Establishment and Characterization of 7 New Monoclonal Antibodies to Tissue Inhibitor of Metalloproteinases-1

TIMP-1 is under regulation of the EGF signaling axis and promotes an aggressive phenotype in KRAS-mutated colorectal cancer cells: a potential novel approach to the treatment of metastatic colorectal cancer

It is now widely accepted that therapeutic antibodies targeting epidermal growth factor receptor (EGFR) can have efficacy in KRAS wild-type advanced colorectal cancer (CRC) patients. What remains to be ascertained is whether a subgroup of KRAS-mutated CRC patients might not also derive benefit from EGFR inhibitors. Metalloproteinase inhibitor 1 (TIMP-1) is a pleiotropic factor predictive of survival outcome of CRC patients. Levels of TIMP-1 were measured in pre-treatment plasma samples (n = 426) of metastatic CRC patients randomized to Nordic FLOX (5-fluorouracil and oxaliplatin) +/− cetuximab (NORDIC VII study). Multivariate analysis demonstrated a significant interaction between plasma TIMP-1 protein levels, KRAS status and treatment with patients bearing KRAS mutated tumors and high TIMP-1 plasma level (> 3rd quartile) showing a significantly longer overall survival if treated with cetuximab (HR, 0.48; 95% CI, 0.25 to 0.93). To gain mechanistic insights into this association we analyzed a set of five different CRC cell lines. We show here that EGFR signaling induces TIMP-1 expression in CRC cells, and that TIMP-1 promotes a more aggressive behavior, specifically in KRAS mutated cells. The two sets of data, clinical and in vitro, are complementary and support each other, lending strength to our contention that TIMP- 1 plasma levels can identify a subset of patients with KRAS-mutated metastatic CRC that will have benefit from EGFR-inhibition therapy.

Tissue Inhibitor of Metalloproteinase-1 Is Confined to Tumor-Associated Myofibroblasts and Is Increased With Progression in Gastric Adenocarcinoma

The tissue inhibitor of metalloproteinase-1 (TIMP-1) inhibits the extracellular matrix-degrading activity of several matrix metalloproteinases, thereby regulating cancer cell invasion and metastasis. Studies describing the expression pattern and cellular localization of TIMP-1 in gastric cancer are, however, highly discordant. We addressed these inconsistencies by performing immunohistochemistry and in situ hybridization analyses in a set of 49 gastric cancer lesions to reexamine the TIMP-1 localization. In addition, we correlated these findings to clinicopathological parameters. We show that strong expression of TIMP-1 protein and mRNA was observed in a subpopulation of stromal fibroblast-like cells at the periphery of the cancer lesions. In a few cases, a small fraction of cancer cells showed weak expression of TIMP-1 protein and mRNA. The stromal TIMP-1-expressing cells were mainly tumor-associated myofibroblasts. In the normal-appearing mucosa, scattered TIMP-1 protein was only found in chromogranin A positive cells. TIMP-1-positive myofibroblasts at the invasive front of the tumors were more frequently seen in intestinal than in diffuse histological subtype cases (p=0.009). A significant trend to a higher number of cases showing TIMP-1 staining in myofibroblasts with increasing tumor, node, metastasis (TNM) stage was also revealed (p=0.041). In conclusion, tumor-associated myofibroblasts are the main source of increased TIMP-1 expression in gastric cancer.

Purification and characterization of bioactive his6-tagged recombinant human tissue inhibitor of metalloproteinases-1 (TIMP-1) protein expressed at high yields in mammalian cells

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is an endogenous inhibitor of matrix metalloproteinases (MMPs) with reported tumor promoting, as well as inhibitory, effects. These paradoxical properties are presumably mediated by different biological functions, MMP-dependent as well as -independent, and probably related to TIMP-1 levels of protein expression, post-translational modifications, and cellular localization. TIMP-1 is an N-glycosylated protein that folds into two functional domains, a C- and an N-terminal domain, with six disulfide bonds. Furthermore, TIMP-1 is processed in the N-terminal sequence. These three biochemical properties make TIMP-1 difficult to produce in conventional bacterial, insect, or yeast expression systems. We describe here a HEK293 cell-based strategy for production and purification of secreted and N-glycosylated recombinant his6-tagged human TIMP-1 (his6-rTIMP-1), which resulted in large amounts of highly purified and bioactive protein. Matrix-assisted laser desorption ionization mass spectrometry confirmed the N- and C-termini of his6-rTIMP-1, and N-glycosylation profiling showed a match to the N-glycosylation of human plasma TIMP-1. The his6-rTIMP-1 was bioactive as shown by its proper inhibitory effect on MMP-2 activity, and its stimulatory effect on cell growth when added to the growth medium of four different breast cancer cell lines. This study provides an easy set-up for large scale production and purification of bioactive, tagged recombinant human TIMP-1, which structurally and functionally is similar to endogenous human TIMP-1, while using an expression system that is adaptable to most biochemical and biomedical laboratories including those that do not perform protein purifications routinely.

