Autologous Multiple Myeloma Cells Research Articles

Melan-A/MART1 Analog Peptide Triggers Anti-myeloma T-cells Through Crossreactivity With HM1.24

The Melan-A(aa26-35) (EAAGIGILTV) peptide is a human leukocyte antigen (HLA)-A2-restricted T-cell epitope within the Melan-A/MART-1 tumor antigen expressed on malignant melanoma cells. Melan-A and Melan-A analog (ELAGIGILTV, Melan-A(aa26-35*A27L)) specific T-cells can be expanded reliably for immunotherapeutic approaches in vitro. We studied the ability of Melan-A analog (ELAGIGILTV, Melan-A(aa26-35*A27L)) specific T-cells to recognize the HM1.24(aa22-30) (LLLGIGILV) peptide within the HM1.24 antigen presented by normal and malignant plasma cells. Peripheral blood mononuclear cells from HLA-A2+ healthy donors and HLA-A2+ multiple myeloma (MM) patients were stimulated with Melan-A analog peptide-loaded autologous dendritic cells, and expanded in vitro. T-cell activation was assessed by interferon-gamma specific enzyme-linked immunosorbent spot and cytotoxicity by (51)Chromium-release-assays. The frequency of Melan-A analog specific CD8+ T-cells was detected by using tetramers. Melan-A analog specific T-cells from HLA-A2+ healthy donors and HLA-A2+ MM patients showed a interferon-gamma secretion mediated by HM1.24(aa22-30) peptide-pulsed T2 cells and lysed the HLA-A2+ HM1.24+ U266 and XG-1 human myeloma derived cell-lines as well as the B-lymphoblastoid cell-line IM-9. Melan-A analog specific T-cells from MM patients specifically lysed autologous MM cells. The current data demonstrate that Melan-A analog specific T-cells crossreact with HM1.24(aa22-30). They might be a tool for the future use in immunotherapy against MM.

Fusion Cell Vaccination In Conjunction With Stem Cell Transplantation Is Well Tolerated, Induces Anti-Tumor Immunity and Is Associated With Responses In Patients With Multiple Myeloma

Autologous transplantation results in improved outcomes in patients with multiple myeloma (MM), but patients relapse from persistent disease. A promising area of investigation is the development of cancer vaccines that educate host immunity to target myeloma cells. We have developed a cancer vaccine in which DCs are fused to autologous MM cells. We are conducting a study in which patients with MM undergo stem cell transplantation followed by post-transplant vaccination with DC/MM fusions. DCs were generated from adherent mononuclear cells cultured with GM-CSF and IL-4 and TNFα.

Fusion Cell Vaccination in Conjunction with Stem Cell Transplantation Is Well Tolerated, Induces Anti-Tumor Immunity and Is Associated with Responses in Patients with Multiple Myeloma

