivoinduction of T-cell responses to idiotype or tumor cell lysate-pulsed autologous dendritic cells in advanced pre-treated multiple myeloma

This study evaluated the feasibility of using dendritic cells (DCs) to generate, ex vivo, anti-tumor cytotoxic T lymphocytes (CTL) in patients with stage III multiple myeloma (MM). Nucleated cells from eight patients who had received chemotherapy (three of whom had undergone autologous hemopoeitic stem cell transplantation) were collected by apheresis. Their monocytes were enriched using counter-current centrifugation, differentiated into DCs which were further co-cultured with autologous CD8 lymphocytes to induce CTL. The DCs were pulsed either with the idiotypic paraprotein (regarded as a tumor-specific antigen) or with autologous MM cell lysate before co-culture. Specific T-cell responses were measured in IFNgamma enzyme-linked immunospot and chromium release assays of autologous plasmocyte targets. A slight increase in IFNgamma secretion by T-cells was observed for two patients (DCs pulsed with idiotypic paraprotein for one, MM cell lysate for the other). No or weak specific lysis of plasmocyte targets was observed in the chromium release assays. In conclusion, the T-cell response to pulsed DCs was very weak or absent. There are clinical and technical reasons that could explain, in part, this lack of response.

Roles of idiotype-specific t cells in myeloma cell growth and survival: Th1 and CTL cells are tumoricidal while Th2 cells promote tumor growth

Idiotype (Id) protein, secreted by myeloma cells, is a tumor-specific antigen. Id-based immunotherapy has been explored in patients with myeloma, and results were disappointing. Although previous studies have shown that Id-specific CTLs are able to lyse myeloma cells, it is unclear whether other types of Id-specific T cells, such as type-1 T-helper (Th1) and type-2 T-helper (Th2) cells, are also able to suppress or kill myeloma cells. Using a 5T murine myeloma model, we generated T-cell clones of different subsets and examined their function in the context of myeloma cells. Id-specific CTLs specifically lysed myeloma cells via MHC class I, perforin, and Fas ligand (FasL), and Th1, but not Th2, cells lysed the myeloma cells by FasL-Fas interaction. CTL and Th1 cells also suppressed the growth and function of myeloma cells, whereas Th2 cells promoted the proliferation and enhanced the secretion of Id protein and cytokines by myeloma cells. CTL and Th1, but not Th2, cells were able to eradicate established myeloma in vivo after adoptive transfer. These results show that Id-specific CTL and Th1 are promising effector cells, whereas Th2 provide no protection and may even promote tumor progression in vivo.

The malignant clone and the bone-marrow environment

Multiple myeloma (MM) is characterized by the clonal expansion of monoclonal immunoglobulin-secreting plasma cells within the bone marrow (BM). It has become clear that the intimate reciprocal relationship between the tumor cell clone and the niches of the BM microenvironment plays a pivotal pathophysiologic role in MM. We and others have identified several new molecular targets and derived novel therapies which induce cytotoxicity against MM cells in the BM milieu, including thalidomide, bortezomib, and lenalidomide. Importantly, these agents induce tumor-cell death, as well as inhibit MM-cell-BM-stromal-cell (BMSC) adhesion and related tumor-cell growth, survival, and migration. Moreover, they block both constitutive and MM-cell binding-induced growth factor and cytokine secretion in BMSCs. Further, they also block tumor angiogenesis and can augment anti-MM immunity. Although all three of these agents are now FDA-approved to treat MM, patients inevitably relapse, and further improvements remain urgently needed. Here we review our current knowledge of the MM cell clone, as well as the impact of the BM microenvironment on tumor-cell growth, survival, migration and drug resistance. Delineating the mechanisms and sequelae of the reciprocal relationship between the MM cell clone, distinct BM extracellular matrix proteins, and accessory cell compartments may provide the basis for new effective therapeutic strategies to re-establish BM homeostasis and thereby improve MM patient outcome.

