Immunoscore and Immunoprofiling in cancer: an update from the melanoma and immunotherapy bridge 2015

The fifth "Melanoma Bridge Meeting" took place in Naples, December 1-5th, 2015. The main topics discussed at this meeting were: Molecular and Immuno advances, Immunotherapies and Combination Therapies, Tumor Microenvironment and Biomarkers and Immunoscore. The natural history of cancer involves interactions between the tumor and the immune system of the host. The immune infiltration at the tumor site may be indicative of host response. Significant correlations were shown between the levels of immune cell infiltration in tumors and patient's clinical outcome. Moreover, incredible progress comes from the discovery of mutation-encoded tumor neoantigens. In fact, as tumors grow, they acquire mutations that are able to influence the response of patients to immune checkpoint inhibitors. It has been demonstrated that sensitivity to PD-1 and CTLA-4 blockade in patients with advanced NSCLC and melanoma was enhanced in tumors enriched for clonal neoantigens. The road ahead is still very long, but the knowledge of the mechanisms of immune escape, the study of tumor neo-antigens as well as of tumor microenvironment and the development of new immunotherapy strategies, will make cancer a more and more treatable disease.

IRF-1 responsiveness to IFN-γ predicts different cancer immune phenotypes

BACKGROUND

Several lines of evidence suggest a dichotomy between immune active and quiescent cancers, with the former associated with a good prognostic phenotype and better responsiveness to immunotherapy. Central to such dichotomy is the master regulator of the acute inflammatory process interferon regulatory factor (IRF)-1. However, it remains unknown whether the responsiveness of IRF-1 to cytokines is able to differentiate cancer immune phenotypes.

METHODS

IRF-1 activation was measured in 15 melanoma cell lines at basal level and after treatment with IFN-γ, TNF-α and a combination of both. Microarray analysis was used to compare transcriptional patterns between cell lines characterised by high or low IRF-1 activation.

RESULTS

We observed a strong positive correlation between IRF-1 activation at basal level and after IFN-γ and TNF-α treatment. Microarray demonstrated that three cell lines with low and three with high IRF-1 inducible translocation scores differed in the expression of 597 transcripts. Functional interpretation analysis showed mTOR and Wnt/β-cathenin as the top downregulated pathways in the cell lines with low inducible IRF-1 activation, suggesting that a low IRF-1 inducibility recapitulates a cancer phenotype already described in literature characterised by poor prognosis.

CONCLUSION

Our findings support the central role of IRF-1 in influencing different tumour phenotypes.

IL-10 stimulatory effects on human NK cells explored by gene profile analysis

The molecular mechanisms underlying the increase of natural killer (NK) cell anticancer activity mediated by interleukin (IL)-10 have not been elucidated. The aim of this study was to identify potential molecular mediators of IL-10 stimulatory effects by exploring the NK cell gene display induced by this cytokine. Gene profile was determined by high-throughput cDNA microarray and quantitative real-time PCR. In vitro, NK cells resting or conditioned with IL-10 were tested for cytotoxicity, migration and proliferation. IL-10 enhanced mRNA levels of cell activation/cytotoxicity-related genes (eg secretogranin, TIA-1, HMG-1, interferon-inducible genes) not upregulated by IL-2. In line with these findings, IL-10 increased NK cell in vitro cytotoxicity against Daudi cells. Unlike IL-2, IL-10 did not show any significant effect on NK cell in vitro proliferation and migration. However, gene profile analysis showed that IL-10 increased the expression of cell migration-related genes (eg L-selectin, vascular endothelium growth factor receptor-1, plasminogen activator, tissue; formyl peptide receptor, lipoxin A4 receptor), which might support a stimulatory effect not evident with the in vitro functional assay. Overall, gene profiling allowed us to formulate new hypotheses regarding the molecular pathways underlying the stimulatory effects of IL-10 on NK cells, supporting further investigation aimed at defining its role in cancer immune rejection.

Consistent cytotoxic-T-lymphocyte targeting of immunodominant regions in human immunodeficiency virus across multiple ethnicities

Although there is increasing evidence that virus-specific cytotoxic-T-lymphocyte (CTL) responses play an important role in the control of human immunodeficiency virus (HIV) replication in vivo, only scarce CTL data are available for the ethnic populations currently most affected by the epidemic. In this study, we examined the CD8(+)-T-cell responses in African-American, Caucasian, Hispanic, and Caribbean populations in which clade B virus dominates and analyzed the potential factors influencing immune recognition. Total HIV-specific CD8(+)-T-cell responses were determined by enzyme-linked immunospot assays in 150 HIV-infected individuals by using a clade B consensus sequence peptide set spanning all HIV proteins. A total of 88% of the 410 tested peptides were recognized, and Nef- and Gag-specific responses dominated the total response for each ethnicity in terms of both breadth and magnitude. Three dominantly targeted regions within these proteins that were recognized by >90% of individuals in each ethnicity were identified. Overall, the total breadth and magnitude of CD8(+)-T-cell responses correlated with individuals' CD4 counts but not with viral loads. The frequency of recognition for each peptide was highly correlated with the relative conservation of the peptide sequence, the presence of predicted immunoproteasomal cleavage sites within the C-terminal half of the peptide, and a reduced frequency of amino acids that impair binding of optimal epitopes to the restricting class I molecules. The present study thus identifies factors that contribute to the immunogenicity of these highly targeted and relatively conserved sequences in HIV that may represent promising vaccine candidates for ethnically heterogeneous populations.

Biased epitope selection by recombinant vaccinia-virus (rVV)-infected mature or immature dendritic cells

Recombinant expression vectors represent a powerful way to deliver whole antigens (Ags) for immunization. Sustained Ag expression in vector-infected dendritic cells (DC) combines Ag-specific stimulation with powerful costimulation and, simultaneously, through 'self-selection' of ad hoc epitopes broadens the scope of immunization beyond restrictions posed by individual patients' human leukocyte antigen (HLA) phenotype. In this study, therefore, we evaluated the efficiency of a recombinant vaccinia virus encoding the gp100/PMel17 melanoma Ag (rVV-gp100) to infect immature (iDC) or mature dendritic cells (mDC) derived from circulating mononuclear cells and the effect of infection on their status of maturation. In addition, we tested the ability of rVV-gp100-infected iDC and mDC to present the HLA-A*0201-associated gp100:209-217 epitope (g209). Irrespective of status of maturation, rVV-gp100 infection induced gp100 expression while only partially reversing the expression of some maturation markers. However, endogenous presentation of the wild-type g209 epitope was inefficient. The low efficiency was epitope-specific since infection of DC with rVV encoding a gp100 construct containing the modified gp100:209-217 (210M) (g209-2M) epitope characterized by high binding affinity for HLA-A*0201 restored efficient Ag presentation. Presentation of an HLA-class II-associated epitope and cytokine release by DC was not altered by rVV infection. Thus, Ag expression driven by rVV may be an efficient strategy for whole Ag delivery. However, since the effectiveness of Ag processing and presentation is subject to stringent HLA/epitope pairing, and for other yet undefined rules, the assumption that whole Ag delivery may circumvent HLA restriction is incorrect and recombinant expression vectors encoding well-characterized polyepitopic constructs may prove more effective.

