Cellular immune response against autologous human malignant melanoma: are in vitro studies providing a framework for a more effective immunotherapy?

Subcutaneous Low-Dose Interleukin-2 plus Alpha Interferon in Advanced Malignant Melanoma

Aims and Background

Interferon (IFN) and interleukin-2 (IL-2) have been proven to be active agents in the treatment of malignant melanoma, but the most effective doses of these cytokines were often associated to important side effects and poor patient compliance. Recently, the subcutaneous administration of low-dose IL-2 was found to be a well-tolerated and effective treatment for renal cancer. Since the combination of low doses of IL-2 and IFN has been hypothesized to have synergistic biologic and cytotoxic effects, we evaluated feasibility and patient compliance of a scheme that combined recombinant IFN-alpha (rIFN-α) (3 million units by intramuscular injection, 3 times a week) plus low-dose IL-2 (9 million IU, 3 to 5 times a week) administered subcutaneously for 2 weeks every 28 days.

Results

Fifteen patients with disseminated malignant melanoma previously treated with chemotherapy entered the study. All but the first 2 self-administered the therapy at home and were followed in an out-patient setting. None of them required in-patient care for toxicity. No WHO grade 4 side effects were detected; the only grade 3 side effects were fever and asthenia in 5 % of the cycles. Mild hematologic toxicity (grade 2) was observed at the highest weekly dose of IL-2. No major responses were observed in this subset of heavily pretreated patients.

Conclusions

We conclude that the regimen studied is feasible and well tolerated in an out-patient setting, but it is unlikely to be effective. The good patient compliance makes this schedule eligible to evaluate whether IL-2 plus rIFN-α can enhance the results of chemotherapy in this disease.

[The involvement of RCAS1 in creating a suppressive tumor microenvironment in patients with pharyngeal squamous cell carcinoma]

INTRODUCTION

Tumor microenvironment makes up the stroma of the neoplasm and is the tissue that determines the growth and progression of the tumor and its ability to create metastases. THE AIM OF THE PRESENT STUDY: has been to evaluate the potential role of RCAS1 protein in creating the suppressive tumor microenvironment in pharyngeal squamous cell carcinomas. The immunoreactivity of RCAS1, CD3, CD25, CD68, CD69 and Foxp3 was assessed in the tissue samples of the tumor, in tumor microenvironment and in the reference samples of palatine tonsils in chronic inflammation.

RESULTS

A statistically significantly higher RCAS1 antigen immunoreactivity was identified in pharyngeal cancer samples than in the stromal samples, the presence of RCAS1 positive macrophages infiltrating the tumor and its stroma was also noticed. The statistically significantly higher RCAS1 antigen immunoreactivity level was identified in the pharyngeal cancer samples in patients with the presence of lymph node metastases in comparison to patients without metastases. The infiltration of CD68 positive cells (macrophages) was significantly higher in the stromal tissue samples than in cancer samples and it was in both, the tumor and the stroma, significantly higher in patients with the presence of lymph node metastases than in patients without metastases. Additionally the presence of CD3 positive TILs was noticed in the tissue of the tumor and in its stroma, the cells were activated, typified by CD69 immunoreactivity which was higher than in the reference samples, and impaired cytotoxicity with low CD25 antigen immunoreactivity. This observation confirmed the presence of selective immune suppression within the tumor and the stroma.

CONCLUSION

RCAS1, an active factor secreted by the tumor and present in its stroma may play an important role in the phenomenon of tumor escape from host immunological surveillance and in creating the immune tolerance for the tumor cells, as well as in the tumor microenvironment remodeling with creating its suppressive profile enabling the further tumor growth and metastases.

Antigen-specific versus antigen-nonspecific immunotherapeutic approaches for human melanoma: the need for integration for optimal efficacy?

Due to its immunogenecity and evidence of immune responses resulting in tumor regression, metastatic melanoma has been the target for numerous immunotherapeutic approaches. Unfortunately, based on the clinical outcomes, even the successful induction of tumor-specific responses does not correlate with efficacy. Immunotherapies can be divided into antigen-specific approaches, which seek to induce T cells specific to one or several known tumor associated antigens (TAA), or with antigen-nonspecific approaches, which generally activate T cells to become nonspecifically lytic effectors. Here the authors critically review the different immunotherapeutic approaches in melanoma.

The Involvement of RCAS1 in Creating a Suppressive Tumor Microenvironment in Patients with Salivary Gland Adenocarcinoma

The tumor microenvironment is the tissue that determines the growth and progression of the tumor as well as its ability to initiate metastases. The aim of the present study has been to evaluate the role of RCAS1 in creating the suppressive tumor microenvironment in cases of parotid adenocarcinoma. The tissue samples of salivary gland adenocarcinomas and their stroma and the palatine tonsils which constituted the reference tissue sample group were obtained during routine surgical procedures. The immunoreactivity of RCAS1, CD3, CD25, CD68, CD69, and Foxp3 antigens was then evaluated by using the immunohistochemistry method. The patient’s consent was obtained in each case. A statistically significantly higher RCAS1 immunoreactivity level was found in the adenocarcinoma tissue samples in comparison to that found in the stromal tissue samples. A statistically significantly higher RCAS1 immunoreactivity was also identified in the adenocarcinoma tissue samples derived from patients who had lymph node metastases in comparison to patients without such metastases. Additionally, we observed the presence of RCAS1-positive macrophages in the stromal tissue samples. The infiltration of CD68-positive cells was significantly stronger in the adenocarcinoma and stromal tissue slides than in the reference group tissue slides; moreover, the infiltration was a good deal more prominent in the stromal tissue than in the adenocarcinoma tissue. The CD68 immunoreactivity levels in both the tumor and stromal tissue samples were found to be significantly higher in those patients who had lymph node metastases than in the patients without such metastases. Additionally, the infiltration of CD3- and CD25-positive cells was more prominent in the reference tissue slides than in the adenocarcinoma and stromal tissue slides, and was stronger in the adenocarcinoma tissue than in the stromal tissue. Furthermore, the infiltration of Foxp3-positive cells was seen exclusively in the stroma whereas it was not even detected in the adenocarcinoma tissue. Lastly, the Foxp3-positive cell infiltration was more prominent in the stromal tissue than in the reference group tissue. The present study demonstrates that RCAS1 expression by both tumor cells and tumor-associated macrophages may participate in creating the immunosuppressive microenvironment in parotid gland adenocarcinoma, thus promoting tumor development as well as metastases.

Cancer immunotherapy targeting tumour-specific antigens: towards a new therapy for minimal residual disease

BACKGROUND

Clinical investigation of cancer immunotherapy has been very active and several approaches have been evaluated in Phase III trials. In particular, the characterisation at the molecular level of tumour-specific antigens, together with expert knowledge from GSK Biologicals in recombinant protein manufacturing and immunological Adjuvant Systems, has led the company to develop Antigen-Specific Cancer Immunotherapeutic (ASCI).

OBJECTIVE/METHODS

This paper reviews the different cancer immunotherapy approaches that have reached Phase III clinical development. A special attention is given to GSK's ASCI approach.

CONCLUSION

Based on encouraging data in a double-blind Phase II trial in non-small-cell lung cancer, the selection of the most suitable adjuvant system in melanoma and the choice of the adequate clinical setting for the clinical development of cancer immunotherapy, the ASCI approach offers the perspective that the long quest towards a new cancer treatment approach is about to succeed.

