Appeal 2007-0741
Application 09/313,625
BACKGROUND
Long term estrogen replacement therapy is common for post-
menopausal and other estrogen deficient women, but has been associated
with undesirable side effects, including “an increased incidence of
endometrial cancer, . . . uterine bleeding and cyclotherapeutic withdrawal
menstrual bleeding during a time in their lives when many women welcome
cessation of menstrual bleeding as a normal occurrence in menopause”
(Spec. 1: 13-29).
One approach to avoiding the ill effects of estrogen therapy is to use a
selective estrogen receptor modulator (SERM) in place of estrogen. SERMs
- also known as anti-estrogens or selective estrogens - bind estrogen
receptors and competitively block the binding of endogenous estrogens (id.
at 2: 9-14). “However, all such [SERMs] can be, in fact, active estrogens
depending on the tissue, dose/regimen and hormonal milieu of the drug
exposure” (id. at 2: 16-18). That is, SERMs can exhibit complex “mixed
function agonistic/antagonistic activities” and “[t]he degree to which the
[SERM] acts as an estrogen also depends on the particular material and the
tissue site” (id. at 2: 18-21). Among the best known of these SERMs are
clomiphene, tamoxifen, and benzothiophenes like raloxifene (id. at 2: 15 and
6: 11).
Nevertheless, “[SERM] therapy . . . is not without its own problems”
(Spec. 2: 22-23), including “a ‘run away’ endogenous estrogen” effect, due
to “derangement” of the “hypothalamic-pituitary-gonadal axis involved in
endogenous hormone production” (id. at 2: 24-25; 3: 22; 4: 12-13).
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