Vaccination of melanoma patients with peptide- or tumor lysate-pulsed dendritic cells

Induction of ovarian tumor-specific CD8+ cytotoxic T lymphocytes by acid-eluted peptide-pulsed autologous dendritic cells

OBJECTIVE

To evaluate the potential of dendritic cells pulsed with acid-eluted peptides derived from autologous ovarian cancer cells for eliciting a tumor-specific cytotoxic T cell response in women with advanced ovarian cancer.

METHODS

CD8+ T lymphocytes derived from peripheral blood mononuclear cells stimulated in vitro with autologous ovarian tumor peptide-pulsed dendritic cells were tested for their ability to induce an HLA class I-restricted cytotoxic T lymphocyte response against autologous tumor cells. To correlate cytotoxic activity by cytotoxic T lymphocytes with T cell phenotype, we used two-color flow cytometric analysis of surface markers and intracellular cytokine expression (interferon-gamma versus interleukin-4).

RESULTS

CD8+ cytotoxic T lymphocyte responses against autologous ovarian tumor cells were elicited in three consecutive women who had advanced ovarian cancer. Although cytotoxic T lymphocyte populations from all women expressed strong cytolytic activity against autologous tumor cells, they did not lyse autologous lymphoblasts or Epstein-Barr virus-transformed cell lines, and they showed negligible cytotoxicity against the natural killer-sensitive cell line K-562. Cytotoxicity against the autologous tumor cells was significantly inhibited by anti-HLA class I (W6/32) and anti-HLA-A2 (BB7-2) monoclonal antibodies. CD8+ cytotoxic T lymphocytes expressed variable levels of CD56 and preferentially expressed interferon-gamma rather than interleukin-4.

CONCLUSIONS

Peptide-pulsed dendritic cells induced specific CD8+ cytotoxic T lymphocytes that killed autologous tumor cells from women with advanced ovarian cancer. This finding might contribute to the development of active or adoptive immunotherapy for residual or resistant ovarian cancer after standard surgery and cytotoxic treatment.

Mage-3 and influenza-matrix peptide-specific cytotoxic T cells are inducible in terminal stage HLA-A2.1+ melanoma patients by mature monocyte-derived dendritic cells

Dendritic cell (DC) vaccination, albeit still in an early stage, is a promising strategy to induce immunity to cancer. We explored whether DC can expand Ag-specific CD8+ T cells even in far-advanced stage IV melanoma patients. We found that three to five biweekly vaccinations of mature, monocyte-derived DC (three vaccinations of 6 x 106 s.c. followed by two i.v. ones of 6 and 12 x 106, respectively) pulsed with Mage-3A2.1 tumor and influenza matrix A2. 1-positive control peptides as well as the recall Ag tetanus toxoid (in three of eight patients) generated in all eight patients Ag-specific effector CD8+ T cells that were detectable in blood directly ex vivo. This is the first time that active, melanoma peptide-specific, IFN-gamma-producing, effector CD8+ T cells have been reliably observed in patients vaccinated with melanoma Ags. Therefore, our DC vaccination strategy performs an adjuvant role and encourages further optimization of this new immunization approach.

Cytokines in cancer therapy

Cytokines are crucial factors in the activation and development of immune response, including responses against tumor cells. Interleukin (IL)-2, a T-cell growth factor, has been largely used to activate T and NK cells in vivo and to maintain such an activation for therapeutic purposes. When given to patients, IL-2 was shown to cause clinical responses, especially in metastatic melanoma and renal cancer patients, though its mechanism of action could not be completely elucidated. Cytokines (IL-2, IL-12, GM-CSF) are also used as natural adjuvants of vaccines of various formulation to help in activating and maintaining an antitumor immune response. This review summarizes findings deriving from the use of cytokines in cancer therapy and provides insights into future approaches when a more appropriate use of cytokines, together with new vaccines, is likely to improve clinical outcome.

Development of dendritic-cell based prostate cancer vaccine

Available treatments for metastatic prostate cancer have failed to demonstrate significant curative potential. Current efforts are now directed towards developments of novel strategies for the treatment of metastatic prostate cancer. Cancer immunotherapeutic strategies utilize patient immune system components to kill cancer cells. This review discusses progress in active specific immunotherapeutic approaches as potential alternative methods in the treatment of metastatic prostate cancer. One of the newest advances in cancer immunotherapy is the use of dendritic cells as the vehicle to deliver cancer antigens for an effective in vivo T cell activation. The development of dendritic cell-based prostate cancer vaccine, as well as results of several clinical trials in prostate cancer involving the administration of peptide-pulsed autologous dendritic cell pulsed are discussed.

Antitumor vaccination using peptide based vaccines

Cytotoxic T Lymphocytes (CTLs) recognize Major Histocompatibility Complex (MHC) class I in complex with peptides. Peptides derived from Tumor Associated Antigens (TAAs) are therefore targets for tumor rejection. A number of TAAs were identified in the last decade from human and murine tumors. Here we summarize the methods for TAA and peptide identification, the nature of TAA peptides and the making of antitumor vaccines.

Autologous, allogeneic tumor cells or genetically engineered cells as cancer vaccine against melanoma

Melanoma is a prototype of immunogenic tumor to which various types of immunotherapy have been applied extensively over the past decades. Melanoma vaccines are designed for the purpose of immune modulation and subsequent anti-tumor effects in the process of an active specific immunotherapy. Previous attempts of these vaccines include immunization with whole tumor cells/cell lysates admixed with nonspecific adjuvants. While these vaccines generated enhanced anti-tumor immunity in a subset of patients, some of which showing prolonged survival compared to historical controls, no clinical benefit has so far been demonstrated in a properly controlled phase III study. New-generation melanoma vaccines, which are based on genetic modifications of tumor cells to express cytokines, generated long-lasting systemic anti-tumor immunity in animal models. Translation of these preclinical results primarily into melanoma patients with advanced diseases, shows the potential of these vaccines to induce systemic anti-tumor immune responses and in some instances tumor regression with acceptably low toxicity. Higher efficacy of this novel vaccine approach would be expected when used in a postsurgical adjuvant setting when the tumor load is small. Also other novel vaccine approaches such as dendritic cell-based therapy hold promise for the treatment of melanoma. But the clinical value of all these new approaches has to be analysed in prospectively randomized clinical studies.

Dendritic cell based tumor vaccines

Dendritic cells (DC) constitute a unique system of cells that induce, sustain and regulate immune responses. Distributed as sentinels throughout the body, DC are poised to capture antigen (Ag), migrate to draining lymphoid organs, and, after a process of maturation, select Ag-specific lymphocytes to which they present the processed Ag, thereby inducing immune responses. DC present Ag to CD4(+) T cells which in turn regulate multiple effectors, including CD8(+) cytotoxic T cells, B cells, NK cells, macrophages and eosinophils, all of which contribute to the protective immune responses. Several key features of the DC system may be highlighted: (1) the existence of different DC subsets that share biological functions, yet display unique ones such as polarization of T cell responses towards Type 1 or Type 2 or regulation of B cell responses; (2) the functional specialization of DC according to their differentiation/maturation stages; and (3) the plasticity of DC which is determined by the microenvironment (e.g. cytokines) and may manifest as (i) the final differentiation into either DC (enhanced antigen presentation) or macrophage (enhanced antigen degradation); (ii) the induction of immunity or tolerance; and (iii) the polarization of T cell responses. Because of these unique properties, DC represent both vectors and targets for immunological intervention in numerous diseases and are optimal candidates for vaccination protocols both in cancer and infectious diseases.