GSK's antigen-specific cancer immunotherapy programme: pilot results leading to Phase III clinical development

From the first evidence that the immune system could recognize tumors, different types of tumor antigens have been identified and deeply characterized. Several different approaches aimed at targeting these antigens have already been the subject of clinical studies. In this field, the GSK Biologicals' approach relying on recombinant proteins combined with an immunological Adjuvant System in a specific clinical setting, has entertained hopes of developing a new class of well tolerated anti-cancer therapy. This methodology led to promising advances with MAGE-A3 immunotherapy in NSCLC and has the potential to be applied to all tumor types.

Melanoma immunology: past, present and future

PURPOSE OF REVIEW

Metastatic melanoma is a disease for which no effective therapeutic options have been developed during the last 30 years with the possible exception of high dose interferon-alpha in the adjuvant setting of stage III patients. The immunotherapy approach was initiated decades ago using cell-based vaccines and adoptive immunotherapy with functionally ill-defined lymphocytes. This paper aims to evaluate the last three decades of research in melanoma immunotherapy and to provide insights in the future of this strategy.

RECENT FINDINGS

Thanks to the development of knowledge in basic and applied immunology, clinical studies of immunotherapy have been followed by trials based on molecular characterization of melanoma antigens and availability of ex-vivo assays allowing the quantitative assessment of the immune response against the given vaccine and against patient tumor cells. This second generation of immunotherapy trials, along with additional preclinical studies, while not yet resulting in a convincing clinical outcome, provided a wealth of data on immunogenicity of different melanoma antigens, mechanism of antigen presentation and factors that impair immune recognition of melanoma cells.

SUMMARY

We discuss how this information will be exploited for designing new and more successful clinical trials of both active and adoptive antigen-specific immunotherapy of metastatic melanoma patients.

Amelanotic malignant melanoma of the esophagus: report of a patient with recurrence successfully treated with chemoendocrine therapy

We report a case of primary amelanotic malignant melanoma of the esophagus, an extremely rare disease. A 58-year-old man was diagnosed as having middle esophageal cancer with lymph node metastasis, which was classified as esophageal cancer, Stage III:T3N1M0, by International Union Against Cancer (UICC) criteria. Preoperative chemotherapy was performed, but the response assessment was no change (NC). The patient underwent a subtotal esophagectomy via right thoracotomy and laparotomy. Reconstruction was performed by pulling up the stomach via the retrosternal route; the site of anastomosis was the neck. Adjuvant chemotherapy consisted of five courses of dacarbazine (DITC), nimustine (ACNU), vincristine (VCR), and interferon-beta. Eleven months after the surgery, computed tomography (CT) demonstrated recurrence in the upper mediastinum. The patient received chemoendocrine therapy, consisting of the first planned course of DITC, ACNU, and cisplatin (CDDP), given intravenously; and tamoxifen (TAM), given orally. Subsequently with a modified regimen of this therapy he attained a complete response (CR). In general, the prognosis of esophageal malignant melanoma is very poor. Although our patient had a recurrence, he is alive 4 years and 5 months after the surgery and 3 years and 6 months after the recurrence. The chemoendocrine therapy probably contributed to this outcome.

Preclinical full-scale evaluation of dendritic cells transfected with autologous tumor-mRNA for melanoma vaccination

Most cancer vaccines to date have made use of common tumor antigens or allogenic cancer cell lines. The majority of tumor antigens may, however, be unique patient-specific antigens. Dendritic cells (DCs) are the most potent antigen-presenting cells known. The present report is a full-scale preclinical evaluation of autologous DCs transfected with autologous tumor-mRNA (tDCs) for vaccination in malignant melanoma. By using autologous tumor-mRNA, we intend to make the DCs present a broad spectrum of tumor-associated antigens relevant to each individual patient. Previously, we have described effective methods for mRNA-transfection into DCs by square-wave electroporation and for generating large numbers of DCs. Here, we demonstrate the ability of tDCs, made under full-scale vaccine conditions, to generate in vitro T-cell responses specific for antigens encoded by the transfected tumor-mRNA. T-cell proliferation assays demonstrated tDC-specific responses for all six patients tested. Responses were further studied by IFNgamma ELISPOT and Bioplex cytokine assays (two patients) and by experiments on isolated CD4(+) and CD8(+) T cells, including HLA-blockage (one patient). Moreover, we describe the results of extensive tumor-RNA analysis using Agilent Bioanalyser, a method that we have implemented in the clinical protocol. Based on this preclinical evaluation, a vaccine trial has been started.

Reduced expression of chemokine (C-C motif) ligand-2 (CCL2) in ovarian adenocarcinoma

Chemokine (C-C motif) ligand-2 (CCL2) is a chemoattractant and activator of macrophages and is a key determinant of the macrophage infiltrate into tumours. We demonstrate here that CCL2 is expressed in normal human ovarian surface epithelium (HOSE) cells and is silenced in most ovarian cancer cell lines, and silenced or downregulated in the majority of primary ovarian adenocarcinomas. Analysis of the CCL2 locus at 17q11.2–q12 showed loss of heterozygosity (LOH) in 70% of primary tumours, and this was significantly more common in tumours of advanced stage or grade. However, we did not detect any mutations in the CCL2 coding sequence in 94 primary ovarian adenocarcinomas. These data support the hypothesis that CCL2 may play a role in the pathobiology of ovarian cancers, but additional studies will be required to evaluate this possibility.

Frequent downregulation of Fas (CD95) expression and function in melanoma

Membrane-bound Fas ligand (FasL, Apo-1L, CD95L) induces rapid apoptosis of Fas (CD95)-sensitive cells on interaction with Fas, and is an important effector molecule of cytolytic T lymphocytes (CTLs). Melanomas are immunogenic and induce the production of specific CTLs, but are usually able to escape immune destruction. We investigated Fas expression and function in 53 cutaneous melanocytic lesions and 13 melanoma cell lines grown in vitro. Immunohistochemical analysis of Fas expression in cutaneous melanocytic lesions showed moderate to high levels of Fas in common benign melanocytic naevi, but low to undetectable levels in atypical naevi, primary (superficial spreading melanoma, nodular melanoma) and cutaneous melanoma metastases. Fluorescence-activated cell sorting (FACS) analysis of Fas expression in melanoma cell lines revealed undetectable or low levels of cell surface Fas expression in five of the 13 melanoma cell lines. Analysis of Fas signalling by quantification of cell death following exposure to recombinant FasL showed that a reduction in Fas expression results in resistance to FasL-mediated cell death. Furthermore, two of the 13 melanoma cell lines were found to be resistant to FasL-mediated cell death despite conserved Fas expression. Thus seven of the 13 melanoma cell lines were found to have impaired Fas signalling. Taken together, our results indicate that downregulation of Fas expression and resistance to Fas-mediated apoptosis are frequent in melanoma.

