Immunogenicity and cross-reactivity with idiotypic IgA of VH CDR3 peptide in multiple myeloma

The multi-faceted potential of CD38 antibody targeting in multiple myeloma

CD38, an adenine dinucleotide phosphate (ADP) ribose cyclase and a cyclic ADP ribose hydrolase, is widely expressed on the surface of multiple myeloma (MM) cells. It is known to play a pivotal role in the downstream pathways that mediate MM cell growth, signal transduction, and adhesion. The clinical use of CD38 monoclonal antibodies (MoAbs), such as daratumumab, either as monotherapy or in combination with other anti-MM agents, has produced impressive results in patients who have failed standard MM therapy. CD38 MoAbs exhibit several cytotoxic mechanisms on MM cells. In addition to the classical effector mechanisms associated with antibody therapy, CD38 MoAbs induce MM apoptosis and clonal T-cell expansion. Here, we summarize the results of some pivotal clinical studies using a human CD38 MoAb, daratumumab, in patients with MM, discuss the anti-MM effector mechanisms induced by CD38 MoAbs, and review the potential tumor antigens that may be suitable targets for immunotherapy of MM. Finally, we present a paradigm of immunotherapy for MM patients using CD38 MoAbs followed by GM-CSF and an immune checkpoint inhibitor in patients who have undergone high dose chemotherapy and autologous stem cell transplant. CD38 MoAbs have emerged as a novel and ultimately very promising immunotherapeutic agent for MM because of its ability to induce MM cytotoxicity through both arms of the adaptive immune responses.

Targeting human B-cell malignancies through Ig light chain-specific cytotoxic T lymphocytes

PURPOSE

The variable regions of Ig (idiotype, Id) expressed by malignant B cells can be used as tumor-specific antigens that induce humoral and cellular immunity. However, epitopes derived from Id that stimulate human CD8(+) T-cell immunity are incompletely characterized.

EXPERIMENTAL DESIGN

The clonal Ig V(L) of human myeloma cell line U266 and five primary B-cell tumors were sequenced, and peptides corresponding to the Ig V(L) region were tested for their ability to stimulate CTLs from 10 HLA-A*0201-positive normal donors. The CTLs thus generated were tested against peptide-pulsed T2 cells and autologous tumor cells.

RESULTS

Fourteen peptides derived from Ig light chain (V(L)) of U266 and primary B-cell tumors were used to generate 68 CTLs lines that specifically produced IFN-γ when cocultured with peptide-pulsed T2 cells. These CTLs lysed peptide-pulsed T2 cell as well as U266 or autologous tumor targets in an HLA class I-dependent manner. Sequence analysis revealed shared V(L) T-cell epitopes in U266 and primary B-cell tumors, not previously reported within Ig heavy chain (V(H)) sequences.

CONCLUSION

This study thus identifies novel immunogenic CTLs epitopes from Id V(L), suggests that they are naturally presented on the surface of B-cell malignancies, and supports their inclusion in next-generation Id vaccines. The ability to prime T cells derived from normal HLA-matched donors, rather than patients, may also have direct application to current strategies, designed to generate allogeneic tumor-specific T cells for adoptive transfer.

Dendritic cells and malignant plasma cells: an alliance in multiple myeloma tumor progression?

The crosstalk of myeloma cells with accessory cells drives the expansion of malignant plasma cell clones and the hyperactivation of osteoclastogenesis that occurs in multiple myeloma (MM). These reciprocal interactions promote defective dendritic cell (DC) function in terms of antigen processing, clearance of tumor cells, and efficacy of the immune response. Thus, myeloma cells exert immune suppression that explains, at least in part, the failure of therapeutic approaches, including DC vaccination. Impairment of DCs depends on high bone marrow levels of cytokines and adhesion molecules that affect both maturation and expression of costimulatory molecules by DCs. Moreover, DCs share with osteoclasts (OCs) a common ontogenetic derivation from the monocyte lineage, and thus may undergo OC-like transdifferentiation both in vitro and in vivo. Immature DCs (iDCs) induce clonogenic growth of malignant plasma cells while displaying OC-like features, including the ability to resorb bone tissue once cultured with myeloma cells. This OC-like transdifferentiation of iDCs is dependent on the activation of both the receptor activator of nuclear factor κB (RANK)-RANK ligand (RANK-L) and CD47-thrombospondin (TSP)-I axes, although interleukin 17-producing T helper-17 clones within the bone microenvironment may also take part in this function. Therefore, iDCs allied with malignant plasma cells contribute to MM osteoclastogenesis, although other molecules released by tumor cells may independently contribute to the bone-resorbing machinery.

