A Quantitative Perspective on Surface Marker Selection for the Isolation of Functional Tumor Cells.

Much effort has gone into developing fluid biopsies of patient peripheral blood for the monitoring of metastatic cancers. One common approach is to isolate and analyze tumor cells in the peripheral blood. Widespread clinical implementation of this approach has been hindered by the current choice of targeting epithelial markers known to be highly variable in primary tumor sites. Here, we review current antigen-based tumor cell isolation strategies and offer biological context for commonly studied cancer surface markers. Expression levels of the most common markers are quantitated for three breast cancer and two non-small cell lung cancer (NSCLC) lineage models. These levels are contrasted with that present on healthy peripheral blood mononuclear cells (PBMC) for comparison to expected background levels in a fluid biopsy setting. A key feature of this work is establishing a metric of markers per square micrometer. This describes an average marker density on the cell membrane surface, which is a critical metric for emerging isolation strategies. These results serve to extend expression of key tumor markers in a sensitive and dynamic manner beyond traditional positive/negative immunohistochemical staining to guide future fluid biopsy targeting strategies.

Autoantibody profiling for lung cancer screening longitudinal retrospective analysis of CT screening cohorts.

Recommendations for lung cancer screening present a tangible opportunity to integrate predictive blood-based assays with radiographic imaging. This study compares performance of autoantibody markers from prior discovery in sample cohorts from two CT screening trials. One-hundred eighty non-cancer and 6 prevalence and 44 incidence cancer cases detected in the Mayo Lung Screening Trial were tested using a panel of six autoantibody markers to define a normal range and assign cutoff values for class prediction. A cutoff for minimal specificity and best achievable sensitivity were applied to 256 samples drawn annually for three years from 95 participants in the Kentucky Lung Screening Trial. Data revealed a discrepancy in quantile distribution between the two apparently comparable sample sets, which skewed the assay's dynamic range towards specificity. This cutoff offered 43% specificity (102/237) in the control group and accurately classified 11/19 lung cancer samples (58%), which included 4/5 cancers at time of radiographic detection (80%), and 50% of occult cancers up to five years prior to diagnosis. An apparent ceiling in assay sensitivity is likely to limit the utility of this assay in a conventional screening paradigm. Pre-analytical bias introduced by sample age, handling or storage remains a practical concern during development, validation and implementation of autoantibody assays. This report does not draw conclusions about other logical applications for autoantibody profiling in lung cancer diagnosis and management, nor its potential when combined with other biomarkers that might improve overall predictive accuracy.

Pilot study of 1650-G: a simplified cellular vaccine for lung cancer.

INTRODUCTION: Cancer immunotherapy is a conceptually attractive since it is highly specific and can deal with disseminated disease with minimal impact on normal tissues. Early phase clinical trials have well established the ability of a variety of immunotherapeutic approaches to induce antigen specific immune responses in lung cancer patients. Although no immunotherapy is likely to be a panacea, recent data from randomized phase IIB studies offer promise of therapeutic activity in both early and late stage lung cancer. METHODS: This report describes early clinical experience with vaccine 1650-G, an allogeneic cellular vaccine using granulocyte macrophage colony stimulating factor as an adjuvant. This nonrandomized pilot study was conducted at four sites in the Commonwealth of Kentucky with primary objective of determining biological activity in a relevant patient population; the use of similar antigen source, immunization schedule, and immunological assessment facilitated comparison to DC vaccines previously tested by our group. RESULTS: Data indicates 1650-G is safe and generated a robust and unequivocal immunological response in 6/11 of immunized patients. The relative frequency and kinetics of the response appears similar to that achieved with DC vaccines (1650+autologous DC). The fact that this vaccine could be transported and delivered to cancer patients in community cancer clinics also fulfills an important objective of our research. CONCLUSIONS: These findings provide critical foundation for further testing of this simple, and comparatively inexpensive multivalent NSCLC vaccine.

Lung cancer-associated auto-antibodies measured using seven amino acid peptides in a diagnostic blood test for lung cancer.

Autoantibody profiling is a developing approach that incorporates immune recognition of myriad aberrant cancer proteins into a single diagnostic assay. We have previously described methodology to screen T7-phage NSCLC-cDNA libraries for phage-expressed proteins recognized by NSCLC-associated antibodies, and developed a multiplex assay that has excellent ability to discriminate NSCLC from control samples. This follow-up report describes the development and testing of a diagnostic autoantibody assay that uses seven amino-acid peptides as capture proteins. A random-peptide M13-phage library was screened for proteins recognized by cancer-associated antibodies. One hundred twenty-one NSCLC case and control samples were divided into two groups for training and validation, or alternately, evaluated sequentially in a leave-one-out analysis. Candidate antibody-markers were ranked by statistical discrimination between cases and controls. Receiver-Operating-Characteristic (ROC-AUC) suggested the predictive potential of various marker combinations. A five-marker combination (AUC = 0.982) afforded 90% sensitivity and 73% specificity in a training-and-testing strategy. Leave-one-out validation provided similar class prediction. Data confirm the potential of antibody profiling to provide high levels of cancer prediction. Random peptide libraries offer a universal source of capture proteins for antibody profiling that obviates the need for tumor-specific library construction and abrogates inherent problems with tumor heterogeneity during biomarker discovery.