Human inflammatory cells within the tumor microenvironment of lung tumor xenografts mediate tumor growth suppression in situ that depends on and is augmented by interleukin-12

The human tumor microenvironment includes a mixture of tumor cells, inflammatory cells, fibroblasts, and endothelial cells, all of which are tethered to an extracellular matrix. It has been difficult to study the dynamic interactions of these cells in human tumors in situ for obvious ethical and logistical considerations that prohibit experimental manipulations of tumors while still in patients. Fresh tissue from human lung tumor biopsy implanted into SCID mice was shown to remain viable, and the histologic appearance of the tumor microenvironment was maintained in the tumor xenografts for at least 3 months. In this study, the authors established that the inflammatory cells within human tumor xenografts can suppress tumor growth, and that this suppression is a result, in part, of endogenously produced interleukin-12 (IL-12) because IL-12 neutralizing antibodies enhance the growth of the tumor xenografts. The tumor-inhibitory activity of the inflammatory leukocytes is also enhanced by the local and sustained release of human recombinant IL-12 into the tumor microenvironment from cytokine-loaded biodegradable microspheres. Neither the anti-IL-12 neutralizing antibody nor the delivery of exogenous IL-12 from microspheres had any effect on tumor xenografts in the absence of the inflammatory leukocytes. In conclusion, the inflammatory cells within the tumor microenvironment of human lung tumor xenografts are functional and can suppress tumor growth, and the dynamic effects of the inflammatory cells can be modulated by exogenous cytokines.

T-cell recognition of melanoma-associated antigens

In this review, we summarize the significant progress that has been made in the identification of melanoma-associated antigens (MAA) recognized by cytotoxic T-lymphocytes (CTL). These antigens belong to three main groups: tumor-associated testis-specific antigens (e.g. , MAGE, BAGE, and GAGE); melanocyte differentiation antigens (e.g., tyrosinase, Melan-A/MART-1); and mutated or aberrantly expressed molecules (e.g, CDK4, MUM-1, beta-catenin). Although strong CTL activity may be induced ex vivo against most of these antigens, often in the presence of excess cytokines and antigen, a clear understanding of the functional status of CTL in vivo and their impact on tumor growth, is still lacking. Several mechanisms are described that potentially contribute to tumor cell evasion of the immune response, suggesting that any antitumor efficacy achieved by immune effectors may be offset by factors that result ultimately in tumor progression. Nevertheless, most of these MAA are currently being investigated as immunizing agents in clinical studies, the conflicting results of which are reviewed. Indeed, the therapeutic potential of MAA has still to be fully exploited and new strategies have to be found in order to achieve an effective and long-lasting in vivo immune control of melanoma growth and progression.

The cancer process as a type of immunocomplex hypersensibility involving C3b, natural killer cytotoxicity and antibody-dependent cell cytotoxicity: proposals for tumour immunotherapy and vaccine

I have previously assumed that stem tumour cells are 'para-embryonal cells' (PECs) poor or missing in major histocompatibility complex (MHC) antigens. PECs might induce adjoining differentiated hyperplastic cells to also express tumoral phenotype and properties, thus transforming them into 'differentiated para-embryonal cells' (DPECs), MHC-endowed. In such a way, PECs, MHC-lacking, would be automatically surrounded by DPECs, MHC-endowed: this tumour organization was experimentally found by Cordon-Cardo et al in a variety of cancers. Now, I suggest that such a tumour histology might preferentially induce an anti-DPEC T cell immune response which, sparing PECs, might release increasing amounts of DPEC antigens in the peritumour site. DPEC antigens might increase synthesis of specific antibodies and subsequent immunocomplex formation at the peritumour site. Here, abundant immunocomplexes might react through their Fc pieces with CD16 receptors of antibody-dependent cell cytotoxicity (ADCC)-endowed immune cells (natural killer (NK) cells, macrophages, polymorphonuclear cells). These cells would thus be stimulated to secrete their lytic factors before and without their coming into contact with target tumour cells. On the other hand, abundant immunocomplexes at the peritumour site might massively activate the complement system, thus generating large amounts of C3b. C3b might react with CD11b receptors of NK cells, stimulating them to also secrete their lytic factors in an ectopic way at the peritumour site, thus impairing NK cytotoxicity. In such a way, in the absence of ADCC and NK cytotoxicity, a tumour cell enhancement might easily occur. In the light of these ideas, a strategy for antitumour immunotherapy and vaccine is then proposed.

Melanomas that develop within the eye inhibit lymphocyte proliferation

Experiments were performed to compare the ability of ocular and skin melanoma cells to stimulate T cells. Primary melanoma cell lines were obtained from a series of patients with either eye or skin melanoma. The ability of tumor cells to stimulate T cells in the absence of exogenous growth factors was assessed in mixed-lymphocyte tumor cell cultures in which allogeneic lymphocytes were stimulated with irradiated ocular or skin melanoma cells. Expression of HLA class I and class II on tumor cells, in the presence or absence of IFN-gamma, was determined by flow cytometry. The ability of tumor cells to inhibit T-cell proliferation was determined by adding various concentrations of irradiated tumor cells to standard mixed-lymphocyte cultures. Our results indicate that primary skin melanoma cells induce vigorous proliferation of allo-antigen-specific T cells. By contrast, ocular melanoma cells failed to induce significant T-cell proliferation. The failure of ocular melanoma cells to stimulate lymphocyte proliferation was not due to low levels of either class I or class II on tumor cells since tumor cells treated with IFN-gamma expressed high levels of class I and class II but still failed to induce lymphocyte proliferation. Ocular melanoma cells inhibited lymphocyte proliferation, as shown by experiments in which a small number of tumor cells prevented proliferation of T cells in mixed-lymphocyte cultures. Inhibition of lymphocyte proliferation required cell-to-cell contact, and supernatants from tumor cell cultures did not prevent lymphocyte proliferation. Moreover, the ability of ocular melanoma cells to inhibit T-cell proliferation was lost when tumor cells migrated from the eye and formed hepatic metastases. We conclude that there is a fundamental difference in the immunogenicity of ocular and skin melanoma cells. Ocular melanomas, but not primary skin melanomas, are poorly immunogenic tumors that inhibit T-cell proliferation. Our results imply that the immunogenicity of melanoma cells is altered when they develop within the unique ocular micro-environment.

Efficient harvest of in vivo IL-2-activated CD3+ lymphocytes for adoptive immunotherapy by selective leukapheresis (lymphocytapheresis)

Autologous activated lymphocytes are an alternative to tumor-infiltrating lymphocytes for adoptive immunotherapy. We developed a method of selective lymphocytapheresis that harvests large numbers of interleukin-2 (IL-2)-activated autologous T lymphocytes. Five patients with metastatic malignant melanoma received 2.4 x 10(6) IU/m2 IL-2 sc. once a day 5 days a week for 3 weeks before lymphocytapheresis. Four patients went through lymphocytapheresis without IL-2 pretreatment. After IL-2 pretreatment, activated memory T cells increased significantly. Increasing CD3+ cells paralleled the significant enhancement of the cytotoxic activity against an HLA-A2-matched allogeneic melanoma cell line during the 3 weeks of IL-2 pretreatment. Lymphocytapheresis was performed 72 h after the last IL-2 injection to obtain the maximum recovery of activated lymphocytes at the peak of the rebound phenomenon. IL-2 pretreatment resulted in many more lymphocytes in the harvest than without pretreatment. The percentage, number, and lytic units of CD3+ cells harvested by the differential apheresis were significantly higher than were present in peripheral blood before lymphocytapheresis. These results show that pretreatment of melanoma patients with low-dose IL-2 before lymphocytapheresis allows the selective harvest of large numbers of activated T lymphocytes for adoptive immunotherapy.

