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T-cell-mediated immunotherapy is a promising therapeutic option for multiple myeloma (MM). Gamma-delta T cells (gammadelta T cells) recognize phosphoantigens and display strong anti-tumour cytotoxicity. The synthetic agonist Phosphostim (bromohydrin pyrophosphate, BrHPP) has been shown to selectively activate Vgamma9Vdelta2 T cells. This study aimed to evaluate the expansion capacity and anti-myeloma cell cytotoxicity of circulating gammadelta T cells from MM patients at different time points throughout the disease, using Phosphostim and interleukin 2 (IL-2). Circulating gammadelta T cell counts in patients with newly diagnosed MM or in relapse did not differ from those in healthy donors. A 14-d culture of peripheral blood mononuclear cells with Phosphostim and IL-2 triggered a 100-fold expansion of gammadelta T cells in 78% of newly diagnosed patients. Gammadelta T cells harvested at the time of haematopoietic progenitor collection or in relapsing patients expanded less efficiently. Expanded gammadelta T cells killed 13/14 myeloma cell lines as well as primary myeloma cells, but not normal CD34 cells. Their killing efficiency was not affected by 2-d IL-2 starvation. This study demonstrated the ability of Phosphostim and IL-2 to expand gammadelta T cells from MM patients, and the efficient and stable killing of human myeloma cells by gd T cells.

Adoptive T cell therapy represents a promising treatment for cancer. Human T cells engineered to express a chimeric antigen receptor (CAR) recognize and kill tumor cells in a MHC-unrestricted manner and persist in vivo when the CAR includes a CD28 costimulatory domain. However, the intensity of the CAR-mediated CD28 activation signal and its regulation by the CTLA-4 checkpoint are unknown. We investigated whether T cells expressing an anti-CD19, CD3 zeta and CD28-based CAR (19-28z) displayed the same proliferation and anti-tumor abilities than T cells expressing a CD3 zeta-based CAR (19z1) costimulated through the CD80/CD28, ligand/receptor pathway. Repeated in vitro antigen-specific stimulations indicated that 19-28z+ T cells secreted higher levels of Th1 cytokines and showed enhanced proliferation compared to those of 19z1+ or 19z1-CD80+ T cells. In an aggressive pre-B cell leukemia model, mice treated with 19-28z+ T cells had 10-fold reduced tumor progression compared to those treated with 19z1+ or 19z1-CD80+ T cells. shRNA-mediated CTLA-4 down-regulation in 19z1-CD80+ T cells significantly increased their in vivo expansion and anti-tumor properties, but had no effect in 19-28z+ T cells. Our results establish that CTLA-4 down-regulation may benefit human adoptive T cell therapy and demonstrate that CAR design can elude negative checkpoints to better sustain T cell function.

Chimeric Antigen Receptors (CARs) are a novel drug class, consisting of engineered receptors for antigen that redirect and reprogram T-cell function. We have shown in both xenogeneic tumor models as well as in leukemia patients, that CD19-targeted T-cells are capable of inducing complete remission of relapsed or refractory B cell malignancies. The inclusion of appropriate co-stimulation is essential for the potency, quality and durability of the CAR T cell response. Here we show that the co-stimulatory domain incorporated within the CAR dictates the kinetics of in vivo anti-tumor response and T-cell accumulation. Additionally, expression of co-stimulatory ligands complementary to the second-generation CAR provides an optimal balance of cytolytic activity and T-cell accumulation resulting in superior anti-tumor function. The combination of 19-28z CAR with 4-1BBL was associated with activation of the endogenous Interferon-β (IFNβ) pathway in an IRF7-dependent manner. This enabled very small T-cell doses to eradicate systemic established leukemia in a xenogeneic model. The unexpected role of the IRF7/IFNβ pathway provides insight into the synergy behind co-stimulatory molecules in T cell activation and a novel mechanism through which engineered T cells can increase tumor control.