Autologous stem cell transplantation results in tumor cytoreduction and improved disease outcomes in patients with multiple myeloma (MM), but patients ultimately relapse from persistent disease. A promising area of investigation is the development of cancer vaccines that educate host immunity to target and eliminate myeloma cells and can be used to eradicate residual disease following autologous stem cell transplantation. The early post-transplant period is characterized by a transient reversal of tumor mediated tolerance due to the reduction in disease bulk, the depletion of regulatory T cells. We have developed a cancer vaccine model in which DCs are fused to autologous MM cells resulting in the presentation of multiple tumor antigens with the capacity to elicit a broad anti-tumor response. We are conducting a study in which patients with MM undergo stem cell transplantation followed by post-transplant vaccination with 3 doses of DC/MM fusions. DCs were generated from adherent mononuclear cells cultured with GM-CSF and IL-4 for 5–7 days and matured with TNFα. DCs strongly expressed costimulatory and maturation markers. Myeloma cells were isolated from bone marrow aspirates and were identified by their expression of CD38, CD138, and/or MUC1. DC and MM cells were fused with polyethylene glycol and fusion cells were quantified by determining the percentage of cells that coexpress unique DC and myeloma antigens. To date, 26 patients have been enrolled. All patients have undergone successful vaccine generation. Mean yield of the DC and myeloma preparations was 171×106 and 70×106 cells, respectively. Mean fusion efficiency was 40% and the mean cell dose generated was 4×106 fusion cells. Mean viability of the DC, myeloma, and fusion preparations was 88%, 86%, and 78%, respectively. As a measure of their potency as antigen presenting cells, fusion cells potently stimulated allogeneic T cell proliferation in vitro. Mean stimulation indexes were 12, 57, 31 for T cells stimulated by myeloma cells, DCs, and fusion cell preparations at an APC: T cell ratio of 1:10. Adverse events judged to be potentially vaccine related were mild, and included injection site reactions, pruritis, myalgias, fever, chills, headache, fatigue and tachycardia. To date 14 patients have completed vaccinations and initial follow up of which 8 have achieved a complete remission and 6 a partial remission. Of note, 4 patients achieved complete remission only after undergoing post-transplant vaccination. We are examining the effect of transplant and vaccination on measures of cellular immunity, antitumor immunity and levels of activated as compared to regulatory T cells. T cell responses to PHA mitogen and tetanus toxoid were transiently depressed post-transplant. Similarly, DTH responses to candida antigen were absent post-transplant in all but 1 patient. In contrast, a significant increase was noted post-transplant in circulating tumor reactive lymphocytes as determined by T cell expression of IFNγ by CD4 and CD8 cells following ex vivo coculture with autologous myeloma cell lysate (Mean percentage of tumor reactive CD8 cells was 0.9 and 11 pre and post-transplant, respectively p=0.01; mean percentage of CD4 cells was 0.7 and 2.7; p=0.02). A further amplification of tumor reactive lymphocytes was seen with vaccination in a subset of patients (mean percentage of CD4 and CD8 tumor reactive T cells was 4.9 and 15, respectively). A decrease in the median levels of circulating regulatory T cells and a relative increase in the ratio of activated (CD4/CD25low)/regulatory (CD4/CD25high) cells was observed following transplantation. This finding suggests that although nonspecific T cell responses are muted in the early posttransplant period, there is a greater capacity to recognize tumor antigens, potentially due to the depletion of regulatory T cells and the decline in tumor mediated immune suppression. In summary, fusion cell vaccination in conjunction with stem cell transplantation was well tolerated, induced anti-tumor immunity and clinical responses in patients with MM. The post-transplant period is characterized by increased levels of activated as compared to regulatory T cells and enhanced levels of T cells with the capacity to respond to myeloma cells. The increase in tumor reactive T cells post-transplant is further amplified following exposure to the DC/MM fusion vaccine.

Ex Vivo Activated Natural Killer (NK) Cells from Myeloma Patients Kill Autologous Myeloma and Killing Is Enhanced by Elotuzumab

Immune-based therapies may improve outcome for multiple myeloma (MM) by eradicating chemo-resistant disease. Our recent trial utilizing IL2 activated, killer immunoglobulin-like receptor-ligand mismatched NK cell transfusions from haplo-identical donors yielded (n) CR in 50% of patients. Unfortunately, after NK cell therapy, 2/10 patients had progressive disease, and the median duration of response for the other 8/10 patients was only 105 days (range 58–593). This may have been due to an insufficient dose of alloreactive NK cells and early rejection. Furthermore, appropriate donors were identified for only 30% of otherwise eligible patients. We therefore investigated whether NK cells from MM patients could be expanded and activated to kill autologous MM. We then examined whether pre-treatment of MM cell targets with elotuzumab, a humanized antibody to the MM tumor antigen CS1, could further enhance NK cell-mediated lysis.PBMC from 5 MM patients were co-cultured for 14 days with irradiated K562 cells transfected with 4-1BBL and membrane bound IL15 in the presence of IL2 (300U/ml) as previously described (Imai et al, Blood 2005; 106:376–383). The degree of NK cell expansion, NK immunophenotype, and ability to kill MM (4 hour 51Cr release assays) were assessed. To determine the ability of ex vivo expanded NK cells to traffic to bone marrow, activated NK cells were injected into the tail vein of NK cell depleted NOD-SCID mice, which were then sacrificed after 48 hours. Flow cytometry for human CD45, CD3, and CD56 was performed on cells from blood, marrow and spleen.There was an average 64-fold expansion of NK cells (range: 8–200) after 2 weeks of co-culture with K562 transfectants. Expansion of T cells was not observed. The NK cell activating receptor NKG2D, and natural cytotoxicity receptors NKp30, NKp44, and NKp46 were up-regulated following the expansion. Expanded NK cells were able to kill autologous MM (E:T ratio 10:1, average 31%, range 22–41%), whereas resting NK cells did not. Pretreatment of autologous MM cells with elotuzumab increased the activated NK cell-mediated killing by 1.7-fold over target cells pretreated with an isotype control antibody. This level of killing was similar to that of the highly NK kill-sensitive cell line K562 (Figure). Autologous PHA blasts and CD34+ stem cells were not killed. Activated human NK cells were detectable in the bone marrow of NOD-SCID mice 48 hours after injection.Ex vivo activation of NK cells from MM patients with K562 transfectants can induce killing of autologous MM and produce large numbers of NK cells for potential therapy. The addition of elotuzumab to activated NK cell therapy enhances anti-MM effects by ADCC thus invoking an additional NK cell-mediated mechanism of MM killing. Importantly, ex vivo activated NK cells traffic to the bone marrow in mice. Autologous NK cell therapy eliminates the issues related to allo-donor availability and early NK cell rejection, and could provide an option for patients refractory to chemotherapy agents. [Display omitted]