Management of malignant melanoma: new developments in immune and gene therapy

Thus far, the use of classical anti-cancer treatment modalities had only rarely a beneficial impact on the prognosis of patients with metastatic melanoma. We as physicians have therefore the obligation as well as the chance to develop and test new therapeutic strategies. Our growing knowledge about the genetic basis of melanoma provides one platform to fulfil this task. Another one comes from our increasing understanding of the molecular and cellular mechanisms involved in the induction/modulation of immune responses, as well as the progress made in the field of identification of melanoma antigens, and allows for the development of a new generation of vaccines. The aim of this article is to discuss several of these new concepts towards the use of immune and gene therapy of melanoma.

Mature dendritic cells pulsed with freeze–thaw cell lysates define an effective in vitro vaccine designed to elicit EBV-specific CD4+ and CD8+ T lymphocyte responses

Immunotherapy trials targeting the induction of tumor-reactive T-cell responses in cancer patients appear to hold significant promise. Because nonmutated lineage-specific antigens and mutated idiotypic antigens may be coexpressed by tumor cells, the use of autologous tumor material to promote the broadest range of antitumor T-cell specificities has significant clinical potential in cancer vaccination trials. As a model for vaccination in the cancer setting, we chose to analyze the promotion of T-cell responses against Epstein-Barr virus (EBV)-transformed B-lymphoblastoid cell line (B-LCL)–derived antigens in vitro. A series of bulk antigenic formats (freeze–thaw lysate, trifluoroacetic acid lysate, extracted membranes, affinity-purified MHC class I– and class II–presented peptides, acid-eluted peptides) prepared from EBV B-LCLs were tested for their ability to stimulate EBV B-LCL–reactive CD4+ and CD8+ T lymphocytes in vitro when pulsed onto autologous dendritic cells (DCs). DC presentation of freeze–thaw lysate material derived from (either autologous or allogeneic) EBV B-LCLs with an Mr of 10 kd or larger stimulated optimal anti-EBV B-LCL responsiveness from freshly isolated CD4+ and CD8+ peripheral blood T cells. These in vivo “memory” T-cell responses were observed only in EBV-seropositive donors. CD4+ T-cell responses to lysate-pulsed DCs were Th1 type (ie, strong interferon-γ and weak interleukin-5 responses). While CD8+ T-cell responses were also observed in interferon-γ Elispot assays and in cytotoxicity assays, these responses were of low frequency unless the DC stimulators were induced to “mature” after being fed with tumor lysates. Optimal-length, naturally processed, and MHC class I– or class II–presented tumor peptides were comparatively poorly immunogenic in this model system.

Progress in active-specific immunotherapy of brain malignancies

Despite the significant advances in neurosurgical techniques and oncology treatment regimens, the prognosis of patients with brain malignancies remains dismal. Brain tumours remain as lethal in the beginning of this new millennium as they were 30 years ago. Among the promising treatment modalities being tested are various immunotherapeutic approaches. Development of cancer vaccines, also known as active-specific immunotherapy, for malignant brain tumours is summarised in this review. Understanding the mechanisms behind vaccinations and the initiation of immune response have helped the design and improvement of the efficacy of clinical vaccines. The emergence of the antigen-presenting properties of dendritic cells brings the cancer vaccine field into a new generation. Preclinical work on the use of dendritic cell-based vaccine for malignant brain tumours are encouraging. The move from these preliminary studies to the clinic is anticipated with high hope.

Expression of the SART3 tumor-rejection antigen in brain tumors and induction of cytotoxic T lymphocytes by its peptides

The authors recently reported on the SART3 tumor-rejection antigen, which possesses epitopes that can induce cytotoxic T lymphocytes (CTLs) in patients with epithelial cancer. To explore a new modality for treatment of patients with brain tumors, this study investigated the expression of the SART3 antigen in patients with brain tumors and the ability of SART3 peptides to induce CTLs from peripheral blood mononuclear cells (PBMCs) of these patients. The SART3 antigen was detected in the cytoplasmic fraction of all 18 glioma cell lines examined and in the majority (31 of 34; 91%) of brain tumor tissues irrespective of their histologies. It was also expressed in the nuclear fraction of all 18 glioma cell lines and in the majority (26 of 34; 76%) of brain tumor tissues. In contrast, the SART3 was not expressed in nontumorous brain tissues. Cytotoxic T lymphocytes were induced in patients with glioma by stimulation with two epitope peptides of SART3. These CTLs could eliminate glioma cells in a HLA-A24-restricted manner. Therefore, the SART3 peptides may be appropriate molecules for use in peptide-based specific immunotherapy of HLA-A24+ patients with brain tumors.

Targeted antigen delivery to antigen-presenting cells including dendritic cells by engineered Fas-mediated apoptosis

Immunity to tumors as well as to viral and bacterial pathogens is often mediated by cytotoxic T lymphocytes (CTLs). Thus, the ability to induce a strong cell-mediated immune response is an important requirement of novel immunotherapies. Antigen-presenting cells (APCs), including dendritic cells (DCs), are specialized in initiating T-cell immunity. Harnessing this innate ability of these cells to acquire and present antigens, we sought to improve antigen presentation by targeting antigens directly to DCs in vivo through apoptosis. We engineered Fas-mediated apoptotic death of antigen-bearing cells in vivo by co-expressing the immunogen and Fas in the same cell. We then observed that the death of antigen-bearing cells results in increased antigen acquisition by APCs including DCs. This in vivo strategy led to enhanced antigen-specific CTLs, and the elaboration of T helper-1 (Th1) type cytokines and chemokines. This adjuvant approach has important implications for viral and nonviral delivery strategies for vaccines or gene therapies.

Mature dendritic cells pulsed with freeze–thaw cell lysates define an effective in vitro vaccine designed to elicit EBV-specific CD4+ and CD8+ T lymphocyte responses

Immunotherapy trials targeting the induction of tumor-reactive T-cell responses in cancer patients appear to hold significant promise. Because nonmutated lineage-specific antigens and mutated idiotypic antigens may be coexpressed by tumor cells, the use of autologous tumor material to promote the broadest range of antitumor T-cell specificities has significant clinical potential in cancer vaccination trials. As a model for vaccination in the cancer setting, we chose to analyze the promotion of T-cell responses against Epstein-Barr virus (EBV)-transformed B-lymphoblastoid cell line (B-LCL)–derived antigens in vitro. A series of bulk antigenic formats (freeze–thaw lysate, trifluoroacetic acid lysate, extracted membranes, affinity-purified MHC class I– and class II–presented peptides, acid-eluted peptides) prepared from EBV B-LCLs were tested for their ability to stimulate EBV B-LCL–reactive CD4+ and CD8+ T lymphocytes in vitro when pulsed onto autologous dendritic cells (DCs). DC presentation of freeze–thaw lysate material derived from (either autologous or allogeneic) EBV B-LCLs with an Mr of 10 kd or larger stimulated optimal anti-EBV B-LCL responsiveness from freshly isolated CD4+ and CD8+ peripheral blood T cells. These in vivo “memory” T-cell responses were observed only in EBV-seropositive donors. CD4+ T-cell responses to lysate-pulsed DCs were Th1 type (ie, strong interferon-γ and weak interleukin-5 responses). While CD8+ T-cell responses were also observed in interferon-γ Elispot assays and in cytotoxicity assays, these responses were of low frequency unless the DC stimulators were induced to “mature” after being fed with tumor lysates. Optimal-length, naturally processed, and MHC class I– or class II–presented tumor peptides were comparatively poorly immunogenic in this model system.

