Impact of Decalcification, Cold Ischemia, and Deglycosylation on Performance of Programmed Cell Death Ligand-1 Antibodies With Different Binding Epitopes: Comparison of 7 Clones.

Programmed cell death ligand-1 (PD-L1) expression levels in patients' tumors have demonstrated clinical utility across many cancer types and are used to determine treatment eligibility. Several independently developed PD-L1 immunohistochemical (IHC) predictive assays are commercially available and have demonstrated different levels of staining between assays, generating interest in understanding the similarities and differences between assays. Previously, we identified epitopes in the internal and external domains of PD-L1, bound by antibodies in routine clinical use (SP263, SP142, 22C3, and 28-8). Variance in performance of assays utilizing these antibodies, observed following exposure to preanalytical factors such as decalcification, cold ischemia, and duration of fixation, encouraged additional investigation of antibody-binding sites, to understand whether binding site structures/conformations contribute to differential PD-L1 IHC assay staining. We proceeded to further investigate the epitopes on PD-L1 bound by these antibodies, alongside the major clones utilized in laboratory-developed tests (E1L3N, QR1, and 73-10). Characterization of QR1 and 73-10 clones demonstrated that both bind the PD-L1 C-terminal internal domain, similar to SP263/SP142. Our results also demonstrate that under suboptimal decalcification or fixation conditions, the performance of internal domain antibodies is less detrimentally affected than that of external domain antibodies 22C3/28-8. Furthermore, we show that the binding sites of external domain antibodies are susceptible to deglycosylation and conformational structural changes, which directly result in IHC staining reduction or loss. The binding sites of internal domain antibodies were unaffected by deglycosylation or conformational structural change. This study demonstrates that the location and conformation of binding sites, recognized by antibodies employed in PD-L1 diagnostic assays, differ significantly and exhibit differing degrees of robustness. These findings should reinforce the need for vigilance when performing clinical testing with different PD-L1 IHC assays, particularly in the control of cold ischemia and the selection of fixation and decalcification conditions.

Cytology for PD-L1 testing: A systematic review.

Evaluation of tumoral programmed cell death ligand-1 (PD-L1) expression is standard practice for patients with advanced non-small-cell lung cancer (NSCLC) who may be candidates for treatment targeting the programmed cell death-1 (PD-1)/PD-L1 pathway. Currently, all of the commercially available immunohistochemistry assays have been validated for use with histology specimens although, in routine clinical practice, approximately 30-40 % of patients with advanced NSCLC have only cytology specimens available for diagnosis, staging, and biomarker analysis. This systematic review evaluated the success rate, concordance, and clinical utility of using cytology specimens to assess tumor PD-L1 expression levels compared with histology specimens from patients with advanced NSCLC. EMBASE and PubMed database searches identified 142 unique, relevant publications, of which 15 met the inclusion criteria for at least one analysis. In 709 specimens, across seven publications, the proportion of cytology specimens evaluable for PD-L1 testing was 92.0 %. Among nine studies eligible for concordance analysis between cytology and histology specimens at a PD-L1 tumor cell expression cutoff of ≥50 %, overall percentage agreement was 89.7 % (n = 428), 72.0 % for positive percentage agreement (n = 218), and 95.0 % for negative percentage agreement (n = 258); results using a tumor PD-L1 expression cutoff of ≥1 % were similar. Our analyses suggest that using cytology specimens to assess PD-L1 expression is feasible, with good levels of concordance between cytology and histology specimens using PD-L1 tumor cell expression cutoffs of ≥1 % and ≥50 %. In conclusion, there is no convincing evidence that cytology specimens are inadequate or inferior to histology specimens for assessing PD-L1 expression in patients with NSCLC.

"Interchangeability" of PD-L1 immunohistochemistry assays: a meta-analysis of diagnostic accuracy.

