Study of SYN818 for the Treatment of Advanced or Metastatic Solid Tumors

This study is testing an experimental drug called SYN818 — which targets a DNA repair protein called Pol theta (POLQ) — in people with advanced or metastatic solid tumors (breast, ovarian, prostate, or other cancers) who have a defect in the body's DNA repair system, including BRCA mutations, and whose cancer has progressed after standard treatments. **You may be eligible if...** - You are 18 or older - You have been diagnosed with advanced or metastatic breast cancer, ovarian cancer, prostate cancer, or another solid tumor - Your cancer has progressed and all available standard treatments have been exhausted - You are willing to provide a tumor tissue or blood sample for genetic testing - You have at least one measurable tumor on scans - Your general health, organ function, and blood counts are adequate **You may NOT be eligible if...** - You have previously taken a POLQ inhibitor drug (the same class as SYN818) - You are allergic to the drug's active ingredient or components - You have active brain or spinal fluid metastases that are not well-controlled - You have another cancer diagnosed within the past 5 years (certain low-risk cancers may be exceptions) - You have conditions affecting swallowing or gut absorption of the drug - You have signs of or risk factors for bone marrow failure (MDS/AML) Talk to your doctor to see if this trial is right for you.