Characteristics of PBMC obtained from leukapheresis products and tumor biopsies of patients with non-small cell lung cancer.

The current study characterized peripheral blood mononuclear cells (PBMC) obtained from leukapheresis products of patients with non-small cell lung cancer (NSCLC) for cytokine release, the ability to incorporate tritiated thymidine following stimulation using PHA as well as the levels of both CD4 and CD8 regulatory T cells (Tregs) as defined by FoxP3 expression. Results were compared to normal donor PBMC obtained from buffy coat products. Heterogeneous levels of Th1 (gamma interferon and IL-2), Th2 (IL-10 and IL-13), pro-inflammatory (TNF-alpha and IL-6) and the hematopoietic inducing cytokine GMCSF were detected from both populations of PBMC as measured using ELISA. Overall, we observed that combined levels of Th1 and Th2 cytokines were higher in lung cancer patients compared to that seen in normal donor PBMC. The increased cytokine production was coupled with an observed decrease in the ability of lung cancer patient PBMC to incorporate tritiated thymidine. Furthermore, cytokine containing supernatants obtained from patients inhibited the incorporation of tritiated thymidine from PBMC obtained from normal donors. Thus, the combined cytokines which included high levels of IL-10, appeared to exhibit suppressive functional activity. While not statistically significant, the overall trend toward a Th2 cytokine environment was supported by an increased level of Tregs observed in the leukapheresis products of lung cancer patients. These levels were variable and were accompanied by higher than normal levels of CD8+ cells co-expressing FoxP3. Finally, tumor biopsies were examined from lung cancer patients along with autologous normal adjacent tissue (NAT). In these studies, both gamma interferon and IL-10 were detected. The levels of IL-10 in the LPS stimulated cultures were statistically greater from the cancer biopsies compared to the NAT. The current study confirms many earlier results in a comprehensive manner and extends the analysis to leukapheresis products. An environment is described in cancer patients which is characterized by increased cytokine production and decreased proliferative potential likely under the influence of a significant population of regulatory T cells (Tregs). Taken together, these results are discussed as they relate to the potential implications in lung cancer patients immune response to their disease.

Immunotherapy for lung cancer.

Immunotherapy is a conceptually attractive approach, because it is highly specific and can deal with disseminated disease with minimal impact on normal tissues. Ability to induce antigen-specific immune responses in patients with lung cancer is now well established in early-phase clinical trials using a variety of immunotherapeutic approaches. Although no immunotherapy is likely to be a panacea, randomized phase IIB studies offer promise of therapeutic activity in both early- and late-stage lung cancer. This review will cover basic concepts of immunotherapy, provide perspective on vaccine development, and update the status of ongoing clinical trials in lung cancer.

Immunization of NSCLC patients with antigen-pulsed immature autologous dendritic cells.

Only a handful of NSCLC patients have been included in dendritic cell (DC) vaccine clinical trials. We had previously reported a series of 16 individuals with stages IA-IIIB NSCLC who received autologous DC vaccines matured with dendritic cell/T cell-derived maturation factor (DCTCMF). Here we report the results of a continuation study with similar inclusion criteria, immunization protocol, and analysis, using an immature DC vaccine. Of the 14 participants, 7 had undergone surgical resection (stage I/II), with or without adjuvant therapy, and 7 with unresectable stage III had been treated with chemo-radiation alone. Autologous DCs were pulsed with apoptotic bodies derived from an allogeneic NSCLC cell line that over-expresses Her2/neu, CEA, WT1, Mage2, and survivin. DCs were not exposed to any maturation stimulus. Individuals received two intradermal vaccines (average 8.1x10(7) DC per immunization) 1 month apart. Immune responses were measured by IFN-gamma ELISPOT, comparing relative number of antigen-reactive T-cells from pre-vaccine to timepoints post-immunization. Immunologic responses were seen in 4/7 stage III unresectable, and 6/7 stage I/II surgically resected patients, including 3/3 resected patients who had also received adjuvant chemo-radiation. There were no related adverse events. One of seven surgically resected patients recurred and 4/7 stage III patients progressed. Three of five patients with progressive disease showed no immunologic response. Data indicate that immature DC pulsed with apoptotic tumour cells have similar biologic activity to a DCTCMF-matured DC preparation delivered in a similar clinical protocol. Therapeutic efficacy is unknown and clinical outcomes are anecdotal.

