Clin Cancer Res
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Comparative Study
Expression of epidermal growth factor receptor and c-erbB2 during the development of tamoxifen resistance in human breast cancer.
Expression of epidermal growth factor receptor (EGFR) or of c-erbB2 in primary breast cancer has been shown to predict for a poor chance of subsequent response of recurrent/metastatic disease to endocrine therapy. To assess the role of these receptors in the development of tamoxifen resistance, we examined their expression immunohistochemically on paraffin-embedded sections from breast cancers from 155 patients whose disease was progressing on tamoxifen therapy. Patients were categorized into those who initially responded to therapy (n = 56), those who never responded (n = 39), and those who relapsed while on adjuvant therapy and may or may not have "responded" (n = 60). ⋯ At the time of disease progression compared to pretreatment, there was no significant change in expression of either receptor, irrespective of initial response. The inverse relationship between EGFR and estrogen receptor was maintained at relapse on tamoxifen. These data argue strongly against the acquired expression of these receptors during treatment playing a major role in the development of tamoxifen resistance in human breast cancer.
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Clinical Trial
Effect of prolonged topotecan infusion on topoisomerase 1 levels: a phase I and pharmacodynamic study.
Topoisomerase 1 (topo-1) inhibitors act on the target enzyme by forming "cleavable complex," a high molecular weight DNA protein adduct. The formation of such cleavable complexes results in depletion of the Mr 100,000 "free" topo-1 band detectable by Western blot. The objectives of this study were to determine the maximally tolerated dose of prolonged topotecan infusion in previously untreated and minimally pretreated patients. ⋯ A strong correlation of topo-1 level with area under the curve and duration of infusion was demonstrated. These data suggest that prolonged administration of topo-1 inhibitory drugs results in sustained depletion of free topo-1 enzyme as measured by Western Blot analysis, which may be an important consideration in the clinical use of these agents. Direct randomized, comparative trials will be necessary to determine whether such schedules will improve therapeutic index and efficacy.
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Clinical Trial Controlled Clinical Trial
Multidrug resistance-associated protein in acute myeloid leukemia: No impact on treatment outcome.
Drug resistance remains a major problem in the treatment of patients with acute myeloid leukemia (AML). Expression of the MDR1 gene in leukemic cells was shown previously to be associated with worse clinical outcome of the patients. The multidrug resistance-associated protein (MRP) has been shown recently to be another protein causing the multidrug resistance phenotype in cell lines, but its impact on clinical outcome in patients with AML remains to be proven. ⋯ Overall survival was also independent of MRP expression. In contrast, patients with P-glycoprotein-positive AML had lower complete remission rates and shorter durations of survival. These data indicate that MRP is expressed in patients with de novo AML but, in contrast to P-glycoprotein, does not predict for outcome of induction chemotherapy or survival.
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A 20-mer phosphorothioate oligodeoxynucleotide (ODN) directed against human C-raf kinase (CGP 69846A or ISIS 5132) was analyzed for its antitumor activity either alone or in combination therapy. Combination studies with CGP 69846A and standard chemotherapeutic agents (cisplatin, mitomycin C, tamoxifen, or Adriamycin) were performed in nude mice that had been transplanted s.c. with a variety of human tumors (breast, prostate, colon, small cell lung, large cell lung, and squamous lung carcinomas). For the majority of the combinations studied, additive antitumor effects with CGP 69846A and the cytotoxins were found. ⋯ CGP 69846A, in combination with cisplatin, showed superadditive antitumor effects against PC3 human prostate carcinomas with tumor cures, and in combination with mitomycin C, superadditive antitumor effects of CGP 69846A with tumor cures against NCI-H460 large cell lung carcinoma were found. These effects appeared to be sequence-specific because a mismatched control ODN was completely without effect as a single agent against NCI-H69 human small cell lung cancers. The combination of the mismatched control ODN with mitomycin C or cisplatin did not influence the antitumor activity of the cytotoxins against NCI-H69 human small cell lung cancers, indicating that the superadditive antitumor effects observed for CGP 69846A in combination with cisplatin or mitomycin C are the result of a sequence-specific mechanism of action in NCI-H69 human small cell lung cancers.
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Multicenter Study Clinical Trial
Phase I trial of temozolomide (NSC 362856) in patients with advanced cancer.
Temozolomide (TMZ) is a new imidazotetrazine derivative with early clinical activity in glioma and melanoma. The purpose of this Phase I study is to characterize the toxicity, pharmacokinetics, and antitumor activity of TMZ administered on an oral 5-day schedule to patients with or without prior exposure to nitrosourea (NU). Thirty-six eligible patients received a total of 77 cycles of therapy with TMZ administered p.o. at doses ranging from 50 mg/m2/day to 250 mg/m2/day for 5 days, every 4 weeks. ⋯ Renal clearance of the parent drug and its metabolism to 3-methyl-2, 3-dihydro-4-oxoimidazo[5,1-d]tetrazine-8-carboxylic acid were minor pathways of TMZ elimination. We conclude that TMZ is well tolerated in this oral 5-day schedule with dose-limiting thrombocytopenia and that it has promising activity in glioma and melanoma. The recommended doses for Phase II studies in patients with and without prior NU are 125 mg/m2/day for 5 days and 225 mg/m2/day for 5 days, respectively.