Conditions: Myelodysplastic Syndrome
Allocation: NA | Intervention model: SINGLE_GROUP
Enrollment: 10
Healthy volunteers: no

Brief summary:
The purpose of this study is to investigate tolerability when SyB C-1101 is orally administered twice daily for 14 consecutive days to the patients with recurrent/relapsed or refractory myelodysplastic syndrome, to determine the dose-limiting toxicity and maximum tolerated dose, and to estimate the recommended dose for phase II studies. Pharmacokinetics and antitumor effects will also be investigated.

Detailed description:
In Cohort 1, SyB C-1101 280 mg/dose group, Participants will be administered 280 mg/dose of SyB C-1101 twice daily orally for 14 consecutive days, followed by 7-day observation period.

In Cohort 2, SyB C-1101 560 mg/dose group, Participants will be administered 560 mg/dose of SyB C-1101 twice daily orally for 14 consecutive days, followed by 7-day observation period.

In both Cohorts, the treatment period of 21 days constitutes 1 cycle, and the treatment was allowed for up to cycles. The participants received SyB C-1101 only once daily on Day 1 and Day 14 of Cycle 1 for the investigation of the pharmacokinetics.

Arms:
arm 1: None

Interventions: intervention 1: SyB C-1101
Intervention descriptions: intervention 1: SyB C-1101（rigosertib sodium） will be administered to two cohorts at either 280 mg/day or 560 mg/day.

The dose will be administered orally twice daily for 14 consecutive days, followed by 7-day observation period. The treatment period of 21 days (14 days of administration + 7 days of observation) constitutes 1 cycle.

The study will involve treatment through the second cycle, but treatment can be continued for 3 or more cycles if conditions for continued administration are satisfied. However, treatment will be limited to a maximum of 6 cycles including the first cycle.

Protocol document: