Long-term follow-up of idiotype vaccination in human myeloma as a maintenance therapy after high-dose chemotherapy

Dendritic Cell-Based Immunotherapy in Multiple Myeloma: Challenges, Opportunities, and Future Directions

Immunotherapeutic approaches, including adoptive cell therapy, revolutionized treatment in multiple myeloma (MM). As dendritic cells (DCs) are professional antigen-presenting cells and key initiators of tumor-specific immune responses, DC-based immunotherapy represents an attractive therapeutic approach in cancer. The past years, various DC-based approaches, using particularly ex-vivo-generated monocyte-derived DCs, have been tested in preclinical and clinical MM studies. However, long-term and durable responses in MM patients were limited, potentially attributed to the source of monocyte-derived DCs and the immunosuppressive bone marrow microenvironment. In this review, we briefly summarize the DC development in the bone marrow niche and the phenotypical and functional characteristics of the major DC subsets. We address the known DC deficiencies in MM and give an overview of the DC-based vaccination protocols that were tested in MM patients. Lastly, we also provide strategies to improve the efficacy of DC vaccines using new, improved DC-based approaches and combination therapies for MM patients.

Harnessing the Immune System Against Multiple Myeloma: Challenges and Opportunities

Multiple myeloma (MM) is an incurable malignancy of plasma cells that grow within a permissive bone marrow microenvironment (BMM). The bone marrow milieu supports the malignant transformation both by promoting uncontrolled proliferation and resistance to cell death in MM cells, and by hampering the immune response against the tumor clone. Hence, it is expected that restoring host anti-MM immunity may provide therapeutic benefit for MM patients. Already several immunotherapeutic approaches have shown promising results in the clinical setting. In this review, we outline recent findings demonstrating the potential advantages of targeting the immunosuppressive bone marrow niche to restore effective anti-MM immunity. We discuss different approaches aiming to boost the effector function of T cells and/or exploit innate or adaptive immunity, and highlight novel therapeutic opportunities to increase the immunogenicity of the MM clone. We also discuss the main challenges that hamper the efficacy of immune-based approaches, including intrinsic resistance of MM cells to activated immune-effectors, as well as the protective role of the immune-suppressive and inflammatory bone marrow milieu. Targeting mechanisms to convert the immunologically “cold” to “hot” MM BMM may induce durable immune responses, which in turn may result in long-lasting clinical benefit, even in patient subgroups with high-risk features and poor survival.

Idiotypic DNA vaccination for the treatment of multiple myeloma: safety and immunogenicity in a phase I clinical study

We report on the safety and immunogenicity of idiotypic DNA vaccination in a phase I, non-randomised, open-label study in patients with multiple myeloma. The study used DNA fusion gene vaccines encoding patient-specific single chain variable fragment, or idiotype (Id), linked to fragment C (FrC) of tetanus toxin. Patients in complete or partial response following high-dose chemotherapy and autologous stem cell transplant were vaccinated intramuscularly with 1 mg DNA on six occasions, beginning at least 6 months post-transplant; follow-up was to week 52. Fourteen patients were enrolled on study and completed vaccinations. Idiotypic DNA vaccines were well tolerated with vaccine-related adverse events limited to low-grade constitutional symptoms. FrC- and Id-specific T-cell responses were detected by ex vivo ELISPOT in 9/14 and 3/14 patients, respectively. A boost of pre-existing anti-FrC antibody (Ab) was detected by ELISA in 8/14 patients, whilst anti-Id Ab was generated in 1/13 patients. Overall, four patients (29 %) made an immune response to FrC and Id, with six patients (43 %) responding to FrC alone. Over the 52-week study period, serum paraprotein was undetectable, decreased or remained stable for ten patients (71 %), whilst ongoing CR/PR was maintained for 11 patients (79 %). The median time to progression was 38.0 months for 13/14 patients. Overall survival was 64 % after a median follow-up of 85.6 months.

Vaccination of multiple myeloma: Current strategies and future prospects

Tumor immunotherapy holds great promise in controlling multiple myeloma (MM) and may provide an alternative treatment modality to conventional chemotherapy for MM patients. For this reason, a major area of investigation is the development of cancer vaccines to generate myeloma-specific immunity. Several antigens that are able to induce specific T-cell responses are involved in different critical mechanisms for cell differentiation, inhibition of apoptosis, demethylation and proliferation. Strategies under development include infusion of vaccine-primed and ex vivo expanded/costimulated autologous T cells after high-dose melphalan, genetic engineering of autologous T cells with receptors for myeloma-specific epitopes, administration of dendritic cell/plasma cell fusions and administration expanded marrow-infiltrating lymphocytes. In addition, novel immunomodulatory drugs may synergize with immunotherapies. The task ahead is to evaluate these approaches in appropriate clinical settings, and to couple them with strategies to overcome mechanisms of immunoparesis as a means to induce more robust clinically significant immune responses.

The bone marrow of myeloma patients is steadily inhabited by a normal-sized pool of functional regulatory T cells irrespectiveof the disease status

Conflicting data have been reported about the frequency and function of regulatory T cells in multiple myeloma. Most studies have investigated peripheral blood rather than bone marrow Tregs and side-by-side comparisons with bone marrow from healthy donors have still not been made. In this study, we show that regulatory T-cells total count, subset distribution, and expression of chemokine receptors are similar in the bone marrow of myeloma patients and healthy donors. Regulatory T cells are not recruited by myeloma cells in the bone marrow and their counts are unaffected by the tumor burden and the disease status. The diversity of T-cell receptor repertoire is highly preserved ensuring broad reactivity and effective suppressor function. Our results indicate that regulatory T cells may not be the main players of immunological tolerance to myeloma cells under base-line conditions, but their fully preserved immune competence may promote their inadvertent activation and blunt T-cell driven anti-myeloma immune interventions even after myeloma cells have successfully been cleared by chemotherapy.

