Clin Cancer Res
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Clinical Trial
A phase I and pharmacological study of topotecan infused over 30 minutes for five days in patients with refractory acute leukemia.
The principal objectives of this study were to determine the feasibility of escalating doses of the hydrophilic topoisomerase I (topo I) inhibitor topotecan (TPT) as a 30-min infusion daily for 5 days in adults with refractory or relapsed acute leukemia and to study the pharmacokinetic behavior of high doses of TPT and pharmacodynamic determinants of TPT activity. Fourteen patients received 27 courses of TPT at doses ranging from 3.5 to 5.75 mg/m2/day every 3 weeks. A constellation of unusual adverse effects, consisting of high fever, rigors, precipitous anemia, and hyperbilirubinemia, was the principal dose-limiting toxicity of high doses of TPT on this schedule. ⋯ Moreover, strong correlations were evident between topo I content and two markers of proliferation, proliferating cell nuclear antigen and nuclear protein B23, raising the possibility that differences in topo I content observed among various leukemia specimens might reflect differences in the proliferating fractions of cells in various leukemia samples. Although complete clearance of circulating leukemia blasts occurred in most courses, neither sustained responses nor hematopoietic recovery were observed in the heavily pretreated, poor-risk patients enrolled in this study, and it was not possible to correlate these differences in topo I content with clinical response. These results indicate that substantial dose escalation of TPT as a 30-minute infusion for a 5-day schedule above myelosuppressive doses is feasible in adults with refractory or relapsed leukemias; however, further development of alternate high-dose schedules in leukemia may be warranted in view of the nature of the dose-limiting toxicity and the lack of sustained clinical responses in this preliminary investigation.
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Interleukin 10 (IL-10) inhibits the production of a wide range of cytokines in various cell types. The purpose of this study was to determine whether the expression of the IL-10 gene can influence tumor growth and metastatic properties of human melanoma cells. The human melanoma cell line, A375P, which does not produce endogenous IL-10, was transfected with a hygromycin expression vector (control) or a vector containing full-length murine IL-10 cDNA. ⋯ Because tumor-associated macrophages are the major source of angiogenic molecules in melanoma, we used reverse transcription-PCR to demonstrate that IL-10 down-regulates the production of vascular endothelial growth factor, the most potent angiogenic factor in activated macrophages. Other factors involved in angiogenesis such as IL-1beta, tumor necrosis factor-alpha, IL-6, and the proteinase matrix metalloproteinase-9 were also inhibited in activated macrophages by supernatants from A375P-IL-10 cells. Collectively, these data suggest that the production of IL-10 by tumor cells inhibits macrophages-derived angiogenic factors, and hence, tumor growth and metastasis.