Exploring the application value of pro-gastrin-releasing peptide in the clinical diagnosis and surgical treatment of medullary thyroid carcinoma.

OBJECTIVE: To investigate the relationship between pro-gastrin-releasing peptide (ProGRP) and the clinical characteristics of patients with medullary thyroid carcinoma (MTC) and the value of ProGRP in surgical treatment monitoring. PATIENTS AND METHODS: A total of 347 patients with MTC and non-MTC malignant and benign thyroid diseases were enrolled. The concentrations of neuron-specific enolase (NSE), carcinoembryonic antigen (CEA), calcitonin (CT), and ProGRP were determined by Elecsys® assays. The NSE, CEA, CT, and ProGRP levels in different thyroid disease groups were compared, and ProGRP levels in different clinicopathological feature groups pre and postoperatively were further compared. RESULTS: The CT, CEA, NSE, and ProGRP levels were upregulated in the MTC group compared to those in the non-MTC malignant and benign thyroid disease groups. The area under the receiver operating characteristic curve (AUC) of ProGRP for the diagnosis of MTC was 0.832(0.787-0.871), similar to that of CT and CEA. The sensitivity and specificity were 71.4% and 92.7%, respectively, and the optimal cut-off value was 61.8 pg/mL. The AUC of ProGRP combined with CT or CEA for the diagnosis of MTC was 0.933 (0.900-0.958) and 0.922 (0.886-0.949), respectively, which were higher than those of a single index. ProGRP levels were higher in patients with lymph nodes and distant metastases than in patients without metastases. The postoperative level of ProGRP was lower than that before treatment. CONCLUSION: ProGRP is comparable to CEA and CT as an MTC biomarker with broad prospects. It has potential application value in the progression of MTC assessment and the evaluation of surgical intervention effects.

Pro-gastrin-releasing peptide as a marker for the Ewing sarcoma family of tumors.

BACKGROUND: Pro-gastrin-releasing peptide (ProGRP) is an established tumor marker of small cell lung cancer. The purpose of this study was to determine if ProGRP could serve as a tumor marker for the Ewing sarcoma family of tumors (ESFTs). METHODS: Sixteen patients with ESFTs (mean age 32 years) were included in this study. As a control group, 42 patients with other tumor types that clinically or pathologically mimic ESFTs were also analyzed. Pre-treatment serum ProGRP and neuron-specific enolase (NSE) levels, the relationships between these levels, and tumor volume were investigated. In addition, serial changes in the serum or plasma ProGRP (6 patients) and NSE levels (5 patients) were measured over the course of treatment. RESULTS: Pre-treatment serum ProGRP levels were higher than the normal range in 8 of 16 patients; for these eight patients, ProGRP levels positively correlated with tumor volume (R = 0.99). In the control group, ProGRP levels were within the normal range, except for the two patients. Changes in ProGRP levels during treatment were consistent with tumor volume. Serum NSE levels were elevated in 14 of 16 patients with ESFTs and 8 of 42 patients with other tumor types. The range of NSE elevation was much smaller compared to that of ProGRP. Our data indicate that ProGRP is superior to NSE in terms of specificity. CONCLUSIONS: Serum ProGRP levels were elevated in half of the patients with ESFTs and reflected therapeutic response. ProGRP is a reliable tumor marker for the diagnosis of ESFTs and evaluation of treatment response.

The influence of different blood samples treatment methods on pro-gastrin-releasing peptide.