High-dose cyclophosphamide (Cy) and G-CSF are widely used to mobilize hemopoietic stem cells for treating patients with high-dose chemotherapy and autologous stem cell transplantation (ASCT). Because lymphocyte count in the graft collected after Cy-G-CSF treatment is an independent survival factor after ASCT for patients with multiple myeloma, our purpose was to study how Cy-G-CSF treatment affects the phenotype and function of T cells in patients with multiple myeloma. Cy induced a 3-fold decrease of T cell counts with a slow and partial T cell recovery of one-third at the time of hemopoietic stem cell collection. Cy-G-CSF treatment did not affect the relative ratios of central memory, effector memory, and late effector CD4+ or CD8+ T cells, but a decrease in the percentage of naive CD4+ cells was observed. The percentages of CD25+ cells increased 2- to 3-fold in CD4+ and CD8+ T cells, the former including both activated CD25low and CD25high cells. CD4+CD25high cells were regulatory T cells (Treg) that expressed high levels of FOXP3, CTLA-4, and GITR and displayed in vitro suppressive properties. The recovery of Treg absolute counts after Cy-G-CSF treatment was higher than the recovery of other lymphocyte subpopulations. In conclusion, Cy-G-CSF treatment induces a severe T cell count decrease without deleting Treg, which are potent inhibitors of antitumor response. The present data encourage novel therapeutic strategies to improve T cell recovery following ASCT while limiting Treg expansion.

International audience; 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.

Current T-cell engineering approaches redirect patient T cells to tumors by transducing them with antigen-specific T-cell receptors (TCRs) or chimeric antigen receptors (CARs) that target a single antigen. However, few truly tumor-specific antigens have been identified, and healthy tissues that express the targeted antigen may undergo T cell-mediated damage. Here we present a strategy to render T cells specific for a tumor in the absence of a truly tumor-restricted antigen. T cells are transduced with both a CAR that provides suboptimal activation upon binding of one antigen and a chimeric costimulatory receptor (CCR) that recognizes a second antigen. Using the prostate tumor antigens PSMA and PSCA, we show that co-transduced T cells destroy tumors that express both antigens but do not affect tumors expressing either antigen alone. This 'tumor-sensing' strategy may help broaden the applicability and avoid some of the side effects of targeted T-cell therapies.

High-dose melphalan (HDM) followed by autologous stem cell transplantation (ASCT) is a standard treatment for patients with multiple myeloma. However, lymphocyte reconstitution is impaired after HDM. Recent work has suggested that the lymphopenia period occurring after various immunosuppressive or chemotherapy treatments may provide an interesting opportunity for adoptive antitumor immunotherapy. The objective of this study was to determine an immunotherapy window after HDM and ASCT, evaluating T cell lymphopenia, and measuring circulating immune cytokine concentrations in patients with multiple myeloma. The counts of T cell subpopulations reached a nadir at day 8 post-ASCT (day 10 post-HDM) and recovered by day 30. IL-6, IL-7, and IL-15 plasma levels increased on a median day 8 post-ASCT, respectively, 35-fold, 8-fold, and 10-fold compared with pre-HDM levels (p ≤ 0.05). The increases in IL-7 and IL-15 levels were inversely correlated to the absolute lymphocyte count, unlike monocyte or myeloid counts. Furthermore, we have shown that CD3 T cells present in the ASC graft are activated, die rapidly when they are cultured without cytokine in vitro, and that addition of IL-7 or IL-15 could induce their survival and proliferation. In conclusion, the early lymphodepletion period, occurring 4–11 d post-HDM and ASCT, is associated with an increase of circulating immune cytokines and could be an optimal window to enhance the survival and proliferation of polyclonal T cells present in the ASC autograft and also of specific antimyeloma T cells previously expanded in vitro.

Cancer-testis (CT) Ags are attractive targets for immunotherapeutic strategies since they are aberrantly expressed in malignant cells and not, or in limited number, in somatic tissues, except germ cells. To identify novel CT genes in multiple myeloma, we used Affymetrix HG-U133 gene expression profiles of 5 testis, 64 primary multiple myeloma cells (MMC), and 24 normal tissue samples. A 5-filter method was developed to keep known CT genes while deleting non-CT genes. Starting from 44,928 probe sets, including probe sets for 18 previously described CT genes, we have obtained 82 genes expressed in MMC and testis and not detected in more than 6 normal tissue samples. This list includes 14 of the 18 known CT genes and 68 novel putative CT genes. Real-time RT-PCR was performed for 34 genes in 12 normal tissue samples, 5 MMC samples, and one sample of five pooled testes. It has validated the CT status of 23 of 34 genes (67%). We found one novel “testis-restricted” gene (TEX14, expression in testis and tumor only), eight “tissue-restricted” (mRNA detected in one or two nongametogenic tissues), and seven “differentially expressed” (mRNA detected in three to six nongametogenic tissues) CT genes. Further studies are warranted to determine the immunogenicity of these novel CT Ag candidates.

