Transcript Phar 404

PHAR 404
Pharmacology of Female Sex
Hormones
Debra A. Tonetti, Ph.D.
Department of Biopharmaceutical Sciences
[email protected]
Objectives
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Understand and be familiar with steroid hormone biosynthesis. General but
not specific structural details are required.
Understand and be able to describe ER and PR signal transduction and
general receptor features.
Understand how oral contraceptives work.
Be familiar with the uses of emergency contraceptives and RU486 and what
they are.
Describe different types of HRT and findings from the Women’s Health
Initiative
Understand the structure, targets and therapeutic application of SERMS.
Understand the goals of the STAR trial
Describe the mechanism of action of aromatase inhibitors, drugs currently
on the market.
Describe the differences between aromatase inhibitors and SERMS in
terms of mechanism and use for treatment of breast cancer.
Leading 20 Therapeutic Classes by Total U.S. Dispensed Prescriptions, 2004
Rank
Class
Total RXs* (U.S. Millions)
% Growth +/-
% Market Share
1
Codeine
157.6
5%
4.5%
2
SSRI/SNRI
147.4
4
4.2
3
Ace Inhibitors
143.8
5
4.1
4
HMG-COA Reductase Inhibitors
139.8
11
4.0
5
Beta Blockers
120.6
7
3.4
6
Proton Pump Inhibitors
93.1
-2
2.6
7
Thyroid Hormone, Synthetic
90.0
6
2.6
8
Calcium Blockers
88.4
0
2.5
9
Seizure Disorders
84.8
7
2.4
10
Oral Contraceptives
82.5
-3
2.3
11
Benzodiazepines
75.8
4
2.2
12
Angiotensin II Antag
67.3
17
1.9
13
Penicillins
66.7
-10
1.9
14
Antiarth, Plain
60.9
6
1.7
15
Diuretics, Other, Non-Injectable
55.6
3
1.6
16
Macrolides & Related
55.4
-8
1.6
17
Beta Agonists
53.9
-5
1.5
18
Antiarth, COX-2 Inhibitors
50.7
-6
1.4
19
Newer Generation
Antidepressants
48.0
10
1.4
20
Antihistamines, Caps/Tabs
47.2
-14
1.3
IMS Health, National Prescription AuditTMPlus, 1/2005
The Top 300 Prescriptions for 2004 by Number of US Prescriptions Dispensed
http://www.rxlist.com/top200a.htm
Estrogen/Progesterone or SERMs represent 17 out of the top 300
prescriptions in 2004
Premarin
Ortho Tri-Cyclen Lo
Apri
Ortho Evra
Prempro
Kariva
Yasmin 28
Necon
Tamoxifen Citrate
Evista
Aviane
Trivora-28
Estradiol
Medroxyprogesterone
Low-Ogestrel
Ortho-Tri-Cylen
Microgestin Fe
Classes of Drugs Related to
Female Sex Hormones
• Estrogen and/or progesterone combinations
– Oral Contraceptives, morning after pill (premenopausal women)
– Hormone replacement (postmenopausal women)
– Treatment of endometriosis, infertility, uterine fibroids, abnormal
uterine bleeding
• Selective Estrogen Receptor Modulators (SERMs)
– Treatment of breast cancer
– Prevention of breast cancer and osteoporosis
• Inhibitors of Estrogen Synthesis (aromatase inhibitors)
– Treatment of breast cancer, potential chemoprevention
Biochemistry of Steroid Hormone Biosynthesis
•
All steroids are synthesized from cholesterol
The Estrogen and Progesterone Receptors
are Members of the Nuclear Receptor Superfamily
Subdivided into 3 Subfamilies:
Type I: Steroid Hormone Receptors
Estrogen Receptor, Progestrerone Receptor,
Glucocorticoid Receptor, Androgen Receptor
Mineralocorticoid Receptor
Type II: Non-steroid Hormone Receptors
Retinoic acid Receptor, Thyroid Receptor,
Vitamin D Receptor
Type III: Orphan Receptors: No known ligands
Estrogen Receptors: Two Known Isoforms
AF-1
ERa
A/B
18%
ERb
DNA Binding
Domain
A/B
C
96%
C
AF-2
Ligand Binding Domain
D
30%
D
E/F
53%
E/F
485 aa
AF1
1
hERa
NH2
180
A/B
AF2
263 302
C
D
DNA Binding
Domain
553
E
595
F
COOH
Ligand Binding
Domain
Nuclear membrane
Response
CoA
Transcriptional
Activation
Transcription
Unit
ER
ER
E2
CoR
ER
ER
1
hERb
NH2
A/B
9
0
17
3
20
2
C D
DNA Binding
Domain
AF
2
E
Ligand Binding
Domain
ERE
Plasma Membrane
45
0
F
47
7
COOH
Progesterone Receptor: Two Known Isoforms
Edwards, D.P., Annu. Rev. Physiol. 2005. 67:335–76
Activation of the Progesterone Receptor
Olive D.L., Obstetrical and Gynecological Survey, 2002: (57)S55
Coactivators
• Three subclasses of p160 family of coactivators
– SRC-1: SRC-1/NCoA1
– SRC-2: GRIP1/TIF2/N-CoA2
– SRC-3: p/CIP/RAC3/ACTR/AIB1/NCoA-3
• Common Features:
• PAS/bHLH domain
• NR Box (LXXLL motif) binds to the LBD of the receptor when
agonists are bound.
