A Study of PARG Inhibitor IDE161 in Participants With Advanced Solid Tumors

Inclusion Criteria:

1. Adult participants must be 18 years of age or older

2. Advanced or metastatic solid tumors excluding primary central nervous system (CNS)tumors

3. For Module 1 only, Have documented evidence of BRCA1/2 and/or genetic alterationsconferring homologous recombination deficiency (HRD) (ATM, BARD1, BRIP1, CDK12,CHEK1, CHEK2, FANCL, PALB2, PPP2R2A, RAD51B, RAD51C, RAD51D, RAD54L, NBN, FANCA) For Module 2 only, results of MSI and/or MMR testing required. For Module 2 only, results of BRCA1/2 and HRD gene testing required.

4. Participant must have progressed on at least one prior line of therapy in theadvanced or metastatic setting that is considered an appropriate standard of care,or for which the participant has documented intolerance

5. For Module 2 only, advanced or metastatic Endometrial Cancer (uterine carcinosarcomais excluded)

6. For Module 2 only, Must have progressed on treatment with an anti-PD-1/L1 monoclonalantibody (MAB)

Exclusion Criteria:

1. Known primary CNS malignancy

2. Impairment of GI function or GI disease that may significantly alter the absorptionof IDE161

3. Have active, uncontrolled infection

4. Clinically significant cardiac abnormalities

5. Major surgery within 4 weeks prior to enrollment

6. Radiation therapy within 2 weeks prior to enrollment

7. Systemic cytotoxic chemotherapy within 4 weeks prior to enrollment

8. Radioimmunotherapy within 6 weeks of enrollment

9. Treatment with a therapeutic antibody within 4 weeks prior to enrollment

10. Treatment with an anti-cancer small molecule within 5 half-lives (t1/2), or 2 weeks,whichever is shorter

11. Have current active liver or biliary disease

12. For Module 2 only, History or allogeneic tissue/solid organ transplant

13. For Module 2 only, Active autoimmune disease that has required systemic treatment inpast 2 years

14. For Module 2 only, History of (noninfectious) pneumonitis/interstitial lung diseasethat required steroids or has current pneumonitis/interstitial lung disease