Monica C. Panelli

Immune selection after antigen-specific immunotherapy of melanoma

BACKGROUND Melanoma antigen (MA)-specific vaccination strongly enhances antitumor reactivity in vivo and is capable of producing strong cytotoxic T lymphocyte responses in vitro. Furthermore, specific human leukocyte antigen-restricted T cell activation is hypothesized to occur in response to peptide-based immunotherapy, which may lead to the preferential killing of tumor cells bearing the relevant MA. The development of melanoma antigen-loss variants may subsequently occur in vivo. METHODS Analysis of 532 melanoma lesions from 204 patients was performed on fine-needle aspiration biopsy specimens. Lesions were graded for the expression of the MAs gp100 and MART-1 with use of immunocytochemistry. A total of 351 melanoma lesions were divided into cohorts on the basis of the treatment received. The pretreatment group (n = 175) consisted of lesions obtained before any form of gp100 immunotherapy, with the posttreatment group (n = 176) consisting of lesions obtained after vaccination with a modified gp100 epitope, gp209-2M +/- interleukin 2 (IL-2). RESULTS The percentage of lesions not expressing the gp100 antigen is greater than the percentage not expressing MART-1 (26% vs 14%). The frequency of lesions with high expression (> 75%) of gp100 significantly decreased with therapy (47% vs 34%) and conversely negative lesions increased (18% vs 29%). Treatment of lesions with peptide alone (no IL-2) revealed a significant decrease in gp100 expression (47% vs 32%), enhanced with the addition of IL-2 to therapy (47% vs 35%). The expression of MART-1 remained essentially unchanged unless IL-2 was added (54% vs 54%, MART-1 peptide alone, 54% vs 43%, MART-1 peptide + IL-2). Of 94 patients (181 lesions) assessed for gp100 expression before treatment, 10 patients responded to therapy. Pretreatment lesions in responding patients expressed some level of gp100 in all cases compared with 27% of nonresponding lesions, which were negative for gp100 expression. CONCLUSIONS. This study indirectly demonstrates that vaccination with an MA-derived peptide can result in immune selection in vivo. Furthermore, it provides strong immunologic evidence for the specificity of MA vaccines and to the relevance of MA expression in predicting the response to vaccination.

Gene expression profiling of cutaneous wound healing

BackgroundAlthough the sequence of events leading to wound repair has been described at the cellular and, to a limited extent, at the protein level this process has yet to be fully elucidated. Genome wide transcriptional analysis tools promise to further define the global picture of this complex progression of events.Study DesignThis study was part of a placebo-controlled double-blind clinical trial in which basal cell carcinomas were treated topically with an immunomodifier – toll-like receptor 7 agonist: imiquimod. The fourteen patients with basal cell carcinoma in the placebo arm of the trial received placebo treatment consisting solely of vehicle cream. A skin punch biopsy was obtained immediately before treatment and at the end of the placebo treatment (after 2, 4 or 8 days). 17.5K cDNA microarrays were utilized to profile the biopsy material.ResultsFour gene signatures whose expression changed relative to baseline (before wound induction by the pre-treatment biopsy) were identified. The largest group was comprised predominantly of inflammatory genes whose expression was increased throughout the study. Two additional signatures were observed which included preferentially pro-inflammatory genes in the early post-treatment biopsies (2 days after pre-treatment biopsies) and repair and angiogenesis genes in the later (4 to 8 days) biopsies. The fourth and smallest set of genes was down-regulated throughout the study. Early in wound healing the expression of markers of both M1 and M2 macrophages were increased, but later M2 markers predominated.ConclusionThe initial response to a cutaneous wound induces powerful transcriptional activation of pro-inflammatory stimuli which may alert the host defense. Subsequently and in the absence of infection, inflammation subsides and it is replaced by angiogenesis and remodeling. Understanding this transition which may be driven by a change from a mixed macrophage population to predominately M2 macrophages, may help the interpretation of the cellular and molecular events occurring in the microenvironment of serially biopsied tissues.

