Inclusion Criteria:

• Histologically confirmed adenocarcinoma of the prostate.
• Clinical stage T1-T3a disease.
• Must be willing to have a tumor biopsy, if previous tumor tissue unavailable for tumor marker analysis.
• Kattan pre-operative nomogram-predicted (based on stage, PSA and Gleason score) 5-year risk of recurrence-free survival of 80% or less
• Must be deemed eligible for radical prostatectomy.
• Must be willing to use an effective method of contraception (hormonal or barrier method of birth control; abstinence) from the time consent is signed until 6 weeks after treatment discontinuation.
• Written informed consent and HIPAA authorization for release of personal health information.
• Age > 18 years at the time of consent.

Exclusion Criteria:

• No evidence of regional, lymph node or distant metastasis on clinical or radiological assessments. All baseline radiology studies must be performed within 28 days prior to registration for protocol therapy.
• No prior malignancy in the past 2 years except for basal cell and squamous cell carcinoma of the skin. Other cancers with low potential for metastasis, such as in situ cancers (e.g., Grade 1, TA TCC (low grade superficial bladder cancer), and colonic polyp with focus of adenocarcinoma) can be enrolled after approval from the Sponsor Investigator.
• No prior hormonal therapy with the exception of oral 5-alpha-reductase inhibitors (finasteride, dutasteride, etc.). Patients who have received prior oral anti-androgen therapies (bicalutamide, flutamide, nilutamide, etc.), prior LHRH agonist therapy (leuprolide, goserelin acetate, etc.), or prior orchiectomy are ineligible.
• No prior systemic chemotherapy or radiotherapy for prostate cancer is allowed. Transurethral resection of the prostate for benign prostatic hypertrophy (BPH) and oral alpha-blockers (terazosin, tamsulosin, doxazosin) are permitted.
• No history of hemorrhage or thrombotic events (cerebrovascular accident, deep vein thrombosis, pulmonary embolism, etc.) within 6 months prior to registration for protocol therapy.
• No history of diagnosed congenital bleeding disorders (e.g., von Willebrand's disease)
• No history of diagnosed acquired bleeding disorder within one year (e.g., acquired anti-factor VIII antibodies) of registration on protocol therapy.
• No history of ongoing or recent (≤ 3 months of registration on protocol therapy) significant gastrointestinal bleeding
• No ongoing anti-coagulation and/or anti-platelet therapies allowed.
• No unresolved pleural or pericardial effusion of any grade within 3 months of registration for protocol therapy.
• No uncontrolled angina, congestive heart failure or MI within 6 months prior to registration for protocol therapy.
• No diagnosed congenital long QT syndrome.
• No history of clinically significant ventricular arrhythmias (such as ventricular tachycardia, ventricular fibrillation, or Torsades de Pointes).
• No prolonged QTc interval on pre-entry electrocardiogram (> 450 msec)
• Following medications must be discontinued at least 7 days prior to registration for protocol therapy and be withheld for the duration of dasatinib therapy:
• Drugs that are generally accepted to have a risk of causing Torsades de Pointes
• Patient must not be receiving any prohibited CYP3A4 inhibitors /inducers/ substrates
• Anti-coagulation and/or anti-platelet therapies - to avoid potential bleeding risks.
• No major surgical procedure, open biopsy, or significant trauma within 28 days prior to registration for protocol therapy.
• Ability to comply with study and/or follow-up procedures and requirements.
• No treatment with any investigational agent for any medical condition within 28 days prior to registration for protocol therapy.
• No clinically significant infections or any other condition which, in the investigator's opinion, deems the patient an unsuitable candidate to receive the study drug.
• Ability to take oral medication (dasatinib must be swallowed whole).
• No known history of hypokalemia that cannot be corrected prior to registration on protocol therapy.
• No known history of hypomagnesemia that cannot be corrected prior to registration on protocol therapy.