Presently available data support the use of IFN maintenance treatment because it significantly prolongs maintenance duration and survival. IFN added to induction chemotherapy resulted in minor improvements at the expense of increased toxicity, highlighting the need for better induction regimens.
Epidermal growth factor receptor (EGFR) expression has been associated with clinical outcome in some studies of renal-cell carcinoma (RCC). We investigated the efficacy and safety of gefitinib (IRESSA), an EGFR tyrosine kinase inhibitor, in RCC patients. This phase II trial recruited 28 patients with advanced, metastatic, or relapsed RCC. Patients received oral gefitinib 500 mg/day. Objective responses (ORs) were assessed every 2 months according to RECIST. Baseline tumor biopsies were analyzed immunohistochemically for EGFR expression. At trial closure (March 2003), no ORs were seen but 14 patients (53.8%) had stable disease. At extended analysis (August 2004), median time to progression was 110 days (95% confidence interval [CI]: 55, 117); median overall survival was 303 days (95% CI 180, 444). Gefitinib was generally well tolerated. Skin rash and diarrhea were the most common drug-related adverse events (AEs) [54 and 39% of patients, respectively] and the most common drug-related grade 3/4 AEs (both 11%). The majority of tumor biopsies (91%) had > or =70% of tumor cells expressing membrane EGFR. Despite the lack of ORs in this study, disease control was observed in 53.8% of patients. Gefitinib was generally well tolerated and no unexpected drug-related AEs were observed.
Cultured myeloid leukemia cells display transferrin receptors but decrease receptor display after differentiation induction or accumulation of intracellular iron. To determine whether regulation of transferrin receptors and ferritin were linked under these disparate conditions, serum-free and fetal bovine serum (FBS) cultures of HL60 promyelocytic leukemia cells were used to investigate relationships between transferrin receptor display and intracellular ferritin. Using 125I-transferrin binding and immunofluorescence staining for transferrin receptors, HL60 cells cultured in serum-free, transferrin-free medium expressed fewer transferrin receptors and contained increased ferritin when compared to cells cultured with FBS or transferrin supplemented, serum-free medium. When placed in medium containing transferrin, cells previously grown in transferrin-free medium rapidly re-expressed transferrin receptors and decreased their ferritin content. HL60 cells induced to differentiate into granulocytes or macrophages also decreased transferrin receptor display and increased their ferritin content. Transferrin receptor display and ferritin content in both proliferating and differentiating myeloid leukemia cells are inversely related and their regulation is closely linked. Regulation of transferrin receptor display and ferritin synthesis may be important events regulating myeloid cell growth and differentiation.
In mammals the major portion of cyanide is converted to thiocyanate by the liver enzyme thiosulfate sulfur transferase (TST) (rhodanese). We have found a much reduced activity of this enzyme in liver biopsies from two affected males of a family with Leber's hereditary optic atrophy and in two isolated cases of the same disease, (compared to liver biopsies from controls or liver samples obtained at autopsy). In one of the patients we studied the effect of a 3-day thiosulfate infusion. The urinary excretion of thiocyanate which was low prior to the infusion was raised during the thiosulfate treatment; in a healthy control person the same thiosulfate infusion did not alter the thiocyanate excretion rate. This suggests that cyanide detoxification which is suboptimal in patients with Leber's disease may be increased by thiosulfate infusion.
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