Granulocyte-macrophage colony stimulating factor (GM-CSF) enhances the clinical responses to interferon-α (IFN) in newly diagnosed chronic myeloid leukemia (CML).

The majority of chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors (TKIs) remain with residual disease. In contrast to TKIs, interferon (IFN) is directly toxic to CML progenitor cells, and myeloid growth factors such as GM-CSF may enhance IFN's cytotoxicity. We performed a phase 2 study of IFN+GM-CSF in 58 newly diagnosed CML patients before imatinib approval. Short-term clinical responses included: 60% major cytogenetic response, 28% complete cytogenetic response and 19% complete molecular response. Six patients remain off all therapy for CML (range: 15 months-12 years) after IFN+GM-CSF treatment. IFN+GM-CSF shows promise as an adjunctive therapy for CML.