Immunotherapy of multiple myeloma: the start of a long and tortuous journey

The field of tumor immunotherapy is still in its infancy. It is becoming clear that the human immune response is the result of highly complex, continuously evolving interactions between cells of the adaptive and innate arms of the immune system, the internal and external environments, and normal and abnormal cells (e.g., myeloma plasma cells). Despite the considerable advances in our knowledge over the past 30 years, we have still only scratched the surface of the immune system's interaction with malignant diseases such as myeloma and to date, this has not translated into significantly better outcomes for patients with this disease. This review will summarize our current knowledge of the fundamental immunology of myeloma, review immunotherapy trials reported to date and discuss whether, in light of the current information, immunotherapy of multiple myeloma is an achievable goal.

Peptide vaccines for hematological malignancies: a missed promise?

Despite the crucial aid that newly developed target therapies are providing to chemotherapy and stem cell transplant, the cure for many hematological malignancies is still an unmet need. Although available therapies are able to induce an effective debulking of the tumor, most of the time, an insidious minimal residual disease survives current treatments and it is responsible for an immediate or delayed relapse. Peptide-derived antitumor vaccines have been developed with the idea that an artificially "educated" immune system may exert an active specific antitumor response able to control and ultimately eradicate underlying post-treatment residual disease. This review will summarize current knowledge of peptide vaccines for hematological malignancies, trying to analyze promises and pitfalls of a safe and intelligent tool that after many years from its first appearance has not yet established its potential role as alternative immune mediated therapeutic approach for hematopoietic tumors.

Tumor cells loaded with α-galactosylceramide promote therapeutic NKT-dependent anti-tumor immunity in multiple myeloma

Tumor cells have been used as the tumor antigen sources for developing cancer vaccines. Due to their low immunogenicity, tumor antigens are combined with various adjuvants to enhance immunogenicity of cancer vaccines. Among them, a natural killer T cell (NKT)-ligand, α-galactosylceramide (αGC) has been reported as a powerful adjuvant showing therapeutic effects in solid tumors as well as hematological malignancies including lymphoma. In this study, we applied αGC-based tumor cell vaccine in mouse multiple myeloma model. The αGC-loaded MOPC315BM myeloma cell vaccine efficiently retarded tumor growth, induced regression of established tumors, and protected surviving mice from tumor rechallenge. Therapeutic responses were associated with induction of strong humoral immune responses, including myeloma-specific antibodies, and cellular immune responses, including myeloma-specific CD8(+) cytotoxic T lymphocytes and memory T cells. In addition, regulatory T cells were significantly decreased in mice that received the αGC-loaded myeloma cell vaccine. Thus, our results demonstrated that αGC-loaded myeloma vaccine efficiently promoted NKT-dependent anti-tumor immunity in a mouse model. These findings are informative for improving the efficacy of tumor-cell-based immunotherapy for patients with MM and other CD1d-expressing tumors.

Immunotherapy strategies for multiple myeloma: the present and the future

Growing knowledge of the complexities of the immune system have led to a better understanding of how it can be harnessed for the purpose of anticancer therapy. Moreover, recent success with immunotherapies for solid tumors, combined with novel therapeutic strategies against myeloma, heighten excitement at the prospect of improving clinical outcomes for myeloma by improving antitumor immunity. Increased understanding of myeloma tumor-associated antigens, availability of more potent vaccines, expanded immune-modulating therapies, development of agents that block immune-suppressive pathways, increased sophistication of adoptive cell therapy techniques and capitalization upon standard autologous transplant are all important standalone or combination strategies that might ultimately improve prognosis of patients with multiple myeloma.

Novel strategies for immunotherapy in multiple myeloma: previous experience and future directions

Multiple myeloma (MM) is a life-threatening haematological malignancy for which standard therapy is inadequate. Autologous stem cell transplantation is a relatively effective treatment, but residual malignant sites may cause relapse. Allogeneic transplantation may result in durable responses due to antitumour immunity mediated by donor lymphocytes. However, morbidity and mortality related to graft-versus-host disease remain a challenge. Recent advances in understanding the interaction between the immune system of the patient and the malignant cells are influencing the design of clinically more efficient study protocols for MM. Cellular immunotherapy using specific antigen-presenting cells (APCs), to overcome aspects of immune incompetence in MM patients, has received great attention, and numerous clinical trials have evaluated the potential for dendritic cell (DC) vaccines as a novel immunotherapeutic approach. This paper will summarize the data investigating aspects of immunity concerning MM, immunotherapy for patients with MM, and strategies, on the way, to target the plasma cell more selectively. We also include the MM antigens and their specific antibodies that are of potential use for MM humoral immunotherapy, because they have demonstrated the most promising preclinical results.

Lenalidomide enhances antigen-specific activity and decreases CD45RA expression of T cells from patients with multiple myeloma

The aim of this study was to investigate whether the specific T cell response against the multiple myeloma Ag HM1.24 is enhanced by the immunomodulatory drug lenalidomide (Revlimid). Ag-specific CD3(+)CD8(+) T cells against the HM1.24 Ag were expanded in vitro by dendritic cells in 29 healthy donors and 26 patients with plasma cell dyscrasias. Ag-specific activation was analyzed by IFN-γ, granzyme B, and perforin secretion using ELISA, ELISPOT assay, and intracellular staining, and generation of Ag-specific T cells was analyzed by tetramer staining. Expression of T cell maturation markers (CD45RA, CD45R0, CCR7, and CD28) was investigated by flow cytometry. We found that activation of HM1.24-specific T cells from healthy donors and patients with plasma cell dyscrasias was enhanced significantly by lenalidomide and furthermore that the impact of lenalidomide on T cells depends on the duration of the exposure. Notably, lenalidomide supports the downregulation of CD45RA on T cells upon activation, observed in healthy donors and in patients in vitro and also in patients during lenalidomide therapy in vivo. We showed for the first time, to our knowledge, that lenalidomide enhances the Ag-specific activation of T cells and the subsequent downregulation of CD45RA expression of T cells in vitro and in vivo.