Pro-gastrin-releasing peptide (ProGRP) is the promising molecular tumor marker of small cell lung cancer (SCLC). Here we study the influence of different blood samples treatment methods on ProGRP.Serum with and without separation gel and heparin plasma from 10 SCLC patients and 5 healthy individuals were assayed for ProGRP immediately and 2, 4, 6, 8, 24, and 48 hours after collection.ProGRP of serum with and without separation gel and heparin plasma detected immediately was basically consistent, whereas there was a significant difference in the level of them assayed after 2 hours. No significant variation with time was observed in heparin plasma, but in serum with and without separation gel, ProGRP concentrations gradually declined with time, with statistical significance. When assayed within 2 hours, each time point of ProGRP in heparin plasma had no significant difference and the difference of PrpGRP in serum separating gel existed at 1.5 hours.Heparin plasma is the best option for clinical test of ProGRP. If serum with separation gel is used, optimization methods of turn-around-time which guarantee samples detected within 1 hour after collection can make results more instructive for clinical treatment.

New and old biomarkers in the differential diagnosis of lung cancer: Pro-gastrin-releasing peptide in comparison with neuron-specific enolase, carcinoembryonic antigen, and CYFRA 21-1.

BACKGROUND: Testing for circulating biomarkers in lung cancer is hampered by the insufficient specificity. We aimed to assess the relative diagnostic accuracy of pro-gastrin-releasing peptide (ProGRP) for the differential diagnosis of small cell lung cancer and compare it with more conventional biomarkers. METHODS: We enrolled a cohort of 390 patients with a clinical suspicion of lung cancer and for whom a histologic assessment was available. Serum or plasma samples were assessed for ProGRP, carcinoembryonic antigen, CYFRA 21-2, and neuron-specific enolase. The performance of each biomarker in discriminating the small cell lung cancer and squamous cell carcinoma/adenocarcinoma from non-malignant lung disease, and small cell lung cancer from squamous cell carcinoma/adenocarcinoma, was assayed by receiver operating characteristic curve analysis. RESULTS: At the cut-off levels suggested by the manufacturers, ProGRP and neuron-specific enolase showed an almost identical sensitivity of 55.2% and 55.6%, respectively, in discriminating small cell lung cancer with respect to non-malignant lung disease. In order to quantify the added value of ProGRP to other conventional markers, we ran a multivariable logistic regression analysis, but the results showed that no markers improve the performance of ProGRP. CONCLUSIONS: ProGRP and neuron-specific enolase individually appear more accurate than other conventional biomarkers for small cell lung cancer, but the union of two markers does not increase the accuracy. The very small target group of patients with small cell lung cancer is a limitation of this study, which can explain why ProGRP alone does not show a sensitivity higher than neuron-specific enolase, as reported by other authors.

[Typical Carcinoid of the Lung with Abnormal Elevation of Serum Pro-gastrin-releasing Peptide (ProGRP)].

A 40-year-old male was referred to our hospital because of a nodular shadow detected in the left lower lobe with the tendency to increase gently. Because fluoro-2-deoxy-D-glucose (FDG) uptake was extremely low on a FDG positron emission tomography (PET-CT), the tumor was highly suspected of the benign tumor. Five years later, a follow-up computed tomography (CT) showed the shadow to be enlarged. FDG uptake was changed to be high, and serum level of pro-gastrin-releasing peptide (Pro-GRP) was extremely elevated. Surgical treatment was chosen under suspicious diagnosis of neuroendocrine tumor, such as small cell carcinoma, large cell neuroendocrine carcinoma, and carcinoid. By the intraoperative aspiration cytology, a small cell carcinoma or a carcinoid was suspected and left lower lobectomy with systemic lymph node dissection was performed. The final histological diagnosis was a typical carcinoid. The elevated serum ProGRP immediately decreased to normal postoperatively.

Pro-gastrin-releasing peptide and outcome in patients with heart failure and anaemia: results from the RED-HF study.

