Measurable disease by RECIST v1.1 Measurable disease by RECIST 1.1 (Phase 2 only) Subject in Phase 2 only: must have measurable disease per RECIST 1.1. 4. Measurable disease per RECIST v1.1 and irRECIST; Measurable disease by RECIST v1.1 with at least one measurable target lesion Measurable disease per RECIST 1.1. Dose Escalation: Evaluable or measurable disease according to RECIST v1.1 Expansion Cohort (additional 30 patients) Measurable disease according to RECIST v1.1. Measurable disease by RECIST v1.1 with at least 1 measurable lesion; Measurable disease per RECIST 1.1. Measurable disease by RECIST 1.1 Subject has at least one measurable lesion per RECIST v1.1. Measurable disease via RECIST Subject must have measurable neoplastic disease according to the RECIST v1.1; Measurable disease by RECIST v1.1 One site of measurable disease by RECIST 1.1 Participants must have measurable disease (RECIST 1.1) Subjects must have measurable lesions (according to standard RECIST 1.1). Baseline measurable disease as measured by RECIST v1. 1. Has measurable disease per RECIST 1.1 as assessed by the investigator/radiology Measurable disease per RECIST v1.1 Presence of measurable disease per RECIST v1.1. Has measurable disease per RECIST 1.1 as determined by investigator Phase 1a: measurable or non-measurable disease per RECIST v 1.1. Phase 1b: measurable disease per RECIST v 1.1 (subjects with non-measurable disease are not eligible for Phase 1b). At least 1 measurable lesion by RECIST 1.1 INCLUSION CRITERIA FOR REGISTRATION (HER2 MUTATION IDENTIFIED AT AN OUTSIDE CLIA CERTIFIED LOCATION): Presence of measurable or non-measurable disease by RECIST 1.1 is acceptable, except to be eligible for the Part II fulvestrant-naive ER+ cohort, at least one measurable disease by RECIST 1.1 is required Disease must be measurable with at least 1 unidimensional measurable lesion by RECIST 1.1. Measurable disease per RECIST v1.1 Measurable disease per RECIST v1.1 by radiographic techniques Presence of at least one measurable lesion according to RECIST v1.1. Presence of at least one measurable lesion according to RECIST v1.1. Measurable disease by RECIST 1.1 PHASE IB: Measurable disease according to RECIST v1.1 Measurable disease, according to RECIST, v1.1 Patients must have measurable disease according to RECIST 1.1 PART II: Patients must have measurable disease, per RECIST 1.1 Measurable disease as outlined in RECIST 1.1 Patients must have metastatic disease, per RECIST 1.1 for the evaluation of measurable disease. Measurable or non-measurable disease according to RECIST v1.1 or RECIL 2017. Measurable disease per RECIST 1.1 Measurable disease by RECIST 1.1 Measurable disease according to RECIST 1.1. COHORT 3: ENDOMETRIAL CANCER: Patients must have measurable disease, per RECIST 1.1 Presence of measurable disease by RECIST 1.1 Presence of measurable disease per RECIST v1.1. Measurable or non-measurable disease according to RECIST v1.1 or RECIL 2017. Measurable disease by RECIST For disease-specific cohort participants: measurable disease per RECIST v. 1.1 Phase 2: Participants must have measurable disease as per RECIST 1.1. Have measurable disease per RECIST v1.1, assessed within 4 weeks prior to study entry Measurable disease (RECIST 1.1) Patients must have measurable soft tissue disease per RECIST 1.1 Measurable disease according to RECIST v1.1 within 28 days prior to randomization Measurable disease per RECIST 1.1 Measurable disease according to RECIST 1.1 within 28 days prior to registration. Measurable disease by RECIST 1.1 Measurable disease by CT or MRI as per RECIST 1.1. Bone-only disease is not permitted. Measurable disease per RECIST v.1.1 Measurable disease according to RECIST 1.1. Measurable disease per RECIST 1.1 (primary or metastases) Measurable disease, according to modified RECIST 1.1 and irRECIST Patients must have measurable disease according to RECIST 1.1 Measurable disease by RECIST 1.1 