In this phase I pilot study, it is planned to investigate the feasibility and safety of adding an interferon therapy to an preexisting imatinib treatment in patients with chronic phase chronic myeloid leukaemia. The participating patients have already reached a response during their imatinib therapy (CCyR) but have still a detectable disease (no molecular response MR 4.5 or better).

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