Prediction of High Affinity Class I-restricted Multiple Myeloma Idiotype Peptide Epitopes

Idiotypic determinants are potential patient-specific tumor antigens in multiple myeloma (MM). In this study, we have determined the DNA sequence of the variable region of the tumor immunoglobulin (Ig) in 6 patients with MM. We then selected high affinity class I-restricted T-cell peptide epitopes in tumor Ig using two different internet-based epitope prediction programs. High affinity binding peptides were identified by at least one program in 4 out of 6 patients. Of these 35 peptides, only 3 scored high by both analyses. Given that all 6 patients had expanded T-cell clones with a cytotoxic (CD57+CD8+CD28-perforin+) phenotype, known to be associated with a longer survival and postulated to recognise tumor epitopes, this analysis indicates that such clones are unlikely to be exclusively directed towards tumor immuoglobulin, and suggests the need to expand the scope of the search for tumor epitopes with the ability to stimulate cytotoxic T cells in vivo.

Improved Therapeutic Outcome Following Combination Immunogene Vaccination Therapy in Murine Myeloma

Increasing evidence suggests a role for immunologic vaccination and therapy in the management of minimal residual myeloma. We have previously demonstrated a synergistic effect of combining the Th1 stimulating cytokine IL-12 with the co-stimulatory molecule CD80 in murine myeloma vaccination therapy. We reasoned that the efficacy of such treatment might be further improved by incorporating additional gene products which enhance the function of antigen presenting cells. Studies were therefore conducted with murine myeloma BM1 cells expressing Flt3L (membrane bound or soluble forms) or GM-CSF and the IL-12 x CD80 combination. Single agent and combined therapeutic approaches were explored. All gene-modified BM1 cells, except BM1/IL-12 x CD80, developed tumors when subcutaneously injected into BALB/c mice. As prophylactic tumor vaccines, the combined use of gene-modified BM1/sFlt3L+GM-CSF+IL-12 x CD80 was most effective, providing 100% protection against subsequent parental BM1 tumor challenge. By comparison, only partial protection was observed with any single gene-engineered tumor vaccine. Notably, IL-12 x CD80 coexpressing BM1 cell vaccines were the most effective therapeutic vaccine in a minimal disease model. Such protective vaccination was achieved by stimulation of lymphocyte proliferation and enhancement of cytotoxic lymphocyte activity.

Dendritic Cells and their Potential Therapeutic Role in Haematological Malignancy

The generation of an effective immune response is dependent on the efficient capture and presentation of antigen by antigen-presenting cells. The most potent antigen-presenting cells are dendritic cells (DC). These cells have the capability of activating naive helper and cytotoxic T cells. In recent years it has been demonstrated that in vivo responses to a number of solid tumours can be generated by DC pulsed with either purified tumour antigen or whole tumour cell lysate. In addition, a number of in vivo studies using DC have also been attempted in solid tumours, with some encouraging results. In haematological malignancies, there is now strong evidence that previous T cell anergy can be reversed and significant anti-tumour immune responses generated, in vitro, against the majority of leukaemias. As far as in vivo studies in haematological malignancies are concerned, although T cell responses have been demonstrated in the majority of cases and some dramatic early clinical responses reported, overall results appear disappointing. However, considering the fact that many of these studies were performed in patients with advanced disease and that such therapeutic strategies are still in their infancy, the overall results are actually quite encouraging. Although there is a real potential for DC immunotherapy in the future, it is important to be realistic about the limitations and obstacles to its development. It is highly unlikely that any form of immunotherapy is going to be effective in advanced disease due to the physical bulk of tumour, the immunosuppressive effects of tumours themselves and to any secondary immunosuppression following standard cancer therapy. The potential for immunotherapy is likely to lie either in adjunctive therapy or for treating minimal residual disease. Even in those situations, one of the major obstacles to be overcome is the state of immunological anergy or tolerance that many tumours seem able to induce. Indeed, there is evidence that, under certain circumstances, DC themselves can present antigen in such a way as to produce this state of anergy. Although, in vitro manipulation of DC and T cells can generate tumour-specific T cells from previously "anergic" cells, once reintroduced in vivo, these cells will be re-exposed to the tumour environment with the risk of being rendered anergic again.

