Dosing strategies and optimization of targeted therapy in advanced renal cell carcinoma

Within the past decade, treatment options for metastatic renal cell carcinoma have expanded dramatically. Currently, seven targeted agents are approved for use in metastatic renal cell carcinoma and have superseded the use of parenteral cytokine therapy with interleukin-2 or interferon, the former standards of care for metastatic renal cell carcinoma. Targeted agents include inhibitors of the vascular endothelial growth factor pathway (i.e. sorafenib, sunitinib, pazopanib, axitinib, and bevacizumab) and inhibitors of the mammalian target of rapamycin pathway (i.e. temsirolimus and everolimus). These newer therapies have been shown to improve progression-free survival compared with previous approaches. Because most of these targeted agents are taken orally, responsibility for dose administration has shifted to patients, which might result in variable adherence. Additionally, with new treatments for metastatic renal cell carcinoma comes the challenge of selecting dosing schemes that maximize therapeutic benefit and minimize adverse events. Much of the information related to the effectiveness of dose modifications for targeted therapies in metastatic renal cell carcinoma has been gathered from clinical studies that have strict inclusion and exclusion criteria, which might not translate directly to real-world patient populations. This review discusses the impact of dose adherence on the effectiveness of targeted agents to treat metastatic renal cell carcinoma, assesses the literature regarding the effectiveness of approved dosing strategies, and provides a summary of alternative dosing strategies.

Improving adherence to oral cancer therapy in clinical practice

Adherence to oral chemotherapy regimens maximizes their effectiveness and minimizes any potential toxicities. Factors specifically related to the treatment, patient, and health care provider may influence medication adherence. Treatment-related factors include the complexity of the regimen, the cost of therapy, the possibility of side effects, and the delay in treatment benefits. Meanwhile, patients may not have an adequate support system or an understanding of the need for the medication, and providers may not fully succeed in communicating the importance of adherence and the types of side effects that may occur. Nonadherence may lead to an increased risk of toxicity, decreased effectiveness, and increased utilization of health care resources. Although various methods for measuring adherence are available, self-reporting is the most widely used. Studies describing adherence in a broad range of cancers are reviewed. Treatment of chronic myeloid leukemia has been revolutionized by the development of oral tyrosine kinase inhibitors that are highly effective in managing the disease when taken consistently. However, nonadherence is relatively common and can lead to reduced rates of response and increased medical costs. Similar effects of nonadherence on outcome and cost have also been observed in patients with various other hematologic malignancies and solid tumors. Interventions to improve adherence to oral chemotherapy regimens include communication about the importance of adherence and the potential consequences of nonadherence, simplification of the patient's medication schedule (if possible), and inclusion of a caregiver or family member in the conversation. Written materials should always be provided to accompany verbal instructions. This review summarizes factors influencing medication adherence, impact of nonadherence on patient outcomes, methods for measuring adherence, previous studies of nonadherence in patients with cancer, common barriers to access, and interventions to improve adherence in the community setting.