Study Core Period:~The first 16 weeks after the initial dose of dasatinib is called the Study Core Period. Patients who are eligible and chose to participate in this study should expect to take 100 mg of dasatinib daily for 8 weeks. If the study doctor believes that they have not achieved a partial response after 8 weeks of treatment, the dose may be increased to 150 mg per day. The study doctor may lower the dosage of dasatinib if the 100 mg treatment is too strong. If the lower dose of dasatinib is still too strong, the study doctor may decide to take the patient off of the study. The patient will continue to receive supportive care as needed during the duration of the trial as well as after completion of the trial.~During the Study Core Period, participants will have a study visit every 4 weeks. Complete Blood Counts (CBCs) will be obtained every 2 weeks for study purposes and disease monitoring. Bone marrow aspiration and biopsy will be obtained at screening, and at 8 weeks and 16 weeks of treatment for response assessment. Additional bone marrow aspirations and biopsies may be obtained at any other time, to evaluate the disease process, at the doctor's judgment. A bone marrow aspirate and biopsy must be done at the time of study discontinuation.~Study Extension Period:~The time after the first 16 weeks of treatment is called the study extension period. If the patient is responding to the treatment, does not experience disease progression or any severe adverse events, the patient may continue dasatinib treatment for up to 48 weeks. If patients continue after 48 weeks, they will be asked to enroll in a separate extension study for future follow up.~During the Study Extension Period, participants will have a study visit every 4 weeks. Complete Blood Counts (CBCs) will be obtained every 2 or 4 weeks for study purposes and disease monitoring. Bone marrow aspiration and biopsy will be obtained every 16 weeks. A bone marrow aspirate and biopsy must be done at the time of study discontinuation.
The main purpose of this study is to learn how patients with myelodysplastic syndrome (MDS) respond to the study drug dasatinib. The study drug, dasatinib, has been approved by the U.S. Food and Drug Administration (FDA) for treatment of leukemia, but has not been approved for the treatment of other kinds of cancer. The use of dasatinib in this study is considered experimental.