Addition of P1101 to Imatinib Treatment in Patients With Chronic Phase Chronic Myeloid Leukaemia Not Achieving a Complete Molecular Response

Inclusion Criteria: * Patients ≥ 18 years of age * BCR-ABL positive chronic myeloid leukaemia in chronic phase treated with imatinib as first line therapy * CHR, CCyR after at least 18 months of imatinib treatment * Adequate organ function, defined as the following: * total bilirubin \< 1.5 x ULN, * AST and ALT \< 2.5 x ULN, * creatinine \< 1.5 x ULN, * ANC \> 1.5 x 109/L, * platelets \> 100 x 109/L * Written, voluntarily signed informed consent Exclusion Criteria: * CMR (molecular remission 4.5 or BCR-ABL transcripts undetectable) * Patient has received any other investigational treatment within 28 days before study entry * Treatment with a second generation tyrosine kinase inhibitor (dasatinib, nilotinib) * ECOG performance status ≥ 3 * Patients with a primary of a different histological origin than the study indication (unless relapse-free interval is ≥ 5 years, except cervical carcinoma, basal cell epithelioma or squamous cell carcinoma of the skin) * Evidence of severe or uncontrolled systemic disease (e.g. unstable or uncompensated respiratory, cardiac, hepatic or renal disease etc.) * Acute chronic infections * Known autoimmune disease (e.g. collagen disease, polyarthritis, immune thrombocytopenia, thyroiditis, psoriasis, lupus nephritis or any other autoimmune disorder) * Female patients who are pregnant or breast-feeding * Known diagnosis of HIV