Serum Vascular Endothelial Growth Factor and Fibronectin Predict Clinical Response to High-Dose Interleukin-2 Therapy

PURPOSE High-dose interleukin-2 (IL-2) induces durable therapeutic responses in a small subset of patients with metastatic melanoma and renal cell carcinoma, but simple pretreatment predictors of response have not been identified. PATIENTS AND METHODS To identify predictive biomarkers of clinical response, sera from patients treated with high-dose IL-2 were collected for analysis using a customized, multiplex antibody-targeted protein array platform that surveyed expression of soluble factors associated with tumor immunobiology. Soluble factors associated with clinical responses were analyzed using a multivariate permutation test, and survival outcomes were determined using Kaplan-Meier and log-rank tests. RESULTS A training set from 10 patients identified 68 potentially relevant soluble factors that were then tested in an independent validation set of 49 patients. Class comparison revealed a cluster of 11 biomarkers that were associated with therapeutic outcome. Vascular endothelial growth factor (VEGF) and fibronectin were identified as independent predictors of response. In particular, high levels of these proteins were correlated with lack of clinical response and decreased overall survival. CONCLUSION Serum VEGF and fibronectin are easily measured pretreatment biomarkers that could serve to exclude patients unlikely to respond to IL-2 therapy.

Gene-expression profiling of the response of peripheral blood mononuclear cells and melanoma metastases to systemic IL-2 administration

Backgroundlnterleukin-2 (IL-2) has direct pluripotent effects on cells with immune and inflammatory function. Which of these effects has a critical role in mediating tumor regression remains enigmatic. In this study, we compared early changes in transcriptional profiles of circulating mononuclear cells with those occurring within the microenvironment of melanoma metastases following systemic IL-2 administration.ResultsThe results suggest that the immediate effects of IL-2 administration on the tumor microenvironment is transcriptional activation of genes predominantly associated with monocyte cell function; minimal effects were noted on migration, activation and proliferation of T cells. However, production of chemokines and markers of adhesion and migration within few hours of IL-2 administration may be responsible for a secondary recruitment of immune cells to the tumor site later.ConclusionOur results suggest that IL-2 induces inflammation at tumor sites with three predominant secondary effects: activation of antigen-presenting monocytes; massive production of chemoattractants that may recruit other immune cells to the tumor (including MIG and PARC, which are specific for T cells); and activation of cytolytic mechanisms in monocytes (calgranulin, grancalcin) and NK cells (NKG5, NK4).

Sequential gene profiling of basal cell carcinomas treated with imiquimod in a placebo-controlled study defines the requirements for tissue rejection

BackgroundImiquimod is a Toll-like receptor-7 agonist capable of inducing complete clearance of basal cell carcinoma (BCC) and other cutaneous malignancies. We hypothesized that the characterization of the early transcriptional events induced by imiquimod may provide insights about immunological events preceding acute tissue and/or tumor rejection.ResultsWe report a paired analysis of adjacent punch biopsies obtained pre- and post-treatment from 36 patients with BCC subjected to local application of imiquimod (n = 22) or vehicle cream (n = 14) in a blinded, randomized protocol. Four treatments were assessed (q12 applications for 2 or 4 days, or q24 hours for 4 or 8 days). RNA was amplified and hybridized to 17.5 K cDNA arrays. All treatment schedules similarly affected the transcriptional profile of BCC; however, the q12 × 4 days regimen, associated with highest effectiveness, induced the most changes, with 637 genes unequivocally stimulated by imiquimod. A minority of transcripts (98 genes) confirmed previous reports of interferon-α involvement. The remaining 539 genes portrayed additional immunological functions predominantly involving the activation of cellular innate and adaptive immune-effector mechanisms. Importantly, these effector signatures recapitulate previous observations of tissue rejection in the context of cancer immunotherapy, acute allograft rejection and autoimmunity.ConclusionThis study, based on a powerful and reproducible model of cancer eradication by innate immune mechanisms, provides the first insights in humans into the early transcriptional events associated with immune rejection. This model is likely representative of constant immunological pathways through which innate and adaptive immune responses combine to induce tissue destruction.