Use of laser scanning cytometry to study tumor microenvironment

The study of phenomena occurring in the tumor microenvironment is a challenging task because of technical difficulties, particularly when dealing with hypocellular specimens. Laser scanning cytometry (LSC) is a new laboratory technology that has been recently introduced to overcome the limitations of other traditional technologies. By combining the properties and the advantages of flow cytometry (FC) and immunohistochemistry (IHC), LSC allows the investigator to obtain objective information on DNA content, protein expression and cellular localization is combination with morphological features. It has been already shown that LSC results are reliable compared to more traditional technologies, and its implementation in the clinical routine is under way. Its use in oncology, which is rapidly expanding, spans from apoptosis analysis to DNA content quantitation and tumor cell phenotyping. Here we describe the technology underlying this novel fluorescence-based device, review its use in oncology by dissecting the phenomena occurring in the tumor microenvironment and propose its application for the immunological follow-up of malignant lesions undergoing immunotherapeutic manipulation.

Advantages of mRNA amplification for microarray analysis

Expanding applications of cDNA microarrays such as fine needle aspiration biopsy and laser capture microdissection necessitate the ability to perform arrays with minute starting amounts of RNA. While methods for amplifying RNA have been advocated, the fidelity of array results using amplified material has not been fully validated. Here we demonstrate preserved fidelity in arrays using one or two rounds of mRNA amplification, validated by downstream real-time quantitative PCR. In addition, the quality of the array data was superior to that obtained using total RNA. Based on these results, we recommend routine mRNA amplification for all cDNA microarray-based analysis of gene expression.

Immunotherapy against antigenic tumors: a game with a lot of players

Our understanding of how immune responses are generated and regulated drives the design of possible immunotherapies for cancer patients. For that reason, we first describe briefly the actual immunological theories and their common perspectives about cancer vaccine development. Second, we describe cancer vaccines that are able to induce tumor-specific immune responses in cancer patients. However, these responses are not always followed by tumor rejection. At the end of the review, we discuss two possible reasons that might explain this dichotomy of cancer immunology. First, the immune response generated, although detectable, may not be quantitatively sufficient to reject the tumor. Second, the tumor microenvironment may modulate tumor cell susceptibility to the systemic immune response induced by the immunization. Finally, we discuss what, in our opinion, might be the best way to improve cancer vaccine strategies and how the relationship between the tumor and its surroundings might be studied in more details.

Melanoma antigen expression in serial fine-needle aspiration samples in patients with metastatic malignant melanoma participating in immunotherapy clinical trials: a preliminary look

BACKGROUND

MART-1 and gp100 currently are utilized as targets in immunotherapy protocols for metastatic malignant melanoma (MMM). Enrollment of patients into ongoing peptide vaccination trials at the National Cancer Institute includes immunophenotyping of samples of metastatic lesions obtained by fine-needle aspiration (FNA). As therapy progresses, immunocytochemistry is performed on serial FNAs of metastatic lesions to monitor changes in antigen expression during treatment. It is theorized that antigen expression of melanoma cells may be diminished because of selective immunodestruction of tumor cells, or perhaps intentionally, to escape immunosurveillance.

METHODS

Thirty-eight lesions from 33 patients were serially monitored for the expression of gp100 (clone HMB-45) and MART-1 (clone M2-7C10), using an avidin-biotin peroxidase technique. The staining intensity of tumor cells was scored on a scale of 0 to 3+, with the proportion of positive cells categorized as less than 25%, 25-50%, 50-75%, and greater than 75%. All lesions were examined within approximately 2 months after the start of peptide vaccination, providing a consistent timepoint for analysis.

RESULTS

Using the Wilcoxon signed rank test, the authors found that there were no significant changes from baseline compared with 2 months later for quantitative antigen expression of HMB-45 or MART-1. However, there was a trend toward a decline in staining intensity of tumor cells for HMB-45.

CONCLUSIONS

Preliminary results evaluating antigen expression during selective immunotherapy indicate a trend in the decline of staining intensity of tumor cells to HMB-45. Thus, although other studies have shown that peptide-based immunotherapy results in immune selection, this does not hinder the diagnostic utility of antibodies to HMB-45 and MART-1 in FNA samples of MMM.

Antigen presentation of a modified tumor-derived peptide by tumor infiltrating lymphocytes

CD8+ T-lymphocytes recognize peptides in the context of major histocompatibility complex (MHC) class I antigens. Upon activation, these cells differentiate into effector cytotoxic T lymphocytes (CTL) and no longer require formal antigen presentation by professional antigen presenting cells (APC). Subsequently, any cell expressing MHC class I/cognate peptide can stimulate CTL. Using TIL specific for a melanoma antigen-derived peptide, IMDQVPFSV (g209 2M), we sought to determine whether these CTL could present peptide to each other. Our findings demonstrate that peptide presentation of the g209 2M peptide epitope by TIL is comparable to conventional methods of using T2 cells as APC. We report here that CTL are capable of self-presentation of antigenic peptide to neighboring CTL resulting in IFN-gamma secretion, proliferation, and lysis of peptide-loaded CTL. These results demonstrate that human TIL possess both APC functions as well as cytotoxic functions and that this phenomenon could influence CTL activity elicited by immunotherapy.

Laser scanning cytometry evaluation of MART-1, gp100, and HLA-A2 expression in melanoma metastases

Assessment of antigen expression by solid tumors has relied predominantly on immunohistochemistry, flow cytometry, and more recently quantitative real-time polymerase chain reaction. However, all these techniques present intrinsic limits. The laser scanning cytometer, by combining the properties of light and fluorescence microscopy with those of laser cytometry, can quantitatively and objectively analyze hypocellular samples such as fine-needle aspirates on an individual cell basis. To validate the fidelity of laser scanning cytometry for quantitative immunophenotyping of fine-needle aspirates, the authors measured the expression of the melanoma-associated antigens MART-1 and gp100 as well as HLA-A2, a HLA class 1 restriction element associated with their recognition by melanoma-specific T cells. Expression of melanoma antigens and HLA was measured by laser scanning cytometry and immunohistochemistry in fine-needle aspirates from melanoma metastases. In addition, transcription levels of both melanoma antigens were recorded by quantitative real-time polymerase chain reaction. A quantity of less than 1,000 cells per sample (average 682 cells) was sufficient for the analysis. Laser scanning cytometry estimates correlated with those of immunohistochemistry and quantitative real-time polymerase chain reaction for MART-1 and gp100. A good correlation in HLA-A2 detection by laser scanning cytometry and immunohistochemistry was also observed. Moreover, the laser scanning cytometer could discriminate subsets of cells from the same lesion with heterogeneous melanoma antigen expression, leading to the observation that cells with a DNA index greater than 2.5 expressed significantly less gp100. Thus, laser scanning cytometry yields detailed information on protein expression in individual cells and represents a new tool for dissecting the immune response in the tumor microenvironment.