TIMP-1 and responsiveness to gemcitabine in advanced breast cancer; results from a randomized phase III trial from the Danish breast cancer cooperative group

Background

Tissue inhibitor of metalloproteinases-1 (TIMP-1) has anti-apoptotic functions, which may protect TIMP-1 positive cancer cells from the effects of chemotherapy such as docetaxel and gemcitabine. The purpose of the present study was to evaluate TIMP-1 immunoreactivity as a prognostic and predictive marker in advanced breast cancer patients receiving docetaxel (D) or gemcitabine plus docetaxel (GD).

Methods

Patients with locally advanced or metastatic breast cancer who were assigned to D or GD by participation in a randomized phase III trial were included in the study. Assessment of TIMP-1 status was performed retrospectively on primary tumor whole-tissue sections by immunohistochemistry and tumor samples were considered positive if epithelial breast cancer cells were stained by the anti-TIMP-1 monoclonal antibody VT7. Time to progression (TTP) was the primary endpoint. Overall survival (OS) and response rate (RR) were secondary endpoints. Associations between TIMP-1 status and outcome after chemotherapy were analyzed by Kaplan-Meier estimates and Cox proportional hazards regression models.

Results

TIMP-1 status was available from 264 of 337 patients and 210 (80%) of the tumors were classified as cancer cell TIMP-1 positive. No significant difference for TTP between TIMP-1 positive versus TIMP-1 negative patients was observed in multivariate analysis, and RR did not differ according to TIMP-1 status. However, patients with TIMP-1 positive tumors had a significant reduction in OS events (hazard ratio = 0.71, 95% confidence interval (CI) = 0.52-0.98, P = 0.03). Additionally, a borderline significant interaction for OS was observed between TIMP-1 status and benefit from GD compared to D (P_interaction = 0.06) such that median OS increased by nine months for TIMP-1 negative patients receiving GD.

Conclusions

TIMP-1 status was an independent prognostic factor for OS but not TTP in patients with advanced breast cancer receiving either D or GD. There was no statistically significant interaction between TIMP-1 status and treatment, but a trend towards an incremental OS from the addition of gemcitabine to docetaxel in patients with TIMP-1 negative tumors suggests further investigation.

TIMP-1 increases expression and phosphorylation of proteins associated with drug resistance in breast cancer cells

Tissue inhibitor of metalloproteinase 1 (TIMP-1) is a protein with a potential biological role in drug resistance. To elucidate the unknown molecular mechanisms underlying the association between high TIMP-1 levels and increased chemotherapy resistance, we employed SILAC-based quantitative mass spectrometry to analyze global proteome and phosphoproteome differences of MCF-7 breast cancer cells expressing high or low levels of TIMP-1. In TIMP-1 high expressing cells, 312 proteins and 452 phosphorylation sites were up-regulated. Among these were the cancer drug targets topoisomerase 1, 2A, and 2B, which may explain the resistance phenotype to topoisomerase inhibitors that was observed in cells with high TIMP-1 levels. Pathway analysis showed an enrichment of proteins from functional categories such as apoptosis, cell cycle, DNA repair, transcription factors, drug targets and proteins associated with drug resistance or sensitivity, and drug transportation. The NetworKIN algorithm predicted the protein kinases CK2a, CDK1, PLK1, and ATM as likely candidates involved in the hyperphosphorylation of the topoisomerases. Up-regulation of protein and/or phosphorylation levels of topoisomerases in TIMP-1 high expressing cells may be part of the mechanisms by which TIMP-1 confers resistance to treatment with the widely used topoisomerase inhibitors in breast and colorectal cancer.

Is TIMP-1 immunoreactivity alone or in combination with other markers a predictor of benefit from anthracyclines in the BR9601 adjuvant breast cancer chemotherapy trial?

