Prediction of initial cytogenetic response for subsequent major and complete cytogenetic response to imatinib mesylate therapy in patients with Philadelphia chromosome-positive chronic myelogenous leukemia [3] (multiple letters)

Indications:167 patients with Philadelphia chromosome positive chronic myeloid leukemia in chronic phase.

Patients:167 patients. Median follow up was 29 months.

TypeofStudy:Letter to the editor.

DosageDuration:Dosage and duration not stated.

Results:131/167 (78%) had achieved a complete cytogenetic response at last follow-up.

AdverseEffects:No adverse events were mentioned.

FreeText:Comment on the prediction of initial cytogenetic response for subsequent major and complete cytogenetic response to Glivec in patients with philadelphia chromosome-positive chronic myelogenous leukemia (CML) and reply. The authors of the study reported that a minor cytogenetic response at 3-12 months was associated with a 35-45% chance of achieving a complete cytogenetic response (CCR) and lack of cytogenetic response at ≥ 6 months to be a good indicator of failure. Thus, they concluded that allogeneic stem cell transplantation (alloSCT) should be used only in patients who fail to achieve a cytogenetic response at 6 months. The comment questions this conclusion. They argued that the study was conducted in patients with established chronic phase (CP) CML, all of whom had failed treatment with interferon. This patient group is likely to have relatively poor-risk disease, as evidenced by the considerably lower incidence of CCR (57%). Second, the incidence of complete molecular remission is rare with Glivec monotherapy compared with alloSCT with a successful outcome. Third, no acknowledgement is given to patient preference; in the absence of evidence for Glivec-induced cure, patients still should be informed that alloSCT remains the only curative measure available to them. The authors replied that the practice of advising patients to consider alloSCT if they have not achieved a major cytogenetic response after only 6-12 months of Glivec therapy or if they demonstrate persistence of residual disease by polymerase chain reaction (PCR) was only supported by little evidence. Their study is the first to indicate that even if a minor cytogenetic response is obtained after 3-12 months of treatment with Glivec, 35-54% of patients may later achieve a complete cytogenetic response with continuation of Glivec. On the second issue, cures have been observed in other malignancies despite persistent minimal residual molecular disease. Long-term event-free survival perhaps depends not on the absolute presence or absence of molecular residual disease, but on reaching a critical threshold. And third, the ultimate choice of therapy is still the patient's.