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.

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-α 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.

International audience; OBJECTIVE: The aim of this study was to confer an antigen-presenting cell (APC) ability on multiple myeloma cell lines (HMCLs) using B7-1 and/or 4-1BBL gene transfer. MATERIALS AND METHODS: HMCLs were retrovirally transduced with B7-1 and/or 4-1BBL cDNAs. Allogeneic or autologous T cells were stimulated by coculture with B7-1- and/or 4-1BBL-transduced HMCLs in the presence of interleukin-2. T cell clones were obtained by limiting dilution. T-cell activation was assessed by interferon-gamma Elispot assays and cytotoxicity by (51)Cr release assays. RESULTS: Neither primary multiple myeloma cells (MMCs) nor HMCLs expressed B7-1 or 4-1BBL, and these molecules could not be induced by CD40 triggering. HMCLs failed to stimulate allogeneic or autologous T cells. Transduction of HMCLs with B7-1 and/or 4-1BBL retroviruses induced a high expression of B7-1 and 4-1BBL molecules and a strong T-cell activation ability. Long-term cultured CD8(+) T-cell lines could be obtained by stimulation with the autologous B7-1/4-1BBL XG-19 HMCL. These cytotoxic T lymphocytes (CTL) efficiently killed the autologous parental XG-19 HMCL as well as autologous primary MMCs and allogeneic HMCLs. They did not kill autologous CD34 cells and autologous EBV cell line or natural killer target K562 cells. Cloned CTL could recognize allogeneic HMCLs, demonstrating that a shared anti-MMC repertoire was expanded. CONCLUSION: Transduction with B7-1 and 4-1BBL retroviruses turned HMCLs into efficient APCs. It permitted the long-term expansion of autologous anti-tumor CTL with a shared anti-MMC repertoire, for one HMCL. These data suggest developing an immunotherapy using modified tumor cells in patients with multiple myeloma.

The lack of understanding of the interplay between hematopoietic stem cells (HSCs) and the immune system has severely hampered the stem cell research and practice of transplantation. Major problems for allogeneic transplantation include low levels of donor engraftment and high risks of graft-versus-host disease (GVHD). Transplantation of purified allogeneic HSCs diminishes the risk of GVHD, but results in decreased engraftment. Here we show that ex vivo expanded mouse HSCs efficiently overcame the major histocompatibility complex barrier and repopulated allogeneic recipient mice. An 8-day expansion culture led to a 40-fold increase of the allograft ability of HSCs. Both increased numbers of HSCs and culture-induced elevation of expression of the immune inhibitor CD274 (B7-H1 or PD-L1) on the surface of HSCs contributed to the enhancement. Our study indicates the great potential of utilizing ex vivo expanded HSCs for allogeneic transplantation, and suggests that the immune privilege of HSCs can be modulated.

3022 Background: Second generation chimeric antigen receptors (CARs) are recombinant receptors for antigen that retarget and reprogram T cell function. We and others have recently demonstrated that...