Antigenicity of fusion proteins from sarcoma-associated chromosomal translocations

Synovial sarcoma (SS), clear cell sarcoma (CCS), and desmoplastic small round cell tumor (DSRCT) are soft-tissue malignancies occurring primarily in adolescents and young adults. These tumors contain specific chromosomal translocations that fuse the 5' region of one gene with the 3' region of another, resulting in the formation of characteristic fusion proteins. These translocations are unique to tumor cells and may be required for persistence, thereby serving as targets for immunotherapy. It was hypothesized that the fusion breakpoint sequences associated with SS, CCS, and DSRCT can serve as tumor-specific neoantigens. To test this, peptides corresponding to the fusion breakpoints were designed and assessed for ability to bind to various class I HLA molecules. Two peptides derived from the SS breakpoint specifically bind the HLA-B7 antigen, and a 10-amino acid minimal epitope was identified for this interaction. Specific binding of a SS peptide and a CCS peptide to HLA-B27 molecule was also observed. Finally, a peptide designed from the DSRCT breakpoint specifically binds the HLA-A3 molecule, and a 9-amino acid optimal epitope was identified for this interaction. The physiological/immunological relevance of these peptide/MHC interactions was demonstrated by the induction of SS-specific CTLs from normal donor lymphocytes using in vitro stimulation with autologous, peptide-pulsed dendritic cells and by the ability of these CTLs to lyse human SS tumor cells endogenously expressing the full-length fusion protein. These results suggest that sequences in the fusion region of sarcoma-associated chimeras can bind class I HLA molecules and serve as neoantigens. These may be useful for the development of novel immunotherapies for sarcoma patients with appropriate HLA molecules and tumors bearing these translocations.

Unmasking cryptic epitopes after loss of immunodominant tumor antigen expression through epitope spreading

The basis of intra-tumoral and systemic T cell reactivity toward cancer remains unclear. In particular the role that peripheral stimuli, whether endogenous or exogenous, play in shaping acquired immune response toward cancer remains poorly understood. In this study we document the surfacing of systemic immune reactivity toward a cryptic epitope from the MAGE-12 gene (MAGE-12:170-178), after temporary regression of a single melanoma metastasis, in response to gp100/PMel17-specific vaccination. This emergence was unlikely related to unusually high expression of MAGE-12 by the tumor, by the influence of analog epitopes to MAGE-12:170-178. Because MAGE-12 was unlikely to be expressed at sites other than the tumor, the demonstration of MAGE-12:170-178 reactivity in post- but not pre-vaccination circulating lymphocytes suggests that the systemically observed immune response was influenced by events induced by the vaccine at tumor site or draining lymph nodal areas. Possibly, as suggested by pre-clinical models, immunologic ignorance is the default response toward cancer in humans unless unusual stimulatory conditions occur in peripheral tissues. Surfacing of MAGE-12 specificity occurred in association with loss of gp100/PMel 17 targeted by the vaccine. This finding suggests that vaccinations might have effects beyond their intrinsic specificity and may trigger broader immune responses through epitope spreading by inducing changes within the tumor microenvironment. This may have important practical implication for the development of immunization strategies. Published 2001 Wiley-Liss, Inc.

Cytokines and immune response in the tumor microenvironment

Over the last few decades a wealth of evidence has been gathered on the potential role that the immune system (IS) can play in the fight against cancer. Together with cell surface adhesion molecules, cytokines (CKs) mediate the activities of IS cells. Therefore, CK kinetics may represent a mirror of the immunologic phenomena occurring in the tumor microenvironment, where immune and malignant cells interact. Yet, CKs are currently used in a clinical setting to polarize the immune response against cancer. Despite the large amount of information available on IS physiology, little is known about the role of CKs in modulating the effectiveness of immunotherapy clinical trials aimed at the treatment of patients with cancer. This underscores our relative ignorance about the complex cascade of events that lead to tumor rejection. Here, we review the properties of some CKs believed to be particularly relevant to tumor immunology (i.e., interleukin [IL]-10, transforming growth factor-beta, interferon-gamma, IL-2, IL-4, and IL-12). We summarized the experience gained with these CKs in vitro, in animal models, and in human beings to illustrate the achievements, the controversies, and the challenges that characterize this fascinating field of oncology. In addition, we added a short section in which a broad view of CKs released in the tumor microenvironment is proposed to underline the variety of factors that contribute to the complexity of tumor-IS interactions.

Discordant cellular and humoral immune responses to cytomegalovirus infection in healthy blood donors: existence of a Th1-type dominant response

Previous studies have documented discordant cellular and humoral immune responses to subjects exposed to HIV-1, and that the nature of such responses may determine susceptibility and resistance to disease. We determined whether there is a spectrum of cellular versus humoral immunodominant responses to cytomegalovirus (CMV) infection. Blood samples from 50 healthy blood donors were tested for anti-CMV IgG antibodies and for proliferative responses of peripheral blood mononuclear cells (PBMC) to CMV antigens. Four patterns of immune responses to CMV were found: no detectable response (30%, Ab(-)/Tc(-)), anti-CMV IgG only (28%, Ab(+)/Tc(-)), both anti-CMV IgG and T lymphocyte proliferation to CMV antigens (18%, Ab(+)/Tc(+)), and, interestingly, T lymphocyte proliferation to CMV only (24%, Ab(-)/Tc(+)). To determine whether these immunodominant phenotypes correlate with the ability of PBMC to secrete IL-2 and IFN-gamma in response to CMV antigens, we found that a greater percentage of individuals with a T cell proliferative response to CMV antigens (Ab(-)/Tc(+) and Ab(+)/Tc(+)) responded with increased IL-2 (P = 0.001) and IFN-gamma levels (P = 0.002), compared to those without a proliferative response (Ab(-)/Tc(-) and Ab(+)/Tc(-)). Our data therefore demonstrate that different individuals exhibit different immunodominant patterns of response to CMV. In particular, some individuals who are exposed to CMV fail to develop an antibody response but do develop cellular immunity. Whether these different patterns predict susceptibility or resistance to CMV-induced disease remains to be determined.

Short-term kinetics of tumor antigen expression in response to vaccination

The melanoma patient's immune response to tumor has been extensively studied. Yet, the frequently observed coexistence of tumor-associated Ag (TAA)-specific T cells with their target cells in vivo remains unexplained. Loss of TAA expression might contribute to this paradox. We studied TAA expression in metastases by obtaining fine-needle aspirations from 52 tumor lesions in 30 patients with melanoma before and soon after immunotherapy. Limitations due to low amounts of starting material were overcome with a high fidelity antisense RNA amplification method. TAA expression was measured by quantitative real-time PCR of anti-sense RNA. Decrease in gp100/Pmel-17 TAA preceded tumor disappearance in several instances and could be best explained by immune selection because most patients had received gp100/Pmel-17-specific vaccination. Conversely, immune selection was absent in nonregressing lesions. These observations suggest that vaccination, when successful, triggers a broad inflammatory reaction that can lead to tumor destruction despite immune selection. Additionally, lack of clinical response might be attributed to lack of this initiating event rather than immune escape. This study provides an insight into the natural history of tumors and defines a strategy for the characterization of gene expression in tumors during therapy.

