Safe to switch to imatinib for long-term use after initial treatment with nilotinib or dasatinib

This study examined whether switching between tyrosine kinase inhibitor (TKI) therapy is safe and effective for patients with chronic myeloid leukemia (CML). This study concluded that after achieving optimal response with a second-generation TKI such as dasatinib (Sprycel) or nilotinib (Tasigna), treatment can be safely switched to imatinib (Gleevac) for long-term use.

TKI therapy, such as imatinib, is the standard first-line treatment for CML. It works by blocking enzymes called tyrosine kinases involved in leukemia cell growth. Nilotinib and dasatinib are two more recently developed TKIs. Studies have shown better treatment response rates with nilotinib and dasatinib compared to imatinib. However, nilotinib and dasatinib are less well tolerated and there is concern over their long-term safety. Long-term exposure to imatinib, on the other hand, is considered safe. CML patients are generally expected to continue TKI treatment throughout their lives. One possible strategy currently under investigation is switching to imatinib after the desired treatment response has been achieved with nilotinib or dasatinib.

The aim of this study was to test the safety of switching from nilotinib or dasatinib to imatinib.

The records of 20 patients with CML were analyzed. Patients received first-line therapy with nilotinib (3 patients) or dasatinib (15 patients). 1 patient was treated with both. 1 patient received first-line therapy with ponatinib (Iclusig), another second-generation TKI. All patients were switched to imatinib after showing optimal treatment response.

The average duration of first-line TKI therapy was 107 days. All 20 patients had achieved optimal treatment response at 3 months.

The most common reasons for switching to imatinib were treatment-related side effects. Two nilotinib-treated patients reported severe anxiety and one reported serious skin rashes. One dasatinib-treated patient experienced fluid around the heart and irregular heart rate and one reported severe headaches. Very low red and white blood cell counts were observed in one dasatinib-treated patient. Ten patients switched due to physician or patient preference.

Average duration of imatinib therapy was 17.4 months. Imatinib was well tolerated except in 2 patients: 1 patient reported a skin rash and 1 patient reported anxiety. Both were switched back to dasatinib. No loss of optimal treatment response was observed after an average follow-up of 27 months. 

This study concluded that imatinib can be safely and effectively administered after achieving optimal treatment response with a second-generation TKI.

Larger studies that randomly assign patients to treatment groups are needed to confirm these findings.