Clonal Cytotoxic T Cells in Myeloma

Multiple myeloma (MM) is a malignant disease characterized by accumulation of morphologically recognizable plasma cells producing immunoglobulin (Ig) in the bone marrow. The occurrence of clonal T cells in MM, as defined by the presence of rearrangements in the T-cell receptor (TCR)-beta chains detected on Southern blotting, is associated with an improved prognosis. This review aims to describe the various ways in which we have demonstrated the presence of such T cell clones, and to describe the phenotype of these cells. Finally, the specificities of these clinically important CD8+ T cell populations will be discussed in the context of immunotherapy.

Dendritic cell-based therapeutic vaccination against myeloma: vaccine formulation determines efficacy against light chain myeloma

Multiple myeloma is an incurable plasma cell malignancy. Immunotherapy in myeloma patients had limited success to date. We have previously demonstrated that dendritic cells (DCs) pulsed with autologous Ig Id induced Id-reactive CD8(+) T cells and protection against a myeloma tumor challenge. In this work, we studied the therapeutic efficacy of chemotherapy combined with different formulations of DC-based vaccines in mice bearing large plasma cell tumors. The comparative study demonstrated that s.c. injection of DCs loaded with Id coupled to keyhole limpet hemocyanin, s.c. injection of DCs loaded with irradiated tumor cells, and intratumoral injection of naive DCs were similarly effective in mediating tumor regression and long-term survival. However, whereas the Id-keyhole limpet hemocyanin-DC vaccine was inefficient against myeloma cells that lost expression of the Ig H chain, intratumoral injection of naive DCs and s.c. injection of DCs loaded with irradiated tumor cells were highly effective against cells producing L chains only. This may be of particular importance for patients with L chain myeloma. Given that T cells respond primarily to peptides derived from H chain CDRs, attempts to treat L chain disease with myeloma protein-pulsed DCs may be futile. Vaccination with tumor cell-loaded DCs may, however, induce an effective antitumor response.

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.

Dendritic cell-based immunotherapy in multiple myeloma

Most patients with multiple myeloma (MM) cannot be cured with currently available therapies. Although complete remission could be achieved in about 50% of newly diagnosed patients with high-dose chemotherapy and tandem transplantation, relapses of the underlying disease occur frequently. To realize long-term disease-free survival, it will be necessary to develop complementary therapies that are non-cross-resistant with chemotherapy. To this end, immunotherapy aimed at inducing or enhancing tumor-specific immunity that may control or eradicate remaining tumor cells may be an appealing method. Dendritic cells (DCs) are professional antigen-presenting cells and considered the best natural adjuvants for immunotherapy in malignancies. Vaccination with tumor antigen-pulsed DCs has been shown to be protective and therapeutic in animal tumor models, and induced a strong tumor-specific immunity and durable tumor regression in human solid tumors and B-cell lymphoma. As a result, clinical trials in various human malignancies have been initiated. This review will focus on DC-based immunotherapy in MM. I will discuss myeloma antigens and antigen-specific immune responses, the capacity of DCs to present myeloma antigens and induce cytotoxic T-cell responses, and clinical experience of DC vaccination in myeloma patients.

Autologous lymphoma vaccines induce human T cell responses against multiple, unique epitopes

The clonotypic surface Ig receptor expressed by malignant B cells, idiotype, is a tumor-specific antigen and an attractive target for active immunotherapy. While Ab's specific for tumor idiotype have been well described in patients with B cell malignancies, the precise antigenic epitopes in human idiotype recognized by autologous T cells remain largely unknown. We report here that T cell lines generated from lymphoma patients actively immunized with idiotype protein specifically recognized multiple, unique immunodominant epitopes in autologous tumor idiotype. Synthetic peptides corresponding to hypervariable, but not framework, regions of Ig heavy chain specifically stimulated CD4(+) and CD8(+) T cells to proliferate and secrete proinflammatory cytokines in an MHC-associated manner. Detailed analysis revealed a minimal determinant of an immunodominant epitope, comprising critical residues at the amino terminus that may be a product of somatic hypermutation. Association of idiotype-specific T cell responses with previously documented molecular remissions in idiotype-vaccinated patients suggests that the newly identified T cell epitopes may be clinically relevant. Such antigenic epitopes may serve as candidates for novel peptide-vaccine strategies, and as tools to selectively expand tumor antigen-specific T cells for adoptive immunotherapy and for monitoring T cell immunity in vaccinated patients.