Targeted idiotype-fusion DNA vaccines for human multiple myeloma: preclinical testing

OBJECTIVES

  A homodimeric fusion DNA vaccine targeting idiotype (Id) to antigen-presenting cells (APC) induced robust tumor protection in a mouse model of multiple myeloma (MM). Similar Id vaccine molecules were generated for four patients with MM with three main objectives: (i) do the vaccine molecules induce bona fide anti-Id immune responses in mice? (ii) does targeting of the vaccine molecules to APC enhance immune responses? (iii) can anti-Id antibodies, generated as by-product in vaccinated mice, be used to establish sensitive assays for complete remission (CR) prior to patient vaccination?

METHODS

  Chimeric vaccine molecules targeting patient Id to mouse major histocompatibility complex (MHC) class II molecules were genetically constructed for four patients with MM.

RESULTS

  DNA vaccination of mice with chimeric vaccines targeting patient Id to mouse MHC class II molecules elicited antibodies specific for the patient's myeloma protein. Targeting MHC class II greatly enhanced anti-Id responses. Mouse anti-Id antibodies were used to establish myeloma protein-specific enzyme-linked immunosorbent assays (ELISAs) that were between 75 and 1500 times more sensitive than conventional serum protein electrophoresis and immunofixation.

CONCLUSIONS

  These results pave the way for testing targeted DNA Id vaccines in patients in CR. Id- and patient-specific ELISA could be established affording evaluation of CR depth beyond current serological methods.

Vaccination with dendritic cell/tumor fusion cells results in cellular and humoral antitumor immune responses in patients with multiple myeloma

We have developed a tumor vaccine in which patient-derived myeloma cells are chemically fused with autologous dendritic cells (DCs) such that a broad spectrum of myeloma-associated antigens are presented in the context of DC-mediated costimulation. We have completed a phase 1 study in which patients with multiple myeloma underwent serial vaccination with the DC/multiple myeloma fusions in conjunction with granulocyte-macrophage colony-stimulating factor. DCs were generated from adherent mononuclear cells cultured with granulocyte-macrophage colony-stimulating factor, interleukin-4, and tumor necrosis factor-α and fused with myeloma cells obtained from marrow aspirates. Vaccine generation was successful in 17 of 18 patients. Successive cohorts were treated with 1 × 10(6), 2 × 10(6), and 4 × 10(6) fusion cells, respectively, with 10 patients treated at the highest dose level. Vaccination was well tolerated, without evidence of dose-limiting toxicity. Vaccination resulted in the expansion of circulating CD4 and CD8 lymphocytes reactive with autologous myeloma cells in 11 of 15 evaluable patients. Humoral responses were documented by SEREX (Serologic Analysis of Recombinant cDNA Expression Libraries) analysis. A majority of patients with advanced disease demonstrated disease stabilization, with 3 patients showing ongoing stable disease at 12, 25, and 41 months, respectively. Vaccination with DC/multiple myeloma fusions was feasible and well tolerated and resulted in antitumor immune responses and disease stabilization in a majority of patients.

Novel immunotherapies

Multiple myeloma is still a fatal disease. Despite advances in high-dose chemotherapy and stem-cell transplantation and the development of novel therapeutics, relapse of the underlying disease remains the primary cause of treatment failure. Strategies for posttransplantation immunomodulation are desirable for eradication of remaining tumor cells. To this end, immunotherapy aimed at inducing myeloma-specific immunity in patients has been explored. Idiotype protein, secreted by myeloma cells, has been the primary target for immunotherapy as it is the best defined tumor-specific antigen. This chapter focuses on novel immunotherapies that are being developed to treat patients with myeloma. I will discuss potential myeloma antigens, antigen-specific T cells, and their function on myeloma tumor cells, and T-cell-based and antibody-based immunotherapies for myeloma. Furthermore, clinical studies of T-cell-based immunotherapy in the form of vaccination, allogeneic stem-cell transplantation and donor lymphocyte infusions, with or without donor vaccination using patient-derived idiotype, and future application of donor-derived or patient-derived, antigen-specific T-cell infusion in this disease are also discussed. Based on the specificity of the immune effector molecules and cells, immunotherapies with specific T cells or therapeutic antibodies may represent novel strategies for the treatment of multiple myeloma in the near future.

Immunology and immunotherapeutic approaches in multiple myeloma

Immunotherapy for patients suffering from multiple myeloma is a lively and emerging field in cancer research. Immunotherapeutic approaches offer unique treatment opportunities for this, to date, mostly incurable disease. Respective basic findings and recent clinical approaches are introduced and discussed. Although several obstacles still need to be overcome, it appears that clinically efficient immunotherapies will become available for multiple myeloma patients in the future.

Drug-mediated and cellular immunotherapy in multiple myeloma

Multiple myeloma is an immunologically relevant disease, which subverts and suppresses immunity, but that may also be amenable to immunological control. Novel drug and cell-based therapies provide an opportunity for the design of antimyeloma immunotherapy. Reversing the immunosuppression associated myeloma remains a substantial challenge. The minimal residual disease setting achieved by autologous stem cell transplant or highly efficacious induction therapy may reverse this immunoparesis and provide a setting for induction of antimyeloma T-cell responses. Adoptive cytotoxic T-lymphocyte/NK therapy and comprehensive treatment with immunomodulatory drug therapy represent means by which antimyeloma immune responses may be promoted. In addition, apoptosis-inducing therapies may prime endogenous antigen presentation via immunogenic cell death, which again may be enhanced by the addition of immunomodulatory drug therapy.