Lack of Predictive Value of KIR-HLA Genotypes for Autologous Transplant Outcome for Multiple Myeloma.

In allogeneic hematopoietic cell transplantation (HCT), donor alloreactive natural killer (NK) cells can prevent leukemia relapse and prolong survival. Donor NK alloreactivity has been shown to be influenced by the killer Ig-like receptor (KIR) repertoire of the donor and the HLA class I KIR ligand phenotype of the recipient. In T-cell depleted HLA-identical sibling HCT, it has been shown that lack of recipient class I ligand for donor inhibitory KIR is associated with improved outcome in acute myelogenous leukemia. In the normal population, more than 60% of individuals lack class I ligand for one or more of their inhibitory KIR. Because autoreactive NK cells are known to occur in normal individuals with low frequency, we sought to determine if these same NK clones driven by autologous KIR-HLA interactions might expand and play a role following treatment involving autologous stem cell infusion for hematologic malignancy. 233 patients with multiple myeloma who underwent high-dose chemotherapy with autologous stem cell infusion were evaluated with HLA and KIR genotyping. KIR-HLA genotype combinations were then correlated with event-free survival (EFS) and overall survival (OS) following autologous HCT. Cox regression models were fit to examine the association of KIR-HLA combinations with the hazards of mortality and relapse. We found that there was no association between lack of KIR ligand for inhibitory KIR and improved EFS (p=0.69) or OS (p=0.36), nor was there any association between presence of specific activating KIRs and transplant outcome. Furthermore, the cumulative effect of more than one activating KIR did not affect outcome, including the specific combination of KIR2DS1 and KIR2DS2 (EFS p=0.86 and OS p=0.67), which have been previously reported to be associated with lower leukemia relapse in allogeneic HLA-identical HCT. The combination of activating KIR with their known or putative HLA ligands was also not associated with improvement in transplant outcome. Patients were also evaluated for KIR haplotype (AA versus AB and BB). There was no association between KIR haplotype and DFS (p=0.59) or OS (p=0.96). These data suggest that KIR genotypes and KIR-HLA genotype combinations are not associated with improved outcome in multiple myeloma patients undergoing autologous HCT. This implies that NK cells in autologous HCT do not significantly impact outcome, either because they are not expanded in the post-HCT period or because they have no activity against autologous multiple myeloma cells.

Killing of Drug-Sensitive and Resistant Myeloma Cells and Disruption of Their Bone Marrow Stromal Interaction by HuLuc63, a Novel Humanized Anti-CS1 Monoclonal Antibody.