Activated long-term peripheral blood cultures as preparation for adoptive alloreactive cell therapy in cancer patients

Different modes of in vitro activation of peripheral blood mononuclear cells (PBMC) were compared for their effect on long-term propagation. PBMC cultures were activated by short exposures to the mitogen phytohemagglutinin (PHA) and the CD3 complex, with or without secondary signals provided by ligands of CD28 costimulatory molecules. Activation and long-term cultures were carried out in the presence of recombinant interleukin-2 (rIL-2). Addition of supernatant derived from IL-2-activated PBMC improved culture cell yield. Cumulative fold expansions ranged between 10(3) and 10(5) within 21 days. The highest cell yield was found after PHA activation. Fewer cells were obtained after activation with a combination of CD3 and CD28, and even fewer were obtained after CD3 activation alone. An increase in CD8+ and CD56+ cells, without change in CD4+ cells, was found in activated cultures when compared with fresh PBMC. Non-MHC-restricted cytotoxic activity was documented in all activated cultures. Cytotoxic activity per culture was highest in PHA-activated PBMC because of the high cell yield on the day of harvest. Successful in vitro expansion of PBMC might be helpful for gene transfer into T lymphocytes, as well as for the induction of an antitumor response, particularly for prevention and treatment of relapse of hematologic malignancies following allogeneic or autologous bone marrow transplantation.

Simultaneous production of T helper-1-like cytokines and cytolytic activity by tumor-specific T cells in ovarian and breast cancer

Cytotoxic T-cell (CTL) cultures were generated from five ovarian cancer patients (OvCTL) and from three breast cancer patients (BrCTL). All CTL lines were T-cell receptor (TcR) alphabeta+ and predominantly CD8+ (73 +/- 13%). These CTL lines preferentially recognized autologous tumor cells in an HLA class I-restricted, and in part HLA-A2-restricted, manner. In addition, the CTL lines recognized allogeneic HLA-A2+ ovarian and breast tumor cells. Specific recognition was determined by T-cell-mediated cytotoxicity as well as cytokine release. Coculture of irradiated autologous tumor cells with OvCTL induced secretion of IFN-gamma, GM-CSF and TNF-alpha, but not IL-4, indicating a T helper-1-type response. Similar results were obtained when OvCTL and BrCTL were stimulated with histologically matched HLA-A2+ tumor cells. Also, BrCTL stimulated with HLA-A2+ but not HLA-A2- ovarian tumor cells produced significant levels of GM-CSF and TNF-alpha. Finally, the Her2/neu peptide p654-662, earlier identified as a tumor antigen in both ovarian and breast cancer, induced cytotoxicity as well as the specific release of IFN-gamma and TNF-alpha but not IL-4 by OvCTL and BrCTL. Thus, tumor-specific recognition by CTL was verified by cytotoxicity and cytokine release. The secretion of Th1-like cytokines as opposed to Th2-like cytokines suggest that therapeutically OvCTL and BrCTL could potentially enhance the endogenous immune response to tumor.

T-cell recognition of melanoma antigens and its therapeutic applications

During the last few years, tumor immunology has gained impetus due to the molecular definition of T-cell-recognized antigens and the mechanisms of such recognition, antigen processing, and presentation. To date, the majority of the identified melanoma antigens are shared among different melanomas and some are also expressed in tumors of different histology. However, unique antigens expressed solely by the melanoma autologous to the T-cell used for their characterization were also found. The identification of the immunogenic peptides, the minimal target entity required for T-cell recognition, has provided novel reagents for the development of peptide-based immunotherapy. These findings, together with the understanding of requirements for T-lymphocyte recognition and activation, allow the design of new therapeutic protocols. In addition, the large body of data now available on the fine mechanism of antigen processing and presentation have revealed not only the role of the MHC molecules but also that of other intracellular proteins, such as transporter associated with antigen processing-1 and -2 and proteosome-related molecules. These findings suggest that, in order to select patients eligible for vaccination, the expression of the MHC allele involved in T-cell recognition, the profile of tumor antigens, and the status of the antigen-processing system should be carefully evaluated in tumors cells of prospective patients. In this review, some of the basic concepts of immune recognition and the current view of melanoma tumor antigens recognized by T-lymphocytes will be discussed along with the potential application of these findings in designing new therapeutic strategies.

Immunotherapy of malignant melanoma

Immunotherapy and biologic therapy of malignant melanoma are based on a sound scientific rationale and show promising preliminary results. As the nature of immune response to melanoma becomes further characterized, it is likely that more specific immune manipulations may be approached clinically. The fact that complete and partial remissions are induced in some patients with metastatic malignant melanoma by INF-alpha, IL-2, LAK cells, TIL cells, tumor vaccines, and the like clearly indicates a potential role for immunotherapy. As the overall response rates to these maneuvers are only in the range of 20%, more basic research is needed to understand more fully the immune mechanisms of tumor rejection. The combination of chemotherapy with biologic therapy has also provided promising leads. A major area waiting for development is the use of immunotherapy and biologic therapy as adjuvant treatment for the prevention of recurrence after surgical removal of high-risk Stage I/II and Stage III disease. The future of immunotherapy, either specific active immunization with appropriate vaccines or adoptive immunotherapy, must be based on well-defined molecules and antigenic systems, with appropriate enhancement based on the principles of immune reaction. Numerous strategies may be developed to enhance immune response, with resultant activation and proliferation of effector cells, including MHC- and non-MHC-restricted cytotoxic effector cells against tumor cells. The practice and principles of immunotherapy of human melanoma may be applied to other solid tumors that are resistant to chemotherapy and radiation therapy. Further experimentation in immunotherapy trials of melanoma may result in reliable and predictable clinical responses.

Cancer: a biological problem without any natural immunological solution? A unified theory, with implications for grafts, pregnancy and tumour immunoprophylaxis

Stem tumour cells would be paraembryonal cells, major histocompatibility complex lacking and able of inducing adjoining cells to become tumour differentiated cells with major histocompatibility complex; thus, they would generate a histological tumour organization into paraembryonal cell clusters surrounded by tumour-differentiated cells. Such an organization, actually found in recent studies, might be one factor responsible for the limits of the immunotherapies carried out so far. But, there might be another, perhaps more important, factor. Analysis of ontogenetic aspects of MHC-nonrestricted immunity would lead, indeed, to the prediction that natural killer clones reactive for stem tumour cells (paraembryonal cells) would be missing in the adult organism, since they would be deleted in particular ontogenetic phases. This might explain why natural killer cells locate only in certain organs and nearly not at all in tumour sites. By such an analysis, possible evolutive and functional correlations between natural killer cells and heat shock proteins, hemopoietic histocompatibility, major histocompatibility complex molecules are suggested. From here, explanations and implications for grafts, pregnancy and tumour immunoprophylaxis arise.

