Oral anticancer agent (OAA) adherence and survival in elderly patients with metastatic renal cell carcinoma (mRCC).

Abstract

280 Background: Multiple effective oral anticancer agents (OAAs) are now approved for the treatment of patients with advanced or metastatic renal cell carcinoma (mRCC) based on improvement in overall and progression-free survival in randomized clinical trials. However, real-world adherence and outcomes associated with OAA use in the general mRCC patient population have not been previously investigated. Methods: Retrospective analysis of SEER-Medicare patients with mRCC who received treatment with an OAA between 2007 and 2015. Adherence was assessed as proportion of days covered (PDC) within 3 months of OAA initiation with PDC > 50% categorized as adherent. The impact of initial OAA adherence on overall and disease-specific survival was analyzed landmarked at 3 months after OAA initiation. Results: A total of 905 patients met study criteria, of which 577 (63.8%) were categorized as adherent to initial OAA treatment. Multivariable analysis adjusting for clinical and demographic factors revealed that living within an impoverished neighborhood was associated with a 20% lower likelihood of adherence (OR 0.80, CI 0.68 – 0.93). No association was observed between adherence and race, ethnicity, marital status, or number of comorbidities. In survival analyses OAA adherence was associated with a significant reduction in both overall (HR 0.71, CI 0.58 – 0.87) and RCC-specific mortality (HR 0.68, CI 0.57 – 0.86). Receipt of sunitinib was associated with a significant reduction in overall and disease specific mortality compared with sorafenib. Post-hoc analysis of patients taking pazopanib as their initial OAA (N = 252) demonstrated reduced all-cause mortality if they received the minimum effective dose of 800 mg daily (HR 0.50, CI 0.35 – 0.72) and decreased adherence associated with initial higher out-of-pocket payments (χ2 test, p = 0.003). Conclusions: Socioeconomic factors predict poor adherence to OAA therapy in Medicare beneficiaries with metastatic RCC, which is in turn associated with poor overall and disease-specific survival. Efforts to improve outcomes and mitigate disparities in the general mRCC population should incorporate considerations of OAA adherence and economic factors. Sunitinib and pazopanib appear associated with favorable survival and remain the most commonly used OAAs in this over 65 year old patient population.