Introduction

Predictive cancer biomarkers to guide the right treatment to the right patient at the right time are strongly needed. The purpose of the present study was to validate prior results that tissue inhibitor of metalloproteinase 1 (TIMP-1) alone or in combination with either HER2 or TOP2A copy number can be used to predict benefit from epirubicin (E) containing chemotherapy compared with cyclophosphamide, methotrexate and fluorouracil (CMF) treatment.

Methods

For the purpose of this study, formalin fixed paraffin embedded tumor tissue from women recruited into the BR9601 clinical trial, which randomized patients to E-CMF versus CMF, were analyzed for TIMP-1 immunoreactivity. Using previously collected data for HER2 amplification and TOP2A gene aberrations, we defined patients as "anthracycline non-responsive", that is, 2T (TIMP-1 immunoreactive and TOP2A normal) and HT (TIMP-1 immunoreactive and HER2 negative) and anthracycline responsive (all other cases).

Results

In total, 288 tumors were available for TIMP-1 analysis with (183/274) 66.8%, and (181/274) 66.0% being classed as 2T and HT responsive, respectively. TIMP-1 was neither associated with patient prognosis (relapse free survival or overall survival) nor with a differential effect of E-CMF and CMF. Also, TIMP-1 did not add to the predictive value of HER2, TOP2A gene aberrations, or to Ki67 immunoreactivity.

Conclusion

This study could not confirm the predictive value of TIMP-1 immunoreactivity in patients randomized to receive E-CMF versus CMF as adjuvant treatment for primary breast cancer.

Salivary tissue inhibitor of metalloproteinases-1 localization and glycosylation profile analysis

Salivary tissue inhibitor of metalloproteinases-1 (TIMP-1) has been associated with pathological conditions in the oral cavity, but the origin of TIMP-1 in saliva remains unknown. Hence, we studied the localization of TIMP-1 in salivary gland tissue and also investigated if TIMP-1 found in blood and saliva is identical. Human salivary gland tissue samples (four parotid gland and four submandibular gland biopsies) were analysed for the presence of TIMP-1 mRNA and protein expression. To assess TIMP-1 glycosylation profiles in blood and saliva, the protein was isolated from plasma and unstimulated and stimulated whole saliva as well as stimulated parotid and submandibular saliva and analysed by MALDI-TOF mass spectrometry. TIMP-1 protein was demonstrated in mucous acinar cells of the submandibular gland and in ductal cells of both the parotid and submandibular gland. However, no TIMP-1 mRNA was detected in any of these cells. The glycosylation profiles of TIMP-1 isolated from whole saliva and saliva from the major glands were highly similar. In contrast, a significant difference was found between the glycoprofiles of salivary TIMP-1 and plasma TIMP-1. Although no clear evidence of TIMP-1 transcription in major salivary glands was demonstrated our results suggest that TIMP-1 in saliva does not originate from plasma.

Lack of TIMP-1 tumour cell immunoreactivity predicts effect of adjuvant anthracycline-based chemotherapy in patients (n=647) with primary breast cancer. A Danish Breast Cancer Cooperative Group Study

PURPOSE

A number of prospective studies have shown that adjuvant CEF significantly improves disease-free and overall survival as compared to CMF in breast cancer patients. Our aim was to determine whether the benefit of epirubicin versus methotrexate differs according to TIMP-1 tumour cell immunoreactivity.

EXPERIMENTAL DESIGN

Tissue micro arrays from 647 patients randomly assigned to CMF or CEF in DBCG trial 89D were included. The primary end-point was invasive disease-free survival (IDFS). A central assessment of tissue inhibitor of metalloproteinases 1 (TIMP-1) status was performed using immunohistochemistry (IHC). Tumours were regarded as TIMP-1 positive if epithelial breast cancer cells were stained using the anti-TIMP-1 monoclonal antibody VT7.

RESULTS

By central assessment 75% of tumours were classified as tumour cell TIMP-1 positive. Among CEF-treated patients, individuals with TIMP-1 negative tumours had a significant longer IDFS than patients with TIMP-1 positive tumours (p=0.047). The multivariate Cox regression analysis of IDFS showed that CEF was superior to CMF among patients with TIMP-1 negative tumours (hazard ratio (HR)=0.51; 95% confidence interval (CI): 0.31-0.84, p=0.0085), while no significant difference could be demonstrated among patients with TIMP-1 positive tumours (HR=0.88; 95% CI: 0.68-1.13, p=0.32). A non-significant TIMP-1 status (positive or negative) versus treatment (CMF or CEF) interaction was detected for IDFS (p=0.06) and OS (p=0.21).

