A pilot study of idiotypic vaccination for follicular B-cell lymphoma using a genetic approach. CRC NO: 92/33. Protocol NO: PH1/027

Lymphoma Immunotherapy: Current Status

The rationale to treat lymphomas with immunotherapy comes from long-standing evidence on their distinctive immune responsiveness. Indolent B-cell non-Hodgkin lymphomas, in particular, establish key interactions with the immune microenvironment to ensure prosurvival signals and prevent antitumor immune activation. However, reports of spontaneous regressions indicate that, under certain circumstances, patients develop therapeutic antitumor immunity. Several immunotherapeutic approaches have been thus developed to boost these effects in all patients. To date, targeting CD20 on malignant B cells with the antibody rituximab has been the most clinically effective strategy. However, relapse and resistance prevent to cure approximately half of B-NHL patients, underscoring the need of more effective therapies. The recognition of B-cell receptor variable regions as B-NHL unique antigens promoted the development of specific vaccines to immunize patients against their own tumor. Despite initial promising results, this strategy has not yet demonstrated a sufficient clinical benefit to reach the regulatory approval. Several novel agents are now available to stimulate immune effector functions or counteract immunosuppressive mechanisms, such as engineered antitumor T cells, co-stimulatory receptor agonist, and immune checkpoint-blocking antibodies. Thus, multiple elements can now be exploited in more effective combinations to break the barriers for the induction of anti-lymphoma immunity.

Current advances, problems and prospects for vaccine-based immunotherapy in follicular non-Hodgkin's lymphoma

Despite advances in chemotherapy, radiotherapy and combined modality treatment, a significant proportion of non-Hodgkin's lymphomas remain incurable. The disease usually responds well to chemotherapy or radiation, but relapses are observed within months to a few years, with frequent failure of subsequent therapies. High-dose chemotherapy with or without radiation and autologous or allogeneic hematopoietic stem cell transplantation provide higher cure rates and longer remissions in certain patients with aggressive lymphomas. However, the higher treatment-related morbidity and mortality of high-dose chemotherapy has driven a search for new and more tumor-specific treatment modalities, such as immunotherapy. Tumor antigens expressed by B-cell lymphomas, such as the "idiotype antigen", are seen as unique and specific target molecules for direct lymphoma immunotherapy. This review will delineate advances, problems and prospects for approaches to anti-B cell lymphoma immunotherapy where pre-clinical studies and proof of principle have been directly translated to patient care.

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.

Current status of therapeutic vaccines for non-Hodgkin's lymphoma

PURPOSE OF REVIEW

Therapeutic vaccines targeting B cell lymphoma idiotype have reached an advanced stage of clinical development, with three multicenter randomized clinical trials ongoing. This review describes the rationale and development of this immunotherapeutic approach, the design of current phase III trials, and other active vaccination approaches likely to move forward into clinical testing for lymphomas.

RECENT FINDINGS

Several groups have achieved promising results in phase II trials of patient-specific idiotype vaccines, with very few side effects noted. Anti-idiotype antibodies, in addition to cytotoxic T cells, are now believed to be important effectors of antitumor immunity after idiotype vaccination. The manufacturing of autologous tumor idiotype proteins is being rapidly refined by the use of molecular technologies. Two trials involving more than 1000 patients are now under way, which use idiotype vaccination after induction chemotherapy; one trial completed accrual in early 2004. A third trial opened in 2004, using rituximab followed by idiotype vaccine with maintenance booster vaccines continuing throughout the period of normal B cell recovery. In accordance with the United States Food and Drug Administration, progression-free survival serves as the accepted primary efficacy endpoint in these studies.

SUMMARY

Lymphoma idiotype vaccination represents a promising immunotherapeutic approach targeting a patient-specific tumor antigen. The results of pivotal phase III trials for three first-generation idiotype vaccines will become available in the next several years. Advanced manufacturing techniques should permit application of this tailor-made treatment to large numbers of non-Hodgkin's lymphoma patients.