Combination immunotherapy using adoptive T-cell transfer and tumor antigen vaccination on the basis of hTERT and survivin after ASCT for myeloma

In a phase 1/2 two-arm trial, 54 patients with myeloma received autografts followed by ex vivo anti-CD3/anti-CD28 costimulated autologous T cells at day 2 after transplantation. Study patients positive for human leukocyte antigen A2 (arm A, n = 28) also received pneumococcal conjugate vaccine immunizations before and after transplantation and a multipeptide tumor antigen vaccine derived from the human telomerase reverse transcriptase and the antiapoptotic protein survivin. Patients negative for human leukocyte antigen A2 (arm B, n = 26) received the pneumococcal conjugate vaccine only. Patients exhibited robust T-cell recoveries by day 14 with supraphysiologic T-cell counts accompanied by a sustained reduction in regulatory T cells. The median event-free survival (EFS) for all patients is 20 months (95% confidence interval, 14.6-24.7 months); the projected 3-year overall survival is 83%. A subset of patients in arm A (36%) developed immune responses to the tumor antigen vaccine by tetramer assays, but this cohort did not exhibit better EFS. Higher posttransplantation CD4(+) T-cell counts and a lower percentage of FOXP3(+) T cells were associated with improved EFS. Patients exhibited accelerated polyclonal immunoglobulin recovery compared with patients without T-cell transfers. Adoptive transfer of tumor antigen vaccine-primed and costimulated T cells leads to augmented and accelerated cellular and humoral immune reconstitution, including antitumor immunity, after autologous stem cell transplantation for myeloma. This study was registered at www.clinicaltrials.gov as NCT00499577.

Cancer dormancy: lessons from a B cell lymphoma and adenocarcinoma of the prostate

Cancer dormancy delineates a situation in which residual tumor cells persist in a patient with no apparent clinical symptoms. Although the precise mechanisms underlying cancer dormancy have not been explained, experimental models have provided some insights into the factors that might be involved in the induction and maintenance of a tumor dormant state. The authors of the present chapter studied a murine B cell lymphoma that can be made dormant when interacting with antibodies directed against the idiotype on its immunoglobulin Ig receptor. This experimental model of antibody-induced dormancy enabled the isolation and characterization of dormant lymphoma cells. The results indicated that anti-Ig antibodies activate growth-inhibiting signals that induced cycle arrest and apoptosis. This process appeared to be balanced by the growth of the tumor cells such that the tumor did not expand. In contrast, antibodies against HER-2expressed on prostate adenocarcinoma (PAC) cells were not growth inhibitory. However, an immunotoxin (IT) prepared by conjugating HER-2 to the A-chain of ricin (RTA) was internalized by PAC cells, followed by induction of cycle arrest and apoptotic death. Infusion of HER-2-specific IT into PAC-bearing immunodeficient mice did not eradicate the tumor but retained it dormant over an extended period of time. Hence, certain aspects of signaling receptors expressed on cancer can be manipulated by antibodies to induce and maintain a tumor dormant state.

Identification of HLA-A2 restricted T-cell epitopes within the conserved region of the immunoglobulin G heavy-chain in patients with multiple myeloma

OBJECTIVE

The aim of this study is the identification of HLA-A2 restricted T-cell epitopes in the conserved region of the immunoglobulin-G-heavy-chain (IgGH) that can be used for immunotherapy in multiple myeloma (MM) patients.

METHODS

After the IgGH gene sequence was scanned for HLA-A2 restricted T-cell epitopes with a high binding affinity to the MHC-I-complex, promising nona-peptides were synthesized. Peptide specific CD8+ T-cells were generated from peripheral blood mononuclear cells (PBMC) of healthy donors (HD) and patients with MM using peptide pulsed dendritic cells (DC) in vitro. The activation and cytotoxicity of CD8+ T-cells was analyzed by IFN-alpha ELISpot-assay and 51Chromium release-assay. HLA-A2 restriction was proven by blocking T-cell activation with anti-HLA-A2 antibodies.

RESULTS

Two HLA-A2 restricted T-cell epitopes-TLVTVSSAS derived from the IgGH-framework-region 4 (FR4) and LMISRTPEV from the constant region (CR)-induced expansion of specific CD8+ T-cells from PBMC in two of three (TLVTVSSAS) and one of three (LMISRTPEV) HD respectively. Specific T-cells were induced from PBMC in two of six (TLVTVSSAS) and eight of 19 (LMISRTPEV) patients with MM. Specific CD8+ T-cells also lysed peptide-pulsed target cells in 51Chromium release-assay. LMISRTPEV specific CD8+ T-cells from MM patients lysed specifically the HLA-A2+ IgG myeloma cell line XG-6.

CONCLUSION

We identified two HLA-A2 restricted T-cell epitopes-TLVTVSSAS and LMISRTPEV--which can yield an expansion of CD8+ T-cells with the ability to kill peptide-loaded target cells and HLA-A2+ IgG+ myeloma cells. We conclude that TLVTVSSAS and LMISRTPEV could be T-cell epitopes for immunotherapy in MM patients.