CONCLUSION

Lack of TIMP-1 tumour cell immunoreactivity seems to predict a favourable effect of epirubicin-containing adjuvant therapy in primary breast cancer. However, an independent study is awaited to validate the potential predictive value of TIMP-1 immunoreactivity.

Low expression of tissue inhibitor of metalloproteinases-1 (TIMP-1) in glioblastoma predicts longer patient survival

In colorectal cancer and breast cancer a high TIMP-1 level has been shown to correlate with a shorter overall patient survival and it has been suggested that TIMP-1 is involved in tumour invasion, proliferation and apoptosis in different types of cancers. TIMP-1 is known to be expressed in gliomas but whether TIMP-1 is a prognostic marker in gliomas has not previously been investigated. In the present study, the TIMP-1 expression was investigated immunohistochemically in 112 formalin-fixed paraffin embedded astrocytomas and related to tumour grade and overall patient survival by scoring the TIMP-1 immunoreactivity of both tumour cells and blood vessels. Moreover, TIMP-1 in situ hybridisation was performed on ten of the glioblastomas. In the vast majority of the tumours TIMP-1 protein was expressed in both tumour cells and blood vessels. In situ hybridisation for TIMP-1 mRNA on glioblastomas confirmed the immunohistochemical expression of TIMP-1. The percentage of TIMP-1 positive tumour cells and blood vessels as well as the staining intensity varied between tumours of the same grade, but the total staining score increased with tumour grade. The multivariate Cox regression test showed that glioblastoma patients with the lowest TIMP-1 expression had a significantly longer overall survival (HR (95% CI) = 3.2 (1.5-6.7), P = 0.004) when compared to the patients with higher TIMP-1 protein expression. In conclusion, this study showed that low TIMP-1 immunohistochemical expression predicts longer overall survival in glioblastoma patients, suggesting a role for TIMP-1 as a biomarker in glioblastoma.

Biology and potential clinical implications of tissue inhibitor of metalloproteinases-1 in colorectal cancer treatment

Colorectal cancer (CRC) is the second leading cause of cancer-related death in the industrialized world. About half of "curatively" resected patients develop recurrent disease within the next 3-5 years despite the lack of clinical, histological and biochemical evidence of remaining overt disease after resection of the primary tumour. Availability of validated biological markers for early detection, selection for adjuvant therapy, prediction of treatment efficacy and monitoring of treatment efficacy would most probably increase survival. Tissue inhibitor of metalloproteinases-1 (TIMP-1) may be such a marker. TIMP-1 inhibits the proteolytic activity of metalloproteinases, which are centrally involved in tumour invasion and metastases. However, in clinical investigations high tumour tissue or plasma levels of TIMP-1 have shown a strong and independent association with a shorter survival time in CRC patients, suggesting that TIMP-1 could have a tumour-promoting function. Furthermore, measurement of plasma TIMP-1 has been shown to be useful for disease detection, with a high sensitivity and high specificity for early-stage colon cancer. This review describes some basic information on the current knowledge of the biology of TIMP-1 as well as the potential use of TIMP-1 as a biological marker in the management of CRC patients.

Comparative studies of tissue inhibitor of metalloproteinases-1 in plasma, serum and tumour tissue extracts from patients with primary colorectal cancer

OBJECTIVE

We have recently shown that preoperative plasma tissue inhibitor of metalloproteinases-1 (TIMP-1) levels are significantly associated with prognosis of colorectal cancer patients. In addition, we have shown that measurement of plasma TIMP-1 yields information on specificity and sensitivity, which could be used for early detection of colorectal cancer. However, it is not clear whether the increased plasma TIMP-1 levels in colorectal cancer patients are derived from the tumour tissue itself in which it is mainly expressed by the stromal cells located in the vicinity of the cancer cells. The purpose of this study was to examine the association between blood TIMP-1 levels and tumour tissue TIMP-1 levels in colorectal cancer patients.

MATERIAL AND METHODS

Preoperative EDTA plasma, citrate plasma and serum, as well as tumour tissue extracts from 49 colorectal cancer patients were measured with a TIMP-1 ELISA that measures total TIMP-1 levels (non-complexed and complexed TIMP-1).