Generation of cytotoxic effector cells against human melanoma

Metastatic or tumor-draining lymph nodes from six of nine melanoma patients undergoing lymph node dissection for metastatic melanoma generated cytotoxic T cells against autologous melanoma when these lymph node cells were treated by in vitro sensitization and recombinant interleukin-2 (IL-2). During the initial lymphocyte culture (2-6 weeks), cross-reactivity with autologous tumor cells, K562 and Daudi cells was usually noted. Cold-target inhibition assay with K562 and Daudi showed K562/Daudi-associated antigens on melanoma cells. During the later phase of lymphocyte culture with repeated in vitro sensitization (over 6-10 weeks), cytotoxicity was noted against autologous and allogeneic melanoma cells but not against K562. Daudi cells or autologous fibroblasts. Repeated in vitro sensitization resulted in the selection of specific cytotoxic lymphocytes against melanoma. Cold-target inhibition assay with autologous and allogeneic melanoma cells revealed shared and individual antigens. Using blocking monoclonal antibodies, MHC-restricted killing was noted in the autologous system. Further, both the autologous and allogeneic systems could be mediated through adhesion molecules such as ICAM-1 and LFA-3 on melanoma cells and LFA-1 on T cells. This study suggests that a constellation of cytotoxic effector cells and melanoma-associated antigens may be pivotal in tumor killing. Thus, future adoptive immunotherapy should modulate and enhance this complex interaction.

Mass spectrometric identification of a naturally processed melanoma peptide recognized by CD8+ cytotoxic T lymphocytes

We and others have previously reported that melanoma-specific, cytotoxic T lymphocytes (CTL) define a minimum of six class I-presented peptide epitopes common to most HLA-A2+ melanomas. Here we show that three of these peptide epitopes are coordinately recognized by a CTL clone obtained by limiting dilution from the peripheral blood of an HLA-A2+ melanoma patient. Tandem mass spectrometry was used to characterize and sequence one of these three naturally processed melanoma peptides. One of the potential forms of the deduced peptide sequence (XXTVXXGVX, X = I or L) matches positions 32-40 of the recently identified melanoma gene MART-1/Melan-A. This peptide (p939; ILTVILGVL) binds to HLA-A2 with an intermediate-to-low affinity and is capable of sensitizing the HLA-A2+ T2 cell line to lysis by CTL lines and clones derived from five different melanoma patients. A relative high frequency of anti-p939-specific effector cells appear to be present in situ in HLA-A2+ melanoma patients, since p939 is also recognized by freshly isolated tumor infiltrating lymphocytes. p939 represents a good candidate for the development of peptide-based immunotherapies for the treatment of patients with melanoma.

Generation and characterization of two human alpha/beta T cell clones. Recognizing autologous breast tumor cells through an HLA- and TCR/CD3-independent pathway

Cell-mediated immune response to breast tumor has only been marginally investigated. To gain insight into this issue we have developed two clones of distinct phenotype, CD3+ alpha/beta, CD4+, CD8-, CD16-, and CD3+ alpha/beta, CD4-, CD8+, CD16-, respectively, from peripheral blood lymphocytes (PBL) of a breast cancer patient. These effectors, selected on the basis of their cytolytic activity against autologous tumor cells and lack of lysis on NK-sensitive cell lines, preferentially recognize autologous tumor cells. The two clones' cytotoxic activity, while inhibited by anti-LFA-1 mAb, could not be abolished by mAbs to CD3, to class I and class II MHC molecules, and by mAbs to molecules involved in T cell function (i.e., CD4, CD8, CD2). The molecular structure of the alpha and beta T cell receptor chains of the two effector cells, confirmed their clonality and showed that, despite an overlapping killing pattern, they possess distinct TCR alpha and beta chains. These findings demonstrate that breast tumor-specific CTL clones can be generated through current technology and that a alpha/beta effector cell population operating through a HLA-unrestricted and TCR/CD3-independent pathway may be involved in the identification and killing of this tumor.

Frequency analysis of tumor-reactive cytotoxic T lymphocytes in peripheral blood of a melanoma patient vaccinated with autologous tumor cells

A limiting-dilution assay was developed and used to determine the frequency of autologous tumor-reactive cytotoxic T lymphocytes (CTL) in peripheral blood of a melanoma patient MZ2, who has been free of detectable disease since several years. In this patient, the frequencies of tumor-reactive CTL spontaneously varied only by a factor of 1.5. After vaccinations with autologous mutagenized and lethally irradiated tumor cells a two- to tenfold increase in frequencies of tumor-reactive CTL was found within the first 2 weeks. Thereafter, CTL frequencies returned to values measured prior to vaccinations. We conclude, that the limiting-dilution assay applied in this study can detect changes in the T cell response to autologous tumor cells. The frequency of tumor-reactive CTL determined with this approach can serve as an immunological parameter for monitoring the T cell response to autologous tumor cells in individual cancer patients receiving tumor cell vaccinations.

Increased expression of perforin and granzyme B genes in patients with metastatic melanoma treated with recombinant interleukin-2

The frequency of peripheral blood cells expressing the perforin gene or the granzyme B gene was evaluated by in situ hybridization in nine patients suffering from metastatic melanoma and treated with recombinant interleukin-2 (rIL-2). A spontaneous expression of both genes was detected in five to seven patients. rIL-2 administration increased the frequency of positive cells in all patients (P < 0.03 for each gene), the highest frequency being reached in the patients who already expressed these genes prior to rIL-2 treatment (P < 0.02). Expressions of the granzyme B gene and of the perforin gene were strongly correlated before IL-2 treatment and they were similarly affected by rIL-2 administration. In contrast, their modification under treatment did not correlate with that of CD56+ cell counts, of natural killer activity and of sCD8 release. This indicates that perforin and granzyme B gene expressions are markers of cytotoxic cell activation independent of those previously described, and that they should be further evaluated in patients with malignancies to delineate their potential value in predicting clinical outcome.

Non-fastidious, melanoma-specific CD8+ cytotoxic T lymphocytes from choroidal melanoma patients

To characterize the anti-melanoma reactivity of CD8+ cytotoxic T lymphocytes (CTL) from choroidal melanoma patients, CTL clones were isolated from the peripheral blood of three patients after mixed lymphocyte/tumor cell culture (MLTC). Clones were derived from lymphocytes stimulated by allogeneic (OCM-1, A24, A28) or autologous (OCM-3, A1, A30) melanoma cells. Their reactivity against a panel of HLA-typed melanoma and nonmelanoma cells was assessed, to determine whether a single CTL clone could recognize and lyse a variety of allogeneic melanoma cell lines. While proportionately more clones derived from autologous MLTC were melanoma-specific than allogeneic MLTC (42% versus 14%), melanoma-specific CTL were recovered from both. Notably, a novel melanoma specificity was identified. These CTL clones were termed non-fastidious because they were capable of lysing melanoma cells with which they had no HLA class I alleles in common. Nonetheless, lysis was mediated by the HLA class I molecule. Since lysis was specific for melanoma cells, these CTL appeared to recognize a shared melanoma peptide(s). Because of their prevalence, we propose that non-fastidious CTL are integral to human anti-melanoma T cell immunity. This reinforces clinical findings that allogeneic melanomas can substitute for autologous tumors in active specific immunotherapy. By circumventing the need for autologous melanoma, it is possible to treat patients after removal of the primary choroidal melanoma in an attempt to prevent metastasis.

