Suppression of clonal evolution in two chronic myelogenous leukaemia patients treated with leucocyte interferon.

Two patients with Philadelphia chromosome-positive (Ph1+) chronic myelogenous leukaemia (CML) were treated with human leucocyte interferon (HuIFN-alpha). Karyotypic changes in addition to the Ph1 chromosome developed in these patients before the start of HuIFN-alpha treatment. In one patient the administration of HuIFN-alpha resulted in clinical haematological remission and stable suppression of the secondary Ph1 clone. The second patient was in myeloid blastic crisis when given HuIFN-alpha. While she was receiving HuIFN-alpha, suppression of the blast cell population in the bone marrow occurred. The subsequent cytogenetic changes included a near-complete suppression of a secondary Ph 1 clone of cells carrying a deletion in the short arm of chromosome 7 and partial population of the bone marrow with primary Ph1 clone. These observations suggest a potential role for interferons in altering the progressive course of CML.