Variations in "rescuability" of immunoglobulin molecules from different forms of human lymphoma: implications for anti-idiotype vaccine development

Idiotypic (Id) vaccination has shown promising results in patients with follicular lymphoma (FL). However, it still remains unclear whether the same approach might be suitable for the treatment of other B-cell malignancies. For this reason, we recently performed an interim analysis of patients proposed to receive this treatment at our center. The feasibility of employing idiotype vaccines was evaluated for five different B-cell malignancies in their first relapse, both in terms of induction and fusion, as well as overall treatment. Our data suggest that, unlike follicular lymphoma (87%), this approach is not feasible to treat other B-cell malignancies (0-20%) such as mantle cell, small lymphocytic, diffuse large cell and Burkitt's lymphoma (P < 0.01). The main difficulties encountered were technical problems related to the survival of idiotype-producing hybridomas (83%) and the early loss of idiotype production by growing hybridomas (17%). However, it remains possible that an idiotype vaccine might still be produced through molecular means for most, if not all cases of relapsing B-cell malignancies.

Toward Personalized Immunotherapy for Non-Hodgkin Lymphoma

The idiotypic determinants of B-cell lymphomas, formed by cell-specific rearrangement of the immunoglobulin genes, are unique and are therefore a suitable target against which to direct immunotherapy. Recent advances in our understanding of the fundamental mechanisms behind an effective immune response, coupled with advances in genetic engineering techniques, have led to a renewed interest in immunotherapy. Early clinical studies have confirmed the immunogenicity of the idiotypic antigen in patients with lymphoma. This review discusses the different methods of idiotypic vaccination currently under investigation in the clinic, including protein, genetic, and cellular vaccines. Protein vaccines are the most clinically advanced, with phase III trials of idiotypic protein linked to GM-CSF currently underway. DNA vaccines are easier to produce but to date only appear to be weakly immunogenic in man. Dendritic cell vaccines have shown promise but their use may be limited by the complexity of this approach. This review also highlights other approaches not yet in the clinic but that have shown promise in the laboratory, such as viral vaccines and T-cell therapy.

CD4+ T cells kill Id+ B-lymphoma cells: FasLigand-Fas interaction is dominant in vitro but is redundant in vivo

B-lymphoma cells express a highly tumor-specific antigen, monoclonal Ig, which is a promising target for immunotherapy. Previous work has demonstrated that B-lymphoma cells spontaneously process their endogenous monoclonal Ig and present variable (V) region peptides (Id-peptides) on their MHC class II molecules to CD4+ T cells. Id-specific CD4+ T cells protect mice against B-lymphoma cells in the absence of antiidiotypic antibodies. The molecular mechanism by which Id-specific CD4+ T cells kill B-lymphoma cells is hitherto unknown. We here demonstrate in an Id-specific T-cell receptor (TCR)-transgenic mouse model that Id-specific CD4+ T cells induce apoptosis of Fas+ B-lymphoma cells in vitro by FasLigand (FasL)-Fas interaction. Moreover, the rare B lymphomas that had escaped rejection in TCR-transgenic mice had down-regulated their sensitivity to Fas-mediated apoptosis. Although these results suggest that FasL-Fas interaction is important, Id-specific CD4+ T cells could eliminate Id+ B-lymphoma cells in vivo by other mechanisms, since three independent ways of blocking FasL-Fas-mediated killing failed to abrogate tumor protection in TCR-transgenic mice. These results suggest that there are several redundant pathways by which Id-specific CD4+ T cells eliminate Id+ B-lymphoma cells in vivo, of which FasL-Fas interaction is only one.