Introduction: Current monoclonal antibody (mAb) therapies for multiple myeloma (MM) have had limited success due to narrow target expression across MM patient samples. A preferred strategy would be to develop cytotoxic human mAbs against novel antigens that are highly expressed in MM cells yet have limited expression in other cell types. CS1 (CD2 subset 1, CRACC, SLAMF7), a member of the CD2 family of cell surface glycoproteins, was found to be highly expressed in myeloma cells. In this study, we investigated the anti-myeloma activity of HuLuc63, a novel humanized anti-CS1 mAb.Methods: Microarray expression profiling was used to determine the CS1 mRNA levels in CD138-expressing myeloma cells from 101 MM patient samples. For detection of CS1 protein, flow cytometry was performed using the anti-CS1 mAb HuLuc63. Functional characterization of HuLuc63 was performed by assessing antibody-dependent cellular cytotoxicity (ADCC) and by assessing MM and bone marrow stromal cell (BMSC) interactions.Results: CS1 mRNA was expressed in CD138 cells from more than 96% (97/101) of MM patients. Flow cytometric analysis confirmed that protein expression mirrors the mRNA profile. Importantly, CS1 is also present in 12 MM cell lines that are either drug-sensitive or resistant. HuLuc63, but not an isotype control antibody, induced ADCC in a CS1-specific, dose-dependent manner against CD138-expressing MM lines and patient MM cells including dexamethasone (dex)-sensitive MM1S and dex-resistant MM1R cells. Significantly, HuLuc63 triggered autologous ADCC against CS1-expressing CD138-purified tumor cells from 11 MM patients resistant to conventional or novel therapies such as bortezomib (Velcade®) and an HSP90 inhibitor. Since CS1 may regulate cell adhesion, we next studied whether HuLuc63 alters MM cell adhesion to BMSCs. HuLuc63 inhibited MM cell adhesion to BMSCs in a dose-dependent manner, whereas human control IgG did not. However, the presence of BMSC appeared to reduce HuLuc63-induced cell lysis against MM1S and MM1R cells. Since the immunomodulatory drug lenalidomide (Revlimid®) enhances NK cell function, we further tested whether HuLuc63-induced ADCC against MM cells is augmented by lenalidomide. Pretreatment with lenalidomide markedly enhanced NK-cell-mediated lysis of autologous patient MM cells triggered by HuLuc63.Conclusions: We show that the new MM antigen, CS1, is expressed in myeloma cells from more than 96% of MM patients. The novel humanized anti-CS1 mAb, HuLuc63, induced significant cytotoxicity against MM cells including drug-resistant cells, and inhibited their interaction with BMSCs. These data suggest that HuLuc63 may have clinical utility in a spectrum of MM patients including those newly diagnosed with the disease as well as patients with late stage refractory disease.

Immunomodulatory Drug Lenalidomide (CC-5013, IMiD3) Augments Anti-CD40 SGN-40–Induced Cytotoxicity in Human Multiple Myeloma: Clinical Implications

SGN-40, a humanized immoglobulin G1 (IgG1) anti-CD40 monoclonal antibody, mediates cytotoxicity against human multiple myeloma (MM) cells via suppression of interleukin (IL)-6-induced proliferative and antiapoptotic effects as well as antibody-dependent cell-mediated cytotoxicity (ADCC). Here, we studied the clinical significance of an immunomodulatory drug lenalidomide on SGN-40-induced cytotoxicity against CD138(+)CD40(+) MM lines and patient MM cells. Pretreatment with lenalidomide sensitized MM cells to SGN-40-induced cell death. Combined lenalidomide and SGN-40 significantly induced MM apoptosis, evidenced by enhanced cleavage of caspase-3/8/poly(ADP-ribose)polymerase and increased sub-G(0) cells, compared with either single agent at the same doses. Pretreatment of effector cells with lenalidomide augmented SGN-40-induced MM cell lysis, associated with an increased number of CD56(+)CD3(-) natural killer (NK) cells expressing CD16 and LFA-1. Importantly, pretreatment with lenalidomide or lenalidomide and SGN-40 markedly enhanced NK-cell-mediated lysis of autologous patient MM cells triggered by SGN-40. Lenalidomide also up-regulated CD40L on CD56(+)CD3(-) NK cells, facilitating IL-2-mediated activation of NK cells. In addition, lenalidomide induced the CD56(dim) NK subset, which are more potent mediators of ADCC against target MM cells than the CD56(bright) NK subset. Finally, pretreatment of both effector and target MM cells with lenalidomide markedly enhanced SGN-40-mediated ADCC against CD40-expressing MM cells. These studies, therefore, show that the addition of lenalidomide to SGN-40 enhances cytotoxicity against MM cells, providing the framework for combined lenalidomide and SGN-40 in a new treatment paradigm to both target MM cells directly and induce immune effectors against MM.