Different clones, protocol conditions, instruments, and scoring/readout methods may pose challenges in introducing different PD-L1 assays for immunotherapy. The diagnostic accuracy of using different PD-L1 assays interchangeably for various purposes is unknown. The primary objective of this meta-analysis was to address PD-L1 assay interchangeability based on assay diagnostic accuracy for established clinical uses/purposes. A systematic search of the MEDLINE database using PubMed platform was conducted using "PD-L1" as a search term for 01/01/2015 to 31/08/2018, with limitations "English" and "human". 2,515 abstracts were reviewed to select for original contributions only. 57 studies on comparison of two or more PD-L1 assays were fully reviewed. 22 publications were selected for meta-analysis. Additional data were requested from authors of 20/22 studies in order to enable the meta-analysis. Modified GRADE and QUADAS-2 criteria were used for grading published evidence and designing data abstraction templates for extraction by reviewers. PRISMA was used to guide reporting of systematic review and meta-analysis and STARD 2015 for reporting diagnostic accuracy study. CLSI EP12-A2 was used to guide test comparisons. Data were pooled using random-effects model. The main outcome measure was diagnostic accuracy of various PD-L1 assays. The 22 included studies provided 376 2×2 contingency tables for analyses. Results of our study suggest that, when the testing laboratory is not able to use an Food and Drug Administration-approved companion diagnostic(s) for PD-L1 assessment for its specific clinical purpose(s), it is better to develop a properly validated laboratory developed test for the same purpose(s) as the original PD-L1 Food and Drug Administration-approved immunohistochemistry companion diagnostic, than to replace the original PD-L1 Food and Drug Administration-approved immunohistochemistry companion diagnostic with a another PD-L1 Food and Drug Administration-approved companion diagnostic that was developed for a different purpose.

Concordance among four commercially available, validated programmed cell death ligand-1 assays in urothelial carcinoma.

BACKGROUND: Antibodies targeting the programmed cell death-1 (PD-1)/PD-ligand 1 (PD-1/PD-L1) checkpoint have shown promising clinical activity in patients with advanced urothelial carcinoma (UC). Expression of PD-L1 in UC tumors has been investigated using different antibody clones, staining protocols, and scoring algorithms. The aim was to establish the extent of concordance among PD-L1 immunohistochemistry (IHC) assays. METHODS: Tumor biopsy samples (N = 335) were assessed using four commercially available PD-L1 assays: VENTANA SP263, VENTANA SP142, PD-L1 IHC 28-8 pharmDx, and PD-L1 IHC 22C3 pharmDx. PD-L1 analytical staining and classification concordance, including agreement between clinically relevant scoring algorithms, were investigated using overall/positive/negative percentage agreement (OPA/PPA/NPA). RESULTS: Good analytical correlation was observed among the VENTANA SP263, PD-L1 IHC 22C3 pharmDx, and PD-L1 IHC 28-8 pharmDx assays for tumor cell (TC) and immune cell (IC) PD-L1 staining with Spearman rank coefficients of 0.92-0.93 for TCs and 0.88-0.91 for ICs. However, concordance (preset criterion: ≥85%) between patient PD-L1 status when applying the TC or ICICArea ≥ 25% (VENTANA SP263) cutoff was only achieved for PD-L1 IHC 22C3 pharmDx versus VENTANA SP263 (OPA 92.2%, PPA 86.4%, NPA 95.4%). Differences were observed between patient populations with UC tumors classified as PD-L1 high versus PD-L1 low/negative using combined positive score (CPS) ≥1, CPS ≥10, IC ≥5%, and TC/IC ≥25%. CONCLUSIONS: The VENTANA SP263 and PD-L1 IHC 22C3 pharmDx assays are analytically similar in UC. When the different PD-L1 assays were combined with their specified clinical scoring algorithms, differences were seen in patient classification driven by substantial differences in scoring approaches.

Impact of Patient Characteristics, Prior Therapy, and Sample Type on Tumor Cell Programmed Cell Death Ligand 1 Expression in Patients with Advanced NSCLC Screened for the ATLANTIC Study.