Clinical significance of autologous tumor killing (ATK) activity and its induction therapy in human cancer

The activity of blood lymphocytes to kill autologous freshly isolated tumor cells tested at the time of surgery predicts a favorable clinical course in patients who have primary localized solid tumor and receive curative operation. The strong correlation of autologous tumor killing (ATK) activity with disease-free interval and total survival indicates that ATK activity is a meaningful prognostic indicator and provides evidence for immunological control of tumor growth and metastasis. Although there is no direct evidence that ATK lymphocytes play a critical role in regression of tumor and prevention of tumor regrowth, the lack of ATK activity in patients who relapsed and died may not result from other factors related to their poor performance status, immune functions and tumor characteristics. Clinical trials with ATK induction therapy resulted in an improvement of the clinical outcome in patients who naturally have no such potential. The data indicate that the presence of both natural and induced ATK activity is strongly associated with long-term survival. In addition, adoptive transfer of BRM-induced ATK effector cells resulted in prolongation of survival time even in patients with documented metastatic tumors. Thus, considerable emphasis should be placed on a strategy that induces ATK activity in vivo. Such an approach may provide a new focus for cancer immunotherapy.

Tumor immunity as autoimmunity: tumor antigens include normal self proteins which stimulate anergic peripheral T cells

Oncogenic transformation is often accompanied by a significant overproduction of otherwise normal cellular proteins. Because of the low expression of such self components during thymic development, T cells specific for these antigens can escape deletion and progress to the periphery. In this viewpoint, Giorgio Parmiani discusses the concept that these T cells can be harnessed to provide an effective anti-tumor response.

T cell receptor (TCR) structure of autologous melanoma-reactive cytotoxic T lymphocyte (CTL) clones: tumor-infiltrating lymphocytes overexpress in vivo the TCR beta chain sequence used by an HLA-A2-restricted and melanocyte-lineage-specific CTL clone

HLA-A2+ melanomas express common melanoma-associated antigens (Ags) recognized in vitro by autologous cytotoxic T lymphocytes (CTL). However, it is not known whether tumor Ags can drive in vivo a selective accumulation/expansion of Ag-specific, tumor-infiltrating T lymphocytes (TIL). Therefore, to evaluate this possibility, 39 CTL clones isolated from several independent mixed lymphocyte tumor cultures (MLTC) of TIL and peripheral blood lymphocytes (PBL) of an HLA-A2+ melanoma patient and selected for T cell receptor (TCR)-dependent, HLA-restricted tumor lysis, were used for analysis of TCR alpha and beta chain structure by the cDNA polymerase chain reaction (PCR) technique with variable gene-specific primers followed by sequencing. Despite absence of oligoclonality in fresh TIL and PBL, as well as in T cells of day 28 MLTC (day of cloning), sequence analysis of TCR alpha and beta chains of TIL clones revealed a dominance of a major category of melanoma-specific, HLA-A2-restricted T cells expressing a V alpha 8.2/J alpha AP511/C alpha and V beta 2.1/D beta 1/J beta 1.1/C beta 1 TCR. The same TCR was also found in 2 out of 14 PBL clones. The other PBL clones employed a V alpha 2.1 gene segment associated with either V beta 13.2, 14, or w22. Clones A81 (V alpha 2.1/J alpha IGRJ alpha 04/C alpha and V beta 14/D beta 1/J beta 1.2/C beta 1) and A21 (V alpha 8.2/J alpha AP511/C alpha and V beta 2.1/D beta 1/J beta 1.1/C beta 1), representative of the two most frequent TCR of PBL and TIL, respectively, expressed different lytic patterns, but both were HLA-A2 restricted and lysed only HLA-A2+ melanomas and normal melanocytes, thus indicating recognition of two distinct HLA-A2-associated and tissue-related Ags. Finally, by the inverse PCR technique, the specific TCR beta chain (V beta 2.1/D beta 1/J beta 1.1/C beta 1) expressed by the dominant TIL clone was found to represent 19 and 18.4% of all V beta 2 sequences expressed in the fresh tumor sample and in the purified TIL, respectively, but < 0.19% of V beta 2+ sequences expressed in PBL. These results are consistent with the hypothesis that a clonal expansion/accumulation of a melanocyte-lineage-specific and HLA-A2-restricted T cell clone occurred in vivo at the site of tumor growth.

Clonal analysis of in vivo activated CD8+ cytotoxic T lymphocytes from a melanoma patient responsive to active specific immunotherapy

To study in vivo activated cytolytic T cells, CD8+ T cells clones were isolated from a melanoma patient (HLA A2, A11) treated with active specific immunotherapy for 5 years. CD8+ T lymphocytes, purified by fluorescence-activated cell sorting, were cloned directly from the peripheral blood without antigen-presenting cells in the presence of irradiated autologous melanoma cells and recombinant interleukin-2 (IL-2) and IL-4. These conditions were inhibitory to de novo in vitro immunization. Of the 28 cytolytic CD8+ T cell clones, 21 lysed the autologous melanoma cell line (M7) but not the autologous lymphoblastoid cell line (LCL-7) nor the two melanoma cell line, M1 (HLA A28) and M2 (HLA A28, A31), used to immunize the patient. The remaining 7 clones were also melanoma-specific, although their reactivities were broader, lysing several melanoma cell lines but not HLA-matched lymphoblastoid cells. Eight clones from the first group, ostensibly self-MHC-restricted, were expanded for further analysis. All expressed cluster determinants characteristic of mature, activated T cells, but not those of thymocytes, naive T cells, B cells or natural killer (NK) cells. They also expressed CD13, a myeloid marker. Of the 8 clones, 3 expressed both CD4 and CD8, but dual expression was not correlated with specificity of lysis. Two CD8+ and 2 CD4+ CD8+ clones were specific for the autologous melanoma cells, the other 4 were also reactive against other HLA-A2-positive melanomas. Cytotoxicity for both singly and doubly positive clones was restricted by HLA class I but not class II antigens. Analysis of the RNA expression of the T cell receptor (TCR) V alpha and V beta gene segments revealed heterogeneous usage by the A2-restricted clones and, perhaps, also by the broadly melanoma-specific clones. Apparent TCR-restricted usage was noted for the self-MHC-restricted clones; 2 of the 4 expressed the V alpha 17/V beta 7 dimer. Since the T cell clones were derived from separate precursors of circulating cytotoxic T lymphocytes (CTL), the V alpha 17/V beta 7 TCR was well represented in the peripheral blood lymphocytes of this patient. In summary, we show that melanoma cells presented their own antigens to stimulate the proliferation of melanoma-reactive CD8+ CTL. CTL with a range of melanoma specificities and different TCR alpha beta dimers were encountered in this patient, perhaps as a result of hyperimmunization.(ABSTRACT TRUNCATED AT 400 WORDS)

Biological significance of autologous tumor-killing activity and its induction therapy

The overall results presented in this review demonstrate that positive ATK activity at the time of surgery predicts a favorable clinical course in patients who have primary localized solid tumor and receive curative operation. The strong correlation of ATK activity with disease-free interval and total survival (a) indicates that ATK activity is a meaningful prognostic indicator and (b) provides evidence for immunological control of tumor growth and metastasis. According to these data, it is unlikely that cancer patients who remain tumor-free after 5 years of follow-up will develop recurrence or die from the disease. Although there is no direct evidence that ATK effector cells play a critical role in regression of tumor and prevention of tumor regrowth, the lack of ATK activity in patients who relapsed and died after surgery may not result from factors related to their poor performance status since no differences have been observed in background factors between ATK-positive and-negative groups. The prognostic value of ATK activity in patients with documented metastatic tumors has not been established yet. In this respect, however, the induction of ATK activity by BRM has positively correlated with prolonged survival time, while such a correlation is not observed with other parameters such as NK cells or LAK cell activity.

