Design, Develop, Validate, and Implement Biomarkers for Clinical Investigations

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The Molecular Targets Core develops technologies and assays that allow investigators to examine the effects of investigational new drugs (INDs) on intended targets and their associated pathways, as well as relevant biomarkers that are indicative of biological responses to the treatment. We have expertise in assay development and validation, biomarker analysis, and mechanism of action studies. Currently, we are designing and developing assays for a number of investigational agents to analyze their effects on cell proliferation, tumor angiogenesis, and apoptosis. 1. Custom Assay Design, Development, and Validation. We develop, validate, and implement assays for clinical specimens using electrochemiluminescence (ECL)-based immunoassays. Although the ECL technology (Roche Diagnostics) that we use is one of the most advanced clinical immunoassay platforms available today, none of the standard tests from Roche is suited for our clinical correlative studies. Therefore it is essential to develop and customize these assays to be specifically tailored to the needs of CCR clinical investigators. Our ECL platform is well suited for this ongoing task because it offers a high degree of flexibility, stability and reliability. Another distinct advantage is its multiplex capability (i.e., the ability to determine the levels of total (t-) and phospho-proteins (p-) in a single assay well using a limited number of clinical specimens. Because clinical samples may vary dramatically, the ability to normalize these samples beyond total protein concentration is critical in generating statistically significant data with patient specimens. The Molecular Targets Core is uniquely positioned to carry out this work. 2. Current and Recently Completed Biomarker Studies. Currently, we are working with about 10 clinical protocols at NCI-CCR. For many of these clinical trials, we helped to design, develop, validate, and implement customized biomarker assays for correlative analytical studies. For a phase II clinical trial of sorafenib in androgen-independent prostate cancer (Dahut WL, et al. Clin. Cancer Res. 14: 209-14, 2008) our laboratory performed assay validation with the investigational agent sorafenib and implemented assays with bone marrow biopsy specimens to determine the its effects on the targeted MAP kinase pathway. For another clinical trial that investigated a combination targeted therapy (sorafenib and bevacizumab), our group developed assays and performed the analysis of angiogenic factor vascular endothelial growth factor (VEGF) and cytokines, including interleukin-6 (IL6) and interleukin-8 (IL8) from plasma obtained from the patients throughout the drug trial period (Azad NS, et al. J. Clin. Oncol. 26: 3709-14, 2008). In another trial, we measured the changes in the relative changes of S6RP signaling from both osteosarcoma biopsies and peripheral blood mononuclear cells (PBMC)following the administration of rapamycin. Our data showed a highly statistically significant reduction of p-S6RP in PBMC. The p/t-S6RP ratio changed from 25% pre-drug to 0.5% post-drug with p less than 0.001, with samples obtained from day 2 to the end of the study. Our results further showed that there is a high degree of variation in tumor biopsies. The statistically significant effect of rapamycin on the S6RP pathway can only be demonstrated as p/t-S6RP ratio using our duplex assay capable of quantitatively measuring both p-S6RP and t-S6RP in the same assay well (unpublished results).