In vitro induction of tumor-specific human lymphocyte antigen class I-restricted CD8 cytotoxic T lymphocytes by ovarian tumor antigen-pulsed autologous dendritic cells from patients with advanced ovarian cancer

OBJECTIVE

The purpose of this study was to evaluate the potential of dendritic cells pulsed with whole-tumor extracts derived from autologous ovarian cancer cells in eliciting a tumor-specific cytotoxic T-cell response in vitro from patients with advanced ovarian cancer.

STUDY DESIGN

CD8(+) T lymphocytes stimulated in vitro with autologous ovarian tumor lysate-pulsed dendritic cells were tested for their ability to induce a human leukocyte antigen class I-restricted cytotoxic T-lymphocyte response able to specifically kill autologous tumor cells in standard 6-hour chromium 51 cytotoxicity assays. In addition, to correlate cytotoxic activity by cytotoxic T-lymphocytes with a particular lymphoid subset, 2-color flow cytometric analysis of intracellular cytokine expression (interferon gamma and interleukin 4) at the single-cell level was performed.

RESULTS

Cytotoxic T lymphocytes specific for autologous ovarian tumor cells were elicited from 3 patients with advanced ovarian cancer. Although cytotoxic T-lymphocyte populations expressed strong cytolytic activity against autologous tumor cells, they did not lyse concanavalin A-stimulated autologous lymphocytes or autologous Epstein-Barr virus-transformed lymphoblastoid cell lines and showed negligible cytotoxicity against the natural killer cell-sensitive cell line K-562. Cytotoxic effect against the autologous tumor cells was inhibited by an anti-human leukocyte antigen class I monoclonal antibody (W6/32). It is interesting that CD8(+) cytotoxic T lymphocytes expressed variable levels of CD56, a marker that may be associated with high cytotoxic activity. Finally, most of the tumor-specific CD8(+) T cells exhibited a T(H)1 cytokine bias, and a high percentage of interferon gamma expressors among cytotoxic T lymphocytes was correlated with higher cytotoxic activity.

CONCLUSION

These data show that tumor lysate-pulsed dendritic cells can consistently induce in vitro specific CD8(+) cytotoxic T lymphocytes able to kill autologous tumor cells from patients with advanced stage ovarian cancer. This novel approach may have important implications for the treatment of residual or resistant disease with active or adoptive immunotherapy after standard surgical and cytotoxic treatment.

Efficient gene transfer to human peripheral blood monocyte-derived dendritic cells using human immunodeficiency virus type 1-based lentiviral vectors

Dendritic cells (DCs) are potent antigen-presenting cells and are capable of activating naive T cells. Gene transfer of tumor antigen and cytokine genes into DCs could be an important strategy for immunotherapeutic applications. Dendritic cells derived from peripheral blood monocytes do not divide and are therefore poor candidates for gene transfer by Moloney murine leukemia virus (Mo-MuLV)-based retroviral vectors. Lentiviral vectors are emerging as a powerful tool for gene delivery into dividing and nondividing cells. A three-plasmid expression system pseudotyped with the envelope from vesicular stomatitis virus (VSV-G) was used to generate lentiviral vector particles expressing enhanced green fluorescent protein (EGFP). Peripheral blood monocyte-derived DCs were cultured in the presence of GM-CSF and IL-4 and transduced with lentiviral or Mo-MuLV-based vectors expressing EGFP. FACS analysis of lentiviral vector-transduced DCs derived either from normal healthy volunteers or from melanoma patients demonstrated transduction efficiency ranging from 70 to 90% compared with 2-8% using Mo-MuLV-based vectors pseudotyped with VSV-G. Comparison of lentiviral vectors expressing EGFP driven by CMV or human PGK promoters showed similar levels of transgene expression. Lentiviral vector preparations produced in the absence of HIV accessory proteins transduced DCs at efficiencies equal to vectors produced with accessory proteins. Alu-HIV-1 LTR PCR demonstrated the genomic integration of the lentiviral vector in the transduced DCs. Transduced cells showed characteristic dendritic cell phenotype and strong allostimulatory capacity and maintained the ability to respond to activation signals such as CD40 ligand and lipopolysaccharide. These results provide evidence that lentiviral vectors are efficient tools for gene transfer and expression in monocyte-derived DCs that could be useful for immunotherapeutic applications.

Differentiation of antigen-presenting cells (dendritic cells and macrophages) for therapeutic application in patients with lymphoma

The recent clinical trial in lymphoma using tumor antigen-loaded DCs (Hsu et al, Nature Med 1996; 2: 52) demonstrates the efficiency of the use of professional antigen presenting cells (APCs) for taking up, processing and presenting tumor protein in a vaccine strategy in cancer. However, the production of large quantities of clinical grade APCs remains to be resolved. Here, we describe that both dendritic cells (DCs) and macrophages (MOs) can be efficiently differentiated in large numbers from lymphoma patients in spite of their disease and previous therapy. These cells were produced using the VAC and MAK cell processors according to standard operating procedures. DCs and MOs were differentiated from circulating monocytes in gas permeable hydrophobic bags, with 2% autologous serum and in the presence of GM-CSF and IL-13 or GM-CSF alone, respectively. DCs and MOs were then purified by counter flow centrifugation. Phenotypic, morphological and functional analysis showed that cells differentiated from patients with lymphoma present quite similar features to DCs and MOs produced from monocytes of healthy donors. Moreover, we show that MOs, when combined with CD20 antibody (Rituximab), can efficiently engulf tumor cells and propose that a such combination could be used for initiating a clinical trial in lymphoma. Thus, the possibility of producing functional DC and MOs in large amounts in conditions compatible with therapeutic application will allow the development of new immune strategies to eradicate lymphoma.

Poxvirus as a vector to transduce human dendritic cells for immunotherapy: abortive infection but reduced APC function

Dendritic cells (DC) are potent antigen-presenting cells (APC). Ongoing preclinical and clinical studies exploit this capacity for the immunotherapy of tumors. We tested vaccinia virus (VV) as a vector to transduce human DC. Immature and mature DC were prepared from blood monocytes and infected with (1) recombinant VV expressing GFP to analyze infection rates, virus replication in DC and the effect of infection on DC phenotype and (2) recombinant VV expressing beta-galactosidase (betaGAL) under the control of viral early, intermediate and late promoters to analyze the poxvirusdriven gene expression. While the infection rate in DC was comparable to a permissive fibroblast cell line, viral betaGAL gene expression was limited to early promoters. Genes under the control of virus late promoters were not expressed by VV in DC, indicating an abortive infection. VV infection selectively reduced the surface expression of the costimulatory molecule CD80 and the DC maturation marker CD83 on mature DC while other surface molecules including CD86 and MHC remained unchanged. In line with this finding, there was a pronounced reduction in the capacity of VV-infected DC to stimulate allogeneic or autologous T cells in mixed lymphocyte reactions. Furthermore, VV infection inhibited the maturation of immature DC after exposure to proinflammatory cytokines. These results indicate that VV-derived vectors may have complex effects on their target cells. In the case of DC used for immunotherapy, this may be detrimental to their function as potent APC and particularly their capacity to activate T helper cells.