Based on the possible biological significance of ATK activity, clinical trials have been conducted to determine whether the induction of ATK activity before surgery by administration of BRM could improve the clinical outcome in patients who naturally have no such potential. The preliminary data indicate that the presence of both natural and induced ATK activity is strongly associated with longterm survival. Thus, considerable emphasis should be placed on a strategy that induces ATK activity in vivo. Such an approach may provide a new focus for cancer immunotherapy.

Usage of T-cell receptor V beta chain genes in fresh and cultured tumor-infiltrating lymphocytes from human melanoma

Tumor-infiltrating lymphocytes (TIL) freshly obtained from human malignant melanomas as well as the same TIL grown in the presence of interleukin 2 (IL2) were studied for gene expression of the T-cell receptor (TCR) variable beta regions (V beta). To perform the TCR-V beta analysis, total RNA was isolated from TIL and reverse-transcribed into cDNA, which was then amplified by PCR using 22 different 5' primers specifically recognizing the sequences of 20 V beta gene families and a 3' primer annealing to the constant region of the beta chain. The TCR-alpha constant region (C alpha) gene was co-amplified as a standard for the calculation of the percentage of each TCR-V beta gene expressed. The frequency of individual V beta regions expressed on TIL was computed from the ratio of cpm V beta to cpm C alpha for each V beta region in relation to the total of all 22 ratios. With fresh TIL obtained from 8 different melanomas, oligoclonal distribution of V beta genes expressed on TIL was observed, in comparison with a broader and unrestricted distribution seen with peripheral-blood T cells of 8 normal individuals. The oligoclonal patterns of V beta-gene expression in fresh melanoma TIL were distinct in every tumor. Several of the V beta-genes usually expressed in normal PBL were not expressed in fresh TIL in melanoma TIL cultured in the presence of IL2 and IL4 and in the absence of autologous tumor (AuTu) or antigen-presenting cells for 23 to 65 days, selection of T-cell lines expressing a restricted number of V beta genes occurred. Although in 4/5 TIL cultures this selection involved the V beta 7 gene, no relationship could be established between V beta gene expression in fresh TIL and that in T-cell lines outgrowing in long-term cultures. Selection in culture of CD3+CD8+ T-cell lines with V beta-gene expression restricted to 1 or 2 V beta families did not correlate with the presence or level of AuTu cytotoxicity mediated by these T cells. The results indicate that in TIL cultures random selection of T-cell lines with reactivity not relevant to AuTu may account for poor expression or loss of AuTu cytotoxicity by most TIL cultured long-term in the presence of cytokines and in the absence of specific antigenic stimulation.

Expression of the neuroglandular antigen and analogues in melanoma. CD9 expression appears inversely related to metastatic potential of melanoma

Immunohistological methods were used to examine the relation between the metastatic potential of melanoma and expression of the neuroglandular antigen (CD63) and other members of this family of molecules, CD53, CD37, CD9 and the target of an anti-proliferative antibody (TAPA-I), as well as MHC-class-I and -II antigens. The criteria used to establish metastatic potential were their relation to thickness of the primary melanoma, and differences in expression between vertical and radial growth phases of primary melanoma and between primary and metastatic melanoma. Studies on basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC) were also included as controls for malignant skin cancers with low metastatic potential. Expression of CD9 and MHC-class-I antigen was found to be inversely related to thickness of the primary tumor, and CD9 was expressed predominantly on primary rather than on metastatic tumors. CD9 expression correlated with MHC-class-I expression on melanoma, and both were expressed on BCCs and SCCs having low metastatic potential, but not on compound nevi. CD63 and TAPA-I were expressed on nevi but not on SCC and BCC. Leu 13 is a molecule associated with TAPA-I in lymphomas, and was found to be expressed in sections from 5 out of 34 primary and 5 out of 21 metastatic melanoma. CD53 and CD37 were not detected on melanoma. Our results indicate that several members of the neuroglandular antigen are expressed in melanoma and that low expression of CD9 on primary melanomas might have prognostic significance with respect to the potential for metastasis.

Melanoma cells and normal melanocytes share antigens recognized by HLA-A2-restricted cytotoxic T cell clones from melanoma patients

HLA-A2-restricted, CD3+, CD8+, alpha/beta+ cytotoxic T cell (CTL) clones were isolated from peripheral blood (PBL) or tumor infiltrating lymphocytes (TIL) of two HLA-A2+ melanoma patients (9742 and 5810), to evaluate the possible recognition of autologous melanoma and of allogeneic HLA-A2-matched normal melanocytes. These CTL clones lysed not only fresh and cultured autologous melanoma cells, but also allogeneic HLA-A2+, but not HLA-A2-, normal melanocytes. The lysis of autologous neoplastic cells and of melanocytes could be inhibited by an anti-HLA-A2 monoclonal antibody (mAb). Lysis of the normal melanocytes was not dependent on the presence of human or fetal calf serum in the culture medium. HLA-A2-restricted CTL clones recognized not only proliferating melanocytes cultured in complete melanocyte medium, but also melanocytes made quiescent by culture for up to 6 d in a basal medium devoid of exogenous factors such as phorbol ester (O-tetradecanoyl phorbol 13-acetate [TPA]), epidermal growth factor, insulin, and pituitary extracts. Analysis of specificity of four CTL clones (A75, A83, A94, and 119) from patient 9742, performed on a panel of 39 targets, indicated that the three HLA-A2-restricted CTL (A75, A83, and A94) lysed all but one of nine allogeneic melanomas expressing the HLA-A2 molecule with no reactivity on nine HLA-A2- allogeneic melanomas. Only a few instances of borderline reactivity were seen by the same effectors on 21 targets of nonmelanocyte lineage, including 12 carcinomas of different histology, four Epstein-Barr virus-transformed B cells (lymphoblastoid cell lines [LCL]), including the autologous LCL, four lines of normal fibroblasts, and normal kidney cells. Lack of reactivity on allogeneic targets of nonmelanocyte lineage occurred in spite of expression of HLA-A2 on 14 of these targets as determined by conventional tissue typing and cytofluorimetric analysis with four different anti-HLA-A2 mAb. These data indicate that tissue-related antigens can be expressed on normal and neoplastic cells of the melanocyte lineage and can be recognized in association with HLA-A2 by CTL clones from melanoma patients.

