Study of Oral SKI-O-703, SYK Inhibitor, in Patients With Persistent and Chronic Immune Thrombocytopenia (ITP)

Inclusion Criteria: * Diagnosis of primary ITP (persistent or chronic) * Failed to respond or relapsed after at least 1 prior therapy, with a platelet count of \<30,000/µL on 2 occasions at least 7 days apart with the confirmatory count on the first day of treatment * Adequate hematologic, hepatic, and renal function * ECOG performance status of 0, 1, or 2 * Male and female subjects, the subject and their partners of childbearing potential agree to use medically acceptable methods of contraception during the study and for 6 months following discontinuation of study drug (excluding women who are not of childbearing potential and men who have been sterilized. Men who have been sterilized should be confirmed to have negative sperm count on 2 consecutive occasions.) * Male subjects agree not to donate sperm for 90 days after the last dose of study drug * Female subjects have negative pregnancy tests at Screening. Exclusion Criteria: * History of current, active malignancy requiring or likely to require chemotherapeutic or surgical treatment during the study, with the exception of non-melanoma skin cancer, carcinoma in situ of the cervix, and localized prostate cancer managed by active surveillance * Transfusion with blood or blood products or plasmapheresis within 2 weeks before the first administration of study drug * History of known inherited coagulopathy, or recent arterial or deep venous thrombosis within the preceding 6 months * Change in corticosteroid or immunosuppressant dose within 2 weeks prior to Day 1 * Treatment with thrombopoietin receptor agonists within 2 weeks before Day 1 * Treatment with rituximab or splenectomy within the 8 weeks prior to Day 1 * Treatment with intravenous immunoglobulins (IVIGs) within 4 weeks prior to Day 1 * Acute infection requiring oral antibiotics within 2 weeks * Infections requiring intravenous antibiotics or hospitalization within 3 months * Positive test results at Screening for human immunodeficiency virus, hepatitis B surface antigen, or hepatitis C virus antibody or positive result for hepatitis B core antibody with a negative result for hepatitis B surface antigen * Received live vaccine within 28 days prior to Day 1 or plan to receive one during the study * History or presence of any gastrointestinal, hepatic, or renal disease or any other condition known to interfere with the absorption, distribution, metabolism, or excretion of drugs * Uncontrolled hypertension * Subject had 12-lead electrocardiogram (ECG) findings of corrected QT interval by Fridericia formula (QTcF) \> 450 msec (males) or \> 470 msec (females), cardiac arrhythmias, or clinically significant cardiac or ECG abnormalities * Subject received any investigational medication within 30 days or 5 half-lives - Concomitant use of any anticoagulants and platelet aggregation inhibiting drugs including aspirin (within 14 days of planned dosing through end of follow-up) * Female subject who is currently pregnant or breastfeeding * Prior treatment with a SYK inhibitor * Planned surgery in the time frame of the dosing period.