Adoptive T-cell therapy using chimeric antigen receptor (CAR) engineered T cells is a promising cancer treatment. First generation CARs include an scFv targeting a surface antigen and the CD3ζ chain to direct tumor cell killing. CAR transduced T cells however need appropriate costimulation to proliferate and persist. Here we assessed in a B-cell leukemia xenograft model, the anti-tumor activities of human T cells transduced with an anti-CD19 CAR harboring the zeta chain alone (19z1+), fused to the CD28 or 4-1BB cytoplasmic domain (1928z+), (19BBz+), along with 4-1BBL (19z1-4-1BBL+), or with CD28 and 4-1BBL (1928z-4-1BBL+). We observed total tumor regression in NALM-6 bearing NSG mice treated with 1928z-4-1BBL+ T cells and no or partial regression in the other T-cell groups, as measured by bioluminescence imaging. 1928z-4-1BBL+ T cells showed the highest bone marrow accumulation and persisted the most. Experiments utilizing purified T cell subsets revealed that naïve and central memory 1928z-4-1BBL+ CD4+ T cells are sufficient to trigger leukemia eradication and are necessary to support CD8+ T-cell in vivo expansion. 1928z-4-1BBL+ CD4+ T cells displayed reduced apoptosis and increased cytotoxicity compared to 1928z+ CD4+ T cells. Thus, constitutive 4-1BBL expression and CAR-mediated CD28 signaling afforded the most efficient costimulatory combination to generate long-lived T cells capable of eradicating aggressive leukemia.

We have developed an adoptive T cell therapy strategy for treating multiple myeloma using chimeric antigen receptors targeting CD56. CD56 is strongly expressed by malignant plasma cells in 70% of patients with myeloma and represents a potential immunotherapy target. CD56 is also expressed at lower levels on normal tissue types including neuronal cells, NK cells and a subset of activated T cells. A second generation CAR was constructed containing the scFv of the murine monoclonal antibody against human CD56 (N901) as well as the CD28 transmembrane and cytoplasmic signaling domains. CD56 CAR cells were generated by retroviral transduction of human T cells and showed antigen dependent proliferation and cytokine secretion in vitro when stimulated with CD56 positive myeloma cells. In vitro cytotoxicity assays showed significant lysis (40-50% lysis at effector to target ratios > 5:1) of CD56 positive myeloma cell lines compared with a control prostate specific membrane antigen (PSMA) targeted CAR. To further assess the antitumor activity of CD56 CARs in vivo we developed a systemic xenograft model of myeloma by injecting the OPM2 myeloma cell line, modified to express the firefly luciferase gene, intravenously into NOD/SCID Il2rαnull mice. Bioluminescence imaging showed tumor progression predominantly within the bone marrow recapitulating the human disease phenotype. If untreated hind limb paralysis occurred at approximately 35 days following injection of 3x106 tumor cells. Cohorts of mice were then treated by intravenous injection of either 1 or 5 x106 CD56 CAR cells or control PSMA CAR cells at 7 days following tumor injection, when disease was firmly established. At the 1x106 T cell dose tumor development was significantly delayed compared to controls (median survival of 49 days compared with 34 days respectively, p=0.02) but 7/8 mice eventually progressed and had to be euthanised. In contrast all mice receiving 5x106 cells (n=8) showed complete tumor regression and remained tumor free at 3 months. Interferon-α secreting CD56 CAR cells were detected in the peripheral blood of these mice and correlated with tumor bulk with numbers eventually declining to low levels that persisted even at 3 months. These results demonstrate for the first time the impressive anti-tumor efficacy of a CD56 targeted chimeric antigen receptor in a systemic xenograft model of myeloma. CD56 CAR therapy therefore represents an attractive immunotherapy option and its use in patients with relapsed refractory myeloma should be considered. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3499. doi:1538-7445.AM2012-3499

Human T cells transduced with a chimeric antigen receptor (CAR) composed of an antibody-derived scFv fragment and the CD3ζ chain can recognize and kill tumor cells on binding to the targeted membrane antigen. The co-transduction of a CAR along with CD80 and 4-1BBL induces auto-costimulation enabling high in vivo T cell expansion and tumor rejection in a prostate tumor model. Here we investigated this concept in T cells harboring either a first generation anti-CD19 CAR (19z1) or a second generation CAR (1928z), which additionally comprises the CD28 cytoplasmic domain. We compared the proliferation and anti-tumor activity of 19z1+, 19z1-4-1BBL+, 19z1-CD80+4-1BBL+, 1928z+ and 1928z-4-1BBL+ transduced T cells in a pro B cell leukemia model (NALM-6). Seven days after IV injection into NALM-6 bearing NOD/SCID/IL2Rγnull mice, 1928z-4-1BBL+ CD8 and CD4 T cells accumulated in the bone marrow and the spleen 100 times more than 19z1+ T cells and 10 times more than 1928z+ T cells, corroborating in vitro proliferative responses to repeated antigen exposure. An increased proportion of central memory CD8 T cells was observed in all groups treated with 4-1BBL-expressing cells. Within 15 days, in vivo bioluminescence imaging showed total tumor regression in the 1928z-4-1BBL+ T cell-treated group and partial regression in the other groups. Thus, constitutive 4-1BBL expression drives high proliferation of anti-tumor CD8 T cells, promoting central memory T cell persistence and tumor eradication.