Kinetics of cytokine expression in melanoma metastases classifies immune responsiveness

Production of cytokines (CKs) in the tumor micro-environment may modulate tumor-host interactions. However, pre-clinical models often provide conflicting data and there is no established role for CKs as modulators of the natural or treatment-related behavior of tumors. Serial sampling by fine-needle aspirates (FNAs) of identical metastases from patients affected with metastatic melanoma and undergoing IL-2-based vaccination allowed prospective measurement of IL-10, TGF-beta1, TGF-beta2 and IFN-gamma transcriptional levels assessed by quantitative real-time PCR. Thus, it was possible to prospectively document the expression of markers relevant to a given treatment and follow at the same time the clinical outcome of the lesions left in place. Eight of 27 metastatic lesions completely regressed in response to the treatment and 1 demonstrated >50% shrinkage. These regressions occurred after the follow-up FNA had been obtained. IL-10 transcript was differentially expressed in pre-treatment FNA of responding lesions (t-test p(2) = 0.002). During treatment, INF-gamma transcript levels significantly increased in regressing compared to non-regressing lesions (t-test p(2) = 0.03). These data suggest that the pre-treatment CK profile of the tumor micro-environment may determine clinical responsiveness to immune therapy. Furthermore, temporal changes in CK expression during treatment might describe the biological characteristics of an effective immune response.

Adoptive transfer of cloned melanoma-reactive T lymphocytes for the treatment of patients with metastatic melanoma

This report describes a phase I study of the adoptive transfer of cloned melanoma antigen-specific T lymphocytes for therapy of patients with advanced melanoma. Clones were derived from peripheral blood lymphocytes or tumor-infiltrating lymphocytes of patients who had received prior immunization with the melanoma-associated antigen, gpl00. In response to its cognate antigen, each clone used for treatment secreted large amounts of interferon-gamma and granulocyte-macrophage colony-stimulating factor, lesser amounts of interleukin (IL)-2 and tumor necrosis factor-alpha, and little or no IL-4 and IL-10. Clones also demonstrated recognition of human leukocyte antigen-matched melanomas using cytokine secretion and lysis assays. Twelve patients received 2 cycles of cells alone; 11 patients received additional cycles of cells and were randomized between two schedules of IL-2 (125,000 IU/kg subcutaneously daily for 12 days versus 720,000 IU/kg intravenously every 8 h for 4 days). A total of 51 cycles of cells were administered, with an average of 1 x 10(10) cells per cycle. Peripheral blood samples were analyzed for persistence of transferred cells by T-cell receptor-specific polymerase chain reaction. Transferred cells reached a maximum level at 1 h after transfer but rapidly declined to undetectable levels by 2 weeks. One minor response and one mixed response were observed (both in the high-dose IL-2 arm). This report demonstrates the safety and feasibility of cloned T-cell transfer as a therapy for patients with cancer. The lack of clinical effectiveness of this protocol suggests that transfer of different or additional cell types or that modulation of the recipient host environment is required for successful therapy.

Kinetics of TCR use in response to repeated epitope-specific immunization

Selection of T cell-directed immunization strategies is based extensively on discordant information derived from preclinical models. We characterized the kinetics of T cell selection in response to repeated antigenic challenge. By enumerating with epitope/HLA tetrameric complexes (tHLA) vaccine-elicited T cell precursor frequencies (Tc-pf) in melanoma patients exposed to the modified gp100 epitope gp100:209-217 (g209-2M) we observed in most patients that the Tc-pf increased with number of immunizations. One patient's kinetics were further characterized. Dissociation kinetics of g209-2M/tHLA suggested enrichment of T cell effector populations expressing TCR with progressively higher affinity. Furthermore, vaccine-elicited T cells maintained the ability to express IFN-gamma ex vivo and proliferate in vitro. Thus, repeated exposure to immunogenic peptides benefited immune competence. These results provide a rationale for immunization strategies.

T-cell-directed cancer vaccines: mechanisms of immune escape and immune tolerance

Recent clinical trials using vaccines directed toward tumour-associated antigens (TA) have shown the increasing capacity of vaccines to cause immunologic responses. In fact, strongly reactive TA-specific cytolytic T-lymphocytes and tumour-infiltrating lymphocytes (TIL) can be identified and expanded ex vivo from patients with metastatic melanoma vaccinated with melanoma-associated antigens. Paradoxically, this strong immunological response does not correlate with clinical tumour regression. Proposed mechanisms responsible for this glaring inconsistency are numerous and varied; systemic immunosuppressive as well as local mechanistic factors are implicated. In this review we will critically evaluate the possible mechanisms that allow tumours to escape immune destruction and be tolerated by the immune system. In addition, strategies that may allow further insight into the biology of tumour rejection are discussed, in the hope of deepening the understanding of this phenomenon and enhancing its therapeutic potential.

T-cell-directed cancer vaccines: the melanoma model

Significant advances in the understanding of the molecular basis for tumour/host interactions in humans have occurred in the last decade through studying patients with metastatic melanoma. This disease is characterised by its tendency to be modulated by immunologic factors. Furthermore, immunologic manipulation of the host with various systemic agents, in particular IL-2, frequently affects this natural phenomenon and can lead to complete rejection of cancer. By studying the cellular immunology occurring in patients undergoing immunotherapy, several tumour antigens (TA) and their epitopes recognised by human leukocyte antigen (HLA) class I-restricted cytotoxic T-lymphocytes (CTL) have been identified. Most of these TA are non-mutated molecules expressed by the majority of melanoma in vivo and most melanoma cell lines. In addition, unique minimal epitopic sequences play an immunodominant role in the context of specific HLA class I alleles. Since melanoma lesions from different patients often share expression of the same TA, and a minimal peptide sequence from a TA can cause immunologic changes in multiple patients, interest has grown in the development of TA-specific vaccines suitable for broad patient populations. Repeated in vitro stimulation of peripheral blood mononuclear cells (PBMC) with TA-derived epitopes can induce a high frequency of TA-reactive T-cells in melanoma patients. The same epitopes can also enhance TA-specific T-cell reactivity in vivo when administered subcutaneously in combination with Incomplete Freund's Adjuvant (IFA). Epitope-based vaccinations, however, have not shown strong clinical efficacy unless combined with IL-2 administration. Attempts to increase the efficacy of these vaccines have combined specialised antigen-presenting cells or the administration of whole TA through DNA- or RNA-based vaccines with the intention of increasing antigen presentation and processing. Save for scattered reports, however, the success of these approaches has been limited and T-cell-directed vaccination against cancer remains at a paradoxical standstill whereby anticancer immunisation can be induced but it is not sufficient, in most cases, to induce tumour regression. Using melanoma as the standard model for immunotherapy, we will review various methods of T-cell-directed vaccination, the monitoring and analysis of the resulting immune response, and several clinical trials in which cancer vaccines have successfully induced immunisation.

A prospective, randomized, double-blind, placebo-controlled trial evaluating the effect of nystatin on the development of oral irritation in patients receiving high-dose intravenous interleukin-2

Interleukin-2 (IL-2) has been used to treat patients with metastatic melanoma and renal cell cancer for nearly two decades, and much progress has been made in ameliorating its adverse effects. One bothersome adverse effect, oral pain or oral irritation, is usually treated with an oral antifungal antibiotic, nystatin. The authors performed a prospective, randomized, double-blind, placebo-controlled trial involving 64 patients to evaluate the effect of prophylactic administration of nystatin or placebo on the development of oral irritation in patients receiving high-dose intravenous IL-2. No difference was found between patients randomized to receive nystatin or placebo in their rates of development of oral irritation, the severity of IL-2 adverse effects, the duration of their treatment, the rate of development of positive studies for oral yeast, or their pattern of experiencing other adverse effects. Thus, patients who receive high-dose intravenous IL-2 should not be treated prophylactically with nystatin to prevent oral irritation, and clinicians should seek evidence of the presence of oral thrush before using antifungal agents to treat oral pain in these patients.

