Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

17-(Allylamino)-17-demethoxygeldanamycin (17AAG), a compound that is proposed for clinical development, shares the ability of geldanamycin to bind to heat shock protein 90 and GRP94, thereby depleting cells of p185erbB2, mutant p53, and Raf-1. Urine and plasma from mice treated i.v. with 17AAG contained six materials with absorption spectra similar to that of 17AAG. Therefore, in vitro metabolism of 17AAG by mouse and human hepatic preparations was studied to characterize: (a) the enzymes responsible for 17AAG metabolism; and (b) the structures of the metabolites produced. These materials had retention times on high-performance liquid chromatography of approximately 2, 4, 5, 6, 7, and 9 min. When incubated in an aerobic environment with 17AAG, murine hepatic supernatant (9000 x g) produced each of these compounds; the 4-min metabolite was the major product. This metabolism required an electron donor, and NADPH was favored over NADH. Metabolic activity resided predominantly in the microsomal fraction. Metabolism was decreased by approximately 80% in anaerobic conditions and was essentially ablated by CO. Microsomes prepared from human livers produced essentially the same metabolites as produced by murine hepatic microsomes, but the 2-min metabolite was the major product, and the 4-min metabolite was next largest. There was no metabolism of 17AAG by human liver cytosol. Metabolism of 17AAG by human liver microsomes also required an electron donor, with NADPH being preferred over NADH, was inhibited by approximately 80% under anaerobic conditions, and was essentially ablated by CO. Liquid chromatography/mass spectrometry analysis of human and mouse in vitro reaction mixtures indicated the presence of materials with molecular weights of 545, 601, and 619, compatible with 17-(amino)-17-demethoxygeldanamycin (17AG), an epoxide, and a diol, respectively. The metabolite with retention time of 4 min was identified as 17AG by cochromatography and mass spectral concordance with authentic standard. Human microsomal metabolism of 17AAG was inhibited by ketoconazole, implying 3A4 as the responsible cytochrome P450 isoform. Incubation of 17AAG with cloned CYP3A4 produced metabolites 4 and 6. Incubation of 17AAG with cloned CYP3A4 and cloned microsomal epoxide hydrolase produced metabolites 2 and 4, with greatly decreased amounts of metabolite 6. Incubation of 17AAG with human hepatic microsomes and cyclohexene oxide, a known inhibitor of microsomal epoxide hydrolase, did not affect the production of metabolite 4 but decreased the production of metabolite 2 while increasing the production of metabolite 6. These data imply that metabolite 2 is a diol and metabolite 6 is an epoxide. Mass spectral fragmentation patterns and the fact that 17AG is not metabolized argue for the epoxide and diol being formed on the 17-allylamino portion of 17AAG and not on its ansamycin ring. These data have implications with regard to preclinical toxicology and activity testing of 17AAG as well as its proposed clinical development because: (a) production of 17AG requires concomitant production of acrolein from the cleaved allyl moiety; and (b) 17AG, which was not metabolized by microsomes, has been described as being as active as 17AAG in decreasing cellular p185erbB2.
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PMID:Metabolism of 17-(allylamino)-17-demethoxygeldanamycin (NSC 330507) by murine and human hepatic preparations. 962 79

(1) There is no standard third-line treatment for locally advanced or metastatic non small-cell lung cancer. (2) Erlotinib, like gefitinib, inhibits the tyrosine kinase activity of the epidermal growth factor (EGF) receptor, and has been licensed for sale in the European Union. (3) A double-blind placebo-controlled trial involving 713 patients who had failed to respond to one or two previous chemotherapy regimens showed that erlotinib increased the median survival time by about 2 months (6.7 versus 4.7 months), without improving the quality of this survival. It is not possible to predict precisely which patients are most likely to respond to erlotinib. (4) In first-line treatment, erlotinib was no more effective than placebo as an adjunct to chemotherapy in 2 trials involving 1079 and 1172 patients. (5) The adverse effect profile of erlotinib seems similar to that of gefitinib, mainly consisting of gastrointestinal disturbances (especially diarrhoea: 54% of patients versus 18% on placebo), skin rash (75% versus 17%), and ocular disorders (conjunctivitis: 12% versus 2%). In the comparative trial of second- or third-line treatment, 0.8% of patients developed interstitial pneumonia. (6) Erlotinib, like gefitinib, is metabolized by the cytochrome P450 isoenzyme CYP3A4, potentially creating a high risk of interactions. (7) In practice, the limited benefit of erlotinib seems to be outweighed by its frequent adverse effects. Erlotinib should therefore only be used in clinical trials designed to identify subgroups of patients in whom the risk-benefit balance may be favourable.
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PMID:Erlotinib: new drug. Non small-cell lung cancer: like gefitinib, no established advantage. 1676 93