Natural variation of the expression of HLA and endogenous antigen modulates CTL recognition in an In vitro melanoma model

Increasing attention has been devoted to elucidating the mechanism of lost or decreased expression of MHC or melanoma‐associated antigens (MAAs), which may lead to tumor escape from immune recognition. Loss of expression of HLA class I or MAA has, as an undisputed consequence, loss of recognition by HLA class I–restricted cytotoxic T cells (CTLs). However, the relevance of down‐regulation remains in question in terms of frequency of occurrence. Moreover the functional significance of epitope down‐regulation, defining the relationship between MHC/epitope density and CTL interactions, is a matter of controversy, particularly with regard to whether the noted variability of expression of MHC/epitope occurs within a range likely to affect target recognition by CTLs. In this study, bulk metastatic melanoma cell lines originated from 25 HLA‐A*0201 patients were analyzed for expression of HLA‐A2 and MAAs. HLA‐A2 expression was heterogeneous and correlated with lysis by CTLs. Sensitivity to lysis was also independently affected by the amount of ligand available for binding at concentrations of 0.001 to 1 mM. Natural expression of MAA was variable, independent from the expression of HLA‐A*0201, and a significant co‐factor determining recognition of melanoma targets. Thus, the naturally occurring variation in the expression of MAA and/or HLA documented by our in vitro results modulates recognition of melanoma targets and may (i) partially explain CTL–target interactions in vitro and (ii) elucidate potential mechanisms for progressive escape of tumor cells from immune recognition in vivo. Int. J. Cancer: 80, 781–790 (1999).

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 μmol/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.

Common Cancer Biomarkers

There is an increasing interest in complementing conventional histopathologic evaluation with molecular tools that could increase the sensitivity and specificity of cancer staging for diagnostic and prognostic purposes. This study strove to identify cancer-specific markers for the molecular detection of a broad range of cancer types. We used 373 archival samples inclusive of normal tissues of various lineages and benign or malignant tumors (predominantly colon, melanoma, ovarian, and esophageal cancers). All samples were processed identically and cohybridized with an identical reference RNA source to a custom-made cDNA array platform. The database was split into training (n = 201) and comparable prediction (n = 172) sets. Leave-one-out cross-validation and gene pairing analysis identified putative cancer biomarkers overexpressed by malignant lesions independent of tissue of derivation. In particular, seven gene pairs were identified with high predictive power (87%) in segregating malignant from benign lesions. Receiver operator characteristic curves based on the same genes could segregate malignant from benign tissues with 94% accuracy. The relevance of this study rests on the identification of a restricted number of biomarkers ubiquitously expressed by cancers of distinct histology. This has not been done before. These biomarkers could be used broadly to increase the sensitivity and accuracy of cancer staging and early detection of locoregional or systemic recurrence. Their selective expression by cancerous compared with paired normal tissues suggests an association with the oncogenic process resulting in stable expression during disease progression when the presently used differentiation markers are unreliable.

A novel cytolysis assay using fluorescent labeling and quantitative fluorescent scanning technology

A novel cellular cytotoxicity assay using Calcein acetoxymethyl (Calcein-AM), a cytoplasmic fluorescent label, has been developed as an alternative to the standard 51Chromium (Cr)-release. Target cells were loaded with Calcein-AM and then co-incubated with effector cells. An additional reagent, FluoroQuench, is added to extinguish fluorescence of dying target cells and of the culture media. Assay plates are read on a quantitative fluorescent scanner for determination of viable target cells. Percent lysis is calculated as one minus the percent viable cells as compared to fluorescent-labeled targets-only wells. The assay was tested to demonstrate the lytic activity of cytotoxic T lymphocyte (CTL) cultures, lymphokine-activated killer (LAK), and natural killer (NK) cell line effectors against peptide-pulsed and melanoma targets. In addition to the acquisition of results comparable to the 51Cr-release assay, the Calcein assay reliably measures cell-mediated cytotoxicity with little variance among replicates. The fluorescent assay represents a simple and useful alternative to the use of radioactive materials and adds the additional benefit of digital images and analysis.

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.