According to another recent report published by Sadeghi and colleagues, cessation of VEGF-targeted therapy in a select subset of patients with mRCC achieving stable disease or better was also found to be a feasible option. In this retrospective analysis, patients with mRCC received VEGF-targeted therapy of either sunitinib (55%), bevacizumab (23%), or sorafenib (18%). After a median duration of therapy of 14.6 months, 6 patients had achieved CR, 29 achieved PR, and 5 achieved SD. Patients (n=40) were then followed for a median of 29.7 months to determine clinical outcome after discontinuation of therapy. At the time of data cutoff, 15 patients (37%) had continued observation without therapy or disease progression for a median of 8.9 months. The overall progression-free survival (PFS) was 13.5 months for all patients included in the study. Independent predictors of prolonged PFS were found to be more favorable Heng risk group (HR, 2.24; 95% CI, 1.05–4.80; P=0.04) and achievement of CR prior to discontinuation of therapy (HR, 0.19; 95% CI, 0.42–0.84; P=0.03).5

Complete responses in mRCC patients are rare yet have been observed in some patients treated with targeted agents. The debate continues as to whether or not these patients should continue therapy or discontinue treatment once a response has been achieved. The reduction in treatment-related toxicity coupled with reduced risk of resistance makes the case for stopping therapy once a response has been achieved. It has also been suggested that administering therapy intermittently may be beneficial in minimizing the overall risk-benefit ratio associated with targeted therapies. While patients with a more favorable risk profile and those who have achieved prior CR have been identified as candidates for this approach, predictive factors of response in the broader mRCC patient population have yet to be defined. Prospective studies are needed to determine optimal approaches for managing mRCC patients who respond to treatment.4,5


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REFERENCES

  1. National Comprehensive Cancer Network. “Clinical Practice Guidelines in Oncology: Kidney Cancer” (V.1.2012).  www.nccn.org.  Accessed January 30, 2012.
  2. Nepple KG, Yang L, Grubb RL, et al. “Population-based analysis of the increasing incidence of kidney cancer in the United States: evaluation of age specific trends from 1975 to 2006.” J Urol. 2012;187(1):32-38.
  3. Proleukin® [package insert]. San Diego, CA: Prometheus Laboratories Inc.; 2011.
  4. Albiges L., Oudard S., Negrier S., et al. “Complete remission with tyrosine kinase inhibitors in renal cell carcinoma.” [published online ahead of print, January 9, 2012]. J Clin Oncol.  doi:10.1200/JCO.2011.37.2516.
  5. Sadeghi S, Albiges L, Wood LS, et al. “Cessation of vascular endothelial growth factor-targeted therapy in patients with metastatic renal cell carcinoma:  feasibility and clinical outcome.” [published online ahead of print, December 2, 2011]. Cancer. doi:10.1002/cncr.26666.