In vivo antigen loading and activation of dendritic cells via a liposomal peptide vaccine mediates protective antiviral and anti-tumour immunity

Initiation of antiviral and anti-tumour T cell responses is probably achieved mainly by dendritic cells (DC) transporting antigen from the periphery into organised lymphoid tissues. To develop T cell vaccines it is, therefore, important to understand the accessibility of the antigen to DC in vivo and whether DC are activated by vaccination. Here we have evaluated the immunogenicity of a liposomal vaccine formulation with antigenic peptides derived from the glycoprotein of the lymphocytic choriomeningitis virus. Liposome-encapsulated peptides were highly immunogenic when administered intradermally and elicited protective antiviral immunity. After intradermal injection, liposomes formed antigen depots which facilitated long-lasting in vivo antigen loading of dendritic cells almost exclusively in the local draining lymph nodes. The immunogenicity of the liposomal peptide vaccine was further enhanced by incorporation of immunostimulatory oligonucleotides leading to activation of DC. This optimised liposomal peptide vaccine elicited also anti-tumour immunity and induced CTL responses comparable to adoptively transferred, peptide-presenting DC. Thus, our data show that liposomal formulations of peptide vaccines are highly effective at direct in vivo antigen loading and activation of DC leading to protective antiviral and anti-tumour immune responses.

Identification of a new HLA-A(*)0201-restricted T-cell epitope from the tyrosinase-related protein 2 (TRP2) melanoma antigen

For the development of peptide-based immunotherapies, the identification of additional tumor antigens and T-cell epitopes is required. Because HLA-A(*)0201 is the most common allele in Caucasians, who represent the majority of patients with melanomas, 6 peptides carrying an HLA-A(*)0201 motif were synthesized from tyrosinase-related protein-2 (TRP2) melanoma antigen and tested for binding affinity to the HLA allele using processing-defective T2 cells. These peptides were then pulsed onto autologous dendritic cells and used to stimulate in vitro CD8(+)-enriched T cells isolated from peripheral blood of HLA-A(*)02(+) healthy donors or melanoma patients for the induction of specific cytotoxic T lymphocytes (CTLs). One peptide, TRP2(288-296) (SLDDYNHLV), the best HLA-A(*)0201 binder, elicited specific CTLs from 1 of 4 patients and 3 of 4 healthy donors. The induced CTLs from the patient and from 1 donor efficiently recognized HLA-A(*)02(+) TRP2(+) melanomas as well as COS-7 cells expressing HLA-A(*)0201 and TRP2 in an HLA class I-restricted manner, as assessed by cytokine production and direct cytolysis. The remaining 2 CTL lines derived from 2 donors displayed low T-cell receptor avidity, which could lyse melanoma cells in the presence of exogenous peptide. Since TRP2 is an antigen expressed in most melanomas, identification of the TRP2/HLA-A(*)0201 peptide SLDDYNHLV may facilitate the design of present peptide-based immunotherapies for the treatment of a large fraction of melanoma patients.

Simplified method to generate large quantities of dendritic cells suitable for clinical applications

The present study describes the optimization of an in vitro culture method for generating large amounts of dendritic cells (DC) in serum-free conditions from leukapheresis containing a mixed population of peripheral blood mononuclear cells (PBMC) which are cultured in the presence of GM-CSF and IL-13. Initial comparisons between the generation of DC from bulk and monocyte-enriched leukapheresis products showed that the presence of lymphocytes during the culture favors the differentiation of monocytes into DC. DC yields obtained from mixed mononuclear cell cultures were between 38 and 54% higher than yields obtained from monocyte-enriched cultures. Both types of cultures resulted in the generation of DC with an immature phenotype (CD83- and high phagocytic activity), which have been previously shown to be good stimulators for T cell responses. DC yields of bulk cultures in serum-free conditions were significantly higher than those obtained in the presence of 2% human serum. The cytokines of the supernatants of serum-free cultures comprised a significant content of pro-inflammatory cytokines such as IL-1, IL-12 and TNF-alpha. Maturation of DC generated by this method can be induced by treatment with double-stranded RNA, LPS or TNF-alpha, resulting in enhanced surface expression of CD80, CD86, CD40, CD83 and MHC molecules on the DC. The methodology described here offers the possibility for generating large amounts of clinical grade DC from bulk leukapheresis products, thus avoiding DC precursor purification steps, and thereby minimizing the risks of contamination. This culture process may be applied to cell-based therapeutic approaches for the treatment of cancer or chronic viral infections.

Efficient presentation of tumor idiotype to autologous T cells by CD83(+) dendritic cells derived from highly purified circulating CD14(+) monocytes in multiple myeloma patients

To generate mature and fully functional CD83(+) dendritic cells derived from circulating CD14(+) cells highly purified from the leukapheresis products of multiple myeloma patients.CD14(+) monocytes were selected by high-gradient magnetic separation and differentiated to immature dendritic cells with granulocyte-macrophage colony-stimulating factor and interleukin-4 for 6-7 days and then induced to terminal maturation by the addition of tumor necrosis factor-alpha or stimulation with CD40 ligand. Dendritic cells were characterized by immunophenotyping, evaluation of soluble antigens uptake, cytokine secretion, capacity of stimulating allogeneic T cells, and ability of presenting nominal antigens, including tumor idiotype, to autologous T lymphocytes. Phenotypic analysis showed that 90% +/- 6% of cells recovered after granulocyte-macrophage colony-stimulating factor and interleukin-4 stimulation expressed all surface markers typical of immature dendritic cells and demonstrated a high capacity of uptaking soluble antigens as shown by the FITC-dextran assay. Subsequent exposure to maturation stimuli induced the downregulation of CD1a and upregulation of CD83, HLA-DR, costimulatory molecules and induced the secretion of large amounts of interleukin-12. Mature CD83(+) cells showed a diminished ability of antigen uptake whereas they proved to be potent stimulators of allogeneic T cells in a mixed lymphocyte reaction. Monocyte-derived dendritic cells, pulsed before the addition of maturation stimuli, were capable of presenting soluble proteins such as keyhole limpet hemocyanin and tetanus toxoid to autologous T cells for primary and secondary immune response, respectively. Conversely, pulsing of mature (CD83(+)) dendritic cells was less efficient for the induction of T-cell proliferation. More importantly, CD14(+) cells-derived dendritic cells stimulated autologous T-cell proliferation in response to a tumor antigen such as the patient-specific idiotype. Moreover, idiotype-pulsed dendritic cells induced the secretion of interleukin-2 and gamma-interferon by purified CD4(+) cells. T-cell activation was better achieved when Fab immunoglobulin fragments were used as compared with the whole protein. When dendritic cells derived from CD14(+) cells from healthy volunteers were analyzed, we did not find any difference with samples from myeloma patients as for cell yield, phenotypic profile, and functional characteristics. These studies demonstrate that mobilized purified CD14(+) cells represent the optimal source for the production of a homogeneous cell population of mature CD83(+) dendritic cells suitable for clinical trials in multiple myeloma.

