Severe cytopenias associated with the sequential use of busulphan and interferon-alpha in chronic myeloid leukaemia

We describe four patients who developed severe thrombocytopenia which progressed to aplasia after the use of alpha-interferon in maintenance therapy of chronic phase CML after busulphan induction. On reviewing over 400 patients in the MRC CML III trial we found that there is a risk of cytopenia developing after busulphan therapy and a lesser risk of cytopenias developing after alpha-interferon therapy. If the therapies are given in a sequential fashion the risk of cytopenia developing appears to be additive, may be pronounced, and may lead to clinically significant problems. Hydroxyurea alone does not lead to sustained cytopenia. Care should be taken to ensure that counts are stable after the use of busulphan before starting alpha-interferon as maintenance therapy.