This clinical trial is for men and women who have a solid tumor cancer (not a blood cancer) that has worsened and has not responded to at least one prior cancer treatment. Participants’ tumor DNA must also have an error in one of the genes associated with the homologous recombination (HR) pathway including but not limited to BRCA1 or 2 (Breast Cancer 1 or 2).
   
The purpose of this study is to find out if an experimental drug called IDE161 used alone is safe and helpful in solid tumors known to be caused by an error in genes that repair DNA. “Experimental” means that the drug has not been approved for use by the U.S. Food and Drug Administration (FDA) and other regulatory authorities. This is the first study of IDE161 in humans.
   
Cells have different ways to repair damaged DNA. One of these paths is called homologous recombination (HR). An error in genes that belong to HR (homologous recombination deficiency, HRD) can lead to abnormal cell growth, which can lead to cancer.
   
IDE161 is a new investigational (experimental) drug that blocks the ability of a protein called Poly(ADP-ribose) glycohydrolase (PARG) from properly functioning. PARG is an important protein in a different DNA repair pathway called Base Excision Repair (BER). Studies have shown that tumors with errors in the HR genes have a greater potential for responding to study treatment with IDE161.
   
Participants will be asked to take the study drug orally (by mouth) once each day. A study treatment cycle is defined as 21 days. Participants will be asked to come to the Study Doctor’s clinic approximately 1-3 times during the first 2 cycles (including 2 long visits lasting up to 8 hours), and then once per cycle for the subsequent cycles until they are no longer receiving the study drug.
   
Participation in this study may occur for up to approximately 30 months, which includes a 28-day screening period, up to 24 months of study treatment, and an estimated follow-up period of 3-6 months. Participants will be followed for survival every 3 months for up to 2 years via telephone calls, medical records, and/or clinic visits.