Marc Baay

A Review of the Most Promising Biomarkers in Colorectal Cancer: One Step Closer to Targeted Therapy

Rapidly growing insights into the molecular biology of colorectal cancer (CRC) and recent developments in gene sequencing and molecular diagnostics have led to high expectations for the identification of molecular markers to be used in optimized and tailored treatment regimens. However, many of the published data on molecular biomarkers are contradictory in their findings and the current reality is that no molecular marker, other than the KRAS gene in the case of epidermal growth factor receptor (EGFR)- targeted therapy for metastatic disease, has made it into clinical practice. Many markers investigated suffer from technical shortcomings, resulting from lack of quantitative techniques to capture the impact of the molecular alteration. This understanding has recently led to the more comprehensive approaches of global gene expression profiling or genome-wide analysis to determine prognostic and predictive signatures in tumors. In this review, an update of the most recent data on promising biological prognostic and/or predictive markers, including microsatellite instability, epidermal growth factor receptor, KRAS, BRAF, CpG island methylator phenotype, cytotoxic T lymphocytes, forkhead box P3-positive T cells, receptor for hyaluronic acid-mediated motility, phosphatase and tensin homolog, and T-cell originated protein kinase, in patients with CRC is provided.

Tumor Cells and Tumor-Associated Macrophages: Secreted Proteins as Potential Targets for Therapy

Inflammatory pathways, meant to defend the organism against infection and injury, as a byproduct, can promote an environment which favors tumor growth and metastasis. Tumor-associated macrophages (TAMs), which constitute a significant part of the tumor-infiltrating immune cells, have been linked to the growth, angiogenesis, and metastasis of a variety of cancers, most likely through polarization of TAMs to the M2 (alternative) phenotype. The interaction between tumor cells and macrophages provides opportunities for therapy. This paper will discuss secreted proteins as targets for intervention.

Generation of Merkel Cell Polyomavirus (MCV)-Like Particles and Their Application to Detection of MCV Antibodies

ABSTRACT The genome of a new human polyomavirus, known as Merkel cell polyomavirus (MCV), has recently been reported to be integrated within the cellular DNA of Merkel cell carcinoma (MCC), a rare human skin cancer. To investigate MCV seroprevalence in the general population, we expressed three different MCV VP1 in insect cells using recombinant baculoviruses. Viruslike particles (VLPs) were obtained with only one of the three VP1 genes. High-titer antibodies against VP1 VLPs were detected in mice immunized with MCV VLPs, and limited cross-reactivity was observed with BK polyomavirus (BKV) and lymphotropic polyomavirus (LPV). MCV antibodies were detected in 77% of the general population, with no variations according to age.

The importance of biological factors (bcl-2, bax, p53, PCNA, MI, HPV and angiogenesis) in invasive cervical cancer

OBJECTIVE The present study was designed to analyse the relationship between apoptosis related proteins (bcl-2 and bax), tumour suppressor protein p53, proliferation markers (PCNA and mitotic index), human papillomavirus (HPV) and angiogenesis in cervical cancer and their impact on clinical outcome. STUDY DESIGN Tumours from 111 patients were assessed by immunohistochemistry for the expression of bcl-2, bax, p53 and PCNA, by PCR for the presence of HPV-DNA, for the quantification of the mitotic index and the microvessel density (CD 31). The results were correlated with various histopathologic characteristics and survival. RESULTS The multiple Coxs regression analysis for overall survival of all prognostic variables gave as best model: bcl-2 (P<0.001), lymphovascular permeation (P=0.004), mitotic index (P=0.019), tumour grade (P=0.048) and FIGO stage (P=0.070). Subanalysis was performed for the patients where the lymph node status was known (n=79). Adding the lymph node status gave as best model for overall survival bcl-2 (P=0.001), lymphovascular permeation (P=0.003) and mitotic index (P=0.044). However, they hardly influenced the association. CONCLUSION In the apoptotic pathway of cervical cancer, bcl-2 is one of most important proteins. It can probably not only mediate cell death but also regulate cell growth. A better understanding of their relations will probably provide the basis for more rational cancer therapies in the future.

Immune Cells in Colorectal Cancer: Prognostic Relevance and Role of MSI

There is growing evidence that both local and systemic inflammatory responses play an important role in the progression of a variety of solid tumors. Colorectal cancer (CRC) results from the cumulative effect of sequential genetic alterations, leading to the expression of tumor-associated antigens possibly inducing a cellular anti-tumor immune response. It is well recognized that cytotoxic lymphocytes (CTLs) constitute one of the most important effector mechanisms of anti-tumor-immunity. However, their potential prognostic influence in CRC remains controversial. In addition, other key players like natural killer cells, tumor associated macrophages and regulatory T cells play an important role in the immune attack against CRC and need further investigation. This review will mainly focus on the role of the adaptive immune system in CRC and particularly in regard to microsatellite instability.