Anti-Myeloma Effects Induced by Myeloma Idiotype Pulsed Dendritic Cells In Vitro.

As the most potent antigen-presenting cells, Dendritic cells (DCs), capable of inducing immune responses from naive T cells, are operative tools for tumor immunotherapy. Derived DCs are extremely effective in capturing and presentation of antigens to T cells and play a key role in the induction of cytotoxic T lymphocytes (CTLs). In vitro culture system containing the combination of GM-CSF, IL-4 and TNF-α cytokine can affect CD14 + progenitor cells from mononuclear cells (MNCs) of peripheral blood (PB) developing into functional DCs, which have enough quantities for application in vitro researches and clinical practices. Multiple myeloma cells(MM)are able to secrete a great quantity of immunoglobulin (Ig) expressing idiotypic antigen called idiotype (Id) in its mutational hotspot. This kind of idiotypic structure regions also expressing on the surface of MM cells are high specific autologous tumor associated antigen (TAA). The combination use of DCs and tumor specific antigen can improve the immunogenicity of MM cells and stimulate specific anti-tumor immunological response effectively, so by using this new kind of DC tumor vaccine, following high dose chemical therapy, the tiny residual pathological changes might be cleared totally in the future.To investigate the specific antitumor immune response induced by Id-pulsed dendritic cells(DCs) in vitro. DCs were generated from peripheral blood monocytes of the multiple myeloma(MM) patients using GM-CSF, IL-4, and TNF-α. pulsed with idiotype protein at the immature stage, DCs could activate T cells to become tumor specific cytotoxic T lymphocytes (CTLs). The morphologic characteristics of those cells were observed with light and electron microscopes. The phenotypic figures were analyzed with FACS analysis. Methy-thiazoly-Tetrazolium (MTT) assay was employed to evaluate the effect of proliferation of autologous T cells and the inhibition rate of CTL on MM cells. DCs precursors in peripheral blood could be induced to typical mature DCs in medium containing GM-CSF, IL-4 and TNF-α. Mature DCs with Id could operatively increase proliferation of the autologous T cells and active naive T cells to become tumor specialized CTLs. Any doses of CTLs had significant inhibition or killing ability on autologous MM cells. These results suggest in suitable cytokine environment, the precursors in peripheral blood of MM patients could be induced to functional DCs, and vaccination with Id-pulsed DCs could induce active antitumor immune response. Multiple cycles of immunization using DC as APC in vitro can be beneficial in generating antigen- specific T cells from normal PBMC, and Id an auto-specific tumor antigen, can be got with ammonium sulfate four-step precipitated method, By digestion of pepsin and affinity chromatography so as to stimulate MM specific immunological responce, and Id-pulsed mature DCs from MM patients can stimulate not only the proliferation of autologous T cells, but also the specific CTL immune response against autologous MM cells. In addition, in vitro immunization may provide an alternative approach to in vivo immunization of MM. We believe that DCs vaccine can bring the breakthrough of therapy to MM in the near future.

Identification and Expansion of Myeloma-Specific Cytotoxic T Cells In Vitro.