INTRODUCTION: We evaluated the impact of patient characteristics, sample types, and prior non-immunotherapy treatment on tumor cell (TC) programmed cell death ligand 1 (PD-L1) expression using samples from patients with advanced NSCLC. METHODS: Patients (N = 1590) screened for the ATLANTIC study submitted a recently acquired (≤3 months) or archival (>3 months to >3 years old) tumor sample for PD-L1 assessment using the VENTANA PD-L1 (SP263) Assay with a cutoff of ≥25% of TCs expressing PD-L1 (TC ≥25%). Samples were acquired either before or after the two or more treatment regimens required for study entry and sample age varied among patients. A subset of patients (n = 123) provided both recent and archival samples. RESULTS: A total of 517 of 1590 (32.5%) patients had TC greater than or equal to 25%: prevalence was greater in smokers versus nonsmokers (p = 0.0005) and those with EGFR- versus EGFR+ tumors (p = 0.0002); these effects were independent. Prevalence of TC greater than or equal to 25% was increased in recent metastatic versus primary (p = 0.005) and recent versus archival (p = 0.039) samples. Chemotherapy or radiotherapy, but not tyrosine kinase inhibition, before sampling was associated with significantly increased PD-L1 prevalence. PD-L1 status (TC ≥25% cutoff) remained unchanged in 74.0% of patients with recent and archival samples; where PD-L1 status changed, it was more likely to increase than decrease over time or with intervening treatment. CONCLUSIONS: Several factors potentially impact PD-L1 TC greater than or equal to 25% prevalence in advanced NSCLC; however, no characteristic can be considered a surrogate for PD-L1 expression. Fresh biopsy may provide more accurate assessment of current tumoral PD-L1 expression where a low/negative result is seen in an archival sample, especially if the patient has received intervening therapy.

Consistency of tumor and immune cell programmed cell death ligand-1 expression within and between tumor blocks using the VENTANA SP263 assay.

BACKGROUND: Several anti-programmed cell death-1 (PD-1) and anti-programmed cell death ligand-1 (PD-L1) therapies have shown encouraging safety and clinical activity in a variety of tumor types. A potential role for PD-L1 testing in identifying patients that are more likely to respond to treatment is emerging. PD-L1 expression in clinical practice is determined by testing one tumor section per patient. Therefore, it is critical to understand the impact of tissue sampling variability on patients' PD-L1 classification. METHODS: Resected non-small cell lung cancer (NSCLC), head and neck squamous cell carcinoma (HNSCC) and urothelial carcinoma (UC) tissue samples (five samples per tumor type) were obtained from commercial sources and two tumor blocks were taken from each. Three sections from each block (~ 100 µm apart) were stained using the VENTANA PD-L1 (SP263) assay, and scored based on the percentage of PD-L1-staining tumor cells (TCs) or tumor-infiltrating immune cells (ICs) present. Each section was categorized as PD-L1 high or low/negative using a variety of cut-off values, and intra-block and intra-case (between blocks of the same tumor) concordance (overall percentage agreement [OPA]) were evaluated. An additional 200 commercial NSCLC samples were also analyzed, and intra-block concordance determined by scoring two sections per sample (≥70 µm apart). RESULTS: Concordance in TC PD-L1 classification was high at all applied cut-offs. Intra-block and intra-case OPA for the 15 NSCLC, HNSCC or UC samples were 100% and 80-100%, respectively, across all cut-offs; intra-block OPA for the 200 NSCLC samples was 91.0-98.5% across all cut-offs. IC PD-L1 classification was less consistent; intra-block and intra-case OPA for the 15 NSCLC, HNSCC or UC samples ranged between 70 and 100% and between 60 and 100%, respectively, with similar observations in the intra-block analysis of the 200 NSCLC samples. CONCLUSIONS: These results show the reproducibility of TC PD-L1 classification across the depth of the tumor using the VENTANA PD-L1 (SP263) assay. Practically, this means that treatment decisions based on TC PD-L1 classification can be made confidently, following analysis of one tumor section. Although more variable than TC staining, consistent IC PD-L1 classification was also observed within and between blocks and across cut-offs.

EGFR mutation prevalence in Asia-Pacific and Russian patients with advanced NSCLC of adenocarcinoma and non-adenocarcinoma histology: The IGNITE study.

OBJECTIVES: Limited understanding exists of epidermal growth factor receptor (EGFR) mutation frequency in less common subgroups of advanced non-small-cell lung cancer (aNSCLC) (e.g. squamous cell carcinoma [SCC]), and to what extent local practices exclude patients from EGFR testing based on their clinical characteristics. MATERIALS AND METHODS: IGNITE (non-comparative/-interventional; NCT01788163) was conducted in 90 centres (Asia-Pacific/Russia). Eligible patients: local/metastatic aNSCLC; chemotherapy-naïve, newly-diagnosed/recurrent disease after resection; ineligible for curative treatment. Patients provided a tissue/cytology (all) and a blood plasma (China/Russia/South Korea/Taiwan) sample. Primary endpoint: EGFR mutation frequency in aNSCLC patients (adenocarcinoma [ADC]/non-ADC), as per local practices. RESULTS: 3382 patients were enrolled. EGFR mutation frequencies for evaluable tissue/cytology samples in Asia-Pacific and Russian patients: 49.3% (862/1749) and 18.0% (90/500) for ADC tumours; 14.1% (74/525) and 3.7% (15/402) for non-ADC; 9.9% (40/403) and 3.7% (13/349) for SCC. Of Russian patients with SCC tumours harbouring common, activating EGFR mutations, 6/9 were never-/former-smokers. Mutation status concordance between 2581 matched tissue/cytology and plasma samples: 80.5% (sensitivity 46.9%, specificity 95.6%). CONCLUSION: EGFR mutation testing should be considered in all Asian aNSCLC patients. Also, as activating EGFR mutations were observed in a small number of Caucasian squamous NSCLC patients, testing here may be appropriate, particularly in those with no/remote smoking history. Circulating free tumour-derived DNA is feasible for mutation analysis employing well-validated and sensitive methods, when tumour samples are unavailable.