Generalization of single immunological experiences by idiotypically mediated clonal connections

Clonal interactions of B cells by idiotope-specific mutual recognition of their antigen receptors with the participation of T cells were assumed to form a web of unknown density, referred to as the idiotypic network. Although these clonal connections were proposed to fulfill important internal regulatory functions, their biological significance, especially in relation to antigen-induced immune responses, remained a mystery. In view of this, we postulate that the basic function of the idiotypic internal connection between B and T cell antigen receptors is to transform antigen-induced cellular activations, by idiotypic crossreactivity, into the regulation of cell clones with different antigen specificities. This process leads not only to the suppression of major clones but also to the activation of minor ones. The latter activating property may allow the generalization of single antigenic experiences, so that the immune system in its entirety benefits in its battle against environmental microbes. Such idiotypic clonal interactions are particularly effective in early ontogeny. During a short neonatal imprinting period, maternal immunological knowledge in the form of somatically mutated, high-affinity IgG antibodies, acquired through a continuous encounter with external antigens, guides the initial ontogenetic development of the immune system and so exerts long-lasting transgenerational advantageous effects in the offspring.

Induction of cytotoxic T-cell responses against immunoglobulin V region-derived peptides modified at human leukocyte antigen-A2 binding residues

Cytotoxic T-lymphocyte (CTL) responses can be generated against peptides derived from the immunoglobulin (Ig) V region in some but not all patients. The main reason for this appears to be the low peptide-binding affinity of Ig-derived peptides to major histocompatibility complex (MHC) class I molecules and their resulting low immunogenicity. This might be improved by conservative amino acid modifications at the MHC-binding residues of the peptides (heteroclitic peptides). In this study, it was found that in 18 Ig-derived peptides, that heteroclitic peptides from the Ig gene with improved binding to human leukocyte antigen (HLA)-A*0201 can be used to improve CTL responses. Amino acid substitution substantially increased predicted binding affinity, and there was a strong correlation between predicted and actual binding to HLA-A*0201. CTLs generated against the heteroclitic peptide had not only enhanced cytotoxicity against the heteroclitic peptide but also increased killing of antigen-presenting cells pulsed with the native peptide. Surprisingly, no difference was observed in the frequency of T cells detected by MHC class I peptide tetramers after stimulation with the heteroclitic peptide compared with the native peptide. CTLs generated against heteroclitic peptides could kill patients' tumor cells, showing that Ig-derived peptides can be presented by the tumor cell and that the failure to mount an immune response (among other reasons) likely results from the low immunogenicity of the native Ig-derived peptide. These results suggest that heteroclitic Ig-derived peptides can enhance immunogenicity, thereby eliciting immune responses, and that they might be useful tools for enhancing immunotherapy approaches to treating B-cell malignant diseases.

Clonal cytotoxic T cells are expanded in myeloma and reside in the CD8(+)CD57(+)CD28(-) compartment

The occurrence of clonal T cells in multiple myeloma (MM), as defined by the presence of rearrangements in the T-cell receptor (TCR)-beta chains detected on Southern blotting, is associated with an improved prognosis. Recently, with the use of specific anti-TCR-variable-beta (anti-TCRV(beta)) antibodies, the presence in MM patients of expanded populations of T cells expressing particular V(beta) regions was reported. The majority of these T-cell expansions have the phenotype of cytotoxic T cells (CD8(+)CD57(+) and perforin positive). Since V(beta) expansions can result from either a true clonal population or a polyclonal response, the clonality of CD8(+)TCRV(beta)(+) T cells was tested by TCRV(beta) complementarity-determining region 3 length analysis and DNA sequencing of the variable region of the TCR. In this report, the CD57(+) and CD57(-) subpopulations within expanded TCRV(beta)(+)CD8(+) cell populations are compared, and it is demonstrated that the CD57(+) subpopulations are generally monoclonal or biclonal, whereas the corresponding CD57(-) cells are frequently polyclonal. The oligoclonality of CD57(+) expanded CD8(+) T cells but not their CD57(-) counterparts was also observed in age-matched controls, in which the T-cell expansions were mainly CD8(-). The CD8(+)CD57(+) clonal T cells had a low rate of turnover and expressed relatively lower levels of the apoptotic marker CD95 than their CD57(-) counterparts. Taken together, these findings demonstrate that MM is associated with CD57(+)CD8(+) T-cell clones, raising the possibility that the expansion and accumulation of activated clonal CD8(+) T cells in MM may be the result of persistent stimulation by tumor-associated antigens, combined with a reduced cellular death rate secondary to reduced expression of the apoptosis-related molecule CD95.