Phase I/II clinical trial of sequential subcutaneous and intravenous delivery of dendritic cell vaccination for refractory multiple myeloma using patient-specific tumour idiotype protein or idiotype (VDJ)-derived class I-restricted peptides

Fifteen multiple myeloma (MM) patients who had failed maintenance therapy after tandem autologous stem cell transplantation underwent anti-idiotype (Id) vaccination with dendritic cells (DCs). CD14(+)-derived DCs were loaded with the autologous Id as whole protein (=6) or Id-derived class I-restricted peptides (=9) and keyhole limpet hemocyanin (KLH). Vaccination consisted of three subcutaneous (sc) and two intravenous injections of increasing DC doses at 2 weeks interval. DC therapy was well tolerated. Most patients developed both humoral and T-cell responses to KLH, suggesting immunocompetence. Eight of 15 patients developed an Id-specific T-cell proliferative response, 8/15 increased interferon-gamma-secreting T cells and 4/15 showed an Id-positive delayed-type hypersensitivity test. Anti-Id cytotoxic T-lymphocyte precursors increased after DC vaccination in 2/2 evaluable patients. A more robust T-cell response was observed after sc DC injections and increased Id-specific T-cell proliferation was found up to 1 year after vaccination. VDJ-derived peptides were as effective as the whole protein in stimulating T-cell responses. Clinically, 7/15 patients have stable disease after a median follow-up of 26 months, one patient achieved durable partial remission after 40 months, and seven patients progressed. In conclusion, sc injections of cryopreserved Id-pulsed DCs were safe and, in contrast with intravenous administrations, induced anti-MM T-cell responses.

Polyclonal immunoglobulin E levels are correlated with hemoglobin values and overall survival in patients with multiple myeloma

PURPOSE

Polyclonal IgG, IgA, and IgM immunoglobulins are often decreased in sera of patients with multiple myeloma (MM), whereas very few data are available on polyclonal IgE levels. We have determined IgE levels in a large series of MM patients at diagnosis and subjects with monoclonal gammopathy of undetermined significance (MGUS) and correlated IgE levels with survival and prognostic factors in MM.

EXPERIMENTAL DESIGN

IgE were determined with a commercially available ELISA kit in 201 MM patients at diagnosis, 144 subjects with MGUS, and 77 age-matched controls.

RESULTS

IgE levels progressively decreased from controls to MGUS and from MGUS to MM (P = 0.001). MM patients with IgE levels of >11.5 IU/mL (median) had a better survival than patients with IgE of <11.5 IU/mL (P = 0.048). The difference was even more significant when MM patients were divided according to clinical cutoff values. Patients with elevated IgE levels (>100 IU/mL) had from 2 to 3 years longer survival than those with low (<10 IU/mL) or intermediate values (10-100 IU/mL; P < 0.01). IgE levels were positively and negatively correlated with hemoglobin (P = 0.006) and beta2-microglobulin levels (P = 0.007), respectively. Univariate and multivariate analyses confirmed that high IgE levels are positive predictors of overall survival (P = 0.03 and 0.08, respectively) and strongly correlated with hemoglobin values.

CONCLUSIONS

Because IgE levels are dependent on Th(2) responses, these data open new perspectives in the interpretation of antitumor immune responses and pathogenesis of anemia in MM.

Immune therapies

Immune cells with specific functions and abilities are vital to cancer treatment prevention. Although there have been many accomplishments made in the areas of immunotherapy and immunobiology of myeloma, there are still many obstacles in the way of conceptualizing the interrelationships between immune cells and tumor cells. To provide better understanding of these concepts and to move toward improved therapies for myeloma, cell-based therapeutic approaches should be developed.

Immunodeficiency and immunotherapy in multiple myeloma

Multiple myeloma is a malignant tumour of plasma cells that remains incurable for the vast majority of patients, with a median survival of 2-3 years. It is characterized by the patchy accumulation of tumour cells within bone marrow leading to variable anaemia, bone destruction, hypercalcaemia, renal failure and infections. Immune dysfunction is an important feature of the disease and leads to infections that are both a major cause of morbidity and mortality and may promote tumour growth and resistance to chemotherapy. Numerous defects of the immune system have been described in multiple myeloma although the relative clinical importance of these remains elusive. There has been considerable interest in the identification of an autologous response against myeloma. Although T cells and humoral responses directed against myeloma-associated antigens have been described, it is uncertain if the immune system plays a role in preventing or controlling myeloma cell growth. There is increasing interest in the potential role of immunotherapy but the success of these interventions is likely to be modified by the immunologically hostile environment associated with multiple myeloma. This review attempts to summarize the current knowledge relating to the immune defects found in multiple myeloma.

Novel approaches to immunotherapy for B-cell malignancies

Immunotherapy for cancer refers to a wide array of novel therapeutic interventions that harness the immune system to target and eradicate malignant cells in the host. Advances in the understanding of how tumor cells evade host immune detection, coupled with improved gene transduction technologies, have enabled investigators to propose and test novel immune-based therapies for B-cell malignancies. As a result, more immunogenic vaccination strategies, able to elicit immune responses to otherwise poorly immunogenic tumor antigens, are being tested in early clinical trials. Furthermore, with the development of efficient T-cell transduction methodologies, investigators are able to generate autologous antitumor T-cell responses through the introduction of chimeric antigen receptors able to target tumor antigens. However, whether the promising preclinical and phase I clinical data presented here will ultimately translate into improved survival of patients with B-cell malignancies remains largely unknown.

High-dose chemotherapy and autologous hematopoietic stem cell transplantation in myeloma patients under the age of 65 years

One or two cycles of high-dose chemotherapy with autologous hematopoietic stem cell transplantation have been shown to improve response rates and survival in myeloma. While this observation has largely been made in patients under the age of 65 years, there is evidence to suggest that the conclusions can be extrapolated to older individuals as well. In contrast to other hematologic malignancies treated with high-dose therapy, autografted myeloma patients continue to relapse several years after transplantation, and few patients are cured with this modality. However, up to a third of patients may be alive beyond a decade; some with excellent quality of life giving rise to the concept of 'operational cure'. Relapsing disease can be treated with novel agents or repeat high-dose chemotherapy and transplantation. The pressing questions to which answers are not obvious at the moment are whether tandem transplantation should be offered to all patients, and whether novel agents should be used before transplantation or reserved for relapse. Despite their excellent activity, there is no evidence so far that novel agents such as thalidomide, bortezomib and lenalidomide can replace high-dose chemotherapy and stem cell transplantation.