Agreement between Programmed Cell Death Ligand-1 Diagnostic Assays across Multiple Protein Expression Cutoffs in Non-Small Cell Lung Cancer.

Purpose: Immunotherapies targeting programmed cell death-1 (PD-1) and programmed cell death ligand-1 (PD-L1) demonstrate encouraging antitumor activity and manageable tolerability in non-small cell lung cancer (NSCLC), especially in patients with high tumor PD-L1 expression, as detected by companion or complementary diagnostic assays developed for individual agents. A laboratory is unlikely to use multiple assay platforms. Furthermore, commercially available diagnostic assays are not standardized, and different assay methods could lead to inappropriate treatment selection. This study establishes the extent of concordance between three validated, commercially available PD-L1 IHC diagnostic assays for NSCLC patients [Ventana SP263 (durvalumab), Dako 22C3 (pembrolizumab), and Dako 28-8 (nivolumab)].Experimental Design: Five hundred formalin-fixed, paraffin-embedded archival NSCLC samples were obtained from commercial sources. Stained slides were read in batches on an assay-by-assay basis by a single pathologist trained in all methods, in a Clinical Laboratory Improvements Amendments program-certified laboratory. An additional pathologist performed an independent review of 200 stained samples for each assay.Results: PD-L1 expression was evaluable with all assays in 493 samples. The three assays showed similar patterns of tumor membrane staining, with high correlation between percent PD-L1 staining. An overall percentage agreement of >90% was achieved between assays at multiple expression cutoffs, including 1%, 10%, 25%, and 50% tumor membrane staining.Conclusions: This study builds optimism that harmonization between assays may be possible, and that the three assays studied could potentially be used interchangeably to identify patients most likely to respond to anti-PD-1/PD-L1 immunotherapies, provided the appropriate clinically defined algorithm and agent are always linked. Clin Cancer Res; 23(14); 3585-91. ©2017 AACR.

Guide to detecting epidermal growth factor receptor (EGFR) mutations in ctDNA of patients with advanced non-small-cell lung cancer.

Cancer treatment is evolving towards therapies targeted at specific molecular abnormalities that drive tumor growth. Consequently, to determine which patients are eligible, accurate assessment of molecular aberrations within tumors is required. Obtaining sufficient tumor tissue for molecular testing can present challenges; therefore, circulating free tumor-derived DNA (ctDNA) found in blood plasma has been proposed as an alternative source of tumor DNA. The diagnostic utility of ctDNA for the detection of epidermal growth factor receptor (EGFR) mutations harbored in tumors of patients with advanced non-small-cell lung cancer (NSCLC) is supported by the results of several large studies/meta-analyses. However, recent real-world studies suggest that the performance of ctDNA testing varies between geographic regions/laboratories, demonstrating the need for standardized guidance. In this review, we outline recommendations for obtaining an accurate result using ctDNA, relating to pre-analytical plasma processing, ctDNA extraction, and appropriate EGFR mutation detection methods, based on clinical trial results. We conclude that there are several advantages associated with ctDNA, including the potential for repeated sampling - particularly following progression after first-line tyrosine kinase inhibitor (TKI) therapy, as TKIs targeting resistance mutations (eg T790M) are now approved for use in the USA/EU/Japan (at time of writing). However, evidence suggests that ctDNA does not allow detection of EGFR mutations in all patients with known mutation-positive NSCLC. Therefore, although tumor tissue should be the first sample choice for EGFR testing at diagnosis, ctDNA is a promising alternative diagnostic approach.

ctDNA Determination of EGFR Mutation Status in European and Japanese Patients with Advanced NSCLC: The ASSESS Study.