Vaccine and antibody-directed T cell tumour immunotherapy

Clearer evidence for immune surveillance in malignancy and the identification of many new tumour-associated antigens (TAAs) have driven novel vaccine and antibody-targeted responses for therapy in cancer. The exploitation of active immunisation may be particularly favourable for TAA where tolerance is incomplete but passive immunisation may offer an additional strategy where the immune repertoire is affected by either tolerance or immune suppression. This review will consider how to utilise both active and passive types of therapy delivered by T cells in the context of the failure of tumour-specific immunity by presenting cancer patients. This article will outline the progress, problems and prospects of several different vaccine and antibody-targeted approaches for immunotherapy of cancer where proof of principle pre-clinical studies have been or will soon be translated into the clinic. Two examples of vaccination-based therapies where both T cell- and antibody-mediated anti-tumour responses are likely to be relevant and two examples of oncofoetal antigen-specific antibody-directed T cell therapies are described in the following sections: (1) therapeutic vaccination against human papillomavirus (HPV) antigens in cervical neoplasia; (2) B cell lymphoma vaccines including against immunoglobulin idiotype; (3) oncofoetal antigens as tumour targets for redirecting T cells with antibody strategies.

New approaches to hematopoietic cell transplantation in oncology

The use of high-dose chemotherapy followed by autologous HCT and the use of allogeneic HCT in children and adolescents with high-risk ALL, AML, and NBL has successfully improved outcomes. For other diseases, however, the role of HCT in treatment remains a subject of further research. The availability of HCT was significantly expanded by developing alternative graft sources that currently include BM, peripheral blood, and UCB from autologous and allogeneic related or unrelated donors. Progress in autologous HCT has been achieved by the identification of more effective and less toxic preparative regimens and by ex vivo purging of stem cell products. In allogeneic HCT, graft-versus-leukemia or graft-versus-tumor effects are being exploited increasingly to lower relapse rates. In addition, immunomodulation to promote tolerance, as well as allogeneic antitumor reactions have been achieved by antibody therapy, cytokine therapy, or cell-based immunotherapy. Future improvements are likely, as evidenced by promising preliminary results in the development of stem cell collection techniques, in vitro stem cell expansion, and purging techniques of stem cell grafts. The development of less intensive or nonmyeloablative preparative regimens may further reduce regimen-related morbidity and mortality Specific immunotherapy may facilitate tolerance induction in mismatched allogeneic HCT and support allogeneic HCT in the setting of donor-host HLA disparity. Ultimately, advances in cytokine therapy, tumor-specific vaccines, and gene therapy may decrease or even eradicate recurrence of the malignant disease after HCT.

Cancer vaccines and immunotherapy

It is now clear that many human tumour antigens can be recognised by the immune system. These tumour antigens can be classified into several groups including cancer-testis, differentiation, tissue specific, over-expressed, and viral-associated antigens. In many cases, there is a known molecular basis of carcinogenesis which provides the explanation for the differentiated expression of these antigens in tumours compared with normal cells. Improved understanding of the biology of the immune response, particularly of immune recognition and activation of T-cells, allow better design of vaccines. Pre-clinical comparative studies allow evaluation of optimal vaccine strategies which can then be delivered to the clinic. Currently, a range of cancer vaccines are being tested including those using tumour cells, proteins, peptides, viral vectors, DNA or dendritic cells. Ultimately, this research should give rise to an entirely new modality of cancer treatments.

DNA fusion vaccines against B-cell tumors

DNA vaccination is currently being explored as a potential strategy for combatting cancer. However, tumor antigens are often weak and the immune system of patients may be compromised. For B-cell tumors, immunoglobulin idiotypic antigens provide defined targets but are poorly immunogenic. Fusion of a sequence derived from tetanus toxin to the genes encoding idiotypic determinants has proved highly effective in activating protective anti-tumor immunity. DNA fusion vaccines containing immuno-enhancing sequences can augment and direct immune attack on a range of target antigens. Gene-based fusion vaccines offer ease of manipulation and flexible design to activate effective attack on cancer.

