With the development and FDA approval of the new targeted therapies (sunitinib and sorafenib), interferon therapy has been largely replaced as a consequence of these issues. There is preclinical data that suggests that lower doses of interferon may be associated with anti-angiogenic and anti-tumoral activity, and may in fact be more efficacious than traditional dosing regimens. Here, Tannir and the group from M. D. Anderson report on the results of a phase II clinical trial comparing low dose interferon with a more standard (here called intermediate dose) regimen.

In this phase II clinical trial, 118 patients with mRCC without prior treatment were randomized to either a low dose (0.5 million units BID) or intermediate dose (5 million q Day) interferon regimen. The primary endpoint of the trial was progression free survival (PFS), with secondary endpoints of response rate (RR), overall survival (OS), toxicity, and quality of life also examined. The authors found no difference in PFS, OS, or RR between the two groups. The median PFS for the low dose group was 3.7 months, as compared to 3.4 months for the intermediate dose group (p=0.46). The median OS for the low dose group was 25.5 months, as compared to 17.5 months for the intermediate dose group (p=0.12). There was one complete response and 3 partial responses in each group. Of note, there was considerably more toxicity and need for dose reductions in the intermediate dose group. Also, quality of life and depression were significantly worse in the intermediate dose group.

The authors conclude that this lower dosing regimen of interferon is associated with decreased toxicity and improved quality of life, while not compromising on anti-tumoral activity. While not significant, there clearly was a trend towards improved survival in the low dose group. Low dose interferon has activity in mRCC, but one questions the relevance of this finding in the setting of the more active targeted therapies currently used in mRCC.

Nizar M. Tannir, Lorenzo Cohen, Xuemei Wang, Peter Thall, Paul F. Mathew, Eric Jonasch, Arlene Siefker-Radtke, Lance C. Pagliaro, Chaan S. Ng, Christopher Logothetis

Cancer 107(9): 2254-2261, 2006.

UroToday.com Renal Cancer Section

Written by Christopher G. Wood, MD, a Contributing Editor with UroToday.

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