Effects of a new clinically relevant antiestrogen (GW5638) related to tamoxifen on breast and endometrial cancer growth in vivo.

PURPOSE: Cross-resistance is an important issue for the evaluation of new antiestrogens to treat advanced breast cancer patients who have failed tamoxifen therapy. In addition, postmenopausal patients treated with long-term adjuvant tamoxifen show a 3-4-fold increase in the risk of developing endometrial cancer. Consequently, a new second line agent should be more antiestrogenic and less estrogen-like on the uterus, and be effective at controlling the growth of breast cancer after exposure to tamoxifen. The purpose was to evaluate the effects of the new tamoxifen analogue GW5638 on breast and endometrial cancer growth. EXPERIMENTAL DESIGN: Athymic mice were transplanted with an endometrial tumor model (ECC-1 E2) that is responsive to estrogen and has never been exposed to antiestrogen. In addition, we used three breast tumor models: a tamoxifen-na?ve tumor (T47D-E2) and two tamoxifen-stimulated tumors (MT2 TAM and MCF-7 TAM LT). The antiestrogen GW5638 (1.5 mg daily), tamoxifen (0.5 mg or 1.5 mg daily), and raloxifene (1.5 mg daily) were given p.o. The pure antiestrogen ICI182,780 (5 mg once a week) was given s.c. Western blots from MCF-7 TAM breast tumors were performed to demonstrate the regulation of estrogen receptor alpha expression by different ligands. RESULTS: Estradiol and GW5638 down-regulated the receptor compared with control. ICI182,780 completely degraded the receptor but tamoxifen had no effect. GW5638 did not promote tumor growth, and was effective in blocking the effects of postmenopausal estradiol on the growth of tamoxifen-na?ve breast and endometrial tumors. However, raloxifene did not completely block the effects of postmenopausal estradiol on the growth of tamoxifen-na?ve endometrial tumor after 14 weeks. GW5638 and ICI182,780 but not raloxifene were also effective in blocking the tamoxifen-stimulated breast tumor growth in athymic mice. CONCLUSIONS: GW5638 is more effective than raloxifene in blocking the effect of estrogen on tamoxifen-na?ve endometrial cancer. More importantly, GW5638, like the pure antiestrogen ICI182,780, is able to block the growth of breast cancer stimulated by tamoxifen differently from raloxifene. GW5638 down-regulates estrogen receptor but does not completely destroy the receptor. Therefore, based on our findings, GW5638 could be developed as a second line agent for advanced breast cancer patients and an important first line agent to evaluate as an adjuvant treatment or chemopreventive.     

The influence of pulmonary growth and development on paediatric respiratory diseases

The mortality, morbidity and symptomatology of respiratory diseases in infants and children may be partially related to age specific phenomena of structure and function. Such are the comparatively smaller functional residual capacity and respiratory surface area; the difference in growth velocity of alveolar numbers and size; the smaller number of intrapulmonary communications; the larger resistance of the peripheral airways accentuated by fewer muscular elements and larger number of mucous glands in the same; and the smaller elastic recoil pressure of the lung in children as compared to adults. Many factors compensate, partially or totally, for these apparent handicaps, but the influence of growth and development on disease processes can certainly not be disregarded.     

Alterations of cerebrospinal fluid 5-hydroxyindoleacetic acid,and total blood serotonin content during clozapine treatment

Cerebrospinal fluid 5-hydroxyindoleacetic acid level, and total blood serotonin content was measured in groups of manic and schizophrenic patients before and after 2, 4, 6, 10, 20, and 30 days of clozapine treatment. CSF 5-HIAA values were elevated after 2 and 4 days and returned to baseline levels after 6 days or more. Blood serotonin content, in contrast, increased gradually and remained high even after 30 days. Neither CSF 5-HIAA nor blood 5-HT correlated with age, drug dose, or clinical effectiveness, but some relationship between these and the sedative component of the clozapine action was observed.