Switching between tyrosine kinase inhibitors: 2-year follow-up of nilotinib after imatinib

This study examined outcomes of nilotinib (Tasigna) as a second-line therapy over 2 years in patients with chronic myeloid leukemia (CML). The results of this observational study add valuable information to the body of evidence on the effectiveness of nilotinib after imatinib in patients with chronic-phase CML.

Targeted therapy is the standard first-line treatment for CML. Tyrosine kinase inhibitors (TKIs) are a type of targeted therapy that block enzymes called tyrosine kinases. Imatinib (Gleevac) is often the first-line TKI therapy used to treat CML. Over time, however, some patients stop responding to imatinib or have to discontinue treatment due to side effects. Second-generation TKIs, such as nilotinib, may be used as second-line TKIs.

Treatment response is often measured based on patients showing few or no abnormal chromosomes (cytogenetic response) or genetic abnormalities (molecular response) in the blood or bone marrow. Second-line TKIs are often associated with good treatment responses. However, more studies are needed to examine long-term outcomes.

146 patients with CML in the chronic (early) phase were included in this study. All patients were treated with nilotinib as second-line therapy after imatinib. Two-thirds of patients switched to nilotinib due to lack of response to imatinib. One-third of patients switched due to side effects. Treatment outcomes were observed for 24 months.

11% of patients showed undetectable molecular disease at 24 months. This was higher for patients that switched treatment due to side effects (24.5%) compared to patients that switched due to lack of response (4.2%).

66.3% of patients achieved major molecular response. 44.2% of patients achieved deep molecular response. The average time to major molecular response was 5.7 months. It was 6.24 months for deep molecular response. Major and deep molecular response was more likely in patients who had achieved this response after imatinib.

43 patients (29.5%) discontinued treatment with nilotinib. 10 patients discontinued due to lack of treatment response. 27 patients discontinued due to side effects and 6 patients for other reasons.

The most common side effects not related to red or white blood cell counts were itchy skin (16.4%), lack of energy (13.7%), and dry skin (13%). 18 patients (12.3%) experienced heart or blood vessel events due to treatment.  

This study adds valuable information to the body of evidence on the effectiveness of nilotinib after imatinib in patients with chronic-phase CML.

This was an observational study thus additional factors that can affect the results may not be controlled for.