AIMS: Neuroendocrine activation is associated with poor outcome in heart failure (HF). The neuropeptide gastrin-releasing peptide (GRP), derived from the precursor proGRP1-125 (proGRP), has recently been implicated in inflammation and wound repair. We investigated the predictive value of proGRP on clinical outcomes in HF patients with reduced ejection fraction. METHODS AND RESULTS: The association between plasma proGRP (time-resolved immunofluorometric assay) and the primary endpoint of death from any cause or first hospitalization for worsening of HF was evaluated using multivariable Cox proportional hazard models in 1541 patients with systolic HF and mild to moderate anaemia, enrolled in the Reduction of Events by Darbepoetin alfa in Heart Failure (RED-HF) trial. Median proGRP levels in the RED-HF cohort were markedly increased [95 ng/L (25th, 75th percentile, 69-129 ng/L)] with 64% patients above the 80 ng/L reference limit. Baseline proGRP correlated with estimated glomerular filtration rate (r = 0.52), N terminal pro brain natriuretic peptide (r = 0.33), troponin T (r = 0.34), and haemoglobin (r = 0.16) (all P < 0.001). The incidence outcome increased with increasing tertiles of baseline proGRP (primary endpoint third tertile vs. the lowest tertile; hazard ratio 1.91; 95% confidence interval 1.60-2.28, P < 0.001). However, these associations were markedly attenuated and non-significant in adjusted models. No interaction between baseline proGRP and the effect of darbepoetin alfa treatment was detected. Moreover, no significant association between changes in proGRP during 6 month follow-up and outcome was observed. CONCLUSIONS: Pro-gastrin-releasing peptide is increased in patients with HF with reduced ejection fraction and anaemia, in particular in patients with poor renal function. However, proGRP adds little as a prognostic marker on top of conventional HF risk factors.

Influence of abiraterone acetate on circulating neuromediators in chemotherapy-naïve castration-resistant prostate cancer.

BACKGROUND: Abiraterone Acetate (AA) represents a highly effective androgen-receptor (AR) axis targeted agent. Treatment with AA in castration-resistant prostate cancer (CRPC) may partly mediate neuroendocrine differentiation (NED) as an escape mechanism, which may have implications for the choice of sequential therapy in CRPC. We evaluated how treatment with AA influences circulating neuromediators chromogranin A (CGA), neuron-specific enolase (NSE), and pro-gastrin-releasing peptide (Pro-GRP) in chemotherapy-naïve CRPC patients. METHODS: We conducted an analysis in chemotherapy-naïve CRPC patients with clinical or radiographic progression of disease. A total of 35 patients were included at five institutions between February 2013 and December 2014. Sixteen of them had received AA. Serum samples were obtained before a docetaxel-based chemotherapy and analyzed in a reference laboratory. Univariable and multivariable analyses were performed to test the influence of AA treatment, its duration of treatment, and other clinicopathological variables on circulating neuromediators. RESULTS: CGA and NSE levels were above the upper limit of normal (ULN) in n = 20 (57.1%) and n = 13 (37.1%), respectively. Treatment with AA and duration of treatment were not associated with levels above the ULN (CGA and NSE) or higher levels (Pro-GRP) of neuromediators. CGA levels were associated with age (P = 0.092), lymph node metastasis (P = 0.014), duration of androgen deprivation therapy (ADT; P = 0.083), and intake of proton pump inhibitors (P = 0.069). Pro-GRP levels were significantly associated with PSA levels (P = 0.002). On multivariate analysis, CGA levels above the ULN were significantly correlated with ADT (P = 0.01) and intake of proton pump inhibitors (P = 0.03). CONCLUSIONS: Circulating neuromediators in chemotherapy-naïve CRPC patients were elevated in a high percentage of patients. ADT was found to be a relevant NED driver in this cohort. Our results may imply that patients with CRPC after first-line treatment with AA in CRPC are not at a higher risk for developing NED. The major limitation of the study represents the one-time analysis of neuromediators. Larger studies with serial blood measurements or biopsy analysis before and after treatment are needed to confirm our results.

Serum pro-gastrin-releasing peptide in diagnosis of small cell lung cancer: A meta-analysis.