INTRODUCTION: To offer patients with EGFR mutation-positive advanced NSCLC appropriate EGFR tyrosine kinase inhibitor treatment, mutation testing of tumor samples is required. However, tissue/cytologic samples are not always available or evaluable. The large, noninterventional diagnostic ASSESS study (NCT01785888) evaluated the utility of circulating free tumor-derived DNA (ctDNA) from plasma for EGFR mutation testing. METHODS: ASSESS was conducted in 56 centers (in Europe and Japan). Eligible patients (with newly diagnosed locally advanced/metastatic treatment-naive advanced NSCLC) provided diagnostic tissue/cytologic and plasma samples. DNA extracted from tissue/cytologic samples was subjected to EGFR mutation testing using local practices; designated laboratories performed DNA extraction/mutation testing of blood samples. The primary end point was level of concordance of EGFR mutation status between matched tissue/cytologic and plasma samples. RESULTS: Of 1311 patients enrolled, 1288 were eligible. Concordance of mutation status in 1162 matched samples was 89% (sensitivity 46%, specificity 97%, positive predictive value 78%, and negative predictive value 90%). A group of 25 patients with apparent false-positive plasma results was overrepresented for cytologic samples, use of less sensitive tissue testing methodologies, and smoking habits associated with high EGFR mutation frequency, indicative of false-negative tumor results. In cases in which plasma and tumor samples were tested with identical highly sensitive methods, positive predictive value/sensitivity were generally improved. CONCLUSIONS: These real-world data suggest that ctDNA is a feasible sample for EGFR mutation analysis. It is important to conduct mutation testing of both tumor and plasma samples in specialized laboratories, using robust/sensitive methods to ensure that patients receive appropriate treatments that target the molecular features of their disease.

Mutation status concordance between primary lesions and metastatic sites of advanced non-small-cell lung cancer and the impact of mutation testing methodologies: a literature review.

Increased understanding of the genetic aetiology of advanced non-small-cell lung cancer (aNSCLC) has facilitated personalised therapies that target specific molecular aberrations associated with the disease. Biopsy samples for mutation testing may be taken from primary or metastatic sites, depending on which sample is most accessible, and upon differing diagnostic practices between territories. However, the mutation status concordance between primary tumours and corresponding metastases is the subject of debate. This review aims to ascertain whether molecular diagnostic testing of either the primary or metastatic tumours is equally suitable to determine patient eligibility for targeted therapies. A literature search was performed to identify articles reporting studies of mutations in matched primary and metastatic aNSCLC tumour samples. Clinical results of mutation status concordance between matched primary and metastatic tumour samples from patients with aNSCLC were collated. Articles included in this review (N =26) all reported mutation status data from matched primary and metastatic tumour samples obtained from adult patients with aNSCLC. Generally, substantial concordance was observed between primary and metastatic tumours in terms of EGFR, KRAS, BRAF, p16 and p53 mutations. However, some level of discordance was seen in most studies; mutation testing methodologies appeared to play a key role in this, along with underlying tumour heterogeneity. Substantial concordance in mutation status observed between primary and metastatic tumour sites suggests that diagnostic testing of either tumour type may be suitable to determine a patient's eligibility for personalised therapies. As with all diagnostic testing, highly sensitive and appropriately validated mutation analysis methodologies are desirable to ensure accuracy. Additional work is also required to define how much discordance is clinically significant given natural tumour heterogeneity. The ability of both primary and metastatic tumour sites to accurately reflect the tumour mutation status will allow more patients to receive therapies personalised to their disease.

EGFR mutation testing practices within the Asia Pacific region: results of a multicenter diagnostic survey.