• Histone Acetyltransferase Activity
• Can recruit Cointigrators
• Cointigrators: p300/CBP, P/CAF- ubiquitous coactivators for
several transcription factors.
• Coactivator/NR complex interacts with the basal transcription factors
(RNA Pol II, TATA binding protein, TAF)
Corepressors
• N-CoR and SMRT
• Possess histone deacetylase activity
• Are recruited when an antiestrogen binds to
prevent transcriptional activation.
Multiple Physical and Functional Interactions
Among Nuclear Receptors, Coactivators, Chromatin
Remodelers and Chromatin
Lee and Kraus, 2001, TRENDS in Endocrinology & Metabolism, 12: 191-197.
Integrative Signaling by Estrogen through Receptors (ER) at the Membrane
and Nucleus in Breast Cancer
Levin, ER., Mol Endocrinol, August 2005, 19(8):1951–1959
Oral Contraceptives
Common Combination (E+P) Oral Contraceptives
Yasmin
Drospiroeone
Alesse
Ortho-Evra
(transdermal)
THE HYPOTHALAMO-PITUITARY AXIS
•LH acts on the ovarian follicle and it induces
ovulation and maintains the corpus luteum.
•FSH causes development of the ovarian follicle
and stimulates secretion of estradiol and
progesterone.
•The sex steroids feed back to inhibit release of
GnRH and therefore LH and FSH. At sustained
high levels however, estradiol causes a sharp
increase in LH secretion linked to ovulation. This
is an example of positive feedback.
Developed from:http://cal.man.ac.uk/student_projects/2000/mnby6kas/homepage.htm
Emergency Contraceptives
Emergency Contraceptives
• Regular contraceptives used in a different way
• Prevent pregnancy after intercourse
• Inhibit ovulation, fertilization, or implantation
• Do not cause an abortion
• Will not interrupt an established pregnancy
• Are not the same as mifepristone
• Do not protect against STIs
James Trussell, PhD, Office of Population Research, Princeton University
Levonorgestrel alone
•Plan B Tablets (Tablet 0.75 mg)
Duramed Pharmaceuticals Inc Sub Barr
Laboratories Inc
•Plan B Tablets (Tab 0.75 mg)
Womens Capital Corp
Levonorgestrel + Ethinyl estradiol
Preven Emergency Contraceptive Kit Tablets (Tab
0.05;0.25 mg;mg)
Gynetics Inc
Preven Emergency Contraceptive Kit Tablets (Tab
0.05;0.25 mg;mg)
Gynetics Inc
Options in the United States
• Emergency use of oral contraceptive pills
containing estrogen and progestin
• Emergency use of oral contraceptive pills
containing only progestin
• Emergency Copper-T IUD insertion
James Trussell, PhD, Office of Population Research, Princeton University
Emergency Contraceptive Pills:
Combined
• Ordinary birth control pills
• Contain estrogen and progestin
• 2 doses of 2 Preven pills or for other OCs
2, 4, or 5 pills, depending on brand
• First dose within 120 hours after
intercourse
• Second dose 12 hours later
• Side effects: nausea (50%) and vomiting
(20%)
James Trussell, PhD, Office of Population Research, Princeton University
Emergency Contraceptive
Pills: Progestin-only
• Birth control pills containing only progestin
• 2 doses of 1 Plan B pill or 20 Ovrette pills
• First dose within 120 hours after
intercourse
• Second dose 12 hours later
• Both doses can be taken at the same time
• More effective than combined ECPs
• Less nausea and vomiting than combined
ECPs
James Trussell, PhD, Office of Population Research, Princeton University
Antiprogestin
Competitive receptor antagonist (both A and B forms)
• FDA Approved 2000
• Termination of early pregnancy (<49 days)
• Postcoital contraceptive
• Investigational and proposed uses: contraceptive,
induction of labor, treatment of endometriosis, uterine
fibroids, breast cancer
Hormone Replacement
Therapy
Chemical Structure(s) For: Conjugated Estrogens, Medroxyprogesterone
Prempro
Women’s Health Initiative
Long-term (15 yrs) NIH study that has focused on strategies for
preventing heart disease, breast and colorectal cancer and
osteoporotic fractures in postmenopausal women.