Anti-idiotype antibodies in cancer treatment

As a cancer immunotherapy tool, idiotypes (Ids) have been used in different ways over the last three decades, depending on the actual human tumor cell target. It all started with passive, monoclonal, anti-Id antibody treatment of B-cell lymphoma, a setting in which results were tantalizing, but logistics unsustainable. It then moved toward the development of anti-Id vaccines for the treatment of the same tumors, a setting in which we have recently provided the first formal proof of principle of clinical benefit associated with the use of a human cancer vaccine. Meanwhile, it also expanded in the direction of exploiting the antigenic mimicry of some Ids with Id-unrelated, tumor-associated antigens for the immunotherapy of a number of solid tumors, a setting in which clinical results are still far from being consolidated. All in all, over the years Id-based immunotherapy has paved the way for a number of seminal therapeutic improvements for cancer patients, including the development of most if not all Id-unrelated monoclonal antibodies that have recently revolutionized the field.

Cancer/testis genes in multiple myeloma: expression patterns and prognosis value determined by microarray analysis

Cancer-testis (CT) Ags are expressed in testis and malignant tumors but rarely in nongametogenic tissues. Due to this pattern, they represent attractive targets for cancer vaccination approaches. The aims of the present study are: 1) to assess the expression of CT genes on a pangenomic base in multiple myeloma (MM); 2) to assess the prognosis value of CT gene expression; and 3) to provide selection strategies for CT Ags in clinical vaccination trials. We report the expression pattern of CT genes in purified MM cells (MMC) of 64 patients with newly diagnosed MM and12 patients with monoclonal gammopathy of unknown significance, in normal plasma cell and B cell samples, and in 20 MMC lines. Of the 46 CT genes interrogated by the Affymetrix HG-U133 set arrays, 35 are expressed in the MMC of at least one patient. Of these, 25 are located on chromosome X. The expression of six CT genes is associated with a shorter event-free survival. The MMC of 98% of the patients express at least one CT gene, 86% at least two, and 70% at least three CT genes. By using a set of 10 CT genes including KM-HN-1, MAGE-C1, MAGE-A3/6/12, MAGE-A5, MORC, DDX43, SPACA3, SSX-4, GAGE-1-8, and MAGE-C2, a combination of at least three CT genes-desirable for circumventing tumor escape mechanisms-is obtained in the MMC of 67% of the patients. Provided that the immunogenicity of the products of these 10 CT genes is confirmed, gene expression profiling could be useful in identifying which CT Ags could be used to vaccinate a given patient.

NY-ESO-1 immunotherapy for multiple myeloma

Most patients with poor-prognosis myeloma (abnormal metaphase cytogenetics) achieve excellent responses with tandem transplants, but the remissions are not durable. Novel interventions such as immunotherapy may eradicate the residual chemotherapy-resistant disease. Immunotherapy targeting weak antigens such as myeloma idiotype or tumor lysate has failed to produce clinically meaningful responses. We previously reported that the NY-ESO-1 antigen is expressed in >60% of poor-prognosis myeloma at diagnosis. Since NY-ESO-1 is highly immunogenic and is not expressed in most normal tissues, it is an ideal target for anti-myeloma immunotherapy. NY-ESO-1 based therapies are already being tested in clinical trials for a multitude of tumors. This review discusses the potential of NY-ESO-1 immunotherapy to improve outcome for myeloma.

The immune system as a foundation for immunologic therapy and hematologic malignancies: a historical perspective

In this review we aim to provide a historical overview of the immunotherapeutic approaches which have been developed for the treatment of hematological malignancies. After briefly summarizing the development of the theory of cancer immune surveillance, we describe how initial studies discovering the efficacy of the immune-mediated graft-versus-tumor effects after allogeneic hematopoietic cell transplantation led to new transplantation approaches (termed non-myeloablative transplantation) relying almost exclusively on graft-versus-tumor effects for tumor eradication. We then summarize important steps in the development of tumor vaccines and autologous adoptive immunotherapy in patients with hematological malignancies. Finally, we describe historical discoveries leading to the recent success with monoclonal antibodies as treatment for lymphomas, chronic lymphocytic leukemia, and acute myeloid leukemia.

Clinical results of vaccine therapy for cancer: learning from history for improving the future

Active, specific immunotherapy for cancer holds the potential of providing an approach for treating cancers, which have not been controlled by conventional therapy, with very little or no associated toxicity. Despite advances in the understanding of the immunological basis of cancer vaccine therapy as well as technological progress, clinical effectiveness of this therapy has often been frustratingly unpredictable. Hundreds of preclinical and clinical studies have been performed addressing issues related to the generation of a therapeutic immune response against tumors and exploring a diverse array of antigens, immunological adjuvants, and delivery systems for vaccinating patients against cancer. In this chapter, we have summarized a number of clinical trials performed in various cancers with focus on the clinical outcome of vaccination therapy. We have also attempted to draw objective inferences from the published data that may influence the clinical effectiveness of vaccination approaches against cancer. Collectively the data indicate that vaccine therapy is safe, and no significant autoimmune reactions are observed even on long term follow-up. The design of clinical trials have not yet been optimized, but meaningful clinical effects have been seen in B-cell malignancies, lung, prostate, colorectal cancer, and melanoma. It is also obvious that patients with limited disease or in the adjuvant settings have benefited most from this targeted therapy approach. It is imperative that future studies focus on exploring the relationship between immune and clinical responses to establish whether immune monitoring could be a reliable surrogate marker for evaluating the clinical efficacy of cancer vaccines.

