Progress in Chemoprevention Drug Development: The Promise of Molecular Biomarkers for Prevention of Intraepithelial Neoplasia and Cancer—A Plan to Move Forward

Abstract

This article reviews progress in chemopreventive drug development, especially data and concepts that are new since the 2002 AACR report on treatment and prevention of intraepithelial neoplasia. Molecular biomarker expressions involved in mechanisms of carcinogenesis and genetic progression models of intraepithelial neoplasia are discussed and analyzed for how they can inform mechanism-based, molecularly targeted drug development as well as risk stratification, cohort selection, and end-point selection for clinical trials.We outline the concept of augmenting the risk, mechanistic, and disease data from histopathologic intraepithelial neoplasia assessments with molecular biomarker data. Updates of work in 10 clinical target organ sites include new data on molecular progression, significant completed trials, new agents of interest, and promising directions for future clinical studies. This overview concludes with strategies for accelerating chemopreventive drug development, such as integrating the best science into chemopreventive strategies and regulatory policy, providing incentives for industry to accelerate preventive drugs, fostering multisector cooperation in sharing clinical samples and data, and creating public-private partnerships to foster new regulatory policies and public education.In most epithelial tissues, accumulating mutations (i.e., genetic progression) and loss of cellular control functions cause progressive phenotypic changes from normal histology to early precancer [intraepithelial neoplasia (IEN)] to increasingly severe IEN to superficial cancer and finally to invasive disease. This process can be relatively aggressive in some settings (e.g., in the presence of a DNA repair -deficient genotype) but generally occurs relatively slowly over years and decades. Cancer chemoprevention can be defined as the prevention of cancer or treatment of identifiable precancers (defined as histopathologic or molecular IEN). The long latency to invasive cancer is a major scientific opportunity but also an economic obstacle to showing the clinical benefit of candidate chemopreventive drugs. Therefore, an important component of chemopreventive agent development research in recent years has been to identify earlier (than cancer) end points or biomarkers that accurately predict an agent's clinical benefit or cancer incidence -reducing effect. In many cancers, IEN is an early end point. In 2002, the AACR IEN Task Force recommended focusing chemopreventive drug development on IEN because of the close association between IEN and invasive cancer and because reducing IEN burden can benefit patients by reducing cancer risk and/or the need for invasive interventions (1). The IEN Task Force proposed several practical and feasible clinical trial designs for developing new agents to treat and prevent precancer in nine cancer target organs.

Microsomal antiestrogen-binding site ligands induce growth control and differentiation of human breast cancer cells through the modulation of cholesterol metabolism

“…8 Breast differentiation therapy is a recent paradigm that emerged from epidemiologic studies showing that fullterm pregnancy and breast-feeding protects the breast against neoplastic transformation (41). This leads to the concept that drugs inducing differentiation of breast tumors can be used as chemopreventive agents (42). The mechanism we describe here supports the possibility that modulation of cholesterol metabolism in tumor cells through the binding to the AEBS can be involved in the chemopreventive action of SERMs in addition to Coulter counter.…”

5α-Reductase inhibitor treatment of prostatic diseases: background and practical implications

“…36 Genetic mutations and the resulting loss of cellular growth control and apoptosis mechanisms cause progression from normal tissue via prostatic intraepithelial neoplasia grade I-III to manifest prostate cancer. This apparently occurs in a stepwise manner providing a potential target for chemoprevention.…”

Early Detection of Oral Neoplasia: Watching with New Eyes

“…The effect of local control by removing head and neck precursor lesions has not been established as a method of reducing cancer risk (7). Although numerous changes contribute to epithelial carcinogenesis, histologically defined intraepithelial neoplasia (IEN), or premalignant lesions, is still considered to be better than any individual molecular marker for predicting cancer risk (8,9).…”

“…These tools will enhance standard screening and may complement established screening approaches for these tissues (35). Colonoscopy with IEN removal (polypectomy) is the standard of care for colorectal cancer risk reduction and has been proven to be significantly effective in this regard (8,9). Despite the anatomic changes associated with colon carcinogenesis that are readily detected (e.g., raised polyps), a number of flat lesions can be missed and cancers can be hidden behind folds in the colon (36).…”