Key Inclusion Criteria:  Age ≥ 18 years Relapsed/metastatic solid tumors treated with prior adequate standard of care therapy for tumor type and stage of disease or where in the opinion of the Investigator, a clinical trial is the best option for the next treatment based on response and/or tolerability to prior therapy. Measurable disease per RECIST v1.1 Eastern Cooperative Oncology Group (ECOG) Performance Status: 0-1 Life expectancy ≥ 12 weeks Adequate organ and marrow function as defined in the protocol  For Sub-Study 1 Part A:  • Histologically or cytologically confirmed metastatic or locally advanced/recurrent breast cancer, ovarian cancer, CCA or endometrial cancer  For Sub-Study 1 Part B:  Histologically or cytologically confirmed metastatic or locally advanced and recurrent disease for the respective cohort:  Cohort B1 (Cholangiocarcinoma): at least one prior systemic line of therapy for metastatic/relapsed disease. Cohort B2 (Serous Ovarian Cancer): at least one prior systemic line of therapy for metastatic/relapsed disease.  Cohort B3 (Triple Negative Breast Cancer): no more than one prior systemic line of therapy for metastatic/relapsed disease.  Exclusion Criteria:  Treatment with any of the following:  Nitrosourea or mitomycin C within 6 weeks prior to the first dose of study treatment Any investigational agents or study drugs from a previous clinical study within 5 half-lives or 28 days (whichever is shorter) prior to the first dose of study treatment  Any other anticancer treatment within the following time periods prior to the first dose of study intervention:  Cytotoxic treatment: 21 days Non-cytotoxic drugs: 21 days or 5 half-lives (whichever is shorter) Biological products including immuno-oncology agents: 28 days Spinal cord compression or a history of leptomeningeal carcinomatosis. Brain metastases unless treated, asymptomatic, stable, and not requiring continuous corticosteroids at a dose of > 10 mg prednisone/day or equivalent for at least 4 weeks prior to start of study. Active infection including tuberculosis and HBV, HCV or HIV History of (non-infectious) ILD/pneumonitis that required steroids, has current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at screening. Clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses  Participants with any of the following cardiac criteria:  History of arrhythmia which is symptomatic or requires treatment (NCI CTCAE v5.0 Grade 3); symptomatic or uncontrolled atrial fibrillation, or asymptomatic sustained ventricular tachycardia. Uncontrolled hypertension. Acute coronary syndrome/acute myocardial infarction, unstable angina pectoris, coronary intervention procedure with percutaneous coronary intervention, or coronary artery bypass grafting within 6 months. History of brain perfusion problems (eg, carotid stenosis) or stroke, or transient ischemic attack in the last 6 months prior to screening. Symptomatic heart failure (NYHA class ≥ 2). Prior or current cardiomyopathy. Severe valvular heart disease. Mean resting QTcF > 470 msec. Risk factors for QTc prolongation or risk of arrhythmic events such as heart failure, congenital long QT syndrome, family history of long QT syndrome or unexplained sudden death under 40 years of age.