Older patients with chronic myeloid leukemia face suboptimal molecular testing and tyrosine kinase inhibitor adherence

Abstract

Tyrosine kinase inhibitor (TKI) use is critical in the care of patients with chronic myeloid leukemia (CML). Quantitative polymerase chain reaction (qPCR) testing for BCR-ABL1 every 3 months during the first year of TKI treatment is recommended to assure achievement of milestone response goals. Real-world evidence for the patterns of qPCR monitoring and TKI adherence in the older patient population is lacking. Using the Surveillance, Epidemiology, and End Results-Medicare database, we identified 1192 patients aged ≥66 years (median age, 74 years) with newly diagnosed CML who were followed up for ≥13 months from TKI initiation. In total, 965 patients (81.0%) had ≥1 test, with 425 (35.7%) and 540 (45.3%) of the patients tested during 1, 2, and ≥3 quarters (optimal monitoring) of the first year from TKI initiation, respectively. In multivariable analysis, diagnosis in later years and influenza vaccination before diagnosis, a proxy for health care access, were associated with optimal qPCR monitoring. Use of low-income subsidy and residing in census tracts with the lowest socioeconomic status were associated with less optimal monitoring. Patients with optimal monitoring were 60% more likely to be TKI adherent (odds ratio, 1.60; 95% CI, 1.11-2.31; P = .01) and had improved 5-year survival (hazard ratio, 0.66; 95% CI, 0.49-0.90; P < .01) than those without such monitoring. In this large, real-world study of CML management patterns, many older patients had suboptimal molecular monitoring, which was associated with decreased TKI adherence and worse survival.