Idiotype-specific cytotoxic T lymphocytes in multiple myeloma: evidence for their capacity to lyse autologous primary tumor cells

Multiple myeloma (MM) is a B-cell malignancy. The monoclonal immunoglobulin, secreted by myeloma plasma cells, carries unique antigenic determinants (idiotype [Id]) that can be regarded as a tumor-specific antigen. Id-based immunotherapy has been explored in myeloma patients for the purpose of enhancing or inducing Id-specific immune responses that might lead to tumor destruction. However, despite some evidence obtained from mouse plasmacytoma models, it is still unclear whether Id-specific immunity may play a role in the regulation of tumor cells in MM. In the current study, using dendritic cells (DCs) as antigen-presenting cells, autologous Id-specific cytotoxic T lymphocyte (CTL) lines containing both CD4+ and CD8+ T cells were generated from myeloma patients. The results show that Id-specific CTLs not only recognized and lysed autologous Id-pulsed DCs but also significantly killed the autologous primary myeloma cells. The cytotoxicity against the primary tumor cells was major histocompatibility complex (MHC) class I- and, to a lesser extent, class II-restricted, indicating that myeloma cells could process Id protein and present Id peptides in the context of their surface MHC molecules. Furthermore, the CTLs lysed the target cells mainly through the perforin-mediated pathway because Concanamycin A, but not Brefeldin A-the selective inhibitors for perforin- or Fas-mediated pathways-abrogated the cytolytic activity of the cells. These CTLs secreted predominantly interferon-gamma and tumor necrosis factor-alpha on antigen stimulation, indicating that they belong to the type-1 T-cell subsets. Taken together, these findings represent the first demonstration that Id-specific CTLs are able to lyse autologous tumor cells in MM and, thus, provide a rationale for Id-based immunotherapy in the disease.

Immunoglobulin framework-derived peptides function as cytotoxic T-cell epitopes commonly expressed in B-cell malignancies

Although the idiotypic structures of immunoglobulin from malignant B cells were the first tumor-specific determinants recognized, and clinical vaccination trials have demonstrated induction of tumor-specific immunity, the function of immunoglobulin-specific CD8+ cytotoxic T lymphocytes in tumor rejection remains elusive. Here, we combined bioinformatics and a T cell-expansion system to identify human immunoglobulin-derived peptides capable of inducing cytotoxic T-lymphocyte responses. Immunogenic peptides were derived from framework regions of the variable regions of the immunoglobulin that were shared among patients. Human-leukocyte-antigen-matched and autologous cytotoxic T lymphocytes specific for these peptides killed primary malignant B cells, demonstrating that malignant B cells are capable of processing and presenting such peptides. Targeting shared peptides to induce T-cell responses might further improve current vaccination strategies in B-cell malignancies.

Increased expression of non-functional killer inhibitory receptor CD94 in CD8+ cells of myeloma patients

