Multiorgan Metabolic Imaging Response Assessment of Abemaciclib

Inclusion Criteria: 1. Age ≥ 18 years old 2. Female or male 3. ECOG performance status ≤ 1 4. Life expectancy of greater than 12 weeks 5. Must have histologically confirmed cancer corresponding to the predefined tumour subtypes (esophageal adenocarcinoma, esophageal squamous cell carcinoma, cholangiocarcinoma, urothelial cancer (progressive after immunotherapy), endometrial cancer) and metastatic or non-resectable and refractory to standard platinum regimens (and progressive after immunotherapy for the urothelial cancer). 6. Presence of at least one metabolically measurable tumour lesion on FDG-PET/CT, according to PERCIST. If previously irradiated, must have been more than 2 months before the baseline FDG PET/CT. 7. Measurable disease according to RECIST v 1.1 8. Serum pregnancy test (for subjects of childbearing potential) negative 9. Women of childbearing potential must agree to the use a highly effective method of contraception prior to study entry, during the course of the study and at least 3 months after the last administration of study treatment. 10. Men with childbearing potential partner must agree to use condom during the course of this study and for at least 3 months after the last administration of the study treatment. 11. Adequate coagulation: International Normalized Ratio (INR) ≤ 1.5 x ULN unless subject is receiving anticoagulant therapy as long as INR and activated partial thromboplastin time \[aPTT\] are within therapeutic range of intended use of anticoagulants 12. Adequate bone marrow function as defined below: * Hemoglobin ≥ 10 g/dL * Absolute neutrophil count ≥ 1500/µL or 1.5x109/L * Platelets ≥ 100000/µL or 100x109/L * Leukocytes ≥ 3,000/µL 13. Adequate liver function as defined below: * Serum total bilirubin within 1.5 × normal institutional limits (except for Gilbert syndrome where direct bilirubin should be \<1.5 institutional ULN) * AST/ALT/ALP) levels \< 3 × institutional upper limit of normal (or ALT and AST \<5 times upper limit of normal if liver metastases are present). 14. Adequate renal function as defined below: Cockcroft-Gault creatine clearance \>50ml/min 15. Completion of all necessary screening procedures 16. Ability to swallow capsules 17. Grade ≤ 1 toxicity due to any previous cancer therapy according to the National Cancer Institute Common Terminology Criteria of Adverse Events (NCI-CTCAE, v.4.03). Grade 2 is allowed in case of alopecia and peripheral sensory neuropathy 18. Availability of primary archived tumour tissue block (1 FFPE tumour tissue) 19. Signed Informed Consent form (ICF) obtained prior to any study related procedure Exclusion Criteria: 1. Subjects meeting one of the following criteria are not eligible for this studyParticipants who have had chemotherapy, radiotherapy, immunotherapy, or targeted therapy within 3 weeks prior study enrolment 2. Participants receiving concomitantly any other experimental agents 3. Patients who have received prior therapy with other CDK4/6 inhibitors 4. Subjects with known brain metastasis; unless the metastasis are asymptomatic and have been stable since at least 2 months prior to treatment start. 5. Patient with meningeal carcinomatosis 6. Have had major surgery within 28 days prior to the start of the treatment to allow for post-operative healing of the surgical wound 7. History of allergic reactions attributed to compounds of similar chemical or biologic composition 8. Bleeding diathesis, thromboembolic event, history of cardiovascular ischemic disease or cerebrovascular incident within the last six months 9. Uncontrolled concurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia 10. Substance abuse, psychiatric illness/social situations, any psychological, familial, sociological, geographical condition, significant medical or surgical condition currently uncontrolled by treatment that would limit compliance with study requirements or interfere with the patient's ability to understand informed consent and participation in the study 11. Pregnant and/or lactating women 12. Uncontrolled Diabetes 13. Known history of HIV infection, or active hepatitis B or C requiring treatment with anti-viral therapy 14. Have received recent (within 28 days prior the enrolment) yellow fever vaccination 15. Individuals with a history of a different malignancy are ineligible except for the following circumstances. Individuals with a history of other malignancies are eligible if they have been disease-free and are deemed by the investigator to be at low risk for recurrence of that malignancy.