Can cervical cancer screening be stopped at 50? The prevalence of HPV in elderly women

Although the relation between cervical cancer and the human papillomavirus (HPV) has been established beyond doubt, the introduction of HPV detection in cervical cancer screening is halted, primarily by the high rate of false positivity in relation to morbidity, since the majority of women infected with HPV will not develop lesions. To counteract overconsumption of cervical cancer screening in elderly women, we wanted to test the hypothesis that women of 50 years or older who are HPV‐negative and have a cytologically normal smear might be encouraged to refrain from further screening. As a first step, the prevalence of high‐risk HPV in a population of 1,936 women of 50 years and older was investigated. After an initial decline, a slightly higher prevalence can be seen with increasing age. There is a decrease in the prevalence of multiple infections with age, paralleled by an increase in single infections, especially of HPV type 16 in the eldest‐age group. However, neither the decrease in multiple infections nor the increase in single infections is statistically significant. The data obtained in this study show that, even in the presence of a slight increase in the HPV prevalence in elderly women, approximately 94% of the elderly women can be withdrawn from the cervical cancer screening. However, a follow‐up study will be necessary to determine the frequency of (re)infection as well as the course of an HPV infection in elderly women.

Anti-Epidermal Growth Factor Receptor Therapy in Head and Neck Squamous Cell Carcinoma: Focus on Potential Molecular Mechanisms of Drug Resistance

Targeted therapy against the epidermal growth factor receptor (EGFR) is one of the most promising molecular therapeutics for head and neck squamous cell carcinoma (HNSCC). EGFR is overexpressed in a wide range of malignancies, including HNSCC, and initiates important signal transduction pathways in HNSCC carcinogenesis. However, primary and acquired resistance are serious problems and are responsible for low single-agent response rate and tumor recurrence. Therefore, an improved understanding of the molecular mechanisms of resistance to EGFR inhibitors may provide valuable indications to identify biomarkers that can be used clinically to predict response to EGFR blockade and to establish new treatment options to overcome resistance. To date, no predictive biomarker for HNSCC is available in the clinic. Therapeutic resistance to anti-EGFR therapy may arise from mechanisms that can compensate for reduced EGFR signaling and/or mechanisms that can modulate EGFR-dependent signaling. In this review, we will summarize some of these molecular mechanisms and describe strategies to overcome that resistance.

Detection of Microsatellite Instability in Colorectal Cancer Using an Alternative Multiplex Assay of Quasi-Monomorphic Mononucleotide Markers

Colorectal malignancies demonstrating microsatellite instability (MSI) have a very heterogeneous histological appearance, better prognosis, and altered response to therapy. Consequently, identification of the MSI phenotype is both relevant and interesting as a screening and prognostic tool and as a potential predictive factor of chemotherapeutic response. Several groups have argued for the exclusive use of mononucleotide markers for MSI analysis. In this study, an alternative MSI typing multiplex system of mononucleotide microsatellite repeats was developed. This system obviates the need to compare allelic profiles between tumor and matching normal DNA, rendering MSI analysis amenable to high throughput. The quasi-monomorphic allelic distribution of five alternative mononucleotide markers was evaluated in genomic DNA. Only SEC63 and CAT25 were found to be quasi-monomorphic and were thus combined with BAT25 and BAT26 from the Bethesda panel. Consequently, 177 colorectal cancer samples previously analyzed by the Bethesda panel were tested for MSI using this alternative mononucleotide panel. In an attempt to resolve discordant cases, immunohistochemistry of MLH1, MSH2, and MSH6 was performed. The concordance between both panels reached 99.4% when microsatellite stability and MSI-L were grouped together. These new markers were subsequently multiplexed in a single polymerase chain reaction assay. The resulting mononucleotide fluorescent multiplex MSI assay has high accuracy, reliability, and throughput, thus reducing the time and cost involved in MSI testing.

Detection of HPV-16 DNA by PCR in histologically cancer free lymph nodes from patients with cervical cancer

The prognostic value of detection of human papillomavirus (HPV) type 16 DNA in histologically cancer free lymph nodes was assessed in left obturator lymph nodes from cervical cancer patients with HPV-16 positive primary tumours. HPV-16 DNA was detected by polymerase chain reaction in 12 of 35 patients with histologically cancer free lymph nodes. Of these 12 patients, only one developed a recurrence, suggesting HPV-16 DNA detection in cancer free lymph nodes has no prognostic value.

Genital schistosomiasis and its unacknowledged role on HIV transmission in the STD intervention studies

Treatment of sexually transmitted infections (STIs) has been hypothesised to decrease HIV transmission. Although observational studies show an association between STIs and HIV, only one prospective randomised controlled trial (RCT) has confirmed this. Female genital schistosomiasis can cause genital lesions, accompanied by bloody discharge, ulcers or malodorous discharge. Genital schistosomiasis is common, starts before puberty and symptoms can be mistaken for STIs. Three observational studies have found an association between schistosomiasis and HIV. Genital lesions that develop in childhood are chronic. This paper sought to explore the possible effects of schistosomiasis on the RCTs of STI treatment for HIV prevention. In the study sites, schistosomiasis was a likely cause of genital lesions. The studies recruited women that may have had genital schistosomal lesions established in childhood. Schistosomiasis endemic areas with different prevalence levels may have influenced HIV incidence in intervention and control sites differently, and some control group interventions may have influenced the impact of schistosomiasis on the study results. Schistosomiasis is a neglected cause of genital tract disease. It may have been an independent cause of HIV incidence in the RCTs of STI treatment for HIV prevention and may have obscured the findings of these trials.