Sequential 5-Aza-2 deoxycytidine-depsipeptide FR901228 treatment induces apoptosis preferentially in cancer cells and facilitates their recognition by cytolytic T lymphocytes specific for NY-ESO-1

Global alterations in chromatin structure profoundly influence gene expression in thoracic neoplasms, silencing tumor suppressors while facilitating the expression of various cancer testis antigens such as NY-ESO-1. Although recent studies have shown that histone deacetylase inhibitors can potentiate tumor suppressor gene induction mediated by demethylating agents in cancer cells, the ability of these agents to augment cancer testis antigen expression have not been fully defined. The authors designed the current study to determine whether the histone deacetylase inhibitor, depsipeptide FR901228 (DP), could enhance NY-ESO-1 induction mediated by the DNA demethylating agent 5-Aza-2'-deoxycytidine (DAC) in cell lines established primarily from thoracic cancers. Quantitative reverse-transcriptase polymerase chain reaction analysis revealed that, under exposure conditions potentially achievable in clinical settings, DAC dramatically induced NY-ESO-1 expression in cultured cancer lines. DP alone mediated negligible target gene induction but significantly augmented DAC-mediated induction of NY-ESO-1. After DAC or sequential DAC-DP treatment, HLA-A*0201 cancer cells were recognized by an HLA-A*0201 CTL specific for NY-ESO-1. Although sequential DAC/DP exposure did not uniformly enhance immune recognition of target cells compared with DAC alone, this treatment mediated profound induction of apoptosis in cancer cells but not normal human bronchial epithelia. The apoptotic effects of DAC, DP, or sequential DAC-DP did not correlate in an obvious manner with histology, or the magnitude of NY-ESO-1 induction in cancer cells. Although the mechanisms have not been fully defined, sequential DAC-DP treatment may be a novel strategy to augment antitumor immunity in cancer patients.

High throughput HLA sequence-based typing (SBT) utilizing the ABI Prism 3700 DNA Analyzer

AIMS AND BACKGROUND

The genetic complexity of the human major histocompatibility complex (MHC) has required the development of various molecular typing methods. The purpose of this paper is to compare the results of two of these molecular methods: sequenced based typing (SBT) and polymerase chain reaction (PCR) using sequence specific primers (PCR-SSP).

METHODS

The SBT method described utilizes an ABI Prism 3700 DNA Analyzer, which has been designed fro high throughput production of sequence data through highly automated operation with significant walk-away time. The ABI Prism 3700 DNA Analyzer is a 96-capillary electrophoresis instrument with the capability of running four 96-well plates black to back in a sixteen-hour period. Potentially, data from this machine can produce Class I sequences for A or B loci for 64 samples in this time frame. The SBT method encompassed exons 2, 3, and 4 with forward and reverse sequence orientation reactions using the PE Biosystems HLA-A and HLA-B Sequenced Based Typing Kits (PE Applied Biopsystems/Perkin-Elmer, Foster City, CA, USA). Most SBT methods previously employed only gather data from exons 2 and 3 which distinguishes most of the polymorphism necessary to identify the majority of alleles in the HLA region. However, in an effort to discern numerous null alleles in the HLA region, exon 4 data is also included. The PCR-SSP method utilized consists of one 96 well tray, with 95 primer mixes and one negative control, per sample designed to produce an intermediate/high resolution HLA-A, B typing.

RESULTS

Data from one 96-well capillary run on the ABI Prism 3700 DNA Analyzer, which consists of results from 16 samples for HLA-A or HLA-B loci, was compared to data derived from sixteen HLA-A and HLA-B PCR-SSP typings. 75% of loci tested achieved a higher resolution HLA typing by the SBT method.

DISCUSSION

The ability to provide allele level HLA typing results can have significant functional implications for the bone marrow transplant community and numerous vaccine studies.

cDNA arrays and the enigma of melanoma immune responsiveness

Melanoma is a cancer characterized by predisposition to natural and induced immune rejection. The occurrence of this phenomenon, however, remains sporadic and capricious while there is no clear understanding of the chain of events responsible. With the progression of the understanding of the molecular immunology of melanoma during the last decade, several theories suggesting immune tolerance (inadequate immune response) and/or immune escape (adaptation of cancer cells to a vigorous immune pressure) as possible modulators of melanoma growth have emerged. As the number of these hypotheses, mostly based on molecular or pre-clinical models, has increased exponentially, the relevance of each individual one has been conversely decreasing leaving the observer without confidence that a theory likely to explain this phenomenon can be soon formulated. In this review, we will discuss a direct approach whereby new theories might be identified by direct observation of human phenomena as they occur by depiction of molecular portraits of melanoma lesions using global transcript analysis.

A natural history of melanoma: serial gene expression analysis

Ena Wang and Francesco Marincola propose a novel strategy whereby tumor-host interactions are studied within the melanoma microenvironment by serial gene expression analysis. Methodological constraints and ways to circumvent them are discussed. This approach might improve our understanding of the molecular basis of tumor regression in response to immune manipulation.

Host response to cytomegalovirus infection as a determinant of susceptibility to coronary artery disease: sex-based differences in inflammation and type of immune response

BACKGROUND

Positive and negative associations between cytomegalovirus (CMV) infection and coronary artery disease (CAD) have been reported. We postulated that the susceptibility to CMV-induced CAD might relate to patterns of inflammatory and immune responses to CMV infection and that sex might have an effect on these responses.

METHODS AND RESULTS

In 151 men and 87 women being evaluated for CAD, blood samples were tested for humoral (Ab+) and cellular (Tc+) responses to CMV and for C-reactive protein (CRP). In men, an elevated CRP level was a significant determinant of CAD even after adjustment for CAD risk factors (OR, 3.1; 95% CI, 1.21 to 7. 97). CMV seropositivity was associated with elevated CRP levels on multivariate analysis (P:=0.006). In contrast, in women, CMV seropositivity was independently predictive of CAD (OR, 41.8; 95% CI, 4.12 to 423.74). CRP level in women with CAD was >25% higher than those without CAD, but the difference did not reach statistical significance. Importantly, compared with CMV Ab-/Tc- women, CAD prevalence was higher in Ab+/Tc- and Ab+/Tc+ (13% versus 68% and 64%, both P:<0.005) but not in Ab-/Tc+ women (25%). There were no differences in age, smoking, diabetes, hypertension, and hypercholesterolemia among women with different types of immune responses to CMV infection.

CONCLUSIONS

The mechanisms by which CMV predisposes to CAD in men and women may be different. In men, CMV appears to contribute to CAD risk, insofar as it predisposes to inflammation. In women, other mechanisms, possibly related to the type of immune response generated by the host, appear to be responsible for the proatherogenic effects of CMV.

