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 Currently, seven targeted agents are approved for use in metastatic renal cell carcinoma and have superseded the use of parenteral cytokine therapy with interleukin-2 or interferon, the former standards of care for metastatic renal cell carcinoma.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.

Clinical Experience of Escalated Sunitinib Dose in Select Patients With Metastatic Renal Cell Carcinoma

OBJECTIVE

Sunitinib is approved multinationally for the first-line treatment of metastatic renal cell carcinoma (mRCC). After mRCC progressed in patients, we escalated the sunitinib dose in selected patients and then retrospectively evaluated the efficacy and safety of dose-escalated sunitinib in these selected patients.

METHODS

From January 2010 to January 2016, 288 patients with mRCC received sunitinib as first-line treatment. Treatment continued until radiologic progression occurred. When the disease progressed, 34 patients with mRCC who had mild or moderate adverse events and missed free second-line target therapy trials were escalated to sunitinib 50 mg once daily continuously. Dose-escalated treatment continued until the disease progressed again, the patient was unable to tolerate sunitinib, or the patient was willing to quit the sunitinib treatment.

RESULTS

All 34 patients (median age, 55 years [range, 28-67 years]; 28 [82.4%] males; 6 [17.6%] females) with confirmed metastatic clear-cell RCC, received an escalated dose of sunitinib and were evaluated for toxicity and response. During treatment at the regular sunitinib dosage, 9 (26.5%) patients achieved partial response and 25 (73.5%) patients had a stable disease condition. With dose-escalated sunitinib, 2 (5.9%) patients achieved partial response, 27 (79.4%) patients had stable disease, and the disease still progressed in 5 (14.7%) patients. Tumor size was reduced in 10 (38.2%) patients. Median progression-free survival was 11.2 months (95% confidence interval [CI], 5.2-17.2 months) with the regular dose of sunitinib. During dose-escalated sunitinib treatment, the median progression-free survival was 4.1 months (95% CI, 2.3-5.9 months). Median overall survival was 25.0 months from the initiation of sunitinib treatment (95% CI, 16.0-34.0 months). During dose escalation, grade 3 adverse events consisted of hand-foot syndrome, fatigue, mucositis, and diarrhea. All grade 3 adverse events were relieved by supporting and symptomatic treatment. No grade 4 adverse events occurred.

CONCLUSION

Sunitinib was efficacious in the treatment of mRCC. For patients who tolerated sunitinib well, the dosage could be cautiously increased to gain better treatment benefit.