Profiling tumor-associated antibodies for early detection of non-small cell lung cancer.

BACKGROUND: A blood test for non-small cell lung cancer (NSCLC) may be a valuable tool for use in a comprehensive lung cancer screening strategy. Here we report the potential of autoantibody profiling to detect early-stage and occult NSCLC. METHODS: T7-phage NSCLC cDNA libraries were screened with patient plasma to identify phage-expressed proteins recognized by tumor-associated antibodies. Two hundred twelve immunogenic phage-expressed proteins, identified from 4000 clones, were statistically ranked for their individual reactivity with 23 stage I cancer patient and 23 risk-matched control samples. All 46 samples were used as a training set to define a combination of markers that were best able to distinguish patient from control samples; this set of classifiers was then examined using leave-one-out cross-validation. Markers were then used to predict probability of disease in 102 samples from the Mayo Clinic CT Screening Trial (six prevalence cancer samples, 40 drawn 1 to 5 years before diagnosis, and 56 risk-matched controls). RESULTS: Measurements of the five most predictive antibody markers in 46 cases and controls were combined in a logistic regression model that yielded area under the receiver operating characteristics curve of 0.99; leave-one-out validation achieved 91.3% sensitivity and 91.3% specificity. In testing this marker set with samples from the Mayo Clinic Lung Screening Trial, we correctly predicted six of six prevalence cancers, 32 of 40 cancers from samples drawn 1 to 5 years before radiographic detection on incidence screening, and 49 of 56 risk-matched controls. CONCLUSIONS: Antibody profiling may be a useful tool for early detection of NSCLC.

Vaccines for lung cancer.

Immunotherapy is based on the knowledge that the immune system can distinguish cancerous cells from normal cells. Conceptually, this is an attractive adjuvant approach because it is highly specific and can deal with disseminated disease with minimal impact on normal tissues. In this review, we focus on strategies that use host immune machinery to generate anti-tumor effects, known as active immunotherapy. Proof of principle in lung cancer is now well established in clinical trials, although no superior approach has been defined and therapeutic efficacy remains unknown. In this review, we discuss rationale, biological theory, application, and clinical implementation to date.

Using protein microarray as a diagnostic assay for non-small cell lung cancer.

RATIONALE: Phenotypic and genotypic heterogeneity of lung cancer likely precludes the identification of a single predictive marker and suggests the importance of identifying and measuring multiple markers. OBJECTIVES: We describe the use of a fluorescent protein microarray to identify and measure multiple non-small cell lung cancer-associated antibodies and show how simultaneous measurements can be combined into a single diagnostic assay. METHODS: T7 phage cDNA libraries of non-small cell lung cancer were first biopanned with plasma samples from normal subjects and patients with non-small cell lung cancer to enrich the component of tumor-associated proteins, and then applied to microarray slides. Two hundred twelve immunogenic phage-expressed proteins were identified from roughly 4,000 clones, using high-throughput screening with patient plasmas and assayed with 40 cancer and 41 normal plasma samples. Twenty patient and 21 normal plasma samples were randomly chosen and used for statistical determination of the predictive value of each putative marker. Statistical analysis identified antibody reactivity to seven unique phage-expressed proteins that were significantly different (p < 0.01) between patient and normal groups. The remaining 20 patient and 20 normal plasma samples were used as an independent test of the predictive ability of the selected markers. MAIN RESULTS: Measurements of the 5 most predictive phage proteins were combined in a logistic regression model that achieved 90% sensitivity and 95% specificity in prediction of patient samples, whereas leave-one-out statistical analysis achieved 88.9% diagnostic accuracy among all 81 samples. CONCLUSION: Our data indicate that antibody profiling is a promising approach that could achieve high diagnostic accuracy for non-small cell lung cancer.

Autologous dendritic cell vaccines for non-small-cell lung cancer.

PURPOSE: Therapeutic outcomes of definitively treated non-small-cell lung cancer (NSCLC) are unacceptably poor. A wealth of preclinical information, and a modest amount of clinical information indicate that dendritic cell (DC) vaccines have therapeutic potential. Only a handful of NSCLC patients have been included in DC clinical trials. We delivered autologous DC vaccines to 16 individuals with stage IA to IIIB NSCLC treated with surgery, chemoradiation, or multimodality therapy. The objectives of the study were to evaluate tolerability and measure immunologic responses to DC vaccines in a heterogeneous group of NSCLC patients. METHODS: DC vaccines were generated from CD14+ precursors, pulsed with apoptotic bodies of an allogeneic NSCLC cell line that overexpressed Her2/neu, CEA, WT1, Mage2, and survivin. DCs were partially matured with a factor that induced surface molecule expression but minimal cytokine production. Individuals were immunized intradermally two times, 1 month apart. Peripheral blood was drawn serially over 16 weeks, and immune responses were measured by interferon-gamma ELISPOT. RESULTS: There were no unanticipated or serious adverse events. Immunologic responses followed three distinct patterns of reactivity: (1) five of 16 patients showed no clear immunologic response, (2) five of 16 patients showed a tumor-antigen independent response, and (3) six of 16 show an antigen specific response. Immunologic responses were independent of stage and prior therapy. Favorable and unfavorable clinical outcomes were independent of measured immunologic responses. CONCLUSION: Vaccines were well tolerated and had biologic activity in a variety of NSCLC patients. Establishing an optimal approach will require comparative studies in well-defined NSCLC patient groups.