Thrombopoietin and chemokine mRNA expression in patient post-chemotherapy and in vitro cytokine-treated marrow stromal cell layers

CD34(+) cells and megakaryocyte progenitors were lower in marrow from patients after hematological recovery from the first cycle of 5-fluorouracil, leucovorin, adriamycin, cyclophosphamide (FLAC) chemotherapy plus PIXY321 (GM-CSF/interleukin 3; IL-3 hybrid) than in FLAC + GM-CSF or pre-FLAC marrows. Marrow stromal layers, an in vitro model of the marrow microenvironment, express a combination of stimulatory and inhibitory factors that modulate hematopoietic progenitor cell proliferation and differentiation. The TaqMan assay and quantitative reverse transcriptase-polymerase chain reaction were used to measure monocyte chemoattractant protein-1 (MCP-1), melanoma stimulatory growth activity, and monokine inducible by interferon-gamma (Mig) (inhibitory chemokines for primitive or megakaryocyte progenitors) mRNA levels in in vitro PIXY and GM-CSF-treated and patient post-FLAC marrow stromal layers. Chemokine mRNA was increased after in vitro GM-CSF and to a lesser extent after PIXY treatment. MCP-1 mRNA levels were fivefold higher in FLAC + PIXY than in FLAC + GM-CSF layers, and Mig mRNA was elevated in FLAC + GM-CSF layers. Thrombopoietin (TPO), insulin-like growth factor I (IGF-I), and IGF-II (stimulatory factors for primitive and megakaryocyte progenitors) mRNA were also measured. TPO mRNA levels were 30% lower in GM-CSF and PIXY-pretreated than in control layers with no decrease in IGF mRNA. TPO mRNA in stromal layers of patients who developed grade 3 thrombocytopenia (platelets < 20 x 10(9)/l) during the third cycle of FLAC was only 24% of levels in stromal layers of marrow from other post-FLAC patients. Results demonstrate that patient and in vitro treatment had modulatory effects on TPO and chemokine mRNA expression in marrow stromal layers.

Melanoma vaccines: the paradox of T cell activation without clinical response

In recent years significant progress in the understanding of the immune biology of melanoma has evolved from the identification of melanoma antigens (MAs) recognized by T cells. MAs consist of intracellular proteins that are expressed on the surface of cancer cells in association with human leukocyte antigen (HLA) class I molecules and therefore are suitable targets for cytotoxic T lymphocytes (CTLs). Several new monitoring strategies have been implemented to evaluate the status of activation and localization of vaccine-induced T cells in the peripheral circulation as well as the tumor site, including limiting dilution, in vitro sensitization, and ELISPOT. Previous studies aimed at monitoring patients receiving vaccination have utilized mainly those three methods. These methods have demonstrated that antigen-specific vaccination can elicit immune responses detectable in the peripheral blood of immunized patients. These assays, however, have been faulted by their requirement for in vitro expansion of T cells (limiting dilution or in vitro sensitization) or for limited sensitivity (ELISPOT). More recently, the use of soluble HLA/peptide complex tetramers, intracellular fluorescence-activated cell sorting (FACS) analysis, and real-time polymerase chain reaction (PCR) has been proposed for the monitoring of vaccine trials. These methods have the appeal of allowing direct enumeration of T cells specific for a particular epitope within relevant samples such as peripheral blood lymphocytes, lymph nodes, and tumors. We are evaluating whether utilizing a combination of HLA/peptide tetramer (tHLA) together with Taqman-based real-time reverse-transcription (RT)-PCR and intracellular FACS analysis could establish a direct and comprehensive strategy for the assessment of epitope-specific immune response in vivo. In conditions close to those of the tumor microenviroment or in peripheral blood lymphocytes, however, a different status of T cell activation can be expected due to a direct stimulation of T cells by tumor or antigen-presenting cells. We observed that activated T cells can easily be detected in the peripheral blood of patients who have received MA-specific vaccines. However, when T cells are stimulated with their relevant epitope, a high level of T cell receptor downregulation occurs that does not allow identification of vaccine-specific T cells directly with tHLA. Thus evaluation of epitope-specific T cells at the tumor site, where they might be exposed to stimulation by interaction with tumor cells and/or in bulk peripheral blood mononuclear cells, might be more efficiently analyzed with functional methods such as intracellular FACS and Taqman-based real time RT-PCR.

Tyrosinase immunoreactivity in fine-needle aspiration samples of metastatic malignant melanoma

BACKGROUND

Tyrosinase, the rate-limiting enzyme in melanin synthesis, is a melanoma associated antigen that is recognized by both CD4+ and CD8+ T-cells in an HLA-restricted fashion. Peptides derived from the tyrosinase antigen currently are being utilized as a target for T-cells in several immunotherapy protocols for metastatic malignant melanoma (MMM) at the National Institutes of Health/National Cancer Institute. Serial fine-needle aspirations of metastatic lesions are performed to monitor the antigen expression of tyrosinase during treatment by immunostaining cytologic preparations with the monoclonal antibody T311.

METHODS

In the current study, 62 samples of MMM were evaluated for tyrosinase immunoreactivity on air-dried, acetone fixed cytospins and the corresponding formalin fixed, paraffin embedded cell block using an avidin-biotin immunoperoxidase method.

RESULTS

Positive immunoreactivity revealed a granular cytoplasmic staining in melanocytic cells. The current study results showed that 92% of samples (57 of 62) were T311 immunoreactive on cell block preparations, whereas only 61% (38 of 62) were immunoreactive on cytospin preparations. In 66% of samples (41 of 62) immunoreactivity for T311 was greater in the cell block sample than in the corresponding cytospin, whereas in only 3% of samples (2 of 62) was it greater in the cytospins. In 31% of samples (19 of 62) there was no significant difference in immunoreactivity between the 2 sample types.

CONCLUSIONS

The results of the current study show that tyrosinase is a sensitive marker for the detection of MMM; however, the optimal method of sample preparation for immunoperoxidase staining appears to be formalin fixation and paraffin embedding as tyrosinase immunoreactivity is diminished significantly in air-dried cytospin samples despite subsequent acetone fixation. Cancer (Cancer Cytopathol)

Real-time quantitative polymerase chain reaction assessment of immune reactivity in melanoma patients after tumor peptide vaccination

BACKGROUND

Monitoring the immune response to epitope-specific vaccination in cancer patients is important for vaccine development. The traditional method, in which the in vitro sensitization of peripheral blood mononuclear cells (PBMCs) with epitope is compared before and after vaccination, is time-consuming and allows only a qualitative assessment of the response. We used a rapid, quantitative, real-time polymerase chain reaction (PCR) assay to directly measure the immune reactivity of patients' PBMCs to the vaccine epitope.

METHODS

PBMCs were obtained from melanoma patients before and after two rounds of vaccination with either g209-2M, a peptide derived from melanoma protein gp100 (n = 24), or ESg209-2M, a modified version of this peptide (n = 20). PBMCs were tested for immune reactivity by assaying interferon gamma (IFN gamma) protein release after in vitro sensitization with the epitope or for IFN gamma messenger RNA expression by real-time PCR. A twofold or more increase in IFN gamma protein release or a 1.5-fold or more increase in IFN gamma transcript accumulation in PBMCs after vaccination was considered to be evidence of a specific response. Correlation between the two methods was tested by use of the Spearman correlation coefficient after the results were ranked as positive or negative. All statistical tests were two-sided.

