New Data on Molecular Targets of Tamoxifen Besides Estrogen Receptors, Their Clinical Significancy.

Tamoxifen is the first target agent with a high-end position in breast cancer therapy till now. In recent years experimental researches revealed new biological effects of tamoxifen on tumor cells. The present study continues the theme of the review published in 2012, where a plenty of tamoxifen effects besides interaction with estrogen receptors was discussed. Thus, there is described a wide range of the drug targets which are the key points of signal cascades activating the cell proliferation and determining the course of the growth of the cancer and its sensitivity to chemotherapy. Also clinical trials of tamoxifen based on existing of targets besides the estrogen receptors are reviewed. Furthermore, the data on the antiviral, antibacterial, antifungal and antiparasitic activities of tamoxifen are indicated.

Estrogen receptors, antiestrogens, and non-small cell lung cancer.

This review considers data on expression of different types of estrogen receptors (ERα and ERß) in in vitro cultured cells of non-small cell lung cancer and also in human and animal lung tumors. Estrogens are shown to play an important role in genesis and development of non-small cell lung cancer because the estrogen-stimulated cell proliferation as well as antiestrogen-caused inhibition of proliferation occurred only in the cells expressing different types of estrogen receptors. In general, the situation is similar to that observed in breast cancer, but in the cells of non-small cell lung cancer not ERα are expressed in more than half of cases but ERß. Just estrogen receptors ß play the crucial role in inducing cell proliferation in response to estrogens, and ERß is a prognostic marker of a favorable course of non-small cell lung cancer. Data on the interactions between ER and EGFR signaling pathways, as well as on the additive antitumor effect of antiestrogens (tamoxifen and fulvestrant) combined with tyrosine kinase inhibitors (gefitinib, erlotinib, and vandetanib) are considered. The review also includes data on the influence of estrogens on genesis and development of lung cancer in humans and animals and the frequency of ERα and ERß expression in non-small cell lung cancer in tissues from patients of the two sexes. Problems of quantitative determination of α and ß estrogen receptors in the tumor cells are also discussed.

Pharmacokinetics and toxicity of two schedules of high dose epirubicin.

Epirubicin, a stereoisomer of doxorubicin, is reported to have equal antitumor activity with lower cardiac and systemic toxicity. Recently the maximum tolerated dose of this drug has been revised upwards with reported increased response rates. However, the pharmacokinetics of epirubicin at high doses have never been reported. Accordingly, this study was designed to evaluate the pharmacokinetics of epirubicin when administered as either a 15-min i.v. bolus or a 6-h i.v. infusion in a phase I study at high doses. Nineteen patients with a variety of malignancies were given a total of 52 cycles of epirubicin at doses of 90 to 150 mg/m2 given once every 3 weeks. The maximum tolerated dose was 150 mg/m2 epirubicin given either as a bolus or as an infusion. The major dose-limiting toxicity was neutropenia. Interpatient variation occurred in the pharmacokinetics at each dose level but overall there were dose-dependent pharmacokinetics. This was manifested as a disproportionate increase in plasma levels and areas under the curve as the epirubicin dose was increased from 90 to 150 mg/m2. The pharmacokinetics of epirubicin could best be described by an open two-compartment model. Peak plasma concentrations were attained at a median of 12 min following the bolus injection and concentrations approached the steady state within a median of 55 min following the start of the 6-h infusion. Administration of the 150 mg/m2 dose over the 6 h compared to the bolus administration was associated with a 92% decrease in peak concentration from 3088 +/- 1503 to 234 +/- 126 ng/ml. This was not associated with an appreciable change in hematological or nonhematological toxicities. The median distribution half-life was 10 min and the median elimination half-life was 42.0 h. The cumulative renal excretion of the parent compound accounted for less than 2% of the administered dose. The major metabolites in both plasma and urine samples were 4'-O-beta-D-glucuronyl-4'-epidoxorubicin, 13-S-dihydro-4'-epidoxorubicin, and 4'-O-beta-D-glucuronyl-13-S-dihydro-4'-epidoxorubicin. This study demonstrates that a 135 mg/m2 bolus infusion given on a 3-weekly schedule is an appropriate initial dose for further clinical studies.