Dickkopf-1 (DKK1) is a widely expressed and potent tumor-associated antigen in multiple myeloma

The identification of novel tumor-associated antigens, especially those shared among patients, is urgently needed to improve the efficacy of immunotherapy for multiple myeloma (MM). In this study, we examined whether Dickkopf-1 (DKK1), a protein that is not expressed in most normal tissues but is expressed by tumor cells from almost all patients with myeloma, could be a good candidate. We identified and synthesized DKK1 peptides for human leukocyte antigen (HLA)-A*0201 and confirmed their immunogenicity by in vivo immunization in HLA-A*0201 transgenic mice. We detected, using peptidetetramers, low frequencies of DKK1 peptide-specific CD8-positive (CD8(+)) T cells in patients with myeloma and generated peptide-specific T-cell lines and clones from HLA-A*0201-positive (HLA-A*0201(+)) blood donors and patients with myeloma. These T cells efficiently lysed peptide-pulsed but not unpulsed T2 or autologous dendritic cells, DKK1-positive (DKK1(+))/HLA-A*0201(+) myeloma cell lines U266 and IM-9, and, more importantly, HLA-A*0201(+) primary myeloma cells from patients. No killing was observed on DKK1(+)/HLA-A*0201-negative (HLA-A*0201(-)) myeloma cell lines and primary myeloma cells or HLA-A*0201(+) normal lymphocytes, including B cells. These results indicate that these T cells were potent cytotoxic T cells and recognized DKK1 peptides naturally presented by myeloma cells in the context of HLA-A*0201 molecules. Hence, our study identifies DKK1 as a potentially important antigen for immunotherapy in MM.

Lentiviral transduction of primary myeloma cells with CD80 and CD154 generates antimyeloma effector T cells

The development of immunotherapy approaches designed to obtain tumor-specific T cells might help eradicate residual malignant cells in multiple myeloma (MM) patients. To this end, we used autologous primary MM cells as antigen-presenting cells (APC). Gene transfer of both CD80 and CD154 by lentiviral vectors was necessary to significantly improve the APC function of human MM cells. Simultaneous CD80/CD154 expression on MM cells allowed the generation of CD8+ T cells that recognized unmodified MM cells in 11 of 16 cases, specifically in six of six patients with low-stage disease, but only in five of ten patients with advanced disease. The activity of CD8+ T cells was MHC restricted and MM specific. In seven of seven cases, CD8+ T cell activity was inhibited by monoclonal antibodies against HLA class I, and in four of four cases, CD8+ T cells recognized autologous MM cells but not autologous normal B and T lymphocytes nor bone marrow stromal cells. In addition, the activity of CD8+ T cells was directed against allogeneic MM cells that shared at least one MHC allele with the autologous counterpart, but not against MHC mismatched MM cells. These data lay the ground for the isolation of new MM antigens and for the design of vaccination protocols with primary MM cells genetically engineered to express immunostimulatory molecules.

Targeting Positive Regulatory Domain I-Binding Factor 1 and X Box-Binding Protein 1 Transcription Factors by Multiple Myeloma-Reactive CTL

Growing evidence indicates that multiple myeloma (MM) and other malignancies are susceptible to CTL-based immune interventions. We studied whether transcription factors inherently involved in the terminal differentiation of mature B lymphocytes into malignant and nonmalignant plasma cells provide MM-associated CTL epitopes. HLA-A*0201 (A2.1) transgenic mice were used to identify A2.1-presented peptide Ag derived from the plasma cell-associated transcriptional regulators, positive regulatory domain I-binding factor 1 (PRDI-BF1) and X box-binding protein 1 (XBP-1). A2.1-restricted CTL specific for PRDI-BF1 and XBP-1 epitopes efficiently killed a variety of MM targets. PRDI-BF1- and XBP-1-reactive CTL were able to recognize primary MM cells from A2.1(+) patients. Consistent with the expression pattern of both transcription factors beyond malignant and nonmalignant plasma cells, PRDI-BF1- and XBP-1-specific CTL activity was not entirely limited to MM targets, but was also associated with lysis of certain other malignancies and, in defined instances, with low-to-intermediate level recognition of a few types of normal cells. Our results also indicate that the A2.1-restricted, PRDI-BF1- and XBP-1-specific human CD8(+) T cell repertoire is affected by partial self tolerance and may thus require the transfer of high-affinity TCR to break tolerance. We conclude that transcription factors governing terminal cellular differentiation may provide MM- and tumor-associated CTL epitopes.

Cross-linking of CD40 using anti-CD40 antibody, 5C11, has different effects on XG2 multiple myeloma cells

A multiple myeloma (MM) cell line, XG2, has high-level expression of CD40, a tumor necrosis factor receptor (TNFR) family member. CD40 is present on the surfaces of a large variety of cells, including B cells, endothelial cells, dendritic cells and some carcinoma cells, and delivers signals regulating diverse cellular responses, such as proliferation, differentiation, growth suppression, cell death. In this research, we study the effects of cross-linking of CD40 on myeloma cells using different concentrations of anti-CD40 monoclonal antibody (mAb), 5C11. We found that low concentrations of 5C11 induced proliferation of XG2, while high concentrations of 5C11 resulted in homotypic aggregation of XG2, and strongly suppression of its proliferation and apoptosis after 24 h of treatment. These dose-dependent effects of 5C11 were verified by flow cytometry, Western blotting and immunoprecipitation. Autocrine or paracrine induction of IL-6, and up-regulation of membrane TNF and phosphorylation of TNFR1 may partially explain the contradictory biological effects of CD40 cross-linking on XG2 by anti-CD40 mAb.

A review of the cytokine network in multiple myeloma: diagnostic, prognostic, and therapeutic implications

Because many studies have focused on growth factors in multiple myeloma, the study of the cytokine network appears to be useful for this purpose. Interleukin-6 (IL-6) and IL-2 with their soluble receptors (IL-3, IL-4, IL-10, and IL-11) have been examined. Plasma cells may produce IL-6 by an autocrine mechanism whereas a paracrine mechanism is believed to be involved in the production of IL-6 by bone marrow stromal cells through an interaction between adhesion molecules present on myeloma plasma cells and their respective receptors that are present on bone marrow stromal cells. In addition, control over production of IL-6 may be exerted by other ILs such as IL-1beta and IL-10. Among target cells, the growth of normal and myeloma plasma cells is supported by IL-6, which also induces the differentiation of myeloma plasmablastic cells into mature plasma cells. This last action also is shared by IL-3, IL-4, and, most likely, IL-8. Evaluation of the serum level of IL-6, C reactive protein, soluble IL-6 receptor (sIL-6R), and soluble IL-2 receptor (sIL-2R), together with the activity exerted by IL-3 and IL-4 on some cellular subsets, may constitute an additional element in the differential diagnosis of borderline cases. However, the concomitant evaluation of all immunologic parameters could be more useful than the value of a single IL. Serum levels of IL-6, sIL-6R, sIL-2R, and the expression of membrane-bound IL-2 receptors, both on bone marrow plasma cells and on peripheral blood mononuclear cells, are correlated with disease activity and disease stage. In addition, IL-6 and sIL-6R serum levels are believed to be correlated with the duration of disease-free survival because a high serum level at the time of diagnosis is believed to be correlated with a short duration of survival. However, some laboratory parameters may express the same prognostic value as high beta(2) microglobulin and lactate dehydrogenase (LDH) serum levels together with a high plasma cell labeling index are correlated with disease activity. Furthermore, if the evaluation is performed at the time of diagnosis, high values of these parameters are correlated with a short disease-free survival. A correlation between laboratory parameters and the serum level of several cytokines was demonstrated. Hence, the real advantage of the prognostic evaluation of cytokines is reserved for patients who do not exhibit uniform results with regard to beta(2) microglobulin and LDH serum levels, or, better, for borderline cases. With regard to the differential diagnosis, all immunologic parameters should be evaluated concomitantly rather than separately to confer a real prognostic value to results. Furthermore, a particular relation was found between a high sIL-6R serum level and a poor response to chemotherapy, therefore suggesting the possibility of identifying in advance a subset of patients with a high risk of treatment failure, as has already been demonstrated in other hematologic malignancies.Finally, the majority of studies indicate that interferons are used mainly in the immunotherapy for multiple myeloma, whereas many clinical trials should still be required for the evaluation of the effectiveness of anti-I-L6 antibodies or antiidiotypic vaccines in reference to the eligible patients for these particular therapies.