The identification of novel tumor-associated antigens is critical for the development of immunotherapeutic strategies. Cancer-testis (CT) antigens represent attractive targets due to their restricted pattern of expression. More than 90 CT genes have been previously classified into four categories according to their expression profiles: testis-restricted (expression in testis and tumor samples only), “tissue restricted” (mRNA detected in 2 or fewer non-gametogenic tissues), “differentially expressed” (mRNA detected in three to six non-gametogenic tissues), and “ubiquitously expressed”. Among those, we previously reported that 18 CT genes were expressed by primary myeloma cells (MMC) of more than 10% of patients with multiple myeloma (MM). This study aimed at finding novel putative CT genes expressed in MM using cDNA microarray analysis and real-time RT-PCR validation. Gene expression profiles of 5 testis samples, 64 MMC, 7 normal memory B cell (MB), 7 normal bone marrow plasma cell samples and 23 normal tissue samples available on a public database were obtained using Affymetrix U133AB microarrays. Out of 45000 probe sets of Affymetrix U133 AB chips, we selected 16982 probe sets which had a “Present” Affymetrix Call in MMC of at least 6/64 patients and in 3/5 testis samples. In order to select genes with a similar pattern of expression than the known CT genes, we developed 4 independent filters making it possible to keep a high number of known CT genes while decreasing the total number of probe sets. Firstly, 2514 of 16982 probe sets had a ratio of the mean signal in MMC with a Present call / mean signal in MB > 2.5. Secondly, 541 of these 2514 probe sets had a Present call in less than 7 of the 23 normal tissues. Thirdly, 333 of these 541 probe sets had a ratio of the mean signal in MMC with a Present call / mean signal in MMC with an Absent call > 2.5. Fourthly, we removed genes whose expression profiles were discordant with different probe sets or discordant with data of the literature. The final probe set list contains 88 probe sets which include 13 of 18 known CT genes reported in MM, thus resulting in a 190-fold enrichment. The expression in 13 normal tissues and in MM samples of 21 out of these 75 putative novel CT genes was investigated by real time RT-PCR. Seven genes were ubiquitously expressed or poorly expressed in MMC samples and further deleted. According to the previously defined CT gene categories, we found one novel “testis-restricted” (TEX14), 8 “tissue-restricted” and 5 “differentially expressed” CT genes. Immunogenicity of one gene product - IGSF11 - was already demonstrated in other cancers by identifying a T-cell epitope. Two genes - NLGN4X and FAM133A - are located in X chromosome and 2 genes - CTNNA2 and FAM133A - are expressed only in brain and testis. In conclusion, by analyzing gene expression patterns with Affymetrix microarrays, we found 75 novel putative CT antigen candidates expressed in MMC of 10 to 100% of patients. Real time RT-PCR validation made it possible to confirm the CT status of 14 genes out of the 21 tested. Further studies are warranted to determine their immunogenicity.

Background. T-cell reconstitution is usually delayed after UCB transplantation, in addition to an impaired thymopoiesis and late memory T cell skewing. NK cells are usually variable, with an initial increase in % and absolute number. The role of these cells is unclear, particularly on tumor control, maybe participating to the T-cell lymphopenia. Patients and methods. F rom 01/03 to 04/07, we retrospectively analysed data concerning lymphocyte recovery for patients having MM and AML, who received allogenic transplantation (AT). We excluded patients with progressive disease before AT, with short follow-up (200 starting at D230 as compared to the PBSC group (D150 for MM and D90 for AML). B cell recovery was faster in the UCB group [MM/UCB and AML/UCB, >200/mm3 at D230 and D150 as compared to D300 and D230 respectively in MM/PBSC and AML/PBSC (p=NS)]. Conclusion. NK cells increased after UBC more intensively and rapidly than after PBSC AT. T-cell recovery appeared to be associated to pre-treatment intensity and use of ATG. CD4, CD8 counts were highly reduced in UCB compared to PBSC except for CD4+ in AML/UCB. B-cell recovery is not different between both groups (i.e. UCB and PBSC). NK cells from 2 patients are now collected for analysis of their functions particularly their anti-tumoral effect in vitro.

