Targeted delivery of therapeutics has been a long-term goal in clinical medicine. Of particular interest is to be able to selectively target a drug to specific cells or tissues which could benefit from the drug activity, and avoid delivery of the drug to other areas where exposure to the drug could result in overt toxicity or other undesirable side effects. Functional RNAi molecules (e.g., shRNA, siRNA, RNAi, miRNA) have highly specific effects on gene expression and have proven to be valuable tools to explore biological pathways and identify novel therapeutic targets. RNAi molecules also have tremendous potential in therapeutic applications but their development as therapeutics requires suitable solutions for a) cell-specific targeting;b) delivery to the RNAi processing machinery as well as c) systemic delivery of these powerful pharmacologic agents. Prostate cancer is the most common form of cancer and the second leading cause of death among men in the United States. Current treatments have only limited success in preventing progression of disease with up to 30% of patients suffering relapse. Thus, there is a significant unmet medical need for development of an effective adjunct therapy for prostate cancer either before or after prostatectomy. During this proposed Phase I research program, we will use b3 bio's core technology to identify RNA molecules that can internalize into prostate cancer cells from various stages of malignant progression, including androgen-dependent cancer cells, androgen independent cancer cells, and highly metastatic cells. These internalizing RNA molecules ("INA") will be evaluated as targeting agents to deliver functional RNAi molecules into the prostate cancer cells. b3 bio has licensed and developed generalized approaches for selecting RNA molecules from RNA libraries that internalize into specific cells of interest, and in creating INAs useful for selective delivery of a cargo (e.g., therapeutic, or diagnostic or imaging agents) into targeted cells. We will couple the INA to a functional RNAi molecule in forming a modular INA molecule ("mINA") to demonstrate delivery of the functional RNAi molecule to the target prostate cancer cells and expression of its activity. Our proposed goal is to therefore generate a modular INA molecule comprised of (a) an internalizing RNA capable of selectively entering targeted prostate cancer cells from various stages of malignant progression;and (b) delivering a functional RNA molecule that can be used to demonstrate selective gene knockdown. We feel the aims presented here represent a proof-of- principle research program, which would be expanded to include preclinical and commercialization development strategies during a subsequent Phase II funding period. PUBLIC HEALTH RELEVANCE: Prostate cancer is the most frequent cancer in Western countries, and is the second leading cause of cancer mortality among men in the United States and Europe. Even with the implementation of screening programs for prostate-specific disease markers (e.g., PSA), annually in the United States, it is projected that there will be over 200,000 new cases of prostate cancer, and over 25,000 deaths caused by prostate cancer. Treatment of prostate cancer is complicated by the fact that the disease progresses through various stages of malignancy, such as androgen dependence, androgen independence, and metastasis. b3 bio has both in-licensed and developed a generalized approach for selecting for RNA molecules that internalize into specific cells of interest. Such internalizing RNA molecules may then be coupled to a cargo of interest to selectively deliver the cargo into the specific cells of interest. [The model used to establish the basis for this technology employed a human prostate cancer cell line in both cell culture and in mouse xenograft studies (see Background and Significance- Advantages of b3 bio delivery system).] Our proposed goal is to therefore use our platform technology to (a) first generate an internalizing RNA molecule ("INA") which can selectively target prostate cancer cells from various stages of malignant progression;and (b) second, generate a modular INA comprised of the internalizing RNA coupled to a functional RNAi molecule and demonstrate its activity in cells from various stages of malignant progression. Achieving this proposed goal will provide an "active" compound that can be further optimized and developed into a lead candidate to address an unmet medical need of targeting delivery to prostate cancer cells from various stages of malignant progression. After successfully accomplishing our Phase I aims, we would like to immediately initiate a Phase II research program testing and optimizing the efficacy of this mINA delivery system in vivo, and designing an optimal pharmacologically active agent to be used with the internalizing RNA molecule for delivery into prostate cancer cells.