• Histologically confirmed leiomyosarcomas.

• Metastatic or unresectable locally advanced disease,

• Documented progression according to RECIST v1.1 confirmed by central review,

• Age ≥ 18 years,

• ECOG ≤ 1,

• Life expectancy \> 3 months,

• No more than 3 previous line of systemic therapy for advanced disease,

• Patients must have advanced disease and must not be a candidate for other approved therapeutic regimen known to provide significant clinical benefit based on investigator judgement,

• Patients must have measurable disease defined as per RECIST v1.1

⁃ Patient must comply with the collection of tumor biopsies, and tumors must be accessible for biopsy,

⁃ At least three weeks since last chemotherapy, immunotherapy or any other pharmacological treatment and/or radiotherapy,

⁃ Adequate hematological, renal, metabolic and hepatic function

⁃ Women of childbearing potential must have a negative serum pregnancy test within 7 days prior to randomization.

⁃ Both women of childbearing potential and men must agree to use a highly effective method of contraception 28 days before start of first dose of study drug

⁃ No prior or concurrent malignant disease diagnosed or treated in the last 2 years except for adequately treated in situ carcinoma of the cervix, basal or squamous skin cell carcinoma, or in situ transitional bladder cell carcinoma,

⁃ Recovery to grade ≤ 1 from any adverse event (AE) derived from previous treatment

⁃ Voluntarily signed and dated written informed consent prior to any study specific procedure,

⁃ Patients with a social security in compliance with the French law.