Cancer-testis (CT) antigens are expressed in testis and malignant tumors, but rarely in non-gametogenic tissues. Due to this pattern, they represent attractive targets for cancer vaccination approaches. The aims of the present study were (1) to assess for the first time the expression of CT genes on a pangenomic basis in multiple myeloma (MM), (2) to provide selection strategies of CT antigens for clinical vaccination trials and (3) to assess the impact of CT gene expression on event-free survival. We report here the expression pattern of CT genes in purified MM cells (MMC) of 64 patients with newly-diagnosed MM, 12 patients with monoclonal gammopathy of unknown significance (MGUS), in normal plasma cell and B cell samples and in 20 MMC lines, using gene expression profiling (GEP). Out of 46 CT genes interrogated by the Affymetrix HG U133 Set arrays, 35 were expressed in MMC of at least one patient, according to the Affymetrix “present” call (frequency range: 2% – 66%). Of these, 24 CT genes were expressed in more than 5% of the MMC samples and 25 are located on chromosome X. MMC of 98% of the patients expressed 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 to circumvent tumor escape mechanisms and immune tolerance - could be obtained in MMC of 67% of the patients. Thus, gene expression profiling can be used to select CT antigens as vaccination targets in individual patients. In a series of MMC from 111 patients treated with the same high-dose chemotherapy and autologous peripheral blood stem cell transplantation protocol and having a median two-year follow-up, we found that the expression of six CT genes, i.e. CTAG-1B, CTAG-2, MAGE-A1, MAGE-A2, MAGE-A3 and MAGE-A6 was associated with a shorter event-free survival (EFS). Furthermore, considering only the 25 CT genes encoded by chromosome X, a CT-Xhigh cluster comprising MMC of one third of the patients (35 of 111) could be defined using a binary hierarchical clustering based on Affymetrix call. Patients in the CT-Xhigh cluster had a shorter EFS (median 13 months) compared to patients in the CT-Xlow cluster (median 18 months, P = .003). The CT-Xhigh clsuter included more patients with a stage III disease (P = .004). These results confirm data from previous studies indicating that patients expressing some CT genes located on chromosome X have a poor outcome.

New therapeutic approaches have been developed to treat follicular lymphoma (FL), the most common type of indolent non-Hodgkin’s lymphoma which should still be regarded as an incurable malignancy with a relentless relapsing course, except in the subset of patients with localized disease. For vaccination purposes, dendritic cells (DC) generated and loaded with tumor antigens ex vivo are focus of attention for already 10 years. In 07/04 we started a phase II study to evaluate a vaccination strategy based on multiple injections of autologous DC loaded with tumor lysate (DC-lysate) in FL patients. We reported here the results we observed for the first 7 enrolled patients (3F/4M, age: 44–61; 1 to 8 previous lines of treatment, including autologous PBSC transplant in 2 pts) who completed their treatment consisting in 5 to 7 DC-lysate vaccinations. At time of inclusion an excisional biopsy of a peripheral lymph node was performed in all patients; tumoral B cells were isolated by negative T cell depletion (using immunomagnetic beads and anti-CD3 antibodies) and then lysed by 5 freezing/thawing cycles to produce tumor lysate. Immature DC were obtained from mononuclear cells collected after Cyclophosphamide (2g/m2) and G-CSF (10μg/kg) administration, cultured for 5 days with GM-CSF and IL-4, pulsed with lysate, and then induced to mature with TNFa and PGE2 for 24h. All DC preparation fitted the quality criteria of viability ≥60%, ≤20% CD14+ cells, ≥60% CD83+ cells. For each vaccine 107 DC-lysate were administered, both intravenously [IV] (5×106 cells) and intradermally [ID] (5×106 cells). Vaccinations were safe and well tolerated. All patients developed significant delayed-type hypersensitivity responses to DC-lysate after several vaccines administration, testifying of the induction of a response. Among the 4 patients vaccinated with measurable disease, 2 who presented with low tumor burden (1 stage I, 1 stage II) achieved CR (with normal CT and absolutely no more FDG uptake on PET), so far persistent 3 and 6 months after the last vaccine, while disease progressed in the 2 remaining patients who presented respectively a stage IV and stage II disease at time of vaccination. The 3 patients vaccinated while in CR showed no disease progression at last tumor evaluation (9 to 12 months post last vaccination). This study demonstrated that DC-lysate vaccines might be efficient in FL patients with low tumor burden disease. Because the cause of disease recurrence is the presence of minimal residual disease after conventional treatments, the adjuvant setting might be the most appropriate therapeutic strategy for active specific immunotherapy, when the immunosuppressive effects of bulky disease are virtually absent and when the effector-target ratio is favorable.

