Very Elderly Patients with Chronic Phase-Chronic Myeloid Leukemia on Imatinib: No Impact of Concomitant Drugs on Complete Cytogenetic Response

Tyrosine-kinase inhibitors (TKIs)have completely changed the expected survival of chronic myeloid leukemia (CML) patients which is now approaching that of the general population: a relevant proportion of CML patients are currently elderly or very elderly. Very elderly patients represent generally a small proportion in published experiences. Older CML patients imatinib treated, as it happens in the general population, receive other drug treatments for associated chronic illnesses. Our aim is to assess if and which classes of concomitant drugs have an impact on cytogenetic response in chronic phase (CP)-CML very elderly (age >75 years) patients.

Two hundred and twelve very elderly CP-CML patients, imatinib treated at 33 italian hematological institutions have been retrospectively evaluated. Median age at diagnosis was 78.5 years (range 75.0-93.0); 111 (52.4%) were male. Sixty-two (29.2%) were Sokal high risk. Sixty-seven (31.8%) were treated with reduced dose imatinib (<400 mg/day), and the remaining patients with imatinib >400 mg/day. Concomitant drugs were 1-2 in 73 (34.4%) patients, 3-4 in 59 (27.8%), and >5 in 64 (30.2%); 16 (7.6%) did not assume any concomitant drug. Drugs more frequently used were antiplatelets, assumed by 104 (49.1%) patients, followed by diuretics in 91 (42.9%) patients, proton pump inhibitors (PPIs) in 86 (40.6%), ACE inhibitors in 55 (25.9%), beta blockers in 44 (20.7%), angiotensin II receptors blockers (ARB) in 41 (19.3%), calcium channel blockers in 34 (16%), statins in 25 (11.8%), and alpha blockers in 11 (5.2%).

Univariate logistic regression models were computed to assess the association between cytogenetic response after 6 or 12 months of imatinib treatment and number of concomitant drugs or selected drug classes. Statistical analyses were done using JMP 11.1 (SAS Institute Inc., Cary, NC, USA).

Complete cytogenetic response (CCyR) was obtained in 124 (58.8%) patients, of whom 70 (33%) within 6 months. Consequently, we focused our study on the impact of number and types of drugs on CCyR rate, which represents the primary therapeutic endpoint in the elderly. Cytogenetic response distribution according to concomitant drugs is reported in table 1.

We did not find any significant correlation between number of concomitant drugs, single classes of antihypertensive drugs, antiplatelets, PPIs or statins and CCyR rate at 6 or 12 months.

Even though few pharmacokinetic interactions are reported between imatinib and some of medications we considered, this does not seem to have an impact on cytogenetic response rate in our cohort. Indeed, our results confirm the well-known safety and efficacy of imatinib also in very elderly CML patients.