A Research Pilot Study in Healthy Volunteers to Evaluate Biomarkers for Novel Anticancer Treatments

Many physiological processes in normal growth, development, injury, and repair are critical for tumor growth and progression. Usually these processes are deregulated, allowing for the potential of tumor selectivity in targeting many of these processes. In many cases, altered host stromal tissues themselves are critical for many of steps in cancer progression. Stromal endothelial cells and fibroblasts produce many tumor growth factors, which act in paracrine loops. In addition, components of the host tissue matrix and plasma proteins also help promote or inhibit tumor growth. These topics have been extensively reviewed.

A large number of targeted therapies for cancer are also in various stages of clinical development. Due to the likely minimal toxicity and only modest single agent activity of these agents, determining the optimal dose and schedule for these agents will depend upon the identification of biomarkers that can demonstrate proof of target inhibition and/or characterize the downstream consequences of this inhibition.

Despite often robust and durable clinical responses, essentially all patients treated with bevacizumab progress, implying primary or acquired resistance, or both. Treatment related changes in VEGF ligands and receptors have been reported in response to anti-VEGF therapy in preclinical models. Treatment related changes have also been noted for many additional angiogenic factors, including PDGF, bFGF, and IGF, all of which have been shown to potentially mediate sensitivity and resistance to anti-VEGF therapy. Despite the known importance of numerous angiogenic factors in both preclinical models and in patients, there have not yet been a broad and systematic evaluation of either baseline or treatment related changes of multiple angiogenic factors in response to bevacizumab. Similar information is also lacking for essentially all targeted therapies.

Biomarkers to better understand the mechanisms of action, primary and acquired resistance, and toxicity of these agents are urgently needed. The topic has been extensively reviewed and is considered a priority by the NCI. The need for such biomarkers is critical given the increasing number of permutations of targeted therapeutics and the need for biomarkers to guide patient and treatment selection both in clinical trials and in general use of anti-cancer therapy. Assay optimization and defining expected values of each marker or panel of markers is critical before use of such assays in large therapeutic clinical trials designed to target specific patient populations. In addition, understanding the biology and regulation of biomarkers related to tumor growth and tumor angiogenesis is also important. Most candidate biomarkers are themselves cellular growth factors, and are involved in not only tumor promotion and growth, but also in normal growth and development and in normal and abnormal tissues responses to injury. The primary purpose of the proposed project is to help refine new biomarkers and new and evolving technologies to assess them.