High-dose chemotherapy (HDC) supported by autograft of hematopoietic progenitors (HP) is a standard therapy for patients with multiple myeloma (MM). High-dose cyclophosphamide (CTX) and G-CSF are widely used to collect HP. As the number of lymphocytes in the autograft is a powerful prognostic factor in patients with MM, our purpose was to study how CTX-G-CSF treatment affects the phenotype and function of T cells, in particular regulatory T cells (Treg), in 15 patients with MM. CTX induced severe T cell immunosuppression with a slow and partial T-cell recovery (a threefold decrease) at the time of HP collection. CTX-G-CSF treatment did not affect the percentages of central memory (CD45RA−, CCR7+), effector memory (CD45RA−, CCR7−), and late effector (CD45RA+, CCR7−) CD4 or CD8 T cells but a decrease of naïve CD4 cells (CD45RA+, CCR7+) was found. The percentages of CD25+ cells increased two- to threefold in CD4 or CD8 T cells, respectively. Post-CTX treatment CD4CD25+ cells included both activated CD4CD25low cells and CD4CD25high T cells. The latter were Treg because they expressed high level of FOXP3 and membrane CTLA-4 mRNA and protein and displayed functional suppressor function. In CTX-G-CSF leukaphereses from 15 patients with MM, the mean Treg number was one fifth that of CD34 and the CD3, CD4 and CD8 numbers respectively 3 fold, 2 fold and equal that of CD34. Post-CTX-G-CSF treatment CD3 cells did not cell cycle in vivo and died in short-term culture in vitro. Adding IL-2 or IL-15 induced their survival and cell cycle, and stimulation with anti-CD3 MoAb led to efficient growth in vitro. These results suggest that following CTX-G-CSF treatment, CD3 cells are preactivated in vivo and do not cell cycle, likely due to a lack of T cell growth factors in vivo. The current data indicate that CTX-G-CSF treatment profoundly affects T cell function without eliminating Treg. The persistence of Treg could be explained by an opposite effect of CTX known to kill Treg and of G-CSF amplifying Treg. Given the major impact of lymphocyte count on patients’ survival post HDC and HP and T cell graft, the present data invite to define novel therapeutic strategies to improve T cell recovery in vivo while limiting Treg expansion.

SummaryT cell engineering is a powerful means to rapidly generate anti-tumor T cells. The costimulatory properties of second-generation chimeric antigen receptors (CARs) determine the overall potency of adoptively transferred T cells. Using an in vivo “stress test” to challenge CD19-targeted T cells, we studied the functionality and persistence imparted by seven different CAR structures providing CD28 and/or 4-1BB costimulation. One configuration, which uses two signaling domains (CD28 and CD3ζ) and the 4-1BB ligand, provided the highest therapeutic efficacy, showing balanced tumoricidal function and increased T cell persistence accompanied by an elevated CD8/CD4 ratio and decreased exhaustion. Remarkably, induction of the IRF7/IFNβ pathway was required for optimal anti-tumor activity. Thus, 1928z-41BBL T cells possess strikingly potent intrinsic and immunomodulatory qualities.

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.