A multicenter phase 2 consortium (P2C) study of the mTOR inhibitor CCI-779 in advanced soft tissue sarcomas (STS)

9504 Background: CCI-779 inhibits the mammalian target of rapamycin (mTOR), a Ser/Thr kinase involved with the initiation of mRNA translation, showing growth inhibition in many tumor cell types. The primary goal was to evaluate the confirmed response rate (RR) of CCI-779 in advanced STS. Methods: Eligibility included pts ≥ 18 yrs, measurable advanced STS, PS 0–2, adequate laboratory function (including Chol ≤ 350 mg/dL and TG ≤ 400 mg/dL), no prior chemo for advanced disease (adjuvant chemo allowed), and no brain metastases. Following premedication with an antihistamine, CCI-779 was given intravenously at 25 mg over 30 minutes on days 1, 8, 15, and 22, repeated q 4 wks. A total 50 pts were to be enrolled, if there were 2 responses at the time of an interim analysis conducted on the initial 20 patients. Pre- and post-treatment blood was collected to evaluate p70S6 kinase, S6 phosphorylation, inhibition of mTOR, and sirolimus levels. Pre-treatment paraffin-embedded tumor tissue was used to evaluate immunohi...