RESULTS

The results obtained with the two methods were strongly correlated (Spearman's rho = 0.72; P =.0006). The g209-2M and Esg209-2M peptides resulted in similar percentages of vaccine-specific reactivity in PBMCs after in vitro sensitization (63% and 65% of patients, respectively; Fisher's exact test P =.6 for comparison of the two groups). The PCR method could detect vaccine-specific reactivity in a subset of patients (38% and 35% of patients, respectively; Fisher's exact test P =.7 for comparison of the two groups).

CONCLUSION

Vaccination induces circulating antitumor lymphocytes, albeit in low frequencies, capable of directly reacting with tumor antigen. PBMCs of vaccinated individuals can respond to a vaccine-specific stimulus in a direct assay that does not require prolonged in vitro manipulations.

Status of activation of circulating vaccine-elicited CD8+ T cells

Selective blunting of the status of activation of circulating tumor-specific T cells was invoked to explain their paradoxical coexistence with unhampered tumor growth. By analogy, lack of tumor regression in the face of observable melanoma vaccine-induced T cell responses might be attributed to their status of activation. We enumerated with HLA-A*0201/peptide tetramers (tHLA) vaccine-elicited T cell precursor frequency directly in PBMC of patients with melanoma undergoing vaccination with the HLA-A*0201-associated gp100:209-217(210 M) epitope (g209-2 M). Furthermore, we tested by intracellular (IC)-FACS analysis and quantitative real-time PCR (qRT-PCR) the ability of postvaccination PBMC to produce cytokine in response to challenge with vaccine-related epitopes or vaccine-matched (HLA-A*0201) melanoma cells. Vaccine-induced enhancement of T cell precursor frequency could be detected with tHLA in PBMC from six of eight patients studied at frequencies ranging between 0.3 and 2.3% of the total CD8+ population. Stimulation with vaccine-related epitopes induced IFN-gamma expression detectable by IC-FACS or qRT-PCR, respectively, in five and six of these patients. Furthermore, down-regulation of tHLA staining was noted upon cognate stimulation that could be utilized as an additional marker of T cell responsiveness. Finally, we observed in six patients an enhancement of reactivity against vaccine-matched tumor targets that was partly independent of documented vaccine-specific immune responses. A strong correlation was noted between tHLA staining of postvaccination PBMC and IFN-gamma expression by the same samples upon vaccine-relevant stimulation and assessed either by IC-FACS or qRT-PCR. Thus, blunting of the status of T cell activation on itself cannot easily explain the lack of clinical responses observed with vaccination.

Detection of HLA antibodies by using flow cytometry and latex beads coated with HLA antigens

BACKGROUND

Detection of HLA class I antibodies in sera is needed in various clinical situations. The standard method for detecting HLA class I antibodies is the complement-dependent lymphocytotoxicity (CDC) assay, but solid-phase assays are now available.

STUDY DESIGN AND METHODS

This study assessed the ability of a flow cytometric assay using latex beads coated with HLA class I antigens to detect HLA class I-specific antibodies. The CDC assay was compared with the pooled-bead assay for the detection of HLA class I antibodies. Thirty-one randomly selected serum samples previously tested by CDC assay were tested with pooled beads and analyzed by flow cytometry. Twenty-seven additional serum samples, chosen by clinical criteria and CDC assay results, were tested against the pooled beads. Next, samples from six patients from whom three or more serum samples were drawn on consecutive days were tested with both methods. Finally, serum samples that were proved positive by both methods were tested with selected beads coated with antigens from a single person.

RESULTS

Among the randomly selected serum samples, there was 90-percent agreement between the two assays. There was 96-percent agreement between the two assays of the 27 samples that were selected by clinical criteria and CDC assay results. Testing the sera with individual beads suggested that the HLA class I antibodies react with beads expressing the corresponding HLA antigen and beads expressing antigens in the same cross-reactive group.

CONCLUSION

The pooled-bead assay can be used as an alternative method for detecting HLA class I antibodies. However, if the specificity of the HLA class I antibody is required, another assay must be used.

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.

Threshold levels of gene expression of the melanoma antigen gp100 correlate with tumor cell recognition by cytotoxic T lymphocytes

The level of expression of melanoma antigens (MA) may modulate the host immunologic response. Thus, the accurate measurement of MA expression may allow proper patient selection for antigen-specific therapies and yield important information for the evaluation of clinical results. In this study, we measured the absolute levels of MA messenger ribonucleic acid (mRNA) in tumor cell lines utilizing real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). mRNA levels of MART-1, gp100, tyrosinase, TRP-1 and TRP-2 melanoma differentiation antigens and MAGE-1, MAGE-3 and ESO-1 cancer testis (CT) antigens were compared in 24 early-passage (<5 passages in culture) and 12 archival melanoma cell lines. MA mRNA expression was extremely variable among cell lines, occasionally reaching levels comparable to ribosomal RNA (rRNA). gp100 and MART-1 mRNA levels correlated with protein expression measurement obtained by FACS analysis. More significantly, a threshold of gp100 mRNA expression required for T-cell stimulation and target-cell killing was identified. This threshold level corresponded to approximately 500 mRNA copies per 10(8) copies of rRNA. Our results suggest that the measurements of MA mRNA levels may yield useful information relevant to the interpretation of clinical outcome during antigen-specific treatments.

A tumor-infiltrating lymphocyte from a melanoma metastasis with decreased expression of melanoma differentiation antigens recognizes MAGE-12

Twenty separate tumor infiltrating lymphocyte (TIL) bulk cultures and a tumor cell line were originated simultaneously from a fine needle aspiration biopsy of a metastasis in a patient with melanoma (F001) previously immunized with the HLA-A*0201-associated gp100:209-217(210 M) peptide. None of the TIL recognized gp100. However, 12 recognized autologous (F001-MEL) and allogeneic melanoma cells expressing the HLA haplotype A*0201, B*0702, Cw*0702. Further characterization of F001-MEL demonstrated loss of gp100/PMel17, severely decreased expression of other melanoma differentiation Ags and retained expression of tumor-specific Ags. Transfection of HLA class I alleles into B*0702/Cw*0702-negative melanoma cell lines identified HLA-Cw*0702 as the restriction element for F001-TIL. A cDNA library from F001-MEL was used to transfect IFN-alpha-stimulated 293 human embryonal kidney (293-HEK) cells expressing HLA-Cw*0702. A 100-gene pool was identified that induced recognition of 293-HEK cells by F001-TIL. Subsequent cloning of the pool identified a cDNA sequence homologous, except for one amino acid (aa 187 D-->A), to MAGE-12. Among 25 peptide sequences from MAGE-12 with the HLA-Cw*0702 binding motif, MAGE-12:170-178 (VRIGHLYIL) induced IFN-gamma release by F001-TIL when pulsed on F001-EBV-B cells at concentrations as low as 10 pg/ml. Peptide sequences from MAGE-1, 2, 3, 4a, and 6 aligned to MAGE-12:170-178 were not recognized by F001-TIL. In summary a TIL recognizing a MAGE protein was developed from an HLA-A*0201 expressing tumor with strongly reduced expression of melanoma differentiation Ags. Persisting tumor-specific Ag expression maintained tumor immune competence suggesting that tumor-specific Ags/melanoma differentiation Ags may complement each other in the context of melanoma Ag-specific vaccination.

