Phase II Trial of the Gamma-Secretase Inhibitor PF-03084014 in Adults With Desmoid Tumors/Aggressive Fibromatosis

Background: * Desmoid tumors (also known as aggressive fibromatosis), are rare, locally invasive, slow-growing soft-tissue tumors. The disease can be either asymptomatic or be associated with severe loss of organ function and significant morbidity. * Treatment with the selective small-molecule Gamma-secretase inhibitor PF-03084014 caused significant tumor shrinkage in patients with unresectable desmoid tumors in an early phase clinical trial. * The Notch pathway is a key regulator of cell differentiation, proliferation and apoptosis; aberrant signaling via the Notch pathway is associated with carcinogenesis. Objectives: * Primary: Determine the response rate (Complete Response (CR)+Partial Response (PR)) of PF-03084014 in patients with desmoid tumors/aggressive fibromatosis * Secondary: Assess symptom measures at baseline and on study; perform genotyping for germline and somatic mutations in adenomatous polyposis coli gene (APC) and catenin-beta 1 (CTNNB1) genes; correlate clinical response to therapy with genotyping data; and assess modulation of the Notch pathway by evaluating notch response genes in tumor biopsies at baseline and after drug administration Eligibility: * Age greater than or equal to18; histologically confirmed desmoid tumor not amenable to curative resection or definitive radiation therapy that has progressed after receiving at least one line of standard treatment; adequate organ function * Willingness to provide blood samples and 10 unstained slides or a tumor block for genetic research studies Study Design: * This is an open-label Phase II trial of PF-03084014; study drug will be administered orally at 150 mg twice a day in 21-day cycles * Optional tumor biopsies for research purposes will be performed at baseline prior to study treatment and at the beginning of cycle 7 (+/- one cycle) * Restaging scans (magnetic resonance imaging (MRI) with diffusion weighting) will be performed at baseline, at the end of cycles 1 and 6, and then every 6