Monoclonal antibody therapy of haematological malignancies

Over the past decade the potential for delivering targeted therapy against malignant disease by the use of monoclonal antibodies (MAbs) has begun to be realised. Haematological malignancies, because of the relative accessibility of the malignant cell in blood and bone marrow and the understanding of haemopoietic lineage-specific antigens, have provided a successful testing ground for this therapy. There have been many technical developments which have allowed the safe delivery of more potent antibody constructs. The development of human or chimeric antibodies has largely overcome the problems associated with host immune responses to rodent-derived MAbs. Protein engineering to combine MAbs with other biologically active molecules such as radioisotopes, toxins, chemotherapy and cytokines, has made available a new range of agents with clinical activity. The purpose of this review is not to give a catalogue of all therapeutic antibodies but rather to outline the principles of this approach, the current state of knowledge, and possible directions for future development. First, the general requirements and strategies for use of both unmodified and conjugated MAbs are discussed, followed by a summary of the trial data in specific lymphoid and myeloid haemopoietic malignancies. The focus is on MAbs that now have an accepted use in clinical practice, with some discussion of newer MAbs under development. Vaccination strategies and the role of MAbs in bone marrow transplantation are not discussed in detail. The trials of the next decade will address issues such as: whether clinical activity translates into improved survival; the optimal strategies and timing for clinical use; whether increasing potency of MAbs (as in radio- and immunoconjugates) will increase toxicity and, finally, what other potential molecules, such as those influencing cell growth and death, may be targeted.

Immunotherapy of Non-Hodgkin's lymphomas

Recent years have witnessed the development of a variety of promising immunotherapies for treating patients with non-Hodgkin's lymphomas. Foremost among these advances is the exciting success of monoclonal antibodies directed against lymphocyte surface antigens. Rituximab is a chimeric (human-mouse) anti-CD20 antibody that induces responses in approximately half of the patients with relapsed indolent lymphomas and a third of patients with relapsed aggressive lymphomas when used as a single agent. Response rates appear even higher (up to 70%) for newly diagnosed patients treated with Rituximab monotherapy. Other promising antibodies for treatment of B cell malignancies include epratuzumab (anti-CD22), CAMPATH-1H (anti-CD52w), and Hu1D10 (anti-class II HLA). Even more exciting than antibody monotherapy is the prospect of combination antibody therapy (e.g. rituximab + epratuzumab) or combination chemotherapy and antibody therapy. In this regard, a recent phase III randomized trial from the GELA group in France demonstrated statistically significantly superior complete and overall response rates and superior event-free and overall survivals for elderly patients with newly diagnosed diffuse aggressive B cell lymphomas treated with CHOP + rituximab compared with CHOP alone. Confirmatory cooperative group trials combining chemotherapy with antibody therapies are currently underway. Another approach to augment the efficacy of antibodies is to deploy them in radiolabeled form. Iodine-131, Yttrium-90, and Copper-67 labeled monoclonal antibodies targeting CD-20, CD-22, HLA class II, and other cell surface antigens have been tested and demonstrate higher overall response rates (50-80%) and complete response rates (20-40%) than unlabeled antibodies. Pilot studies combining radiolabeled antibodies with either standard dose chemotherapy or myeloablative chemoradiotherapy with stem cell transplantation also appear very promising. Lymphoma vaccines have also produced very encouraging results in single institution studies at Stanford and the National Cancer Institute, with responding patients demonstrating superior event-free and overall survival than historical controls. Phase III randomized trials of idiotype vaccines are currently underway and novel new vaccine approaches are also being tested.

The history of the development of vaccines for the treatment of lymphoma

Exploitation of the immune system is an attractive strategy for developing selective lymphoma therapies. In the past several decades, increased knowledge of tumor immunology has granted investigators the tools to formulate a variety of lymphoma-specific vaccines. Vaccines targeting the tumor-specific immunoglobulin (idiotype) of B-cell lymphomas were the first to be developed, owing to successful active vaccination studies in animal models and clinical studies of passive anti-idiotype monoclonal antibodies. In initial clinical trials, patient-specific idiotype vaccines have been found to induce anti-idiotype immune responses that correlate with improved disease-free and overall survival and the reduction of the level of detectable residual disease. More recent strategies for improving the potency and practicality of idiotype vaccines are utilization of dendritic cells, recombinant idiotype proteins, and DNA vaccination. Custom-made vaccines utilizing whole autologous tumor cells are also being developed. Given the exciting results of these early lymphoma vaccine studies and the accelerated pace of immunologic research, it is hoped that vaccines will someday expand the armamentarium of effective lymphoma therapies.