Abstract This SBIR Phase IIb proposal builds on the success of our Fast-track award supporting the pre-clinical development of FAPXIL, an oral sustained-release micro-particulate formulation of Interleukin-10 for the treatment of Familial Adenomatous Polyposis (FAP). The Phase I portion of our Fast-track project provided validation of our large-batch methods and activity in a clinically-relevant murine model of human FAP. The Phase II segment further optimized the treatment protocol, defined the long-term therapeutic potential and assessed potential effects of long-term treatment on local and systemic immune homeostasis. Additional Phase II tasks included production of multiple scale-up batches for validation of batch-to-batch consistency, long-term stability analysis, transfer of manufacturing methods to a CMO with GMP capability, and a Type C pre-IND meeting with the FDA to inform future toxicology. Agency recommendations and responses to our interrogatives form the Aims of this Phase IIb application to continue the development of FAPXIL® towards clinical trials in FAP patients. To this end, Aim 1 will continue pharmaceutical quality and development activities; Aim 2 will establish safety, tolerability and pK of FAPXIL in non-human primates; Aim 3 will complete a Type B pre-IND meeting with the US FDA; Aim 4 will assess Investigational New Drug (IND) readiness and submit an orphan-drug designation request for FAPXIL. The Aims proposed above will enable Therapyx, Inc. to continue pre-clinical work required to obtain IND approval for this first-in-class oral biologic. Subsequent production of clinical grade drug product and IND submission will be supported via NIH's SBIR Commercialization Readiness Program and Company funds.