A recent study examined the effect of medication nonadherence on progression-free survival (PFS) among patients with renal cell carcinoma, published in Cancer Management and Research (November 2017; 9:731-739).
Axitinib and everolimus are oral anticancer agents often used as second-line therapy for renal cell carcinoma. However, nonadherence to these drugs may negatively affect outcomes.
Jason Shafrin, Precision Health Economics (Los Angeles, CA), and colleagues conducted a study to examine how observed nonadherence to second-line axitinib and everolimus impacts PFS among patients with renal cell carcinoma. Researchers sampled 2164 patients from the Medical Expenditure Panel Survey. An adherence-exposure-outcome model was used to simulate the impact of adherence on PFS. Researchers utilized a pharmacokinetic/pharmacodynamic population model to simulate therapy exposure, which was measured by the area under the plasma concentration-time curve (AUC) and minimum blood or trough concentration based on optimal adherence and real-world adherence.
Researchers also used previously published pharmacokinetic/pharmacodynamic models to estimate the effect of drug exposure on PFS outcomes under optimal and real-world adherence scenarios.
Researchers noted that average adherence measured using medication possession ratios was 76%.
Results of the study showed that drug exposure was significantly higher among adherent patients compared with nonadherent patients for axitinib (AUC, 249.5 VS 159.8 ng×h /mL, respectively; P < .001) and everolimus (AUC, 185.4 vs 118.0 µg×h/L, respectively; P < .001). Additionally, patient nonadherence in the real world reduced the expected PFS by 29% for those taking axitinib (8.4 months with optimal adherence vs 6.0 months with real-world adherence; P < .001) and by 5% for those taking everolimus (5.5 vs 5.2 months, respectively; P < .001).
In their concluding remarks, researchers concluded that nonadherence to second-line axitinib or everolimus in the real-world is likely to result in decreased PFS.—Zachary Bessette