Identification of circulating antibodies to tumor-associated proteins for combined use as markers of non-small cell lung cancer.

Currently only a limited number of tumor markers for non-small cell lung cancer (NSCLC) are available. Antibodies to tumor-associated proteins may expand the number of available tumor markers for lung cancer and be used together in a serum profile to enhance sensitivity and specificity. In this study, we isolated 57 tumor-associated proteins from two NSCLC cDNA T7 phage libraries using biopan enrichment techniques with NSCLC patient and normal sera. Sequence analysis showed that among the 57 phage-displayed proteins 45 have sequence identity with known or putative tumor-associated proteins. Immunochemical reactivity of patient sera with phage-expressed proteins showed enrichment on the number of immunogenic phage clones in the biopanning process and also confirmed that antibodies were present in patient sera but not in normal sera. Antibodies to five phage-expressed proteins were measured by enzyme-linked immunosorbent assay (ELISA) to validate the concept that combinations have greater predictive value than any single antibody alone. Logistic regression analysis showed that combined measurements of five antibodies was more predictive of disease than any single antibody alone, underscoring the importance of identifying multiple potential markers. The resulting antibody profiling is a feasible diagnostic strategy for NSCLC. An inventory of corresponding proteins may have significant relevance to tumor biology, novel drug development, and immunotherapies.

Antibodies to HSP70 and HSP90 in serum in non-small cell lung cancer patients.

Heat shock proteins (HSPs) are components of a physiologic stress response that are also over-expressed in various cancers including non-small cell lung cancer (NSCLC). During NSCLC serum-antibody screening of a NSCLC cDNA T7 phage library for immunogenic proteins we isolated HSP70 and HSP90 proteins. Isolation of these proteins suggested that corresponding antibodies could be elevated in NSCLC patient sera, a novel finding that could pilot their use as markers of NSCLC. We showed histochemically that patient sera were more reactive with each phage-expressed protein than normal sera. Antibody affinity for each phage-expressed protein was confirmed by limiting the dilution of individual sera assayed by Ab enzyme-linked immunosorbent assay (ELISA). Sera from 49 NSCLC patients assayed by Ab ELISA and normalized to 40 controls showed that HSP70 antibodies were significantly greater in patient sera than in normals (P=0.0002), while HSP90 antibodies were not significantly different (P=0.11). Analysis of the results with logistic regression and receiver operating characteristics (ROC) curves showed that HSP70 antibodies were modest markers of NSCLC (sensitivity 0.74 and specificity 0.73; area under the curve or AUC=0.731), while HSP90 antibodies appeared to be poor in both criteria with an AUC of 0.602. Further evaluation of HSP70 antibodies as potential markers of disease may be rational.

Plasma PGE-2 levels and altered cytokine profiles in adherent peripheral blood mononuclear cells in non-small cell lung cancer (NSCLC).

INTRODUCTION: PGE-2 is constitutively produced by many non-small cell lung cancers (NSCLC) and its immunosuppressive effects have been linked to altered immune responses in lung cancer. We asked whether elevated levels of plasma PGE-2 correlated with monocyte IL10 production in the NSCLC environment. Looking for correlation in NSCLC patient blood we assayed plasma from NSCLC patients for PGE2 and IL10; we further evaluated production of IL10 by adherent mononuclear cells from a subset of these patients looking for an altered cytokine profile. RESULTS: Our initial in vitro experiments show that monocyte IL10 induction correlates with tumor cell PGE-2 production, confirming similar reports in the literature. Data show plasma PGE-2 levels in 38 NSCLC patients are elevated compared to normal controls. Plasma IL10 levels were not significantly elevated; however, adherent monocytes derived from NSCLC patient blood did produce significantly more IL10 in 24 hr primary culture than those from normal controls (p < 0.01). The association of elevated plasma PGE-2 and monocyte derived IL-10 was not significant. CONCLUSIONS: Elevated plasma PGE-2 and monocyte IL10 production are associated with NSCLC. The biological significance to elevated PGE-2 levels in NSCLC are unclear. Further investigation of each as a nonspecific marker for NSCLC tumor is warranted.