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

Abstract

Tyrosine kinase inhibitor (TKI) use is critical to the care of patients with chronic myeloid leukemia (CML). Quantitative BCR-ABL1 polymerase chain reaction (qPCR) testing 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 of 74 years) with newly-diagnosed CML followed for ≥13 months from TKI initiation. Nine hundred sixty five patients (81.0%) had at ≥1 test with 425 (35.7%) and 540 (45.3%) of 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 (compared with 2007-2010, 2011-2014 odds ratio [OR]=1.97, 95% confidence interval [CI]: 1.43-2.7, p<0.01; 2015-2017 OR=2.33, 95%CI: 1.66-3.27, p<0.01) and influenza vaccination before diagnosis, a proxy for healthcare access (OR=1.31, 95%CI: 1.01-1.70, p=0.04) 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 (OR=1.60, 95%CI: 1.11-2.31, p=0.01) and had improved 5-year survival (hazard ratio=0.66, 95%CI: 0.49-0.90, p<0.01). 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.