TKI outcomes ‘unfavourable’ in young CML patients

By Lynda Williams, Senior medwireNews Reporter

Adolescent and young adult (AYA) patients with chronic myeloid leukaemia (CML) may have an unfavourable outcome on tyrosine kinase inhibitor (TKI) therapy compared with their older counterparts, suggests a study of Japanese patients.

The review found that the 19 patients aged 15 to 29 years had a slightly different baseline profile than the 114 patients aged 30 years or older, with a significantly higher white blood cell count and a significantly lower percentage of basophils. The Hasford score was significantly lower in AYA than older patients, indicating a poorer prognosis, although the EUTOS risk score was comparable.

TKI choice and dosage was similar between the age groups and there was no significant difference in the proportion of AYA and older patients who achieved a complete cytogenetic response, at 81.6% versus 92.0%.

At 2 years, however, AYA patients were significantly less likely than their older peers to have achieved a major molecular response (60.5 vs 87.0%) or a complete molecular response (17.4 vs 33.4%).

And estimated event-free survival was significantly lower in the AYA patients than the older group, with 7-year rates of 58.0% versus 80.1%.

One older patient experienced progression to accelerated-phase disease, leading to haematopoietic stem cell transplantation. No patients died during the median follow-up of 82 and 88 months in the AYA and older groups, respectively.

In all, 37.0% of AYA patients required dose reduction and one patient a dose interruption, as did 36.0% and four of the older patients. Side effects were also comparable between the age groups.

Masatoshi Sakurai, from Keio University School of Medicine in Tokyo, and co-authors believe that the differences in the outcomes of the younger and older patient groups might be explained by biological factors, such as the higher baseline white blood cell counts in AYAs, or by nonbiological factors, such as adherence to treatment.

“Large-scale prospective studies focusing on the biological factors, drug metabolism, and drug adherence are clearly warranted to further improve the outcome of AYA patients with CML treated with TKIs”, they conclude in the International Journal of Hematology.

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