Background: Preclinical data suggest that anti-vascular endothelial growth factor agents combined with mammalian target of rapamycin inhibitors yield synergistic antitumor effects. A phase I trial with a 3+3 dose escalation design of S with T was stopped after the first dose pair led to 2 of 3 patients experiencing dose-limiting toxicity (DLT).
Patients and methods: To explore multiple potential dosing pairs of S and T, a 2-stage outcome-adaptive Bayesian dose-finding method was designed. The primary objective was to find the MTD of S and T in patients with advanced renal cell carcinoma. A 3-week treatment cycle consisted of daily S, 2 weeks of treatment, 1 week without treatment, and weekly T.
Results: Twenty patients received study drugs; the median number of previous therapies was 1. The number of patients (S and T doses in mg) was: 2 (S, 12.5; T, 6), 1 (S, 25; T, 12.5), 1 (S, 12.5; T, 8), 8 (S, 12.5 alternate 25; T, 9), 2 (S, 25; T, 6), 2 (S, 25 alternate 37.5; T, 6), 2 (S, 37.5; T, 6), and 2 (S, 37.5; T, 8). Six patients required dose reduction, 3 because of Grade 3 stomatitis, 2 because of Grade 3 thrombocytopenia; the mean number of cycles was 6.6 ± 5.3, the mean time during study was 159 ± 120 days. One patient experienced a DLT in cycle 1 and was nonevaluable, 1 had a partial response, 16 had stable disease, and 2 had progressive disease as best response. There were 21 Grade 3/4 adverse events but no treatment-related deaths.
Conclusion: The MTD of S and T were not determined because of premature trial closure. S 37.5 mg/d, 2 weeks of treatment, 1 week with no treatment, and T 8 mg to 10 mg weekly are close to the MTD.
Keywords: Combination; Kidney; Neoplasm; Study; Therapeutics.
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