Adhering to imatinib treatment affects how well patients respond to treatment

This study examined how adhering to imatinib (Gleevac) treatment for chronic myeloid leukemia (CML) affects response rates. Researchers reported superior treatment response rates among patients with high adherence to the treatment regime. They suggested that poor adherence may therefore contribute to poorer treatment outcomes.

Targeted therapy is the standard first-line treatment for CML. This refers to a type of treatment that uses drugs or small molecules that block the growth and spread of cancer. Tyrosine kinase inhibitors are a type of targeted therapy that block enzymes called tyrosine kinases. Imatinib is a type of tyrosine kinase inhibitor commonly used to treat CML.

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. Major molecular response is often considered the main goal of CML treatment. Adherence to imatinib treatment (following the treatment regime) is believed to affect the likelihood of achieving molecular response, but exactly how important it is has not been fully studied.

The aim of this study was to examine the effect of imatinib treatment adherence on molecular response rates.

87 patients with chronic (early) phase CML were included in this study. A(26.4%) had an adherence rate of 90% or less. In 12 patients (14%), the adherence rate was 80% or less. Patients with an adherence rate over 90% were significantly more likely to achieve major molecular response. The estimated rate of these patients achieving major molecular response over a period of 6 years was 94.5%. In contrast, only 28.4% of patients with an adherence rate of 90% or less were estimated to reach major molecular response within 6 years. Complete molecular response was also significantly more likely with an adherence rate over 90%. No molecular responses were observed when adherence was 80% or less. Overall, a high adherence rate increased the likelihood of reaching major molecular response 11.7-fold.

Low adherence was more common among younger patients. The average age for patients with an adherence rate of 90% of less was 43.8 years. In contrast, the average age for patients with an adherence rate above 90% was 53.8 years. Adherence rate was also lower among those patients experiencing more side effects. These included fatigue, nausea, muscle cramps, and bone or joint pains.

This study concluded that poor adherence to treatment may be the main reason behind an inability to acheive an adequate molecular response.

Larger studies are needed to confirm these results.