Vaccines in oncology: background and clinical potential

Cancer is one of the leading causes of death in Western society. Despite improvements in screening, diagnosis and treatment of cancer, many patients ultimately succumb to their disease. Advances in molecular biology and our increased understanding of how the immune system functions have led to an intense interest in the development of cancer vaccines.

Gene therapy approaches for multiple myeloma

Several different myeloma gene therapy approaches are currently being explored, seeking to impact on the disease process in diverse ways. Therapeutic benefit may result from destroying the myeloma cells directly, provoking an antimyeloma cell immune response, interfering with the paracrine growth signaling pathways between osteoclasts and myeloma cells, or genetically manipulating hematopoietic progenitors or mature T cells in a stem cell transplantation setting. Encouraging progress in each of these areas is being fueled by the development of improved viral and nonviral gene transfer vectors.

Anti-idiotype vaccines for human follicular lymphoma

Cancer vaccines are conceived as therapeutic tools, in contrast to the prophylactic vaccines that have resolved the problem of a number of infectious diseases in a highly cost-effective way. Over the last decade, anti-idiotype vaccines for human follicular lymphoma have started to come into their own. Whereas 10 years ago it was not even known whether patients could be immunized against an antigen of their own tumor, a phase III clinical trial based on this finding is now already underway. The rapidity of this development encourages the hope that active immunotherapy may become decisive in oncology sooner than expected. Many important results have already been achieved. These include evidence of vaccine-induced, tumor-specific humoral and cellular responses along with the first documented molecular remissions following vaccination. Crucial questions still awaiting an answer include: do Id vaccines actually cure at least a fraction of FL patients? What is the most effective vaccine formulation? Is it possible to reduce the workload involved in producing an effective Id vaccine?

Adoptive immunotherapy for leukemia: donor lymphocytes transduced with the herpes simplex thymidine kinase gene

The overall goal of adoptive immunotherapy with genetically modified lymphocytes is to decrease the morbidity and mortality associated with allogeneic bone marrow transplantation. The initial data reviewed here suggest that the behavior of the allogeneic HStk transgenic cells can be modified after administration to patients. Further study is needed to identify the response rates and risks associated with this procedure. In particular, larger studies will be needed with appropriate randomization to determine if the response rate to genetically modified cells is equivalent to the response rates with unmodified cells. Wider application of these techniques in the initial setting of allogeneic transplantation will undoubtedly occur and such trials have been initiated at several institutions. Careful attention to vector, suicide gene, selectable marker, efficiency of transduction, and cell dose will be necessary when comparing different trials since these variables will probably affect transgenic cell survival and response rates. [figure: see text]

Nucleic acid immunization: concepts and techniques associated with third generation vaccines

A radical change in vaccine methodology arrived nine years ago with the advent of nucleic acid immunization. Aspects such as plasmid design, gene selection, the use of immunostimulatory complexes and clinical trials are discussed in this review. Furthermore, concepts and protocols involved in the construction, evaluation and immunization of a DNA vaccine have been examined as new strategies to enhance this technology continues to grow.

DNA vaccines with single-chain Fv fused to fragment C of tetanus toxin induce protective immunity against lymphoma and myeloma

Vaccination with idiotypic protein protects against B-cell lymphoma, mainly through anti-idiotypic antibody. For use in patients, DNA vaccines containing single-chain Fv derived from tumor provide a convenient alternative vaccine delivery system. However, single-chain Fv sequence alone induces low anti-idiotypic response and poor protection against lymphoma. Fusion of the gene encoding fragment C of tetanus toxin to single-chain Fv substantially promotes the anti-idiotypic response and induces strong protection against B-cell lymphoma. The same fusion design also induces protective immunity against a surface Ig-negative myeloma. These findings indicate that fusion to a pathogen sequence allows a tumor antigen to engage diverse immune mechanisms that suppress growth. This fusion design has the added advantage of overcoming potential tolerance to tumor that may exist in patients.