Recent Trends and Advances in Immunodiagnostics of Solid Tumors

Abstract

The development of new cancer immunodiagnostic tests measuring soluble markers can be divided along the lines of single analyte measurement versus multiplex analysis. In the measurement of single analytes, newly proposed test analytes still struggle with the same issues as their predecessors; namely, can the measurement of a single biomarker be sufficiently sensitive and specific for screening the general population? Probably the best example of this challenge is in the area of bladder cancer detection, where several newly identified markers are being clinically evaluated in multicenter trials. In order to surmount this hurdle, multiplex analysis has become an increasingly important research focus. By combining the statistical power of measuring many cancer-associated analytes, it is hoped that highly specific diagnostic tests can be developed that are suitable for screening the general population. Some of the most impressive data for multiplex cancer biomarker detection derive from a non-immunologic technique - mass spectroscopy. Multiplex analysis has also recently been applied to the measurement of serum antibodies to tumor-associated antigens. Recent data link the development of antibodies to tumor-associated antigens with the presence of solid tumors. This strategy is a departure from the more traditional assay format of measuring the antigens themselves, and is another promising emerging area of investigation for the early detection of solid tumors. Solid tumor analysis by quantitative immunohistochemical staining is another rapidly growing area of cancer immunodiagnosis. This field has become especially important in the context of pharmacodiagnostics - the coupling of cancer therapy to the outcome of a test measurement from a patient biopsy. Standardization and assay reproducibility appear to be the most significant challenges in this context. In summary, developments over the past several years give reason for excitement and optimism about the potential for cancer immunodiagnostics to meaningfully impact cancer patient survival. In this review we take a fresh look at the field of cancer immunodiagnostics, to identify these recent and emerging trends that may impact on clinical practice over the next few years.