Active immunotherapy of multiple myeloma

Since myeloma cells express various potential target antigens, active immunotherapy is being investigated as a novel treatment modality for myeloma. Immunization against the clonal myeloma immunoglobulin (idiotype) elicits protective immunity in mouse models. Idiotype vaccination of myeloma patients can induce cellular immunity, albeit as yet without firm evidence for improved clinical outcome. Other tumour-associated antigens (including cancer/testis antigens) are expressed with various frequencies in myeloma. T cells with specificity for these antigens may exist in myeloma patients, and immunization trials with some of these antigens are ongoing. Future studies need to identify the best antigen, the optimal vaccine formulation and schedule, and the preferable clinical situation for vaccination with myeloma antigens. In addition, immunization of stem cell donors with myeloma antigens may improve the efficacy and outcome of allogeneic stem cell transplantation through transfer of idiotype-directed immunity to the patient, and has already shown promising clinical results.

Combined vaccination with idiotype-pulsed allogeneic dendritic cells and soluble protein idiotype for multiple myeloma patients relapsing after reduced-intensity conditioning allogeneic stem cell transplantation

BACKGROUND AND OBJECTIVE

To combine the use of idiotype-pulsed allogeneic dendritic cells (alloDC) and soluble protein Id conjugated with KLH (Id-KLH) in a vaccine strategy for multiple myeloma (MM).

DESIGN AND METHODS

Four MM patients received the combined vaccine after having experienced disease relapse/progression following reduced intensity conditioning (RIC) allogeneic stem cell transplantation (alloSCT) and failure to rescue therapy with donor lymphocyte infusion or chemotherapy (CHT).

RESULTS

Vaccination was well tolerated and induced an anti-KLH antibody response in all 4 patients as well as substantial cell proliferation. In contrast, no case showed similar effects against either tumor-specific Id or irrelevant isotype control immunoglobulins (Ig). In turn, vaccination was associated with modulation of biological responses linked to both inflammatory and T-cell activation, with secretion of effector Th1 cytokines. In particular, an important increase in the spontaneous ex vivo secretion of TNFalpha, IL-6 and IFNgamma as well as IL-2 and IL-10 was frequently observed prior to the fourth vaccination. Moreover, in vitro stimulation with Id-KLH and Id-KLH plus alloDC, but not with alloDC alone was associated with an enhanced number of TNF-alpha+ T-cells and an increased secretion of IFNgamma and IL-2 before the third and fourth vaccination. From a clinical standpoint, 2 patients had a transient response and 1 has stable disease after stopping vaccination, while 3 of them ultimately progressed.

INTERPRETATION AND CONCLUSIONS

The results show for the first time that the use of Id-pulsed alloDC following RIC alloSCT is safe and feasible. However, crucial strategy improvements are warranted to possibly achieve clinical benefit.

Identification of a new HLA-A2-restricted T-cell epitope within HM1.24 as immunotherapy target for multiple myeloma

OBJECTIVE

The aim of this study was identification of human leukocyte antigen (HLA)-A2-restricted T-cell epitopes within the HM1.24 antigen as target for multiple myeloma (MM)-directed specific peptide-based immunotherapy.

METHODS

The HM1.24 sequence was scanned for immunogenic peptides using the HLA-binding prediction software SYFPEITHI and BIMAS. Peripheral blood mononuclear cells from HLA-A2(+) healthy volunteers/blood donors (ND) were stimulated with autologous HM1.24-peptide-loaded dendritic cells, and expanded in vitro. Activation of T cells was assessed by ELISpot and cytotoxicity by (51)Chromium ((51)Cr)-release assays. T2-cells pulsed with irrelevant peptide, the HM1.24(-)/HLA-A2(+) breast carcinoma cell line MCF-7 and the HM1.24(+)/HLA-A2(-) myeloma cell line RPMI-8226 were used as controls. Expression of the HM1.24 gene (BST2) was assessed using purified plasma cells and Affymetrix-U133A+B microarrays. Frequency of peptide-specific CD8(+) T cells was detected using the flow-cytometric tetramer technique.

RESULTS

Of eight nona-peptides with the highest probability of binding to HLA-A2, the HM1.24 aa22-30 peptide (LLLGIGILV) showed the most frequent activation of CD8(+) T cells in healthy volunteers (specific activation in 8 of 11 [73%] ND; compared with 5-19% for the 7 other HM1.24 peptides). Antigen recognition by the HM1.24 aa22-30-specific CD8(+) T cells was HLA-A2-restricted (ELISpot with HLA-A2-blocking antibodies: median, 15; range, 14-18 spots/well; isotype-control antibodies: median, 47; range, 44-48). HM1.24-aa22-30-specific CD8(+) T cells lysed HLA-A2(+) myeloma-derived cell lines ((51)Cr-release assay: XG-1 vs MCF-7, 91% vs 0%; U266 vs MCF-7, 38% vs 4.2%; IM-9 vs RPMI-8226, 22% vs 0%). Using the cross-reactive Neisseria meningitidis peptide LLSLGIGILV-specific CD8(+) T cells recognizing target cells loaded with the HM1.24 aa22-30 peptide (LLLGIGILV) as well as the myeloma-derived cell line U266 could be expanded from MM patients. The HM1.24 gene was expressed at comparable levels by plasma cells from 65 MM patients, 7 patients with monoclonal gammopathy of undetermined significance, and 7 ND.

CONCLUSIONS

HM1.24 aa22-30 is a newly identified HLA-A2-restricted T-cell epitope that is processed and presented by major histocompatibility complex class I. Specifically activated CD8(+) T cells are able to lyse MM cell lines. We conclude that HM1.24 aa22-30 represents a suitable candidate target for a specific peptide-based immunotherapy of MM.