Presence of at least one measurable lesion according to RECIST v.1.1 Disease must be measurable by RECIST 1.1 Patients must have measurable disease as per RECIST v1.1 At least one measurable lesion of the disease on imaging (CT or MRI; RECIST 1.1) Measurable or non-measurable disease according to RECIST v1.1 or RECIL 2017. Subject has at least one measurable lesion according to RECIST 1.1. Patient with measurable disease according to RECIST Has measurable disease per RECIST 1.1 as assessed by the local site investigator/radiology Measurable disease per RECIST 1.1 as assessed by the local site investigator/radiology. Measurable Disease by RECIST v1.1 Measurable disease according to RECIST v1.1. Measurable disease per RECIST v1.1 for patients with solid malignancies. Measurable disease by RECIST 1.1 guidelines For the expansion cohort only: measurable disease by RECIST v1.1 with at least one measurable target lesion Measurable disease as assessed by modified RECIST for MPM for thoracic disease (Appendix A) and RECIST 1.1 for extra-thoracic disease (Appendix B). Measurable disease according to RECIST 1.1 within 30 days prior to registration. Participants must have measurable disease by RECIST 1.1 Presence of measurable disease according to RECIST 1.1 Patients must have measurable disease according to RECIST 1.1 Measurable disease according to RECIST v1.1 Measurable disease as per RECIST 1.1. Subject must have extracranial metastasis as measurable disease Measurable lesions by RECIST v1.1 Patients must have measurable disease according to RECIST (v.1.1). Radiologically measurable disease according to RECIST v1.1 Measurable disease per RECIST v1.1 One or more tumors measurable on CT scan per RECIST 1.1. Measurable Disease per RECIST 1.1 as determined by the Investigator Measurable disease on CT or MRI by RECIST 1.1. Measurable disease by RECIST Has measurable disease per RECIST 1.1 as assessed by BICR. Subject must have either measurable disease or bone only non measurable disease, according to RECIST1.1 Measurable disease according to RECIST v1.1 Has measurable disease per RECIST 1.1 as assessed by the investigator/site radiologist. Measurable disease per RECIST 1.1 guidelines. Measurable disease per RECIST v1.1 Measurable disease per RECIST v1.1 Measurable disease according to RECIST v1.1 Measurable disease per RECIST v1.1 Presence of at least one measurable lesion according to RECIST v.1.1 Disease must be measurable by RECIST 1.1 Measurable disease, according to the RECIST v1.1 Non-measurable disease according to RECIST 1.1, with the exception of bone-only non-measurable disease. Patients must not have measurable progressive disease (RECIST 1.1) Measurable disease per RECIST v1.1 (see Appendix 3) Presence of measurable disease per RECIST v1.1. Cancer antigen-125 (CA-125) only disease without RECIST 1.1 measurable disease Does not have measurable disease per RECIST 1.1 Disease must be measurable by RECIST 1.1 Measurable disease according to RECIST 1.1. Measurable disease per RECIST v1.1. Evidence of measurable disease per RECIST 1.1 Have measurable disease according to RECIST v1.1 obtained by imaging within 28 days prior to registration. Measurable disease as per RECIST v1.1 Subjects must have at least one measurable lesion per RECIST 1.1 Presence of measurable lesions (RECIST V1.1) Measurable disease according to RECIST 1.1 Patient has measurable disease by (RECIST). Measurable disease according to RECIST v1.1 Patients must have RECIST v1.1 measurable disease Measurable disease per RECIST 1.1 as determined by the investigator. Disease must be measurable, with ?1 unidimensional measurable lesion per RECIST 1.1. Measurable disease as per RECIST v. 1.1. Presence of measurable disease per RECIST v1.1 Measurable disease according to RECIST v 1.1 obtained by imaging within 28 days prior to registration Measurable disease as per RECIST 1.1 Measurable disease according to RECIST 1.1 Measurable