Generation of dendritic cells from human chronic myelomonocytic leukemia cells in fetal calf serum-free medium

It is generally believed that the immune system plays a role not only in the acquisition of malignant diseases but also in the rejection of microscopic as well as established tumor cells. Failure of the immune system to eliminate tumor cells may be, among other factors, due to an insufficient presentation of tumor antigens. Dendritic cells (DCs), as professional antigen-presenting cells, therefore, may be therapeutically used to initiate or enhance immune responses in patients with malignancies. In this study we demonstrate that peripheral blood cells of patients with chronic myelomonocytic leukemia (CMML) can be induced to acquire DC characteristics. Upon culture with granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4) plus tumor necrosis factor alpha (TNFalpha), CMML cells develop DC morphology and acquire the phenotypic characteristics of DCs. When a CD14+ cell population is used for DC generation, a homogeneous differentiation towards the DC lineage occurs similar to that, observed in normal peripheral blood monocytes. CMML-derived DCs are potent stimulators of the allogeneic mixed lymphocyte reaction (MLR) when compared with uncultivated cells. The demonstration of a deletion of the long arm of chromosome 7, del(7)(q22), in 86% of highly enriched CD1a+ cells by fluorescence in situ hybridization (FISH) indicates the leukemic origin of generated DCs. In addition, we present data that generation of CMML-derived DCs is also possible under fetal calf serum-free conditions for a potential clinical use. These DCs may be used as a cellular vaccine to induce anti-tumor immunity in patients with CMML.

Advances in specific immunotherapy of malignant melanoma

Management of malignant melanoma continues to present a challenge to dermatologists, particularly in advanced cases. In light of the steady increase in the worldwide incidence and mortality rates for melanoma, better understanding of the immune mechanisms regulating melanoma progression and interaction with the host's immune system seems eminently important. New studies on the role of immune mechanisms in the pathogenesis and clinical course of melanoma have recently been published. We review the immune mechanisms involved in tumor progression and ways in which these mechanisms may be applied toward immunotherapeutic management of malignant melanoma.

LEARNING OBJECTIVE

After the completion of this learning activity, participants should be familiar with (1) the immune mechanisms involved in host-tumor interaction and tumor rejection, (2) factors allowing the escape of melanoma cells from immune recognition, and (3) the current rationale for the different types of specific immunotherapy in melanoma. Better understanding of basic mechanisms in tumor immunology should raise awareness of future immunotherapeutic approaches in patients with melanoma, particularly in those who are at high risk of recurrence or who present with advanced disease.

Requirement of mature dendritic cells for efficient activation of influenza A-specific memory CD8+ T cells

It is critical to identify the developmental stage of dendritic cells (DCs) that is most efficient at inducing CD8+ T cell responses. Immature DCs can be generated from monocytes with GM-CSF and IL-4, while maturation is accomplished by the addition of stimuli such as monocyte-conditioned medium, CD40 ligand, and LPS. We evaluated the ability of human monocytes and immature and mature DCs to induce CD8+ effector responses to influenza virus Ags from resting memory cells. We studied replicating virus, nonreplicating virus, and the HLA-A*0201-restricted influenza matrix protein peptide. Sensitive and quantitative assays were used to measure influenza A-specific immune responses, including MHC class I tetramer binding assays, enzyme-linked immunospot assays for IFN-gamma production, and generation of cytotoxic T cells. Mature DCs were demonstrated to be superior to immature DC in eliciting IFN-gamma production from CD8+ effector cells. Furthermore, only mature DCs, not immature DCs, could expand and differentiate CTL precursors into cytotoxic effector cells over 7 days. An exception to this was immature DCs infected with live influenza virus, because of the virus's known maturation effect. Finally, mature DCs pulsed with matrix peptide induced CTLs from highly purified CD8+ T cells without requiring CD4+ T cell help. These differences between DC stages were independent of Ag concentrations or the number of immature DCs. In contrast to DCs, monocytes were markedly inferior or completely ineffective stimulators of T cell immunity. Our data with several qualitatively different assays of the memory CD8+ T cell response suggest that mature cells should be considered as immunotherapeutic adjuvants for Ag delivery.

Functional characterization of an IL-7–dependent CD4+CD8αα+ Th3-type malignant cell line derived from a patient with a cutaneous T-cell lymphoma

CDR3 of the functional rearranged T-cell receptor variable β region (TCR-Vβ) transcript was sequenced in order to demonstrate for the first time the identity between a long-term cultured T-cell line derived from a cutaneous T-cell lymphoma (CTCL) patient and the malignant T-cell clone present in the blood. The patient's peripheral blood lymphocyte-derived cultured T-cell line had a CD3+Vβ22+CD4+CD8+CD25−phenotype. It was named Pno and had been cultured for more than 1 year. Both fresh and long-term–cultured tumor cells proliferated highly in response to interleukin-7 (IL-7), and exogeneous IL-7 prevented Pno lymphocytes from apoptosis and maintained high levels of Bcl-2 expression. This unique malignant cloned lymphocyte line was further used to carry out functional studies. The results indicated that the CD3/TCR structures expressed by the Pno lymphocytes were functional because an immobilized anti-CD3 monoclonal antibody (mAb) or the combination of a soluble anti-CD3 mAb with submitogenic doses of phorbol 12 β-myristate 13 -acetate induced a proliferative response. Further, the CD2 and CD28 coreceptors were functional because they were able to induce a strong proliferative response upon their specific stimulation. Finally, the Pno T cell line had a Th3-type cytokine profile because it produced high amounts of the immunosuppressor cytokine tumor growth factor–β1 (TGF-β1). This high production of TGF-β1 may inhibit antitumor specific responses in CTCL.

Potential applications of gene therapy in the patient with cancer

The elderly population has much to gain from the advances of molecular medicine, although at present genetic pharmacology remains mostly at the conceptual level. Cancer, in particular, is an increasing health burden and the majority (over 70%) of gene therapy trials are aimed at tackling this problem. Available strategies employ both viral and synthetic vectors with the selective delivery and expression of therapeutic genes a pivotal requirement. Clinical trials are now in progress with a view to modulating disease at many different levels, including the direct replacement of abnormal genes. suicide-gene formulations, and the delivery of 'gain of function' genes, which seek to alter the malignant phenotype by indirect means, such as, immunopotentiation and stromal reorganisation. Early data from these studies is tantalising and we must remain optimistic that gene therapy will benefit the patient with cancer by both reducing morbidity and extending life.