OBJECTIVE: The purpose of this study was to assess the diagnostic sensitivity and specificity for serum pro-gastrin-releasing peptide (Pro-GRP) in diagnosis of small cell lung cancer (SCLC) through pooling all the open published data. MATERIALS AND METHODS: Databases of PubMed, Cochrane, ISI Web of Knowledge, and CNKI were electronic, searched by two reviewers to find the diagnostic study serum Pro-GRP in diagnosis of SCLC. The diagnostic sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the receiver operating characteristic (ROC) were calculated by Med DiSc1.4 software. RESULTS: Finally, 21 studies were included in this meta-analysis. Because of statistical heterogeneity, the specificity, specificity, positive/negative likelihood ratio, and DOR were pooled by random effect model. The pooled sensitivity, specificity, PLR, NLR, DOR, and area under the ROC were 64% (95% confidence interval [CI]: 62%-66%), 94% (95% CI: 94%-95%), 11.87% (95% CI: 8.62-11.35), 0.32% (95% CI: 0.26%-0.39%), 40.98% (95% CI: 27.77%-60.64%), and 0.94 (95% CI: 0.91%-0.96%). CONCLUSION: Serum Pro-GRP was promising biomarker for SCLC diagnosis.

Synthesis and characterization of Bombesin-superparamagnetic iron oxide nanoparticles as a targeted contrast agent for imaging of breast cancer using MRI.

The targeted delivery of superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent may facilitate their accumulation in cancer cells and enhance the sensitivity of MR imaging. In this study, SPIONs coated with dextran (DSPIONs) were conjugated with bombesin (BBN) to produce a targeting contrast agent for detection of breast cancer using MRI. X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer analyses indicated the formation of dextran-coated superparamagnetic iron oxide nanoparticles with an average size of 6.0 ± 0.5 nm. Fourier transform infrared spectroscopy confirmed the conjugation of the BBN with the DSPIONs. A stability study proved the high optical stability of DSPION-BBN in human blood serum. DSPION-BBN biocompatibility was confirmed by cytotoxicity evaluation. A binding study showed the targeting ability of DSPION-BBN to bind to T47D breast cancer cells overexpressing gastrin-releasing peptide (GRP) receptors. T2-weighted and T2*-weighted color map MR images were acquired. The MRI study indicated that the DSPION-BBN possessed good diagnostic ability as a GRP-specific contrast agent, with appropriate signal reduction in T2*-weighted color map MR images in mice with breast tumors.

The prognostic significance of the circulating neuroendocrine markers chromogranin A, pro-gastrin-releasing peptide, and neuron-specific enolase in patients with small-cell lung cancer.

Lung cancer is the most common cancer, and small-cell lung cancer (SCLC) accounts for around 20 % of lung cancers. SCLC has a neuroendocrine cellular origin, and the tumor cells usually express neuroendocrine markers. There have been major recent advances in the management of SCLC, and multimodal approaches are now the norm. An improved knowledge of the prognostic variables would assist in defining which patients were better candidates to receive these newer intensive therapies. This single-center retrospective study of 97 previously untreated and histologically proven SCLC patients analysed the circulating neuroendocrine markers chromogranin A (CGA), pro-gastrin-releasing peptide (ProGRP), and neuron-specific enolase (NSE) in addition to the other more classical variables. Fifty patients had limited-stage disease and 47 had extensive disease. Sixty patients had an ECOG performance status (PS) of 0-1 and 37 had PS 2-4. Median survival for the whole study population was 13 months. Univariate analysis and univariate Cox regression modeling found a statistically significant association between survival and PS, disease stage, and CGA, ProGRP, and NSE levels. Age and sex were not prognostic. A shorter survival time was found in patients with a PS equal to or >2, extensive stage disease, a serum CGA level >56 ng/ml, a serum ProGRP level >58 pg/ml, and a serum NSE level >19 ng/ml. This study has found that there is a potential role for ProGRP, NSE, and CGA in both staging and prognosing survival in SCLC patients.

