Joëlle Guilhot

BACKGROUND: Treatment with interferon prolongs survival in chronic myelogenous leukemia. We conducted a clinical trial to assess the efficacy of treatment with a combination of interferon and cytarabine. METHODS: Previously untreated patients with chronic myelogenous leukemia were randomly assigned to receive either hydroxyurea (50 mg per kilogram of body weight per day) and interferon alfa-2b (5 million units per square meter of body-surface area per day), or hydroxyurea and interferon in the same dosages plus monthly courses of cytarabine (20 mg per square meter per day, for 10 days). The end points were overall survival, complete hematologic remission at 6 months, and major cytogenetic response (less than 35 percent Philadelphia chromosome-positive cells in the bone marrow) at 12 months. RESULTS: The trial was stopped when a sequential analysis showed a benefit of interferon and cytarabine. A significant improvement in survival was observed in the interferon-cytarabine group (360 patients) as compared with the interferon group (361 patients) (P=0.02; relative risk of death, 0.64; 95 percent confidence interval, 0.44 to 0.93). After three years, the survival rate was 85.7 percent with interferon and cytarabine and 79.1 percent with interferon alone. The rate of hematologic response was higher in the interferon-cytarabine group than in the interferon group (P=0.003). Major cytogenetic responses were observed 12 months after randomization in 126 of 311 patients treated with interferon and cytarabine (41 percent) and in 75 of 314 patients treated with interferon only (24 percent, P<0.001). CONCLUSIONS: The combination of interferon and cytarabine, as compared with interferon alone, increases the rate of major cytogenetic response and prolongs survival in patients with the chronic phase of chronic myelogenous leukemia.

The outcome of chronic myeloid leukemia (CML) has been profoundly changed by the introduction of tyrosine kinase inhibitors into therapy, but the prognosis of patients with CML is still evaluated using prognostic scores developed in the chemotherapy and interferon era. The present work describes a new prognostic score that is superior to the Sokal and Euro scores both in its prognostic ability and in its simplicity. The predictive power of the score was developed and tested on a group of patients selected from a registry of 2060 patients enrolled in studies of first-line treatment with imatinib-based regimes. The EUTOS score using the percentage of basophils and spleen size best discriminated between high-risk and low-risk groups of patients, with a positive predictive value of not reaching a CCgR of 34%. Five-year progression-free survival was significantly better in the low- than in the high-risk group (90% vs 82%, P = .006). These results were confirmed in the validation sample. The score can be used to identify CML patients with significantly lower probabilities of responding to therapy and survival, thus alerting physicians to those patients who require closer observation and early intervention.

Purpose Imatinib (IM) can safely be discontinued in patients with chronic myeloid leukemia (CML) who have had undetectable minimal residual disease (UMRD) for at least 2 years. We report the final results of the Stop Imatinib (STIM1) study with a long follow-up. Patients and Methods IM was prospectively discontinued in 100 patients with CML with UMRD sustained for at least 2 years. Molecular recurrence (MR) was defined as positivity of BCR-ABL transcript in a quantitative reverse transcriptase polymerase chain reaction assay confirmed by a second analysis point that indicated an increase of one log in relation to the first analysis point at two successive assessments or loss of major molecular response at one point. Results The median molecular follow-up after treatment discontinuation was 77 months (range, 9 to 95 months). Sixty-one patients lost UMRD after a median of 2.5 months (range, 1 to 22 months), and one patient died with UMRD at 10 months. Molecular recurrence-free survival was 43% (95% CI, 33% to 52%) at 6 months and 38% (95% CI, 29% to 47%) at 60 months. Treatment was restarted in 57 of 61 patients with MR, and 55 patients achieved a second UMRD with a median time of 4 months (range, 1 to 16 months). None of the patients experienced a CML progression. Analyses of the characteristics of the study population identified that the Sokal risk score and duration of IM treatment were significantly associated with the probability of MR. Conclusion With a median follow-up of more than 6 years after treatment discontinuation, the STIM1 study demonstrates that IM can safely be discontinued in patients with a sustained deep molecular response with no late MR.