Functional characterization of an IL-7–dependent CD4+CD8αα+ Th3-type malignant cell line derived from a patient with a cutaneous T-cell lymphoma

CDR3 of the functional rearranged T-cell receptor variable β region (TCR-Vβ) transcript was sequenced in order to demonstrate for the first time the identity between a long-term cultured T-cell line derived from a cutaneous T-cell lymphoma (CTCL) patient and the malignant T-cell clone present in the blood. The patient's peripheral blood lymphocyte-derived cultured T-cell line had a CD3+Vβ22+CD4+CD8+CD25−phenotype. It was named Pno and had been cultured for more than 1 year. Both fresh and long-term–cultured tumor cells proliferated highly in response to interleukin-7 (IL-7), and exogeneous IL-7 prevented Pno lymphocytes from apoptosis and maintained high levels of Bcl-2 expression. This unique malignant cloned lymphocyte line was further used to carry out functional studies. The results indicated that the CD3/TCR structures expressed by the Pno lymphocytes were functional because an immobilized anti-CD3 monoclonal antibody (mAb) or the combination of a soluble anti-CD3 mAb with submitogenic doses of phorbol 12 β-myristate 13 -acetate induced a proliferative response. Further, the CD2 and CD28 coreceptors were functional because they were able to induce a strong proliferative response upon their specific stimulation. Finally, the Pno T cell line had a Th3-type cytokine profile because it produced high amounts of the immunosuppressor cytokine tumor growth factor–β1 (TGF-β1). This high production of TGF-β1 may inhibit antitumor specific responses in CTCL.

Tumor infiltrating lymphocytes in melanoma comprise high numbers of T-cell clonotypes that are lost during in vitro culture

Melanoma is generally accepted as being an antigenic tumor capable of eliciting T-cell responses that, however, in most cases are inadequate to control tumor growth. Tumor-infiltrating lymphocytes (TIL) in melanoma lesions comprise clonotypic T cells, indicating the in situ recognition of melanoma-associated peptide epitopes. Cultured TIL have been studied in order to unveil characteristics of TIL and the interactions of TIL and melanoma cells. Whether in vitro cultured TIL mirrors the in situ situation has, however, been questioned. In the present study we have taken advantage of T-cell receptor clonotype mapping methodology to conduct a full and detailed analysis of the T-cell clonotypes in melanoma lesions and in corresponding lines of TIL established in vitro. All melanoma lesions and the corresponding TIL cultures comprised high numbers of T-cell clonotypes, typically in the range of 40 to more than 60. The subsequent comparison of T-cell clonotypes present in the original lesions and in the corresponding T-cell lines established in vitro demonstrated that a very limited number of the T-cell clonotypes established in vitro are identical to the T-cell clonotypes expanded in situ. These results demonstrate that in situ T-cell clonotypes in melanoma are not readily expanded in vitro and that the majority of T-cell clonotypes present in cultured TIL are not present in situ.

Skin tests predict survival after autologous tumor cell vaccination in metastatic melanoma: experience in 81 patients

BACKGROUND

Currently there is no standard adjuvant treatment following surgical resection of metastatic melanoma. We investigated whether surgery followed by autologous tumor cell-BCG vaccination was beneficial for malignant melanoma patients. In this study we focus on the prognostic value of DTH response following vaccination therapy.

PATIENTS AND METHODS

Eighty-one patients with AJCC stage III and IV melanoma were selected. Whenever feasible, radical metastasectomy was performed. ASI was initiated by the administration of three weekly intra-cutaneous vaccinations with 10(7) irradiated autologous tumor cells, starting four weeks after surgery. Depending on the size of DTH response to the first three injections, subsequent vaccinations were planned. The first two vaccines also contained 10(7) BCG organisms as an immune stimulatory adjuvant.

RESULTS

Induration as well as erythema correlated strongly with survival (P < 0.0001 and P = 0.0004). After radical metastasectomy in stage III melanoma patients a five-year survival of 48% was observed. In stage IV disease, a five-year survival of 34% was seen, after radical surgery had been performed. When macroscopic disease was present at start of vaccination treatment, no clinical responses occurred. Apart from transient skin ulceration at the site of BCG-containing vaccinations, no serious side effects were observed.

CONCLUSIONS

This study shows that large-scale preparation of autologous melanoma cell vaccines is feasible. while vaccination results in DTH responses that correlate significantly with survival. ASI seemed to be beneficial in stage III and stage IV melanoma when given in the adjuvant setting, while causing only very mild side effects.

Anti-idiotype vaccines for human follicular lymphoma

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

Adenoviral transduction of human 'clinical grade' immature dendritic cells enhances costimulatory molecule expression and T-cell stimulatory capacity

The therapeutic use of dendritic cells (DC) in antigen-specific anti-tumor vaccines, requires sufficient numbers of functional DC, the preparation of which should comply with the code of Good Manufacturing Practice. In addition, the expression of tumor specific antigen should be possible in these DC. As a preclinical step, the method reported here was developed in healthy volunteers. Monocytes (Mo) were isolated by leukapheresis from 12 donors, purified by elutriation and then cultured for 6 days in sealed bags in AIM-V serum free medium with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-13 (IL-13). Between 6x10(8) and 1x10(9) immature DC (iDC) could be differentiated from one leukapheresis. Cells displayed a characteristic iDC phenotype (CD1a(+), CD14(-), CD80(+), CD86(+), HLA DR(+), CD83(-)), and had potent allogeneic and antigen dependent autologous T cell-stimulatory capacity. Moreover, iDC could be further differentiated into mature DC by CD40 ligation as assessed by CD83 expression and the upregulation of HLA-DR and costimulatory molecules. After infection with a recombinant adenovirus encoding for beta-galactosidase (betaGal), 50% to 80% of iDC expressed betaGal without toxicity. Adenovirus infection increased the expression of both costimulatory molecules and CD83, and also increased allogeneic stimulatory capacity. Thus, the method developed here allows us to use large numbers of functional iDC as will be required for therapeutic uses in man. These DC can express a transgenic protein.

Dendritic cells in cancer immunotherapy

The potential to harness the potency and specificity of the immune system underlies the growing interest in cancer immunotherapy. One such approach uses bone marrow-derived dendritic cells, phenotypically distinct and extremely potent antigen-presenting cells, to present tumor-associated antigens and thereby generate tumor-specific immunity. Support for this strategy comes from animal studies that have demonstrated that dendritic cells, when loaded ex vivo with tumor antigens and administered to tumor-bearing hosts, can elicit T cell-mediated tumor destruction. These observations have led to clinical trials designed to investigate the immunologic and clinical effects of antigen-loaded dendritic cells administered as a therapeutic vaccine to patients with cancer. In the design and conduct of such trials, important considerations include antigen selection, methods for introducing the antigen into MHC class I and II processing pathways, methods for isolating and activating dendritic cells, and route of administration. Although current dendritic cell-based vaccination methods are cumbersome, promising results from clinical trials in patients with malignant lymphoma, melanoma, and prostate cancer suggest that immunotherapeutic strategies that take advantage of the antigen presenting properties of dendritic cells may ultimately prove both efficacious and widely applicable to human tumors.

Identification of CD4+ T cell epitopes from NY-ESO-1 presented by HLA-DR molecules

In previous studies, the shared cancer-testis Ag, NY-ESO-1, was demonstrated to be recognized by both Abs and CD8+ T cells. Gene expression of NY-ESO-1 was detected in many tumor types, including melanoma, breast, and lung cancers, but was not found in normal tissues, with the exception of testis. In this study, we describe the identification of MHC class II-restricted T cell epitopes from NY-ESO-1. Candidate CD4+ T cell peptides were first identified using HLA-DR4 transgenic mice immunized with the NY-ESO-1 protein. NY-ESO-1-specific CD4+ T cells were then generated from PBMC of a patient with melanoma stimulated with the candidate peptides in vitro. These CD4+ T cells recognized NY-ESO-1 peptides or protein pulsed on HLA-DR4+ EBV B cells, and also recognized tumor cells expressing HLA-DR4 and NY-ESO-1. A 10-mer peptide (VLLKEFTVSG) was recognized by CD4+ T cells. These studies provide new opportunities for developing more effective vaccine strategies by using tumor-specific CD4+ T cells. This approach may be applicable to the identification of CD4+ T cell epitopes from many known tumor Ags recognized by CD8+ T cells.

