Reverse-phase protein microarray highlights HER2 signaling activation in immunohistochemistry/FISH/HER2-negative breast cancers

Utility of Reverse-Phase Protein Array for Refining Precision Oncology

Despite the early successes of targeted therapies and continuous improvements in next-generation sequencing technology over the last two decades, genomics-driven precision oncology has helped only a minority of cancer patients; thus treatment regimens are still not matched to the vast majority of cancer patients. It has become apparent that genomic profiling in itself is limited with respect to optimal selection of patients for targeted therapy. Proteomics-based approaches (in contrast to genomics-based and transcriptomics-based approaches) capture biological processes (e.g., diversity of protein expression patterns and post-translational modifications) directly contributing to cancer pathogenesis. This encourages incorporation of concordant proteomic analyses into the next stage of precision oncology. Reverse-phase protein array (RPPA) is well suited to pharmacodynamic analysis due to its ability to precisely map signaling status using limited amounts of clinical sample. In addition, the cost-effectiveness and rapid turnaround time of the RPPA platform offer a substantial advantage over existing molecular profiling technologies in a clinical setting. In this chapter, we begin by reviewing the current status of genomics-driven precision oncology, along with its limitations and challenges. Finally, we discuss the utility of RPPA technology as a means of improving precision oncology.

Signaling pathway profiling using reverse-phase protein array and its clinical applications

INTRODUCTION

Increased accessibility to next-generation sequencing within the last decade has led to a paradigm shift in cancer treatment from one-size-fits-all medicine to precision medicine providing therapeutic strategies tailored to the requirements of individual patients. However, the effect of even the most successful agent yet tested is only transient, and durable efficacy has yet to be achieved. Genome- and transcriptome-based approaches cannot fully predict the diversity of protein expression patterns or post-translational modifications that directly contribute to cancer pathogenesis and physiology. This underscores the need for concordant proteomic analysis in the next stage of precision medicine. Areas covered: This review begins with an overview of the recent advances and trends in precision medicine that currently rely on genomics, and highlights the utility of antibody-based reverse-phase protein array (RPPA) technology as a proteomic tool in this context. Expert commentary: RPPA is well suited for pharmacodynamics analysis in view of its ability to precisely map signaling status using limited amounts of clinical samples. In addition, the cost-effectiveness and rapid turn-around time of the RPPA platform offer a substantial advantage over existing molecular profiling technologies in clinical settings.

Signaling pathway profiling by reverse-phase protein array for personalized cancer medicine

Deregulation of intracellular signaling through accumulation of genetic alterations is a hallmark of cancer. In the past few decades, concerted and systematic efforts have been made to identify key genetic alterations and to develop therapeutic agents targeting active signaling molecules. However, the efficacy of molecular therapeutics often varies among individuals, and precise mapping of active molecules in individual patients is now considered an essential for therapy optimization. Reverse-phase protein array or microarray (RPPA or RPPM) is an emerging antibody-based highly quantitative proteomic technology, especially suitable for profiling of expression and modification of signaling proteins in low abundance. Because the supply of clinical materials is often limited, RPPA technology is highly advantageous for clinical proteomics in view of its high sensitivity as well as accurate quantification. RPPA has now begun to be incorporated into various clinical trials employing molecular-targeted therapeutics. In this article we review and discuss the application of RPPA technology in the fields of basic, preclinical, and clinical research. The RPPA Global Workshop was recently launched to accelerate the exchange of rapidly expanding knowledge of this fascinating technology among academic laboratories and industries worldwide. This article is part of a Special Issue entitled: Medical Proteomics.

Implications of functional proteomics in breast cancer

Breast cancer is one of the major public health problems of the Western world. Recent advances in genomics and gene expression-profiling approaches have enriched our understanding of this heterogeneous disease. However, progress in functional proteomics in breast cancer research has been relatively slow. Allied with genomics, the functional proteomics approach will be important in improving diagnosis through better classification of breast cancer and in predicting prognosis and response to different therapies, including chemotherapy, hormonal therapy, and targeted therapy. In this review, we will present functional proteomic approaches with a focus on the recent clinical implications of utilizing the reverse-phase protein array platform in breast cancer research.