HAMBURG, GERMANY (UroToday.com) - With a tissue microarray, the expression of mTOR, phosphorylated mTOR (p-mTOR), and 4E binding protein in different tumor tissue samples were analyzed. There were 40 samples of clear cell renal cell carcinoma (RCC), 25 samples of papillary RCC and 17 samples of chromophobe RCC. As a control, 27 oncocytomas and 32 benign renal tissue samples were taken. Expression of mTOR was higher than 90% in all histologic subtypes except clear cell RCC. P-mTOR was lower in oncocytomas than in malignant tumors, and 4E binding protein was low in chromophobe RCC compared to other samples. High expression of mTOR, p-mTOR, and 4E binding protein in papillary RCC could be due to low activation of the mTOR pathway in these tumors. The authors conclude that their findings could have an impact on the choice of mTOR inhibitors in specific histologic subtypes of RCC.
In the randomized phase-III trials comparing temsirolimus with interferon-alpha, and a combination of these drugs in patients with poor prognosis RCC, patients with non-clear cell RCC demonstrated better outcome with temsirolimus compared to interferon-alpha than patients with clear cell RCC. However, immunohistochemical markers would be extremely helpful to stratify patients. However, these studies were not included in that randomized phase-III trial and it is doubtful whether the results from small studies like the one presented will translate into clinical decisions in the near future.
Presented by P. Mercy et al. at the Deutsche Gesellschaft für Urologie (DGU) - 63rd Annual Congress - September 14 - 17, 2011 - Congress Center - Hamburg, Germany
Reported for UroToday by Christian Doehn, MD, PhD, Urologikum Lubeck, Lubeck, Germany.
The opinions expressed in this article are those of the UroToday.com Contributing Medical Editor and do not necessarily reflect the viewpoints of the Deutsche Gesellschaft für Urologie.
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