High-fidelity mRNA amplification for gene profiling

The completion of the Human Genome Project has made possible the comprehensive analysis of gene expression, and cDNA microarrays are now being employed for expression analysis in cancer cell lines or excised surgical specimens. However, broader application of cDNA microarrays is limited by the amount of RNA required: 50-200 microg of total RNA (T-RNA) and 2-5 microg poly(A) RNA. To broaden the use of cDNA microarrays, some methods aiming at intensifying fluorescence signal have resulted in modest improvement. Methods devoted to amplifying starting poly(A) RNA or cDNA show promise, in that detection can be increased by orders of magnitude. However, despite the common use of these amplification procedures, no systematic assessment of their limits and biases has been documented. We devised a procedure that optimizes amplification of low-abundance RNA samples by combining antisense RNA (aRNA) amplification with a template-switching effect (Clonetech, Palo Alto, CA). The fidelity of aRNA amplified from 1:10,000 to 1:100,000 of commonly used input RNA was comparable to expression profiles observed with conventional poly(A) RNA- or T-RNA-based arrays.

HLA B*5701 is highly associated with restriction of virus replication in a subgroup of HIV-infected long term nonprogressors

A unique cohort of HIV-1-infected long term nonprogressors (LTNP) with normal CD4(+) T cell counts and <50 copies/ml of plasma were prospectively recruited for study. HLA typing revealed a dramatic association between the HLA B*5701 class I allele and nonprogressive infection [85% (11 of 13) vs. 9.5% (19 of 200) in progressors; P < 0. 001]. Antigen-specific CD8(+) T cells were enumerated by flow cytometric detection of intracellular IFN-gamma in response to HIV antigens and HLA B*57-gag tetramer staining. No quantitative differences in the total HIV-specific CD8(+) T cell responses were observed between B*57(+) LTNP and five B*57(+) progressors (P = 0.4). Although similar frequencies of peptide specific CD8(+) T cells were also found, the gag-specific CD8(+) T cell response in the LTNP group was highly focused on peptides previously shown to be B*57-restricted. These findings indicate that, within this phenotypically and genotypically distinct cohort, a host immune factor is highly associated with restriction of virus replication and nonprogressive disease. They also strongly suggest a mechanism of virus specific immunity that directly operates through the B*5701 molecule. Further characterization of qualitative differences in the virus-specific responses that distinguish HLA B*57(+) LTNP from progressors may ultimately define mechanisms of effective immune mediated restriction of virus replication.

Frequency of human leukocyte antigen-A 24 alleles in patients with melanoma determined by human leukocyte antigen-A sequence-based typing

The analysis of immune responses of patients with melanoma has led to the identification of melanoma-associated antigens targeted by T cells. Cytotoxic T lymphocytes recognize peptides from melanoma-associated antigens presented on the cancer cell surface in the context of HLA class I molecules. Immunodominant melanoma-associated antigen epitopes are being evaluated for their ability to immunize patients with advanced melanoma. However, these vaccination efforts are limited by the extensive polymorphism of the HLA class I heavy chain, which occurs in functional domains of the molecule. Patients with melanoma with the HLA-A-24 phenotype were recruited for vaccination with the peptide AFLPWHRLF from the melanoma-associated antigen tyrosinase. This peptide is recognized in association with HLA-A*2402. The HLA-A24 family includes at least 15 alleles whose frequency and ability to present the same peptide are unknown. The distribution of HLA-A24 alleles was studied in a melanoma population for the practical purpose of identifying patients suitable for vaccination with HLA-A*2402 epitopes. An HLA-A locus-specific polymerase chain reaction method followed by sequencing was developed to determine the HLA-A alleles in genomic DNA. HLA-A 24 was also typed in healthy persons of various ethnic backgrounds to further explore the HLA-A24 family. In white persons, the HLA-A*2402 allele was most common (in 85% of white persons and in 97% of the patients with melanoma). Fewer persons carried the HLA-A*2403 allele (13% in all samples, 3% in melanoma patients). Finally, two new alleles, HLA-A*2422 and HLA-A*24 null, were identified. These results suggest that vaccination with HLA-A*2402-associated epitopes has the potential for broad use in this patient population.

Heterogeneity in expression of human leukocyte antigens and melanoma-associated antigens in advanced melanoma

The study of tumor immunology has led to many innovative therapeutic strategies for the treatment of melanoma. The strategies are primarily dependent on melanoma-associated antigen peptide vaccination or T-cell-based therapy. These immunotherapies are totally reliant on proper copresentation of human leukocyte antigen class I molecules in sufficient quantity and the presence and availability of melanoma-associated antigenic peptides. Altered expression of either HLA class I molecules or melanoma antigens is known to occur. These defects lead to altered manufacture and copresentation of HLA class I molecules with melanoma-associated antigens to T-cells. Defects in any one combination can lead to loss of recognition of melanoma cells and their subsequent destruction by cytotoxic T-lymphocytes. Thus, these immunotherapy strategies can be thwarted by defects or heterogeneity of expression of human leukocyte antigen class I or of melanoma-associated antigens.

Expansion of tumor-T cell pairs from fine needle aspirates of melanoma metastases

Lymphocytes expanded from excised specimens can be used to characterize intratumoral T cell responses. These analyses, however, are limited to one time point in the natural history of the removed tumor. The expansion of autologous tumor cells and tumor-infiltrating lymphocytes (TIL) from fine needle aspirates (FNA) of tumors potentially allows a dynamic evaluation of T cell responses within the same lesion at moments relevant to the disease course or response to therapy. Fourteen TIL cultures and 8 tumor cell lines were generated from 18 FNA (12 patients). Five of six TIL that could be tested against autologous tumor demonstrated specific reactivity. Two additional TIL for which no autologous tumor was available demonstrated recognition of HLA-matched melanoma cell lines. Serial FNA of the same lesions were performed in five HLA-A*0201 patients vaccinated with the emulsified melanoma Ag (MA) epitopes: MART-1:27-35; tyrosinase:368-376(370D); gp100:280-288(288V); and gp100:209-217 (210M). FNA material was separately cultured for a short time in IL-2 (300 IU/ml) after stimulation with irradiated autologous PBMC pulsed with each peptide or FluM1:58-66 (1 micromol/ml). No peptide-specific TIL could be expanded from prevaccination FNA. However, after vaccination, TIL specific for gp100:280(g280), gp100:209 (g209), and MART-1:27-35 (MART-1)-related epitopes were identified in three, three, and two patients, respectively. No Flu reactivity could be elicited in TIL, whereas it was consistently present in parallel PBMC cultures. This excluded PBMC contamination of the FNA material. This analysis suggests the feasibility of TIL expansion from minimal FNA material and localization of vaccine-specific T cells at the tumor site.