RESULTS

The median TIMP-1 level in the 49 tumour extracts was 18.7 ng/mg proteins (range 3.5-152.0 ng/mg protein). The median TIMP-1 value was 133.5 ng/ml (range 58.1-559.0 ng/ml) in EDTA plasma, 130.2 ng/ml (range 57.0-572.0 ng/ml) in citrate plasma and 207.2 ng/ml (range 72.6-828.0 ng/ml) in serum. No significant correlations were found between TIMP-1 content in the tumour extracts and in blood.However, EDTA and citrate plasma TIMP-1 levels (r=0.75; p <0.0001) as well as EDTA plasma and serum TIMP-1 levels (r= .064; p<0.0001) were highly correlated.

CONCLUSIONS

The lack of correlation between tumour tissue TIMP-1 and blood levels of TIMP-1 suggests that other sources than the tumour tissue itself may contribute to the increased levels of plasma TIMP-1 in patients with colorectal cancer. However, degradation of cell membranes, rapid secretion into the blood stream and other factors may be responsible for the observed lack of association between TIMP-1 concentrations in blood and tumour tissue extracts.

A TIMP-1 splice variant transcript: possible role in regulation of TIMP-1 expression

A splice variant of tissue inhibitor of metalloproteinases-1 (TIMP-1) mRNA lacking exon 2 (TIMP-1-v2) has been identified in human cancer cells and in colorectal and breast cancer tumors. The purpose of this study was (1) to study the level of full length TIMP-1 and TIMP-1-v2 transcripts in colorectal tumors; (2) to investigate if TIMP-1-v2 is translated to protein. Full length TIMP-1 and TIMP-1-v2 mRNA levels were compared between colorectal tumors and normal mucosa by Q-PCR. Both full length TIMP-1 and TIMP-1-v2 transcripts were upregulated in tumor tissue. However, the level of TIMP-1-v2 relative to full length TIMP-1 was higher in normal compared to tumor tissue. Translation of TIMP-1-v2 to protein was analyzed in CHO cells. In this system, no TIMP-1-v2 protein was produced. Thus, the variant transcript seems to be an untranslated mRNA. These findings suggest that alternative splicing of TIMP-1 pre-mRNA to TIMP-1-v2 mRNA might be involved in regulating TIMP-1 expression.

Identification of alternatively spliced TIMP-1 mRNA in cancer cell lines and colon cancer tissue

TIMP-1 is a promising new candidate as a prognostic marker in colorectal and breast cancer. We now describe the discovery of two alternatively spliced variants of TIMP-1 mRNA. The two variants lacking exon 2 (del-2) and 5 (del-5), respectively, were identified in human cancer cell lines by RT-PCR. The del-2 variant was, furthermore, detected in extracts from 12 colorectal cancer tissue samples. By western blotting additional bands of lower molecular mass than full-length TIMP-1 were identified in tumor tissue, but not in plasma samples obtained from cancer patients. The two splice variants of TIMP-1 may hold important clinical information, and either alone or in combination with measurement of full-length TIMP-1 they may improve the prognostic and/or predictive value of TIMP-1 analyses.

Rapid and individual-specific glycoprofiling of the low abundance N-glycosylated protein tissue inhibitor of metalloproteinases-1

A gel-based method for a mass spectrometric site-specific glycoanalysis was developed using a recombinant glycoprotein expressed in two different cell lines. Hydrophilic interaction liquid chromatography at nanoscale level was used to enrich for glycopeptides prior to MS. The glycoprofiling was performed using matrix-assisted laser desorption/ionization MS and MS/MS. The method proved to be fast and sensitive and furthermore yielded a comprehensive site-specific glycan analysis, allowing a differentiation of the glycoprofiles of the two sources of recombinant protein, both comprising N-glycans of a highly heterogeneous nature. To test the potential of the method, tissue inhibitor of metalloproteinases-1 (TIMP-1), a secreted low abundance N-glycosylated protein and a cancer marker, was purified in an individual-specific manner from plasma of five healthy individuals using IgG depletion and immunoaffinity chromatography. The corresponding TIMP-1 glycoprofiles were determined to be highly similar, comprising mainly bi- and triantennary complex oligosaccharides. Additionally it was shown that platelet-derived TIMP-1 displayed a similar glycoprofile. This is the first study to investigate the glycosylation of naturally occurring human TIMP-1, and the high similarity of the glycoprofiles showed that individual-specific glycosylation variations of TIMP-1 are minimal. In addition, the results showed that TIMP-1 derived from platelets and plasma is similarly glycosylated. This comprehensive and rapid glycoprofiling of a low abundance glycoprotein performed in an individual-specific manner allows for future studies of glycosylated biomarkers for person-specific detection of altered glycosylation and may thus allow early detection and monitoring of diseases.