INTRODUCTION: The efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in EGFR mutation-positive non-small-cell lung cancer (NSCLC) patients necessitates accurate, timely testing. Although EGFR mutation testing has been adopted by many laboratories in Asia, data are lacking on the proportion of NSCLC patients tested in each country, and the most commonly used testing methods. METHODS: A retrospective survey of records from NSCLC patients tested for EGFR mutations during 2011 was conducted in 11 Asian Pacific countries at 40 sites that routinely performed EGFR mutation testing during that period. Patient records were used to complete an online questionnaire at each site. RESULTS: Of the 22,193 NSCLC patient records surveyed, 31.8% (95% confidence interval: 31.2%-32.5%) were tested for EGFR mutations. The rate of EGFR mutation positivity was 39.6% among the 10,687 cases tested. The majority of samples were biopsy and/or cytology samples (71.4%). DNA sequencing was the most commonly used testing method accounting for 40% and 32.5% of tissue and cytology samples, respectively. A pathology report was available only to 60.0% of the sites, and 47.5% were not members of a Quality Assurance Scheme. CONCLUSIONS: In 2011, EGFR mutation testing practices varied widely across Asia. These data provide a reference platform from which to improve the molecular diagnosis of NSCLC, and EGFR mutation testing in particular, in Asia.

Panel based MALDI-TOF tumour profiling is a sensitive method for detecting mutations in clinical non small cell lung cancer tumour.

BACKGROUND: Analysis of tumour samples for mutations is becoming increasingly important in driving personalised therapy in cancer. As more targeted therapies are developed, options to survey mutations in multiple genes in a single tumour sample will become ever more attractive and are expected to become the mainstay of molecular diagnosis in non-small cell lung cancer (NSCLC) in the future. MATERIALS AND METHODS: 238 non-small cell lung cancer (NSCLC) tumour samples were analysed using a custom panel of 82 mutation assays across 14 oncogenes including KRAS and EGFR using Sequenom iPlex Matrix Assisted Laser Desorption/Ionisation Time of Flight Mass Spectrometry (MALDI-TOF). We compared the data generated for KRAS mutations to those detected by Amplification Refractory Mutation System (ARMS) based DxS TheraScreen K-RAS Mutation Kit. RESULTS: The ARMS detected mutations in 46/238 tumour samples. For samples with mutations detected by both approaches, 99.1% overall agreement was observed. The MALDI-TOF method detected an additional 6 samples as KRAS mutation positive and also provided data on concomitant mutations including PIK3CA and TP53. CONCLUSIONS: The Sequenom MALDI-TOF method provides a sensitive panel-based approach which makes efficient use of patient diagnostic samples. This technology could provide an opportunity to deliver comprehensive screening of relevant biomarkers to the clinic earlier in disease management, without the need for repeat biopsy and allow for additional downstream analysis in NSCLC where available tissue may have been exhausted.

Comparison of the anti-inflammatory effects of Cilomilast, Budesonide and a p38 Mitogen activated protein kinase inhibitor in COPD lung tissue macrophages.

Chronic Obstructive Pulmonary Disease (COPD) is a disease characterized by a largely irreversible airflow obstruction and a persistent, excessive inflammatory response. Alveolar macrophages (AMs) are increased in the lungs of COPD patients, and act as orchestrators of the inflammatory response, releasing a range of mediators to coordinate recruitment and activation of leukocytes. Attempts to treat the inflammatory component of COPD with anti-inflammatory drugs such as steroids has met with limited success. In this study, we compared the ability of the phosphodiesterase IV (PDEIV) inhibitor Cilomilast, the steroid Budesonide, and the p38 mitogen activated protein kinase inhibitor BIRB-796 to inhibit tumour necrosis factor alpha (TNFα) and interleukin 6 (IL-6) releases from AMs isolated from COPD lung transplant tissue. All studies were carried out with appropriate ethical approval and written, informed consent was obtained from each subject. Cilomilast had little effect on cytokine release from AMs. There was considerable variability in the responsiveness of AMs to Budesonide, with a subset of AMs responding poorly to Budesonide. BIRB-796 inhibited TNFα release from all AM donors, including those that responded poorly to steroids. Treatment with BIRB-796 and Budesonide together gave an additive decrease in TNFa release. These results suggest that a p38 inhibitor may provide advantages over existing anti-inflammatory treatments for COPD, either as an add-on to existing therapy, or to treat patients who respond poorly to steroids.

Reference measurement procedures for Alzheimer's disease cerebrospinal fluid biomarkers: definitions and approaches with focus on amyloid ß42.

Cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD) are increasingly used in clinical settings, research and drug trials. However, their broad-scale use on different technology platforms is hampered by the lack of standardization at the level of sample handling, determination of concentrations of analytes and the absence of well-defined performance criteria for in vitro diagnostic or companion diagnostic assays, which influences the apparent concentration of the analytes measured and the subsequent interpretation of the data. There is a need for harmonization of CSF AD biomarker assays that can reliably, across centers, quantitate CSF biomarkers with high analytical precision, selectivity and stability over long time periods. In this position paper, we discuss reference procedures for the measurement of CSF AD biomarkers, especially amyloid ß42 and tau. We describe possible technical approaches, focusing on a selected reaction monitoring mass spectrometry assay as a candidate reference method for quantification of CSF amyloid ß42.

