Inclusion Criteria:  Male or female and ≥18 years-of-age at the time of signature of the informed consent Confirmed advanced solid tumors resistant or refractory to standard treatment Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1. Measurable disease as per RECIST v1.1 Next generation sequencing (NGS) report obtained in CLIA-certified or equivalent laboratory demonstrating eligible tumor biomarkers. Submission of available tumor tissue or willingness to have a biopsy performed if safe and feasible Acceptable hematologic and organ function at screening Negative pregnancy test for women of childbearing potential at Screening and prior to first study drug. Ability to swallow and retain oral medications.  Exclusion Criteria:  Prior therapy with an ATR or DNA-dependent protein kinase (DNA-PK) inhibitor. Chemotherapy, small molecule anticancer or biologic anticancer therapy given within 10 days or 5 half-lives (whichever is longer), prior to first dose of study drug. Use of radiotherapy (except for palliative reasons) within 7 days prior to first dose of study drug. History or current condition, therapy, or laboratory abnormality that might confound the study results, or interfere with the patient's participation for the full duration of the study treatment. No other anticancer therapy is to be permitted while the patient is receiving study treatment. Major surgery ≤28 days or minor surgical procedures ≤7 days prior to first study treatment dose. Uncontrolled, symptomatic brain metastases. Uncontrolled high blood pressure History of myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) diagnosis Presence of other known active invasive cancers. Pregnant or breastfeeding women. Psychological, familial, sociological, or geographical conditions that do not permit compliance with the study protocol and/or follow-up procedures outlined in the protocol.