What is the effect of treatment breaks on chronic myeloid leukemia?

This study examined the effect of dose reductions or interruptions on the effectiveness of dasatinib (Sprycel) and nilotinib (Tasigna). The authors concluded that dose reductions or treatment breaks did not affect response or survival rates in chronic myeloid leukemia (CML) patients.

The tyrosine kinase inhibitor (TKI) imatinib (Gleevac) is the standard first treatment for patients with CML. Imatinib is associated with decreased levels of the Philadelphia chromosome (an abnormal chromosome responsible for CML) in 89% of patients. However, 20%-30% of patients progress or have severe negative side effects due to imatinib.

Other TKI therapies can be tried in these patients. Dasatinib and nilotinib are both effective as second-line treatments. However, 41%-87% of those treated with dasatinib and 15% of those treated with nilotinib need to interrupt treatment at some point. It is not clear whether treatment breaks or dose reductions have an effect on long-term survival.

This study examined the safety of treatment breaks and dose reductions on CML survival. The records of 280 patients who took part in previous clinical trials were examined. 46% were treated with nilotinib. 54% were treated with dasatinib. 63% needed a dose reduction or interruption at least once (49% of those treated with nilotinib and 75% of those treated with dasatinib). Older patients, females, and those treated with dasatinib were more likely to need a dose reduction. The average treatment interruption was 35 days (ranging from 2 to 321 days).

There were no significant differences in cytogenic response or survival in patients who needed a dose reduction or treatment break compared to those who did not.

Decreases in dose intensity (the amount of treatment received if the treatment was taken as prescribed) did not affect survival rates.

This study concluded that treatment interruptions or dose reductions did not affect response or survival in patients treated with dasatinib or nilotinib.