Multiple myeloma (MM) has been considered as low immunogenic incurable disease. The attempts has been made to invert the immune status to recognize myeloma cells by T cells or other cells of the immune system. Here we studied biology of myeloma-specific T cells in vitro.Irradiated myeloma cell line ARH 77 has been used as tumor antigen to stimulate peripheral blood mononuclear cells (PBMC) of 8 healthy volunteers. Dendritic Cells loaded by irradiated autologous MM cells has been used to stimulate PBMC of 10 MM patients. Activated responder T cells have been immunomagnetically separated based on surface expression of interferon gamma (Miltenyi Biotech) and expanded in 5 cases by phytohemaglutinin and repeated high-doses of interleukin 2. Cytotoxicity against the original myeloma cells has been tested after the expansion using propidium iodide or 7-amino actinomycin D. Responder T cells were labeled by CFSE to distinguish them from myeloma cells. Third-party PBMC and interferon gamma negative fraction of T cells served as controls.The percentage of interferon gamma positive cells in healthy donors has been enriched from 2.8±0.9 and 2.6±0.8 to 48.6±23.4 and 73.2±25.9 of CD3+CD4+ and CD3+CD8+ T cells, respectively, by immunomagnetic separation. Interferon gamma positive T cells have been further expanded in vitro from 0.54x106 ± 0.05x106 to 214.00x106 ± 103.46x106 within 4 weeks. A specific cytotoxicity has been tested after expansion. The killing of myeloma cells by expanded IFN g+ T cells reached 68.1±14.2%, while interferon gamma negative fraction killed only 0.8±0.3% of myeloma cells. As another control, killing of third-party PBMC by expanded interferon gamma positive T cells was 6.9±2.5%. Similar observations were made in MM patients and will be presented at the meeting.These data demonstrate a specific cytotoxic effect of expanded interferon gamma positive T cells against myeloma cell line ARH 77 and open the possibility for clinical use of tumor-specific T cells in MM.

Immunomodulatory Drug Lenalidomide (CC-5013, IMiD3) Augments Anti-CD40 SGN-40-Induced Cytotoxicity in Human Multiple Myeloma: Clinical Implications.

SGN-40, a humanized immoglobulin G1 (IgG1) anti-CD40 monoclonal antibody, mediates cytotoxicity against human multiple myeloma (MM) cells via suppression of IL-6-induced proliferative and antiapoptotic effects, as well as antibody-dependent cell-mediated cytotoxicity (ADCC). We here studied the clinical significance of an immunomodulatory drug lenalidomide on SGN-40-induced cytotoxicity against CD138+CD40+ MM lines and patient MM cells. Pretreatment with lenalidomide sensitized MM cells to SGN-40-induced cell death. Combined lenalidomide and SGN-40 significantly induced MM apoptosis, evidenced by enhanced cleavage of caspase 3/8/PARP and increased subG0 cells, compared with either single agent at the same doses. Pretreatment of effector cells with lenalidomide augmented SGN-40-induced MM cell lysis, associated with an increased number of CD56+CD3− NK cells expressing CD16 and LFA-1. Importantly, pretreatment with lenalidomide or lenalidomide and SGN-40 markedly enhanced NK-cell-mediated lysis of autologous patient MM cells by SGN-40. Lenalidomide also upregulated CD40L on CD56+CD3− NK cells, facilitating IL-2-mediated activation of NK cells. In addition, lenalidomide induced the CD56dim NK subset, which are more potent mediators of ADCC against target MM cells than the CD56bright NK subset. Finally, pretreatment of both effector and target MM cells with lenalidomide markedly enhanced SGN-40-mediated ADCC against CD40-expressing MM cells. These studies therefore demonstrate that the addition of lenalidomide to SGN-40 enhances cytotoxicity against MM cells, providing the framework for combined lenalidomide and SGN-40 in a new treatment paradigm to both target MM cells directly and induce immune effectors against MM.

Adenoviral-mediated transfer of human wild-type p53, GM-CSF and B7-1 genes results in growth suppression and autologous anti-tumor cytotoxicity of multiple myeloma cells in vitro.

