CLINICAL TRIAL / NCT05798611

Inclusion Criteria: - Patients who have discontinued all previous treatments for cancer for at least 21 days or 5 half-lives (not including palliative radiotherapy at focal sites), whichever is shorter. Palliative radiotherapy must have completed 1 week prior to start of study treatment. - Resolution of all toxicities of prior therapy or surgical procedures to baseline or Grade 1 (except for hypothyroidism requiring medication, neuropathy, and alopecia, which must have resolved to Grade ≤2). - Have adequate organ function. - Patients of childbearing potential and patients with partners of childbearing potential are required to use highly effective contraception. - Have an estimated life expectancy of ≥12 weeks, in the judgment of the investigator. - Performance status of 0-1 on the Eastern Cooperative Oncology Group scale. - Have a non-irradiated tumor tissue sample (archival or newly obtained core biopsy of a tumor lesion) available. Inclusion Criteria specific to each Arm Inclusion Criteria for Arm 1 [ART0380 monotherapy (endometrial cancer patients)] - Persistent or recurrent EC with biological selection. - Patients should have received taxane/platinum chemotherapy unless contraindicated. - Measurable disease. Inclusion Criteria for Arm 2 [ART0380 monotherapy (solid tumors patients)] - Advanced or metastatic solid cancers of any histology with biological selection. - If a Programmed cell death protein-1 /Programmed death-ligand-1 inhibitor (e.g., pembrolizumab) is approved and available for the patient's cancer, the patient should have received such treatment before participating in this study. - Radiologically evaluable disease. Exclusion Criteria: - Patients who are pregnant. - Prior treatment with an inhibitor of ATR, WEE1, checkpoint kinase 1 or PKMYT1. - Have a serious concomitant systemic disorder that would compromise the patient's ability to adhere to the protocol. - Have ongoing interstitial lung disease or pneumonitis (whether symptomatic or asymptomatic). - Patients with treated brain metastases are eligible if follow-up brain imaging after central nervous system (CNS) directed therapy shows no evidence of progression. - Have any major gastrointestinal issues that could impact absorption of ART0380. - Have a history of allergy or hypersensitivity to study drug components. - Have a significant bleeding disorder or vasculitis or had a Grade ≥3 bleeding episode within 12 weeks prior to enrollment. - Patients receiving potent inhibitors and inducers of CYP3A4 or CYP3A4 substrates which have a narrow therapeutic range or CYP3A4 sensitive substrates within 2 weeks before the first dose of study treatment will be excluded. - Patients receiving the following within 2 weeks of the first dose will be excluded from study treatment. 1. P-glycoprotein or breast cancer resistance protein (BCRP) inhibitors 2. Statins - Patients who plan to father a child while in the study or within 16 weeks (5 months in France) after the last administration of study treatment.