Evaluation of an improved tissue inhibitor of metalloproteinase 1 dual monoclonal sandwich immunoassay

BACKGROUND

It has previously been shown that increased levels of plasma tissue inhibitor of metalloproteinase 1 (TIMP-1) is associated with shorter survival for patients with colorectal cancer (CRC). Furthermore, plasma TIMP-1 levels have been found to be elevated in patients with early-stage CRC.

OBJECTIVE

It was the aim of this study to develop a new dual monoclonal antibody (mAb) sandwich immunoassay for TIMP-1 in order to achieve better resolution of non-cancer and cancer plasma specimens.

METHODS

Chemiluminescence immunoassay techniques were used to screen 240 combinations of TIMP-1 mAbs for their ability to interact with each other and to allow for further characterization of the sandwiching antibody pairs. Five mAb pair combinations were selected for assessment of their ability to resolve non-cancerous and cancerous plasma specimens by TIMP-1 measurement. Based on this testing, a final assay format was chosen for further validation. The results for the final assay were compared with measurements obtained in a TIMP-1 ELISA that had previously demonstrated the ability to resolve healthy blood donors and CRC specimens.

RESULTS

The clinical results support that the new dual monoclonal immunoassay has statistical discrimination equivalent to the ELISA. Additionally, the immunoassay had a high reproducibility and specificity.

CONCLUSION

The clinical evaluation of five TIMP-1 immunoassays resulted in the development of a new immunoassay. The new TIMP-1 immunoassay showed superior analytical performance to our previously used ELISA.

Characterization of anti-TIMP-1 monoclonal antibodies for immunohistochemical localization in formalin-fixed, paraffin-embedded tissue

The aim of this study was to evaluate seven anti-TIMP-1 (tissue inhibitor of metalloproteinase-1) monoclonal antibodies by immunohistochemical (IHC) staining of formalin-fixed, paraffin-embedded (FFPE) tissue. Detection of the TIMP-1 protein was studied by IHC in FFPE human archival normal and neoplastic samples. Indirect IHC technique was used, and the seven antibodies (clones VT1, VT2, VT4, VT5, VT6, VT7, and VT8) were tested in various concentrations using different pretreatment protocols. All seven VT antibodies specifically immunostained the cytoplasm of islets of Langerhans cells in normal pancreas, epithelial cells of hyperplastic prostate, tumor cells of medullary thyroid carcinoma, and fibroblast-like cells of malignant melanoma. Specificity of the anti-TIMP-1 antibodies was confirmed by several controls, e.g., Western blotting on proteins extracted from FFPE tissue showed that the VT7 antibody reacted specifically with a protein band of approximately 28 kDa, corresponding to the molecular mass of TIMP-1. However, sensitivity varied with the different antibodies. Use of heat-induced epitope retrieval (HIER) and the VT7 clone applied at low concentrations demonstrated more intense immunoreactivity with the TIMP-1-positive cell types compared to the other six clones. Furthermore, when tested on a range of normal and neoplastic endocrine tissues, the VT7 clone demonstrated immunoreactivity with all neuroendocrine cell types. In conclusion, all seven antibodies detected TIMP-1 protein in various normal and neoplastic FFPE tissues, but one clone, VT7, was superior for IHC staining of TIMP-1 in FFPE tissue sections when using HIER.

Survey of the year 2005 commercial optical biosensor literature

We identified 1113 articles (103 reviews, 1010 primary research articles) published in 2005 that describe experiments performed using commercially available optical biosensors. While this number of publications is impressive, we find that the quality of the biosensor work in these articles is often pretty poor. It is a little disappointing that there appears to be only a small set of researchers who know how to properly perform, analyze, and present biosensor data. To help focus the field, we spotlight work published by 10 research groups that exemplify the quality of data one should expect to see from a biosensor experiment. Also, in an effort to raise awareness of the common problems in the biosensor field, we provide side-by-side examples of good and bad data sets from the 2005 literature.