Immunity for tumors and microbes after autotransplantation: if you build it, they will (not) come

Relapses after autologous stem cell transplants for hematopoietic malignancies are frequent and post-transplant infections continue to cause significant post-transplant morbidity and even mortality. The post-transplant period is typically characterized by low lymphocyte counts and impaired immune cell function. Early restoration of immune function may contribute to better disease control and enhance protection from infections. Indeed the attainment of a 'minimal residual disease' status following high-dose therapy makes the early post-transplant period ideal for the introduction of antitumor immunotherapy. Attempts to generate immunity against tumor and microbial antigens after autotransplantation have included vaccinations, T cell infusions (both resting and activated) and combinations of vaccinations and adoptive T cell infusions. One successful strategy for generating robust immune responses against microbial antigens was the combination of pre and post-transplant immunizations along with an early (post-transplant) infusion of in vivo vaccine-primed and ex vivo co-stimulated autologous T cells. Whether this or similar strategies will lead to the generation of effective antitumor immunity is unknown. The lessons gained from efforts to rebuild immune system function in the setting of autotransplantation may also be applicable to the problem of restoring immunity in other immunodeficient groups such as patients with cancer or HIV disease and the elderly.

Vaccine strategies to treat lymphoproliferative disorders

Lymphoproliferative disorders, including follicular lymphoma (FL), multiple myeloma (MM) and chronic lymphatic leukaemia (CLL), are slowly progressive malignancies which remain incurable despite advances in therapy. Harnessing the immune system to recognise and destroy tumours is a promising new approach to treating these diseases. Dendritic cells (DC) are unique antigen-presenting cells that play a central role in the initiation and direction of immune responses. DC loaded ex vivo with tumour-associated antigens and administered as a vaccine have already shown promise in early clinical trials for a number of lymphoproliferative disorders, but the need for improvement is widely agreed. Recent advances in the understanding of basic DC biology and lessons from early clinical trials have provided exciting new insights into the generation of anti-tumour immune responses and the design of vaccine strategies. In this review we provide an overview of our current understanding of DC biology and their function in patients with lymphoproliferative disorders. We discuss the current status of clinical trials and new approaches to exploit the antigen presenting capacity of DC to design vaccines of the future.

Immunotherapy in multiple myeloma - possibility or probability?

In a small number of patients with multiple myeloma (MM), long-term disease-free survival has been achieved by harnessing the immune phenomenon, 'graft-versus-tumour' effect, induced by allogeneic haemopoietic stem cell transplantation. This has prompted many investigators to examine ways in which a patient's own immune system can be more effectively directed against their disease, with the ultimate aim of tumour eradication. In this review we assess the current understanding of immunobiology in MM, and how the different components of the immune system, such as dendritic cells, T cells and natural killer cells, may be harnessed using in-vitro and in-vivo priming techniques. We look at the clinical immunotherapy trials reported to date and whether, in light of the current information, immunotherapy for MM is an achievable goal.

Effector gammadelta T cells and tumor cells as immune targets of zoledronic acid in multiple myeloma

The aim of this study was to investigate the in vitro immunomodulatory effects of zoledronic acid (Zol) on peripheral blood Vgamma9/Vdelta2 (gammadelta) T cells of normal donors and multiple myeloma (MM) patients. gammadelta T cells were stimulated with Zol and low doses of interleukin-2 (IL-2), and then analyzed for proliferation, cytokine production, and generation of effector activity against myeloma cell lines and primary myeloma cells. Proliferation of gammadelta T cells was observed in 100% of normal donors and 50% of MM patients. gammadelta T cells produced IFN-gamma, surface mobilized the CD107a and CD107b antigens, and exerted direct cell-to-cell antimyeloma activity irrespective of the ability to proliferate to Zol and IL-2. The memory phenotype was predominant in the MM gammadelta T cells that proliferated in response to Zol (responders), whereas effector cells were predominant in those that did not (nonresponders). Zol induced antimyeloma activity through the monocyte-dependent activation of gammadelta T cells and by enhancing the immunosensitivity of myeloma cells to gammadelta T cells. Mevastatin, a specific inhibitor of hydroxy-methylglutaryl-CoA reductase, completely abrogated this antimyeloma activity.

Exposure to myeloma cell lysates affects the immune competence of dendritic cells and favors the induction of Tr1-like regulatory T?cells

The aim of this work was to investigate the interactions of tumor cells with dendritic cells (DC) in normal donors and patients with multiple myeloma (MM). Normal and MM DC internalized necrotic lysates derived from myeloma cell lines (MCL) with high efficiency, whereas necrotic lysates from primary myeloma cells (PMC) were internalized with significantly lower efficiency. A positive correlation was found between susceptibility to internalization and the ability to induce DC maturation. After PMC exposure, DC produced large amounts of IL-10 and measurable amounts of IL-4 but no detectable IL-12. Two rounds of exposure to PMC-treated DC generated autologous T cells with low proliferative capacity, decreased IFN-gamma production and increased IL-10 production in the absence of IL-4 production. These data indicate that myeloma cells can affect host immunity by priming DC towards a maturation state favoring the generation of T cells with a regulatory rather than an effector phenotype.

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.

The role of idiotype vaccines in the treatment of human B-cell malignancies

Twelve years after the first formal demonstration that it is possible to vaccinate a cancer patient against an antigen derived from his/her own tumor, idiotype vaccines are now well into Phase III clinical trials for the treatment of follicular lymphoma. Meanwhile, their potential has also begun to be explored in other non-Hodgkin's lymphoma settings, such as that of mantle cell lymphoma. Another well known field of potential application for idiotype vaccines is that of multiple myeloma. However, the currently available results, even with the advent of dendritic cells, seem to be less promising than those obtained in lymphoma, to such an extent that idiotype vaccines are currently tested in multiple myeloma patients in the context of more aggressive therapeutic strategies.