Patients will receive dasatinib, a Src inhibitor, at an initial dose of 50 mg PO BID, with real-time PharmacoDynamic dose adjustment following 4 weeks of therapy based on inhibition of phosphorylation of SRC, focal adhesion kinase (FAK) and paxillin, until progression. The primary objective is to assess tolerability and estimate the proportion of patients who are progression-free at 16 weeks from the date of study enrollment.