20-Year follow-up of imatinib in chronic myeloid leukaemia after failure with interferon

In the longest follow-up of patients on imatinib therapy ever reported, Dr Maria Vazquez (MD Anderson Cancer Center, Houston, USA) and colleagues demonstrated the long-term benefit of the tyrosine kinase inhibitor imatinib in patients with chronic phase chronic myeloid leukaemia (CML), after these patients no longer responded to interferon (IFN) treatment [1].

In this single-institution study, 154 patients whose disease was refractory to IFN in 1999/2000 were switched to 400 mg imatinib. The majority of patients who passed away (36%), were lost to follow-up (29%), or switched to a different tyrosine kinase inhibitor (37%). The purpose of this study was to evaluate the long-term effects of imatinib on CML disease response. Dr Vasquez reported the available intention-to-treat responses for 63 patients, with a median follow-up of 232 months.

The median overall survival was 51%. Major cytogenic response was reported in 35% of these patients at 3 months, while complete cytogenic response at this time was reported to be 13%. Over time, responses gradually improved with no clear plateau; the overall best response rates (at any time) were 87% for major cytogenic response and 79% for complete cytogenic response.

Transcript detection of the BCR-ABL fusion gene was similarly reduced. A major molecular response over time was achieved by 62% of the patients, with 51% even achieving a “deep” molecular response (MR4 and MR4.5), and 33% reaching the goal of a complete molecular response, with no transcripts detectable. The median duration of sustained molecular response was 139 months. Only 3 patients (15%) lost their molecular response while on therapy. At 19 years, failure-free survival was 20%, event-free survival was 40%, and treatment-free survival was 70%.

In conclusion, the introduction of imatinib into the practice of treating IFN-refractory CML 20 years ago afforded long-term survival for many patients with remarkable improvements in both clinical and molecular parameters.

Figure: 20-Year survival of CML partients on imatinib. Modified from [1]



OS, overall survival; FFS, failure-free survival; EFS, event-free survival; TFS, treatment-free survival.

1. Vazquez MR, et al. Abstract 2927, ASH 2019, 7-10 December, Orlando, USA.

Posted on 5 March, 202030 March, 2021