• I1. Male or female patient ≥ 18 years of age

• I2. Histologically or cytologically confirmed diagnosis of soft tissue sarcoma with documented p53 wild-type (wt) status and known MDM2 status (amplification or no amplification).

• Note: p53 wt status has to be determined by Next-generation sequencing of the full coding sequence using a tumor sample collected no longer than 36 months before inclusion.

• I3. Previously treated by at least one prior chemotherapy line of treatment in the advanced/metastatic setting.

• I4. STS subtypes eligible to pazopanib treatment according to respective SmPC Note: The following tumour types are eligible: Fibroblastic (adult fibrosarcoma, myxofibrosarcoma, sclerosing epithelioid fibrosarcoma, malignant solitary fibrous tumours), so-called fibrohistiocytic (pleomorphic malignant fibrous histiocytoma \[MFH\], giant cell MFH, inflammatory MFH), leiomyosarcoma, malignant glomus tumours, skeletal muscles (pleomorphic and alveolar rhabdomyosarcoma), vascular (epithelioid hemangioendothelioma, angiosarcoma), uncertain differentiation (synovial, epithelioid, alveolar soft part, clear cell, desmoplastic small round cell, extra-renal rhabdoid, malignant mesenchymoma, PEComa, intimal sarcoma), malignant peripheral nerve sheath tumours, undifferentiated soft tissue sarcomas not otherwise specified (NOS) and other types of sarcoma (not listed as ineligible)and liposarcoma.

• The following tumour types ARE NOT eligible: All rhabdomyosarcoma that are not alveolar or pleomorphic, chondrosarcoma, osteosarcoma, Ewing tumours/primitive neuroectodermal tumours (PNET), GIST, dermofibromatosis sarcoma protuberans, inflammatory myofibroblastic sarcoma, malignant mesothelioma and mixed mesodermal tumours of the uterus

• I5. Documented progressive disease and presence of at least one measurable lesion according to RECIST 1.1 (Appendix 01) based on screening tumor assessment.

• I6. Performance Status score of 0 or 1 according to the Eastern Cooperative Oncology Group (ECOG) scale.

• I7. Adequate organ system function as assessed by the following minimal requirements (within 7 days prior to first administration of study drugs (C1D1)):

• Absolute Neutrophil Count (ANC) ≥ 1.5 x 109/L Platelets ≥ 100 x 109/L Hemoglobin ≥ 9 g/dL (5.6 mmol/L). Transfusion is not allowed within 2 weeks of screening assessment.

• aspartate transaminase and alanine aminotransferase ≤ 2.5x Upper limit of normal or up to 5 Upper limit of normal in case of liver metastasis Bilirubin ≤ 1.5 Upper limit of normal (except in the setting of isolated Gilbert syndrome) Serum creatinine clearance ≥ 30 mL/min (calculated by CKD-EPI -Appendix 03) Calcium, magnesium and potassium within normal limits. Urine Protein to Creatinine ratio (UPC) \<1; if UPC ≥1, 24-hour urine protein must be \<1g (use of urine dipstick for renal function assessment is not acceptable).

• I8. Adequate cardiovascular function:

• QTcF (corrected QT using Fridericia) ≤450ms, from 3 electrocardiograms on screening ECG, within 14 days prior to C1D1 Resting blood pressure systolic \<140 mmHg and diastolic\< 90 mmHg, Left Ventricular Ejection Fraction ≥50% as determined by transthoracic echocardiogram or Multiple Gated acquisition.

• I9. Resolution (i.e. ≤ Grade 1 with the exception of alopecia all grades and Grade 2 for neuropathy, lab values presented in inclusion criteria) of any toxicities related to previous anti-cancer treatment.

• I10. Patients able to swallow orally administered medication and do not have any clinically significant gastrointestinal abnormalities that may alter absorption of study drugs such as malabsorption syndrome or major resection of the stomach or bowels.

• I11. Availability of archival Formalin Fixed Paraffin Embedded tumor sample. This sample must be sent to sponsor once eligibility is confirmed.

• I12. Expansion part only - Presence of at least one biopsiable lesion i.e. at least one lesion with a diameter ≥10 mm, visible by medical imaging and accessible to repeatable percutaneous or endoscopic sampling that permit core needle biopsy without unacceptable risk and suitable for retrieval of a minimum of three, but ideally four, cores using a biopsy needle of at least 16-gauge. Note: RECIST target lesion are not to be biopsied.

• I13. Women patient of child-bearing potential must have a negative serum pregnancy test before C1D1 and must agree to use effective forms of contraception from the time of the negative pregnancy test up to 6 months after the last dose of study drugs

• I14. Sexually active and fertile men must agree to use contraceptive measures up to 100 days after the last study drugs.

• I15. Written informed consent from patient before any study-specific screening procedures, and willingness to comply to study visits and procedures.

• I16. Patients must be covered by a medical insurance