Multiple myeloma (MM) remains incurable despite the use of high-dose chemotherapy and stem cell transplantation. However, immunotherapy is expected to offer long-term disease control, or even possibly a cure. We have previously demonstrated the suppressive effect of a recombinant adenovirus carrying human wild-type p53, granulocyte-macrophage colony-stimulating factor, and B7-1 genes (Ad-p53/GM-CSF/B7-1) on the growth of laryngeal cancer cells. In the present study, we evaluated the effects of an Ad-p53/GM-CSF/B7-1-modified myeloma cell vaccine strategy aimed to induce apoptosis and to augment the immunogenicity of MM cells. Both MM cell lines and purified primary myeloma cells were infected with Ad-p53/GM-CSF/B7-1. High expression levels of these three genes were confirmed separately by Western blot, enzyme-linked immunosorbent assay (ELISA), and flow cytometry. When wild-type p53, GM-CSF and B7-1 genes were introduced, the growth of MM cells was inhibited via enhanced apoptosis and the immunogenicity of tumor cells was augmented. The combinatorial effect of these three genes on inducing cytotoxic T lymphocytes (CTLs) was more evident than that of p53 individually or any combinations of two (p53 plus GM-CSF or p53 plus B7-1). Furthermore, significant proliferation of autologous peripheral blood lymphocytes (PBLs) and specific cytotoxicity against autologous primary MM cells were induced in vitro. These results suggest that myeloma cell vaccination co-transferred with p53, GM-CSF and B7-1 genes may be a promising immunotherapeutic approach against MM.

Lentiviral Transduction of Primary Myeloma Cells with CD80 and CD154 Generates Antimyeloma Effector T Cells

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

Natural cytotoxicity to autologous antigen-pulsed dendritic cells in multiple myeloma.

To analyse autologous lymphocyte cytolytic activities of potential importance for cell-based immunotherapy in multiple myeloma (MM), in vitro differentiated dendritic cells (DCs) loaded with patient-specific monoclonal immunoglobulin (mIg) were used as autologous target cellsin cytotoxicity assays. Effector populations consisted of purified natural killer (NK) cells (CD56+, CD3-) and T cells (CD3+). The MM patients' NK cells cultured in the presence of interleukin 2 (IL-2) showed pronounced cytotoxic activity towards autologous mature DCs. Autologous MM DC targets displayed similar susceptibility to NK cell lysis, compared with allogeneic control DC targets, despite high surface expression of self major histocompatibility complex (MHC) antigens. However, some degree of classic MHC class I-mediated negative regulation was implicated in the NK-DC interactions, as indicated by class I blocking experiments. NK-mediated lysis was also discerned towards primary autologous MM cells. The results indicated that the major effector mechanism was mediated through the perforin-granzyme exocytosis pathway. In conclusion, NK cells from MM patients displayed significant and consistent cytotoxicity towards autologous mature DCs, suggesting that innate immunity could be implicated in MM and may influence the outcome of the administration of tumour antigen-pulsed DCs in treatment trials.

Malignant plasma cells are sensitive to LAK cell lysis: pre‐clinical and clinical studies of interleukin 2 in the treatment of multiple myeloma

To assess the role of the cytokine interleukin 2 (IL2) in the treatment of patients with multiple myeloma, we examined the sensitivity of plasma cell lines and malignant plasma cells from multiple myeloma (MM) patients to cell and cytokine-mediated killing induced by IL2. Unstimulated peripheral blood mononuclear cells (PBM) from normal donors produced little killing (mean lysis 1.0 +/- 1.0%, effector:target (ET) ratio 50:1), but cytotoxicity was modestly increased when PBM were incubated with IL2 prior to assay (8.0 +/- 2.9%). Unstimulated PBM from patients with MM also failed to kill autologous malignant plasma cells (mean 0.6 +/- 0.6%), but after exposure to IL2 they induced substantial lysis of autologous malignant cells (mean 55.3 +/- 22.1%). In addition, tumour necrosis factor (TNF) and interferon-gamma (IFN-gamma), two cytokines released from mononuclear cells in response to IL2, also reduced the survival and thymidine uptake of malignant plasma cells in culture. To determine whether these potentially beneficial immunomodulatory effects could be reproduced by in vivo administration of IL2, we have administered seven courses of IL2 to four patients with MM after autologous bone marrow transplant (ABMT). No serious adverse effects were noted. Increases in natural killer (NK) and lymphokine-activated killer (LAK) activity of PBM occurred during IL2 infusion, although cells capable of killing autologous MM cells did not circulate. However, IL2 infusions also induced substantial increases in the production of the cytokines TNF and IFN-gamma from peripheral blood lymphocytes. These results suggest that the in vivo administration of IL2 in MM deserves further evaluation, particularly for its potential to control minimal residual disease.