Different MHC class I-specific killer inhibitory receptors (KIRs) are expressed in vivo by a minor fraction of activated memory CD8+ cells. It has been postulated that KIRs may 'fine-tune' specific responses by altering their threshold of activation by the TCR-CD3 complex. We have previously shown that, in multiple myeloma (MM) patients, a large fraction of peripheral blood CD8+ cells display the phenotype of chronically activated memory T cells (CD38+, HLA-DR+, CD25-, CD45R0+, CD28-). We investigated the expression of KIRs on MM T cells and determined their possible influence on cytolytic responses elicited via the CD3-TCR complex. The expression of CD94, a molecule that is part of a heterodimeric KIR recognizing the non-classical MHC surface HLA-E molecule, was almost threefold higher in MM T cells than in age-matched normal control subjects (P < 0.0001). CD94 expression was preferentially confined to CD8+ cells but not restricted to activated (HLA-DR+) and/or memory (CD45R0+) T cells. Unlike normal T cells, in which CD94 is assembled with glycoproteins of the NKG2 family to form functional receptors with activating or inhibitory properties, most CD94+ MM T cells were devoid of both the NKG2-A and NKG2-C glycoproteins detected in the inhibitory or activating form respectively. CD94 blockade did not significantly affect either T-cell proliferation or cytotoxic T-lymphocyte generation induced by the myeloma-derived cell lines NCI and RPMI 8226. Similarly, the cytolytic activity induced by direct anti-CD3-mediated targeting of MM T cells to FCR+ P815 target cells was unaffected by the addition of anti-CD94 and/or anti-NKG2-A/C monoclonal antibodies (mAbs). These data indicate that the large majority of MM CD8+ cells do not express a functional CD94 receptor. Thus, their ability to 'fine-tune' an appropriate immune response against tumour cells can be impaired.

Expression of testicular genes in haematological malignancies

The gene expression of a new group of tumour antigens known as cancer/testis (CT) antigens is now well-recognized in some solid tumours. However, their expression in haematological malignancies remained unclear. In this study, we have used reverse transcription polymerase chain reaction and Southern blot analysis to examine the presence of transcripts for the three CT antigens, NY-ESO-1, SSX2 and SCP1 in haematological malignant cells. We found that transcripts for SCP1 could be detected in 10% of myeloma, 5.7% of acute myeloid leukaemia and 23% of chronic myeloid leukaemia. In contrast, NY-ESO-1 and SSX2 were not detected in any of the 107 tumour samples.

Idiotypic protein-pulsed dendritic cell vaccination in multiple myeloma

Idiotypic protein (Id) produced by myeloma cells is clone-specific and may be a suitable tumor-specific antigen for immune targeting. Advances in dendritic cell (DC) technology suggest the opportunity for using this potent antigen presentation system to deliver myeloma Id to the autologous host to elicit anti-tumor immune responses. We have generated DCs from adherent PBMCs from 6 patients with IgG myeloma. These cells were pulsed with the autologous Id and a control vaccine, KLH, and re-infused i.v. back to the patients on 3 separate occasions. Immune responses to KLH and autologous Id were measured and clinical responses monitored. We found that all treatments were well tolerated without any side effects. All patients developed both B- and T-cell responses to KLH, suggesting the integrity of the host immune system to mount immune responses to an antigen delivered using our vaccination strategy. Id-specific responses were also observed. PBMC proliferative responses to Id were observed in 5 of the 6 patients following treatment. In 2 patients, the responses were associated with the production of IFN-gamma. There were also increases in cytotoxic T-cell precursor frequencies for Id-pulsed autologous targets in 3 patients. B-cell responses characterized by the production of anti-Id IgM occurred in 3 and anti-Id IgG in 4 of the 5 evaluated patients. In 1 patient, a modest (25%) but consistent drop in the serum Id level was observed. Id-pulsed DC vaccination can therefore elicit potentially useful anti-myeloma immune responses in patients with multiple myeloma.

Idiotype Vaccination in Human Myeloma: Generation of Tumor-Specific Immune Responses After High-Dose Chemotherapy

Igs contain unique portions, collectively termed idiotypes (Id), that can be recognized by the immune system. Id expressed by tumor cells in B-cell malignancies can be regarded as tumor-specific antigens and a target for vaccine immunotherapy. We have started a vaccination trial in multiple myeloma (MM) using Id-specific proteins conjugated to keyhole limpet hemocyanin (KLH) as immunogens and low doses of subcutaneous granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-2 (IL-2) as immunoadjuvants. Twelve patients who had previously been treated with high-dose chemotherapy followed by peripheral blood progenitor cell (PBPC) transplantation entered this study from August 1995 to January 1998. All patients were in first remission at the time of vaccination. They received subcutaneous injections of Id vaccines and immunoadjuvants in an outpatient setting. The generation of Id-specific T-cell proliferative responses was documented in 2 patients, whereas a positive Id-specific delayed-type hypersensitivity (DTH) reaction was observed in 8 of the 10 patients studied. DTH specificity was confirmed in 1 patient by investigating the reactivity to synthetic peptides derived from the VDJ sequence of the tumor-specific Ig heavy chain. None of the patients generated soluble immune responses to Id, whereas the generation of soluble and cellular immune responses to KLH was observed in 100% and 80%, respectively. Eleven patients completed the treatment, whereas 1 patient failed to finish owing to progression of disease. Freedom from disease progression (FFDP), measured from the date of first Id/KLH injection to the date of first treatment after vaccination or last follow-up, ranged from 9 to 36 months. These data indicate that the immune competence status of MM patients is still susceptible to specific immunization after high-dose chemotherapy and PBPC transplantation. It remains to be determined whether generation of Id-specific immune responses can reduce the relapse rate of patients with minimal residual disease.