T-cell-receptor engagement and tumor ICAM-1 up-regulation are required to by-pass low susceptibility of melanoma cells to autologous CTL-mediated lysis

Tumor-specific and non-specific CD3+, TcR alpha beta+, CD8+ cytotoxic T-cell (CTL) clones, isolated from tumor-infiltrating lymphocytes (TIL) or peripheral blood lymphocytes (PBL) of a melanoma patient and allogeneic LAK cells, were used to investigate the requirements for bypassing the low lysability of some melanoma clones derived from an s.c. metastasis from which highly lysable clones were also obtained. Cytofluorimetric analysis showed that all melanoma clones expressed ICAM-1, although to different extents, reaching a 10-fold difference in fluorescence units, while HLA class-I antigens were similarly expressed. The differences in expression of ICAM-1 among tumor clones correlated with differences in lysability, by both specific and non-specific CTL, but were not large enough to affect lymphocyte-tumor conjugate formation. Cytokine- or gene-transfer-mediated up-regulation of ICAM-1 did not induce de novo lysis of ICAM-1low tumor cells; however, it markedly enhanced a low level of killing of the same cells by tumor-specific, TcR-dependent and HLA-restricted CTL clones but not by non-specific, TcR-independent effectors. In addition, lysis of melanoma clones by any effector was similarly inhibited by anti-ICAM-1 and anti-LFA-1 antibodies. This indicates that by-pass of low lysability of ICAM-1low melanoma clones by CTL clones, after ICAM-1 up-regulation, is possible only if simultaneous LFA-1 and TcR engagement takes place. In addition, these results suggest that the constitutive high level of expression of ICAM-1 on the subset of ICAM-1high melanoma cells must be only one of the factors contributing to the high lysability of these cells by any effector.

Strategies for cytokine utilisation in tumor therapy

The state of the art with regard to the employment of various cytokine-based tumor immunotherapy strategies and their mechanisms of action are critically reviewed. As matters now stand, adoptive transfer of LAK cells or tumor infiltrating lymphocytes together with high doses of IL-2 constitutes the only immunologic way to hinder tumor growth in advanced stages of cancer. On the other hand, many experimental data show that the local presence of cytokines, either injected repeatedly at tumor site or released by cytokine-gene engineered tumor cells, arouses immunogenicity in apparently nonimmunogenic spontaneous tumors. By strengthening the notion that most tumors are potentially immunogenic, these findings offer substantial evidence to stress the potential use of cytokines as a component of new tumor vaccines.

Treatment with tumour infiltrating lymphocytes and interleukin-2 in patients with metastatic melanoma: a pilot study

Tumour infiltrating lymphocytes (TIL) were isolated and expanded from biopsy samples of 4 patients with metastatic melanoma. The patients were treated with autologous expanded TIL and continuous or bolus infusion of Interleukin 2 (IL-2) at a dose of 18 x 10(6) International Units/m2/day for 5 days starting 36-48 hours after administration of cyclophosphamide at a dose of 1 g/m2. The number of TIL infused ranged from 10(10) to 5.56 x 10(10) cells. Two patients had stable disease (SD) lasting for 2 1/2 and 4 months respectively and they died 24 and 13 months after therapy. One patient died during therapy due to a pseudomonas septicaemia and another patient developed progressive disease (PD). He died 3 months after the start of therapy. The side effects were substantial but most of them were reversible upon cessation of the treatment. The majority of the expanded TIL of all patients were of the CD8+ phenotype. Cutaneous metastases from two patients, removed after treatment with IL-2 and TIL, showed moderate lymphocytic infiltration also mainly of CD8+ T cells. The treatment with IL-2 and TIL is feasible, but further investigations should continue in an attempt to improve the efficacy of the therapy, to reduce toxicity and to diminish the costs and labour of the culture methods.

HLA-B5-restricted auto-tumor-specific cytotoxic T cells generated in mixed lymphocyte-tumor-cell culture

T-cell-enriched lymphocyte populations derived from the malignant exudate of a patient with ovarian carcinoma were exposed to autologous tumor cells in the mixed lymphocyte-tumor-cell culture (MLTC) and propagated for 42 days. Proliferation of lymphocytes depended on exposures to autologous tumor cells and on the presence of IL-2. After 7 days, the MLTC-lymphocytes lysed K562 and the autologous tumor cells. The latter effect was not inhibited by monoclonal antibodies (MAbs) reactive with MHC class-I antigens or with CD3. After 7 restimulations, the culture was enriched in CD8+ cells (92%) and showed selective lytic activity against the autologous tumor. This function was inhibited by the alpha-class I or alpha-CD3 MAbs, and also by antibodies reactive with the HLA B locus or B5 allele products. The antibodies reactive with HLA A molecules had no such effect. It seems therefore that the function of the CTLs was restricted by HLA B5. Analysis of the TCR beta genes indicated clonal T-cell expansion in this culture. This MLTC was 1 of 21 initiated with 11 blood- and 10 tumor-derived lymphocyte (TIL) populations prepared from the malignant effusions of ovarian carcinoma patients. None of these ex-vivo lymphocytes lysed autologous tumor cells. In 17 MLTCs the lymphocytes did not proliferate, and in 3 cultures the proliferation was maintained only for 2-3 weeks. In 3 of 4 cultures auto-tumor cytotoxicity was induced.

Memory T-lymphocytes are the main population of tumor-infiltrating lymphocytes obtained from human primary liver tumors

The phenotypic characteristics of freshly isolated tumor-infiltrating lymphocytes (TIL) obtained from human liver tumors were analyzed by two-color flow cytometry. TIL consisted of mainly CD3+ T-lymphocytes (70-80%). The ratio of CD4/CD8 in TIL from primary and metastatic liver tumors and autologous peripheral blood lymphocytes (A-PBL) was 1.3, 1.1 and 1.3, respectively. The majority of CD3+ T-lymphocytes (mean +/- SD; 95 +/- 11%) expressed T-cell antigen receptor (TCR) alpha/beta, and gamma/delta TCR positive T-cells were only 5 +/- 4.5% in TIL from both primary and metastatic liver tumors. TIL showed significantly higher percentages of transient activation markers, such as CD25 (Tac) and HLA-DR, than A-PBL. TIL also contained significantly more populations of CD3+ CD45RO+ T-lymphocytes, which are considered to be expressed on primed (memory) T-lymphocytes, than A-PBL. Furthermore, TIL from primary liver tumors demonstrated significantly higher percentages of CD3+ CD45RO+ T-cells than those from metastatic liver tumors. These data indicate that TIL from human liver tumors are an apparently distinct population from A-PBL, and that local immune responses against human primary and metastatic liver tumors might be different. Moreover, TIL from primary liver tumors consisted of mainly activated or primed (memory) T-cells, suggesting that they were sensitized and activated by autologous tumor cells in vivo. These observations may imply the possibility of adoptive immunotherapy using TIL against human primary liver tumors.

Cell retargeting by bispecific monoclonal antibodies. Evidence of bypass of intratumor susceptibility to cell lysis in human melanoma

Intratumor heterogeneity for susceptibility to cytotoxic T lymphocytes (CTL)-mediated lysis represents a major obstacle to cancer adoptive immunotherapy. To overcome the heterogeneity observed in terms of susceptibility of target cells to cell-mediated lysis, in this study we used two purified bispecific monoclonal antibodies (bsmAbs) that recognize molecules expressed by cytotoxic effector cells (CD3 and IgG Fc receptorial molecules), as well as one high molecular weight melanoma-associated antigen (HMW-MAA). The ability of these reagents to enhance or induce a relevant in vitro cytotoxic activity by a CTL clone (CTL 49) isolated from PBL of a melanoma patient was tested on a large panel of autologous and allogeneic melanoma cell lines and clones. Functional studies revealed that the CTL 49 clone lysed all the HMW-MAA+ tumor lines in the presence of bsmAbs and that these reagents affected the target lysis in a cooperative fashion. The effectiveness of bsmAbs in overcoming the heterogeneous susceptibility of human melanoma cells to cell-mediated lysis may find practical implications in cancer adoptive immunotherapy.