Ex vivo targeting of the macrophage mannose receptor generates anti-tumor CTL responses

MUC1 is highly expressed in adenocarcinomas and is a possible target for immunotherapy. In mice, oxidized mannan linked to MUC1 (M-FP), given in vivo, induces potent MHC-restricted CTL and tumor protection. Because of the resistance of cancer patients to immunization, ex vivo immunization of macrophage/dendritic cells was examined using oxidized mannan MUC1 to target the mannose receptor and the MHC Class I antigen presentation pathway. Here, we show that murine mannose receptor (MR) bearing macrophages derived from peritoneal exudate cells (PEC) and cultured ex vivo with M-FP can, after adoptive transfer, efficiently present MUC1 to T cells, leading to the generation of high frequency of CTL and protection from tumor challenge. Mice immunized once with syngeneic PEC pulsed with M-FP elicit a similar CTLp frequency to that obtained with three in vivo immunizations. Targeting the MR is crucial to obtain high frequency CTL, and without oxidation the CTLp frequency was low. GM-CSF is important, as GM-CSF o/o mice gave reduced responses, a deficiency corrected by in vivo GM-CSF. In addition, the treatment of macrophages ex vivo with GM-CSF gave enhanced responses and treating mice with GM-CSF prior to M-FP immunizations also enhanced cellular responses. M-FP targets the MR and ensures rapid passage of peptides to Class I molecules, and can also directly stimulate in vitro IL-12 production by macrophages. While many studies are now focussing on dendritic cells, in this study the cells involved were adherent F4/80+ 33D1- macrophages. The findings could be of benefit for the immunization of patients with cancer.

Immunobiology of dendritic cells

Dendritic cells (DCs) are antigen-presenting cells with a unique ability to induce primary immune responses. DCs capture and transfer information from the outside world to the cells of the adaptive immune system. DCs are not only critical for the induction of primary immune responses, but may also be important for the induction of immunological tolerance, as well as for the regulation of the type of T cell-mediated immune response. Although our understanding of DC biology is still in its infancy, we are now beginning to use DC-based immunotherapy protocols to elicit immunity against cancer and infectious diseases.

MAGE-B5, MAGE-B6, MAGE-C2, and MAGE-C3: four new members of the MAGE family with tumor-specific expression

A number of genes of the MAGE-A, B, and C families have been shown to code for antigens that are recognized on many human tumors by autologous cytolytic T lymphocytes. These antigens ought to be strictly tumor specific because the encoding MAGE genes are not expressed in normal adult cells except for male germline cells, which lack HLA expression. To identify new genes of this type, we performed representational difference analysis on a melanoma cell line by subtraction with a normal skin sample. This led to the identification of MAGE-C2, a new member of the MAGE-C family. A search for nucleotide sequences encoding MAGE-like proteins in public databases led to the identification of three additional MAGE genes, which were named MAGE-B5, MAGE-B6, and MAGE-C3. The four new MAGE genes are not expressed in normal tissues, except for testis, and are expressed in tumors of different histological origins. Therefore, like other MAGE genes expressed specifically in tumors, MAGE-B5, MAGE-B6, MAGE-C2, and MAGE-C3 ought to encode antigens that could be targets for cancer immunotherapy.

Development and therapeutic effect of adoptively transferred T cells primed by tumor lysate-pulsed autologous dendritic cells in a patient with metastatic endometrial cancer

We describe a 65-year-old woman with a large surgically unresectable and chemoresistant liver metastasis of endometrial carcinoma who was treated by infusion with peripheral blood T cells stimulated with tumor lysate-pulsed autologous dendritic cells (DC). Extensive in vitro characterization of the DC-activated T cells included phenotypic analysis, cytotoxicity, and intracellular cytokine secretion. High cytotoxicity was observed against autologous tumor cells, but not against NK-sensitive K562 cells, autologous Con-A lymphoblasts, or autologous Epstein-Barr virus-transformed lymphoblastoid cells. Blocking studies demonstrated that lytic activity was HLA class I restricted. Two-color flow cytometric analysis revealed that a significant proportion of CD8+ T cells was also CD56+, and analysis of intracellular IFN-gamma and IL-4 expression suggested a type 1 cytokine bias. The patient was treated by three infusions of tumor-specific T cells at 3- to 4-week intervals, and in vivo distribution of the T cells was followed by (111)In oxine labeling and serial gamma camera imaging. Tumor localization and accumulation of labeled lymphocytes was consistently detected at serial time points following each injection. However, deep infiltration of the large tumor mass by activated T cells was minimal, as evaluated in 3 dimensions by single photon emission computerized tomography (SPECT) imaging. Transient serum increases of the tumor marker lactate dehydrogenase (LDH), were detectable after each injection. Similar posttreatment elevations were seen for serum uric acid and potassium. Clinically, stabilization of the large liver metastasis was obtained during treatment. Collectively, these results indicate that tumor-specific CD8+ cytotoxic T-cell responses can be generated in patients with endometrial cancer, and suggest that T-cell immunotherapy may be of therapeutic value in patients harboring metastatic disease.

T311--an anti-tyrosinase monoclonal antibody for the detection of melanocytic lesions in paraffin embedded tissues

Tyrosinase is a key enzyme in melanin biosynthesis and represents a marker of melanocytic differentiation. We previously generated T311, a murine monoclonal antibody to the tyrosinase recombinant protein. This study was performed to evaluate T311 as a diagnostic immunohistochemical reagent for use on formalin-fixed paraffin-embedded pathological material. We analyzed the specificity of the antibody on a panel of normal and neoplastic tissues, and we assessed its sensitivity in a large number of metastatic and primary malignant melanomas, nevi, three angiomyolipomas, and two vitiligo specimens. T311 revealed intense reactivity on paraffin-embedded material. Immunoreactivity was limited to cells of melanocytic differentiation and no immunostaining was present in unrelated normal tissues and tumors. Eighty-four percent of metastatic malignant melanomas were immunoreactive with T311 and showed predominantly a homogeneous expression pattern. However, in primary melanomas of the desmoplastic/spindle cell type, T311 revealed a poor immunoreactivity. Nevi showed intense staining at the junctional zone, while the dermal component revealed decreasing reactivity towards deeper areas. Only one angiomyolipoma was focally immunoreactive with T311. Vitiligo specimens were immunonegative. We conclude that T311 is a specific and sensitive marker for the detection of melanocytic lesions in formalin-fixed paraffin-embedded tissues and a useful serological reagent for diagnostic pathology.