Gastrin-releasing peptide receptor antagonism induces protection from lethal sepsis: involvement of toll-like receptor 4 signaling.

In sepsis, toll-like receptor (TLR)-4 modulates the migration of neutrophils to infectious foci, favoring bacteremia and mortality. In experimental sepsis, organ dysfunction and cytokines released by activated macrophages can be reduced by gastrin-releasing peptide (GRP) receptor (GRPR) antagonist RC-3095. Here we report a link between GRPR and TLR-4 in experimental models and in sepsis patients. RAW 264.7 culture cells were exposed to lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-α and RC-3095 (10 ng/mL). Male Wistar rats were subjected to cecal ligation and puncture (CLP), and RC-3095 was administered (3 mg/kg, subcutaneously); after 6 h, we removed the blood, bronchoalveolar lavage, peritoneal lavage and lung. Human patients with a clinical diagnosis of sepsis received a continuous infusion with RC-3095 (3 mg/kg, intravenous) over a period of 12 h, and plasma was collected before and after RC-3095 administration and, in a different set of patients with systemic inflammatory response syndrome (SIRS) or sepsis, GRP plasma levels were determined. RC-3095 inhibited TLR-4, extracellular-signal-related kinase (ERK)-1/2, Jun NH(2)-terminal kinase (JNK) and Akt and decreased activation of activator protein 1 (AP-1), nuclear factor (NF)-κB and interleukin (IL)-6 in macrophages stimulated by LPS. It also decreased IL-6 release from macrophages stimulated by TNF-α. RC-3095 treatment in CLP rats decreased lung TLR-4, reduced the migration of cells to the lung and reduced systemic cytokines and bacterial dissemination. Patients with sepsis and systemic inflammatory response syndrome have elevated plasma levels of GRP, which associates with clinical outcome in the sepsis patients. These findings highlight the role of GRPR signaling in sepsis outcome and the beneficial action of GRPR antagonists in controlling the inflammatory response in sepsis through a mechanism involving at least inhibition of TLR-4 signaling.

An elevated progastrin-releasing peptide level in patients with well-differentiated neuroendocrine tumours indicates a primary tumour in the lung and predicts a shorter survival.

BACKGROUND: Progastrin-releasing peptide (proGRP) is a recently identified biomarker of small-cell lung cancer. In well-differentiated neuroendocrine tumours (WDNETs), this study investigates the association between proGRP and tumour characteristics and the prognostic value of proGRP levels compared with chromogranin A (CgA) levels. PATIENTS AND METHODS: Serum samples were obtained in 282 patients with WDNET. The receiver operating characteristic (ROC) curve technique was used to assess specificity and sensitivity in the identification of a primary tumour location. Cox proportional hazards models and Kaplan-Meier curves were constructed to determine the association of patients' characteristics and tumour markers with survival. RESULTS: For proGRP, the ROC curve indicated a cut-off level of 90 ng/l (approximately twice the upper reference value), with a specificity of 99% and a sensitivity of 43% in distinguishing primary pulmonary tumours from other sites. In the multivariate Cox model, both proGRP and CgA were strongly associated with survival (P < 0.0001 for both variables). CONCLUSIONS: A high-risk proGRP level (more than twice the upper reference value) in patients with WDNETs is a strong indication for a primary tumour in the lung. Besides CgA, proGRP is a complementary tumour marker for prognosis and treatment monitoring in patients with neuroendocrine tumour.

Gastrin-releasing peptide: predictor of castration-resistant prostate cancer?

