“The bottleneck to improving cancer survival rates lies in early diagnosis,” said Ruo-Pan Huang, M.D., Ph.D., president of RayBiotech. Dr. Huang discussed the role of protein and antibody arrays in cancer biomarker discovery, stressing the poor prognosis for late-stage ovarian cancer. He bemoaned the fact that tremendous effort has been expended in the search for individual, cancer-specific markers with few positive results.
Indeed, a list of 1,261 proteins believed to be differentially expressed in human cancers have been compiled by researchers at the Plasma Proteome Institute, yet only nine have made the epic voyage to final FDA approval as tumor-associated antigens. Many workers in the field now believe that the search for individual cancer biomarkers will be fruitless, and multiple biomarkers will be required to identify cancers in screening protocols.
Dr. Huang’s group has designed immunoarrays in which antibodies are carefully printed onto substrates in order to optimize sensitivity and dynamic range, and then subjected to performance testing. The arrays were based on cytokine proteomics, recognizing the role that cytokines are known to play in a number of disease processes. In fact, cytokines are the most widely studied of all protein families. The arrays can detect more than 500 cytokines in one experiment in the picogram range with high specificity and little cross-reactivity. They have proven easy and cost-effective to use.
Dr. Huang and his collaborators have used RayBio® Cytokine Antibody Arrays to measure the presence of 174 different cytokines in a sample of malignant ovarian tumors, benign tumor material, and normal tissue. The data was analyzed using a neural network procedure, a statistical data-modeling tool that permits classification of the different markers according to their predictive power. The results demonstrated that the antibody array analysis had a high agreement (between 60 and 90%) with the standard criteria derived from clinical diagnosis.
“We concluded that protein and antibody arrays are a reliable tool for biomarker discovery,” Dr. Huang continued. “Unique expression patterns using protein and antibody arrays can be used to predict ovarian cancer with high accuracy. It is our hope that further study may lead to identification of clinically useful biomarkers for early detection of this disease. In addition, our platform can also be easily applied to other biomarker discovery programs.”