Phase 1 study in patients with metastatic melanoma of immunization with dendritic cells presenting epitopes derived from the melanoma-associated antigens MART-1 and gp100

Dendritic cells (DCs) have been shown to enhance anti-tumor immune responses in several preclinical models. Furthermore, DC-like function can be elicited from peripheral blood monocytes cultured in vitro with interleukin-4 and granulocyte-macrophage colony-stimulating factor. For this reason, a phase 1 study was initiated at the Surgery Branch of the National Cancer Institute to test the toxicity and biological activity of the intravenous administration of peripheral blood monocyte-derived DCs. The DCs were generated by 5- to 7-day incubation in interleukin-4 (1,000 U/mL) and granulocyte-macrophage colony-stimulating factor (1,000 U/mL) of peripheral blood monocytes obtained by leukapheresis. Before administration, the DCs were pulsed separately with the HLA-A*0201-associated melanoma epitopes MART-1(27-35) and gp-100-209-2M. The DCs were administered four times at 3-week intervals. A first cohort of patients (n = 3) was treated with 6 x 10(7) DCs and a second cohort (n = 5) with 2 x 10(8) DCs (in either case, one half of the DCs were pulsed with MART-1(27-35) and the other half was pulsed with gp-100-209-2M). In a final cohort under accrual (n = 2) 2 x 10(8) DCs were administered in combination with interleukin-2 (720,000 IU/kg every 8 hours). The recovery of DCs after in vitro culture ranged from 3% to 35% (mean, 15%) of the original peripheral blood monocytes. Administration of DCs caused no symptoms at any of the doses, and the concomitant administration of interleukin-2 did not cause toxicity other than that expected for interleukin-2 alone. Monitoring of patients' cytotoxic T lymphocyte reactivity before and after treatment revealed enhancement of cytotoxic T lymphocyte reactivity only in one of five patients tested. Of seven patients evaluated for response, one had a transient partial response with regression of pulmonary and cutaneous metastases. A relatively large number of DCs can be safely administered intravenously. The poor clinical outcome of this study perhaps could be explained by the type of protocol used for DC maturation, the route of administration, or both. For this reason, this clinical protocol was interrupted prematurely, whereas other strategies for DC preparation and route of administration are being investigated at the authors' institution.

Immune reconstitution following high-dose chemotherapy with stem cell rescue in patients with advanced breast cancer

The present study examines the nature of humoral and cellular immune reconstitution in 28 patients with advanced breast cancer following high-dose chemotherapy with stem cell rescue. Patients underwent testing of T, B, NK and dendritic cell function at serial time points until 1 year post transplant or until the time of disease progression. Abnormalities in T cell phenotype and function were observed following high-dose chemotherapy that persisted for at least 6-12 months. The vast majority of patients experienced an inversion of the CD4/CD8 ratio and demonstrated an anergic response to candida antigen. Mean T cell proliferation in response to PHA and to co-culture with allogeneic monocytes was significantly compromised. In contrast, mean IgG and IgA levels were normal 6 months post transplant and NK cell yields and function were transiently elevated following high-dose chemotherapy. Dendritic cells generated from peripheral blood progenitors displayed a characteristic phenotype and were potent inducers of allogeneic T cell proliferation in the post-transplant period. The study demonstrates that patients undergoing autologous transplantation for breast cancer experience a prolonged period of T cell dysfunction. In contrast, B, NK, and DC recover more rapidly. These findings carry significant implications for the design of post-transplant immunotherapy.

NY-ESO-1 tumour associated antigen is a cytoplasmic protein detectable by specific monoclonal antibodies in cell lines and clinical specimens

NY-ESO-1 gene encodes a novel member of the cancer/testis (CT) family of human tumour-associated antigens (TAA). Specific monoclonal antibodies (mAb) have identified the corresponding gene product in lysates of tumour cell lines as a 22 kDa protein but no data are available concerning its intracellular location or distribution within neoplastic tissues. We have generated NY-ESO-1 specific mAbs recognizing the target molecule in cytospin preparations and in sections from clinical tumour specimens. These reagents identify NY-ESO-1 TAA in melanoma cell lines expressing the specific gene as a cytoplasmic protein, sharing the intracellular location of most MAGE TAA. In a series of 12 melanoma specimens, specific staining, limited to neoplastic cells, was detectable in the five cases where NY-ESO-1 gene expression was observed. In two of them over 90% of tumour cells showed evidence of positive staining. Lower percentages of positive neoplastic cells ranging between single cells and 50% were observed in the remaining tumours. These data suggest that active specific immunotherapies targeting NY-ESO-1, alone or in combination with other TAA could be of high clinical relevance in sizeable subgroups of melanoma patients.

Repeated administration of cytosine-phosphorothiolated guanine-containing oligonucleotides together with peptide/protein immunization results in enhanced CTL responses with anti-tumor activity

The development of therapeutic anti-cancer vaccines designed to elicit CTL responses with anti-tumor activity has become a reality thanks to the identification of several tumor-associated Ags and their corresponding peptide T cell epitopes. However, peptide-based vaccines, in general, fail to elicit sufficiently strong CTL responses capable of producing therapeutic anti-tumor effects (i.e., prolongation of survival, tumor reduction). Here we report that repeated administration of synthetic oligonucleotides containing foreign cytosine-phosphorothiolated guanine (CpG) motifs increased 10- to 100-fold the CTL response to immunization with various synthetic peptides corresponding to well-known T cell epitopes. Moreover, repeated CpG administration allowed the induction of CTL to soluble protein even in the absence of additional adjuvant. Our results indicate that the potentiating effect of CpG in CTL responses required the participation of Th lymphocytes. Repeated CpG administration resulted in overt splenomegaly and lymphadenopathy with a significant increase in the numbers of CTL precursors and dendritic cells. Protein vaccination in combination with repeated CpG therapy was effective in delaying tumor cell growth and extending survival in mice bearing melanoma tumors. These findings support the contention that repeated administration of CpG-oligonucleotides enhances the effect of peptide and protein vaccines leading to potent anti-tumor responses, presumably through the induction of Th1 and dendritic cells, which are essential for optimal CTL responses. The immunostimulatory properties of CpG motifs may be key in inducing a consistent long term immunity to tumor-associated Ags when using peptides or proteins as T cell-inducing vaccines.

Dysfunctional regulation of the development of monocyte-derived dendritic cells in cancer patients

Dendritic cells (DCs) are highly effective antigen (Ag)-presenting cells (APCs) that are required for the initiation of the immune response. DCs derived from cancer patients have been shown to be defective in several phenotypic and functional properties. However, little is known about the capacity of monocytes derived from cancer patients to differentiate into DCs. Herein, we examined the differentiation of monocyte-derived DCs in cancer patients. Flow cytometric analysis revealed that monocytes derived from cancer patients cultured with granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4) exhibited lower levels of CD11c, CD40, CD86, and HLA-DR expression as compared with those of monocyte-derived DCs from healthy volunteers. Furthermore, the capacities of DCs derived from cancer patients' monocytes to stimulate allogeneic T cell responses and to migrate in response to regulated-on-activation normal T cells expressed and secreted (RANTES) were impaired in comparison with those of monocyte-derived DCs from healthy volunteers. However, the two cell types had similar pinocytotic capacities for fluorescein isothiocyanate labeled-dextran (FITC-DX) and lucifer yellow (LY). These results suggest that monocytes from cancer patients may be defective in the capacity to develop into DCs.