Prostaglandin D2 regulates CD4+ memory T cell trafficking across blood vascular endothelium and primes these cells for clearance across lymphatic endothelium.

Memory lymphocytes support inflammatory and immune responses. To do this, they enter tissue via blood vascular endothelial cells (BVEC) and leave tissue via lymphatic vascular endothelial cells (LVEC). In this study, we describe a hierarchy of signals, including novel regulatory steps, which direct the sequential migration of human T cells across the blood and the lymphatic EC. Cytokine-stimulated (TNF and IFN) human BVEC preferentially recruited memory T cells from purified PBL. Lymphocyte recruitment from flow could be blocked using a function-neutralizing Ab against CXCR3. However, a receptor antagonist directed against the PGD(2) receptor DP2 (formerly chemoattractant receptor-homologous molecule expressed on Th2 cells) inhibited transendothelial migration, demonstrating that the sequential delivery of the chemokine and prostanoid signals was required for efficient lymphocyte recruitment. CD4(+) T cells recruited by BVEC migrated with significantly greater efficiency across a second barrier of human LVEC, an effect reproduced by the addition of exogenous PGD(2) to nonmigrated cells. Migration across BVEC or exogenous PGD(2) modified the function, but not the expression, of CCR7, so that chemotaxis toward CCL21 was significantly enhanced. Thus, chemokines may not regulate all stages of lymphocyte migration during inflammation, and paradigms describing their trafficking may need to account for the role of PGD(2).

Discovery of isoindoline and tetrahydroisoquinoline derivatives as potent, selective PPARδ agonists.

Small molecule isoindoline and tetrahydroisoquinoline derivatives have been identified as selective agonists of human peroxisome proliferator-activated receptor δ (PPARδ. Compound 18 demonstrated efficacy in a biomarker for increased fatty acid oxidation, with upregulation of pyruvate dehydrogenase kinase, isozyme 4 (PDK4) in human primary myotubes.

Synthesis and biological evaluation of N-alkylated 8-oxybenz[c]azepine derivatives as selective PPARδ agonists.

We describe the discovery of small molecule benzazepine derivatives as agonists of human peroxisome proliferator-activated receptor δ (PPARδ) that displayed excellent selectivity over the PPARα and PPARγ subtypes. Compound 8 displayed good PK in the rat and efficacy in upregulation of pyruvate dehydrogenase kinase, isozyme 4 (PDK4) mRNA in human primary myotubes, a biomarker for increased fatty acid oxidation.

Differential gene expression analysis in human monocyte-derived macrophages: impact of cigarette smoke on host defence.

Alveolar macrophages have been implicated in the pathophysiology of chronic obstructive pulmonary disease (COPD). In this setting they are routinely exposed to cigarette smoke and a range of pathogens including bacteria and viruses. The gene expression changes that result from these challenges may contribute to the initiation and progression of the disease. Understanding such changes is therefore of great interest and could aid the discovery of novel therapeutics. To study this, we stimulated monocyte-derived macrophages (MDM) from smokers and non-smokers with either cigarette smoke extract (CSE) or bacterially derived lipopolysaccharide (LPS) and profiled global transcriptional changes using Affymetrix arrays. LPS and CSE stimulation elicited markedly different transcriptome profiles with the former agent producing a larger number of significant changes. The CSE evoked changes showed some overlap with those observed when comparing habitual smokers with non-smokers, although the latter changes were generally of a more subtle nature. Detailed pathway analyses indicated that a number of genes involved in host defence were regulated following CSE stimulation and in MDM from smokers. In particular the interferon gamma (IFNgamma)-signalling pathway was significantly down-regulated following CSE stimulation, a finding that was confirmed by RT-PCR analysis. Furthermore, these changes were associated with suppressed release of the IFNgamma-induced chemokines, CXCL10 and CXCL9 from CSE treated MDM. In summary, our data provides evidence that smoking alters key mechanisms of host defence in macrophages. Such changes may explain the increased susceptibility of COPD patients to the lung infections that are associated with exacerbations of this disease.