Long-acting Low Dose Ropeginterferon for Chronic Myeloid Leukemia Treated With Bosutinib From Diagnosis

Inclusion Criteria: * Signed written informed consent form (ICF) before any procedure related to the study * Newly diagnosed (≤ 3 months) BCR-ABL positive chronic myeloid leukemia (CML) in chronic phase * Major BCR-ABL transcripts (p210 b2a2(e13a2) and/or b3a2 (e14a2) * Not previously treated for CML except with hydroxyurea or anagrelide * ECOG Performance Status (ECOG PS) ≤ 2 * Adequate organ function: Total bilirubin \< 1,5 times the institutional Upper Limit of Normal (ULN); Hepatic enzymes ASAT and ALAT \< 2 times the institutional ULN; Serum Creatinine \< 1.5 time the institutional ULN; Lipase \< 1.5 time the institutional ULN * Women of childbearing potential (WOCBP) must be using an adequate method of contraception to avoid pregnancy throughout the study. * WOCBP must have a negative serum or urine pregnancy test at screening. * Free subject, without guardianship nor subordination * Health insurance coverage Exclusion Criteria: * Patients with BCR-ABL transcript other than M-BCR-ABL * Patients previously treated with tyrosine kinase inhibitors (TKIs). * Inability to freely provide consent through judiciary or administrative condition. * Ongoing participation to another clinical investigational study. * Medical history and concurrent diseases: a) Hypersensitivity to any of the excipients of BOS or RoPegIFN, b) Prior treatment with Interferon-α, contraindication to interferon-α, c) Autoimmune disorder, concomitant immunosuppressive treatment or corticosteroids, d) Pre-existing thyroid disease unless controlled with conventional treatment, auto-immune thyroiditis, e) Chronic liver disease, f) Prior or ongoing severe psychiatric disease, g) HIV positivity, chronic hepatitis B or C, h) Uncontrolled or severe cardiac (NYHA Class III or IV) or pulmonary disease, echocardiography with LVF \< 45% or LLN, peak velocity of tricuspid regurgitant flow \> 2,8 m/s, pulmonary arterial hypertension (PAH), QTc\>450 ms (by Barrets correction) * Other malignant disease during the last 5 years prior to the inclusion except non-melanoma skin carcinoma or carcinoma in situ of the cervix, * History of significant bleeding disorder unrelated to CML or diagnosed congenital bleeding disorder, * Subjects with an uncontrolled undercurrent illness or any concurrent condition that, in the investigator's opinion, would jeopardize the safety of the subject or compliance with the protocol. * Prohibited treatments and/or therapies: strong inhibitors/inducers of the CYP 3A4, * History / any condition for poor compliance to medical treatment. * Women who are pregnant or breastfeeding are not eligible for this study