Safety and Preliminary Efficacy of SA53-OS in Patients With Locally Advanced or Metastatic Solid Tumors

The objective of this study is to assess the safety, efficacy, and pharmacokinetics of SA53-OS in adult participants with refractory solid tumors. The study is comprised of 2 parts: Part 1 called dose escalation, and Part 2a called dose expansion. This study starts with Part 1 where participants who are diagnosed with advanced or metastatic solid tumor cancers receive different doses of SA53-OS (starting with the lowest dose) to find the maximum tolerated dose (MTD) of SA53-OS. Once the MTD of SA53-OS is known, the study continues to Part 2a where participants who are diagnosed with dedifferentiated liposarcoma (DD LPS) or other solid tumor cancers will receive SA53-OS at the MTD. The study drug, SA53-OS, will be administered for 3 consecutive days every 3 weeks as an oral solution for up to 2 years.