BACKGROUND: Neuroendocrine (NE) cells of the prostate are known to be androgen-independent and NE peptides like gastrin-releasing peptide (GRP) or neuron-specific enolase (NSE) can stimulate growth in a paracrine manner, and this is thought to be one of the escape mechanisms in castration-resistant prostate cancer (CRPCa). In a longitudinal study, we investigated the development of the NE serum factors GRP, NSE, and chromogranin A and their correlation with prostate-specific androgen (PSA) during hormonal treatment. MATERIALS AND METHODS: Thirty two patients, with histology-proven, localized or metastatic prostatic carcinoma (PCa), who were undergoing therapy with LHRH analogue or a combination of LHRH analog and peripheral androgen blockade, took part in the study. In addition, eight healthy volunteers were each tested twice for serum GRP to elicit a "physiological" standard value. Blood samples were taken periodically from each patient within an 18-month time frame. RESULTS: We defined the standard value for GRP in the healthy participants as 0.852 ng/ml (mean + 2 SD) and observed that the GRP values for patients with PCa were significantly higher (P = 0.034). There was a positive correlation between PSA and GRP in patients with biochemical failure. CgA correlated with PSA development in the CRPCa patients. NSE values rose steadily over the study period, but with no correlation to PSA. CONCLUSION: Our data confirm that NE factors are elevated during hormonal treatment of prostate cancer. GRP is higher in PCa patients undergoing androgen deprivation therapy and is possibly involved in the initiation of hormonal escape in PCa.

Reduction in serum levels of substance P in patients with rheumatoid arthritis by etanercept, a tumor necrosis factor inhibitor.

We determined the effects of etanercept on the serum concentrations of neuropeptides in RA patients. In a total of 11 patients who had been injected with etanercept, the serum levels of substance P, calcitonin gene-related peptide (CGRP), and gastrin-releasing peptide (GRP) were analyzed. Average levels of serum substance P were significantly reduced from 1.53 to 0.62 ng/ml after the injection of etanercept. In the CGRP and GRP analyses, these average levels dropped from 1.57 and 0.51 ng/ml to 0.44 and 0.04 ng/ml, respectively. Etanercept appears to decrease substance P levels with an improvement in disease activities.

[The value of plasma pro-gastrin-releasing peptide, cytokeratin 19-fragments and carcinoembryonic antigen in patients with lung cancer].

OBJECTIVE: To evaluate the value of plasma ProGRP, CYFRA 21-1 and CEA in patients with lung cancer. METHODS: The levels of plasma ProGRP, CYFRA 21-1 and CEA were detected in 85 healthy control, 49 benign lung diseases and 143 lung neoplasms. The levels of ProGRP in the patients with SCLC was monitored. RESULTS: The level of plasma ProGRP in SCLC (M 179.1 ng/ml) was significantly higher than adenocarcinoma (M 35.3 ng/ml), squamous-cell carcinoma (M 33.3 ng/ml), healthy control (M 35.6 ng/m) and benign lung diseases (M 33.3 ng/m), P < 0.001. The sensitivity and specificity for diagnosing SCLC by ProGRP were 60.6% and 95.0% respectively. In the effective treatment group, ProGRP reduced 45.9%, in the progression group, ProGRP increased 103.1%, P < 0.05. The level of CEA in the metastatic adenocarcinoma (M 10.22 ng/ml) was significantly higher than non-metastatic adenocarcinoma (M 3.85 ng/ml) and squamous cell carcinoma (M 2.56 ng/ml) (P < 0.01). CONCLUSION: The plasma ProGRP is a good indicator for diagnosing and evaluating cure effect in SCLC; the high expression of CEA is related to the metastatic adenocarcinoma.

IL-6 and VEGF in small cell lung cancer patients.

Recent data suggest a link between chronic inflammation, angiogenesis, and the development of cancer. The aim of this study was the evaluation of serum IL-6 and VEGF in comparison with the tumor markers NSE and ProGRP, with respect to the prognosis of small cell lung cancer patients. The study of IL-6, VEGF, NSE, ProGRP and platelet count was performed in a group of 72 patients with previously untreated small cell lung cancer at different stages of disease: 40 with limited and 32 with extensive disease. Significantly higher IL-6 and VEGF concentrations and platelet count, as well as NSE and ProGRP levels, were found in patients with small cell lung cancer in comparison with the reference group. Patients with extensive cancer had significantly higher levels of IL-6, VEGF, NSE and ProGRP than those with limited cancer. Elevated VEGF levels, with no significant differences in frequency of elevated NSE and ProGRP concentrations, were often observed in patients with IL-6 levels higher than 5.1 ng/l. Univariate analysis confirmed a significant relationship not only between overall survival and stage of disease or gender, but also with VEGF, IL-6, NSE and ProGRP levels. Moreover, multivariate analysis revealed that only the extent of the disease and IL-6 may be independent prognostic factors in the group of small cell lung cancer patients under investigation. However, simultaneous determinations of ProGRP and IL-6, as well as ProGRP and VEGF, in addition to the extent of the disease, may serve as additional, independent prognostic factors in small cell lung cancer.

Automated time-resolved immunofluorometric assay for progastrin-releasing peptide.

BACKGROUND: Small cell lung cancer accounts for approximately 20% of new cases of lung cancer, and advanced disease is prevalent at the time of diagnosis. Neuron-specific enolase (NSE) has been the primary tumor marker in small cell lung cancer but it has relatively low sensitivity in early-stage disease. Progastrin-releasing peptide (proGRP) is a promising alternative or complementary marker for NSE. We have previously described a time-resolved immunofluorometric assay (TR-IFMA) for proGRP that lacked the necessary sensitivity and robustness for use in the routine clinical laboratory. Herein we describe the development of an improved assay using a novel monoclonal antibody pair. METHODS: Mice were immunized with different conjugated proGRP peptides, including residues 31-98, 1-98, and preproGRP(-23-125). Pair combinations of the resulting monoclonal antibodies (mAb) were tested. The improved TR-IFMA was compared with the only other available proGRP assay, the proGRP ELISA (IBL). RESULTS: A panel of 12 high-affinity mAbs was produced. The best assay combination was between our original E146 mAb as solid-phase antibody and the new mAb M16 as tracer. The new TR-IFMA had a linear dose-response curve, a wide dynamic range (13-13 500 ng/L), and a limit of detection of 2.8 ng/L. Total CV was <5.6% over the whole measuring range. Bland-Altman difference analysis indicated a significant positive bias between the IFMA and the ELISA. CONCLUSIONS: We describe a sensitive and robust mAb-based TR-IFMA for proGRP. The assay is fully automated and displays high quality performance.

Targeted determination of the early stage SCLC specific biomarker pro-gastrin-releasing peptide (ProGRP) at clinical concentration levels in human serum using LC-MS.

Pro-gastrin-releasing peptide (ProGRP) is used as a specific diagnostic marker for small cell lung cancer (SCLC), a rapidly growing neoplasm with high mortality. Our object was to develop an LC-MS method for the detection and quantification of ProGRP in human serum using the specific tryptic digestion product NLLGLIEAK (m/z 485.8 for [M + 2H](2+)). For this purpose the sample pretreatment, clean-up, enrichment, and LC-MS conditions were evaluated. Sample pretreatment was carried out using ACN precipitation to decrease the sample complexity. Although ProGRP (31-98) standards were soluble in 99% ACN, it showed that optimal signal intensities were obtained by adding ACN to the serum in a 1:1 ratio v/v. A simplified tryptic digest protocol was carried out using 100 mM triethanolamine buffer to ensure pH stability during the whole procedure. The simplified protocol also includes omission of reducing and alkylating reagents. Necessary additional sample clean-up was achieved by trapping NLLGLIEAK on a RAM column (ADS-C8) which was back-flushed onto the analytical BioBasic C8 column. Volume of injection, sample enrichment, and column capacity are among the factors optimized to reach a mass LOD of 150 pg on column (OC) ProGRP (31-98). Detection of ProGRP in the serum sample of a patient suffering from SCLC with a clinically relevant concentration shows the potential of the method in diagnosis, prognosis, and monitoring of the disease.