disease per RECIST v1.1 (see Appendix 6) Measurable disease per RECIST v1.1 Measurable disease by RECIST 1.1 Measurable disease per RECIST v1.1 Measurable disease as per RECIST v1.1 Measurable disease per RECIST v1.1 Subjects may have measurable or non-measurable disease according to RECIST 1.1. Measurable disease per RECIST 1.1 guidelines. Cohort 2 may include up to 10 subjects with advanced MET amplified, G/GEJ/E adenocarcinoma with non-measurable tumor per RECIST v1.1 At least 1 site of disease measurable by RECIST ver1.1 At least one measurable or non-measurable lesion as per RECIST 1.1 criteria for patients in Phase Ib; Measurable disease as determined by RECIST v1.1 for Phase II patients Measurable disease that can be monitored per RECIST throughout the course of study participation. Patient must have either measurable disease by RECIST 1.1 or bone lesions in absence of measurable disease. Measurable disease (per RECIST v1.1) prior to the start of first-line chemotherapy Measurable disease by RECIST 1.1 Measurable disease as per RECIST 1.1 Disease that is measurable per RECIST v1.1 Measurable disease by RECIST v1.1 with at least one measurable target lesion Measurable disease per RECIST 1.1 Measurable lesion by RECIST 1.1 ECOG performance status 0 or 1 5. Measurable disease per RECIST v1.1 Measurable disease as per RECIST v1.1 Measurable disease as per RECIST 1.1. At least one measurable lesion per RECIST v1.1. However, breast cancer patients with only bone disease are also eligible. Patient has progressive and measurable disease as per RECIST 1.1. or other appropriate hematological guidelines. Patient has progressive and measurable disease as per RECIST 1.1 or other appropriate hematological guidelines. Measurable disease per RECIST v1.1. Measurable disease per RECIST 1.1 Patients must have at least one measurable site of disease according to RECIST 1.1 that has not been previously irradiated Measurable disease by RECIST At least one measurable disease site per RECIST v1.1. Disease that is measurable per modified RECIST v1.1 Measurable radiographic evidence of disease according to RECIST v1.1 Measurable disease (by RECIST 1.1) Measurable disease according to RECIST v1.1 prior to administration of study drug Measurable disease by RECIST 1.1 with PCWG2 modifications Measurable disease according to RECIST v1.1 Measurable disease per RECIST v 1.1 Measurable Disease per RECIST 1.1 Measurable disease by RECIST v1.1 Measurable disease per RECIST v1.1 Measurable disease as determined by RECIST 1.1 Measurable disease according to RECIST Measurable disease at presentation with disease measurable by RECIST required in the phase II cohort Measurable disease according to RECIST and obtained by imaging within 30 days prior to registration for protocol therapy. Measurable disease by RECIST 1.1 For the expansion cohort only: measurable disease by RECIST v1.1 with at least one measurable target lesion Have measurable disease per RECIST v.1.1. Measurable disease per RECIST v1.1 Subjects must have at least one lesion that is measurable by RECIST v1.1 At least 1 measurable tumor lesion per RECIST v1.1 (exception: subjects in Part 1 are not required to present with measurable disease) Evidence of measurable disease by RECIST 1.1 Tumor to be irradiated as measurable by RECIST 1.1 or PRC Measurable disease according to RECIST v1.1 Measurable disease by RECIST 1.1 With the exception of patients with non-measurable neuroblastoma patients must have measurable disease as per RECIST 1.1 Presence of measurable (by RECIST v1.1) and active extracranial disease will be excluded; patients with measurable extra cranial disease by RECIST v1.1 will be eligible to enroll if sites of disease are stable and not considered to be active after discussion with the sponsor The participant has measurable or non-measurable disease according to RECIST 1.0 guidelines. Patients must have measurable disease per RECIST v. 1.1.