Predicting Melanoma Response to BAY 43-9006/Chemotherapy

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DESCRIPTION (provided by applicant): Mortality from melanoma is rising due to the increase in incidence and lack of effective therapy once the disease has metastasized. One of the most promising new therapies is carboplatin (C), paclitaxel (T) and BAY43-9006 (B), which revealed very high response rates with unusually long mean time to disease progression in a Phase l/ll trial in metastatic melanoma. ECOG is opening a randomized trial comparing CT to CTB, called E2603. The precise mechanism of BAY 43-9006 is unknown, and response to CTB appears not to be associated with B-RAF activating mutations. We hypothesize that (a) mechanisms other than B-RAF inhibition are involved in the activity of this combination of drugs and (b) CTB will benefit only a subset of melanoma patients. We strive to find markers that predict response in the individual patient in order to ultimately treat only those patients that are likely to respond. We will screen selected markers for association with response to therapy, and perform comprehensive analysis on the best predictive markers. We will use a novel, objective, automated quantitative method of tissue microarray analysis (AQUA) to evaluate expression of proteins from three groups that are known to be induced by these drugs; the MARK pathway, apoptotic pathways and pro-angiogenic proteins. We will start with rigorous validation of antibodies to a subset of these proteins, followed by initial evaluation on tumors from 50 patients treated with CTB in the Phase l/ll study. Markers with differences in expression between responders and non-responders will be further evaluated on 300 archival melanoma specimens and 300 benign nevi to assess prevalence of markers expression in metastatic melanomas. Concurrently, specimens from patients enrolled in E2603 will be prospectively collected. Using AQUA on tissue microarrays, we will study differences in marker expression between responders and non-responders on both treatment arms, with the goal of developing an assay to specifically predict response to CTB. We will assess individual markers as well as panels of markers.