Intervention: Rigosertib sodium
Trial phase: Phase 1
SMILES: COc1cc(OC)c(C=CS(=O)(=O)Cc2ccc(OC)c(NCC(=O)[O-])c2)c(OC)c1.[Na+]
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 1
Group description: SyB C-1101 （rigosertib sodium）:

Following Cycle 6 of Study 2012002, the treatment in this study was initiated. One cycle was defined as a 21-day cycle; 14-day oral administration of SyB C-1101 twice daily (Days 1 to 14) followed by a 1-week observation period (Days 15 to 21). The starting dose of SyB C-1101 in this study (Cycle 7) was the same as that was determined for the next cycle in Cycle 6 of Study 2012002.
Eligibility criteria:
Inclusion Criteria:

Patients must satisfy the following conditions listed below.

Patients enrolled in the study 2012002 of SyB C-1101 in Patients With Myelodysplastic Syndrome.
Patients who were not judged as disease progression* nor progressive disease/relapse** at the end of the cycle 6 in the study 2012002. * hematologic remission according to IWG 2006 criteria ** hematologic improvement according to IWG 2006 criteria

Patients who met the continuation criteria*** after Cycle 6 week 3 (Day 22±3) in the study 2012002.

***defined in the study 2012002 protocol "4.5 Criteria for Transition to the Next Cycle "

Patients who can be expected to survive at least three months or longer.
Patients who have score of 0 to 2 in Eastern Cooperative Oncology Group (ECOG) Performance Status (PS).

Patients with adequate function in major organs (heart, lungs, liver, kidneys, etc.).

Aspartate aminotransferase (AST): no more than 3.0 times the upper boundary of the reference range at each institution
Alanine aminotransferase (ALT): no more than 3.0 times the upper boundary of the reference range at each institution
Total bilirubin: no more than 1.5 times the upper boundary of the reference range at each institution
Serum creatinine: no more than 1.5 times the upper boundary of the reference range at each institution
ECG: no abnormal findings requiring treatment
Echocardiography: no abnormal findings requiring treatment
Patients who personally signed an informed consent document for participation in this study.

Exclusion Criteria:

Patients who satisfy any of the following conditions after Cycle 6 week 3 (Day 22±3) in the study 2012002 will not be enrolled in the study.

Patients with anemia caused by factors other than MDS(hemolytic anemia, gastrointestinal hemorrhage, etc.).
Patients with obvious infectious diseases (including viral infections).
Patients with serious complications (liver failure, renal failure, etc.).
Patients with a complication of serious heart disease (myocardial infarction, ischemic heart disease, etc.)
Patients with a serious gastrointestinal condition (severe or significant nausea/vomiting, diarrhea, etc.)
Patients with serious bleeding tendencies (disseminated intravascular coagulation (DIC), internal hemorrhage, etc.).
Ascites or pleural fluid requiring active medical management including paracentesis, or hyponatremia (defined as serum sodium value of < 130 mEq/L).
Patients with known allergy to polyethylene glycol or gelatin capsules.
Patients with an addiction to a legal or illegal drug, or with alcohol dependency.
Patients who are nursing, pregnant or may become pregnant, or lactating mothers.

Patients who have not consented to the following contraceptive measures. Patients will avoid sexual intercourse with sexual partners or should use the following contraceptive methods in these time periods: for male patients during the administration period of the trial and for six months after the end of administration; female patients during the administration period of the trial and until a second menstrual period is confirmed after the end of administration (or in the case of female patients with no menstrual period, for two months after the end of administration). 1) Male patients: Patients will always use a condom.

For effective contraception, it is recommended that the female partner also use the contraceptive methods for female patients. 2) Female patients: Female patients who may become pregnant should use one or more types of the following contraceptive methods. In addition, the male partner will always use a condom.

Oral contraceptive (birth control pills)
Intrauterine device (IUD)
Tubal ligation
Other patients judged to be unsuitable by an investigator or sub-investigators.