Idiotype Vaccination in Human Myeloma: Generation of Tumor-Specific Immune Responses After High-Dose Chemotherapy

Igs contain unique portions, collectively termed idiotypes (Id), that can be recognized by the immune system. Id expressed by tumor cells in B-cell malignancies can be regarded as tumor-specific antigens and a target for vaccine immunotherapy. We have started a vaccination trial in multiple myeloma (MM) using Id-specific proteins conjugated to keyhole limpet hemocyanin (KLH) as immunogens and low doses of subcutaneous granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-2 (IL-2) as immunoadjuvants. Twelve patients who had previously been treated with high-dose chemotherapy followed by peripheral blood progenitor cell (PBPC) transplantation entered this study from August 1995 to January 1998. All patients were in first remission at the time of vaccination. They received subcutaneous injections of Id vaccines and immunoadjuvants in an outpatient setting. The generation of Id-specific T-cell proliferative responses was documented in 2 patients, whereas a positive Id-specific delayed-type hypersensitivity (DTH) reaction was observed in 8 of the 10 patients studied. DTH specificity was confirmed in 1 patient by investigating the reactivity to synthetic peptides derived from the VDJ sequence of the tumor-specific Ig heavy chain. None of the patients generated soluble immune responses to Id, whereas the generation of soluble and cellular immune responses to KLH was observed in 100% and 80%, respectively. Eleven patients completed the treatment, whereas 1 patient failed to finish owing to progression of disease. Freedom from disease progression (FFDP), measured from the date of first Id/KLH injection to the date of first treatment after vaccination or last follow-up, ranged from 9 to 36 months. These data indicate that the immune competence status of MM patients is still susceptible to specific immunization after high-dose chemotherapy and PBPC transplantation. It remains to be determined whether generation of Id-specific immune responses can reduce the relapse rate of patients with minimal residual disease.

In-vivo immune responses to idiotypic VH complementarity-determining region 3 peptide vaccination in B-cell non-Hodgkin's lymphoma

Idiotypic IgM expressed by B-cell non-Hodgkin's lymphoma (NHL) is clone specific and an ideal tumour antigen for immune targeting. We previously showed that repeated rounds of in vitro stimulation of peripheral blood mononuclear cells (PBMC) with autologous idiotypic heavy variable (VH) complementarity-determining region (CDR)-3 peptide produced T-cell lines able to proliferate, produce Th1 cytokines and kill autologous target cells pulsed with the CDR3 peptide. Furthermore, fresh autologous lymphoma cells were lysed by these T-cell lines, suggesting a potential for the clinical use of the CDR3 peptide for lymphoma vaccination. In this study, we determined the specific immune responses of a patient following vaccination with VH CDR3 peptide to determine if similar immune responses observed in vitro could be elicited in vivo. The patient received three fortnightly subcutaneous injections of idiotypic CDR3 peptide. The injection sites developed inflammation after the second and third vaccinations. Peripheral blood T cells were able to proliferate and produce IFN-gamma upon rechallenge with the CDR3 peptide in vitro. Cytotoxic T lymphocytes (CTLs) for autologous CD3-depleted CDR3-pulsed PBMC were detected, but only after the first vaccination. T-cell lines generated after vaccination could lyse peptide-pulsed autologous target cells. We also detected the production of anti-CDR3 peptide antibodies in the patient's serum. We conclude that naked CDR3 peptide vaccination can result in the generation of potentially beneficial specific immune responses as predicted by in vitro studies.