Hormone Therapy Trials (HT): This component examined the effects of
combined hormones or estrogen alone on the prevention of coronary heart
disease and osteoporotic fractures, and associated risk for breast cancer.
Women participating in this component took hormone pills or a placebo
(inactive pill) until the Estrogen plus Progestin and Estrogen Alone trials
were stopped early in July 2002 and March 2004, respectively. All HT
participants continued to be followed without intervention until close-out.
Dietary Modification Trial (DM): The Dietary Modification component evaluated
the effect of a low-fat and high fruit, vegetable and grain diet on the prevention of
breast and colorectal cancers and coronary heart disease.
Calcium/Vitamin D Trial (CaD): Evaluated the effect of calcium and vitamin D
supplementation on the prevention of osteoporotic fractures and colorectal
cancer.
Recommendation: GET OFF HRT!!!
The estrogen plus progestin trial of the
WHI involved 16,608 women ages 50
to 79 years with an intact uterus
NO OVERALL BENEFIT
Conjugated equine estrogens should not be used to prevent
chronic disease overall, and heart disease
The estrogen-alone study involved women ages 50 to
79 years. Study participants were randomly assigned
to a daily dose of estrogen-- 0.625 mg/day of
conjugated equine estrogen (Premarin™)--or a
placebo.
SERMS or “Designer Estrogens”
Applications
Cancer Therapeutic
Chemopreventive
Breast Cancer
Breast and Endometrial Cancer
Glioblastoma Multiforme
Coronary Artery Disease
Osteoporosis
Memory (Alzheimer’s Disease)
Hot Flashes
Estrogen-related Risks Associated
With Breast Cancer
Increased Risk
Reduced Risk
• early menarche
• nulliparity
• late menopause
• late menarche
• pregnancy before
age 30
• bilateral
oophorectomy
• early menopause
Tamoxifen
• Selective Estrogen Receptor Modulator: SERM
• Adjuvant therapy used to treat node-negative,
positive, early and advanced disease
• Reduces the incidence of contralateral disease by
40%
• Reduces the annual odds of death by 24%
• In 1998 was approved for the prevention of breast
cancer in women at high risk
TAMOXIFEN
MIXED ESTROGEN/ANTIESTROGEN
Breast cancer treatment
Prevention of breast cancer
N
N
O
O
Metabolic activation
OH
Tamoxifen
4-hydroxytamoxifen
Fisher et al. JNCI 1998
SERMs and SERDs In Clinical Use
Tamoxifen (Nolvadex, AstraZeneca): Currently approved for the
treatment of ER+/PR+ breast cancer, all stages, both pre- and
postmenopausal Patients. Approved for the prevention of breast cancer
in women at high risk.
Raloxifene (Evista, Lilly): Currently approved for the prevention of
osteoporosis. In Phase III clinical trial (STAR) for the prevention
of breast cancer. Safe in the uterus.
Toremifene: Currently approved for the treatment of metastatic
breast cancer, no clinical advantage over tamoxifen.
ICI 182,780 (Faslodex, AstraZeneca): Selective Estrogen Receptor
Downregulator (SERD). Pure Antiestrogen. Currently approved for
advanced disease.
Developed because of
lack of DNA adducts in
rat liver. Equal clinical
benefit to tamoxifen
Phase III study
shows Less
activity than
tamoxifen
Chemical Structures of Second and Third Generation SERMS
Phase III trial in Europe
as first-line therapy for
metastatic breast
cancer
Not uterotropic in
rats. In phase II
trial
Derived from the
prodrug EM800
Approved for metastatic
disease. Monthly IM
injection. Active in
tamoxifen-resistant
disease.
Study of Tamoxifen And Raloxifene
The STAR Trial
•Basis for the STAR trial:
A secondary result of the MORE trial (Multiple
Outcomes for Raloxifene Evaluation) revealed a 65%
reduction in breast cancer incidence and provided the
basis of the STAR trial
•Primary Aim: To determine if long-term therapy is
effective in preventing the occurrence of invasive breast
cancer in postmenopausal women that are at high risk for
developing the disease.
•Phase III, double-blind trial
The STAR Trial
22,000 Risk eligible
Postmenopausal women
Stratification:
Age
Relative risk
Race
History of LCIS
Tamoxifen
20 mg/day
5 years
Raloxifene
60 mg/day
5 years
Aromatase Inhibitors for the Treatment
(Prevention) of Breast Cancer
Biosynthesis of Estrogens
Site of Action of Aromatase Inhibitors
Cholesterol
(intermediate)
20,22-Lyase
17aHydroxypregnenolone
Dehydroepiandrosterone
17,20 Lyase
Pregnenolone
17a-Hydroxylase
Progesterone
(intermediate)
17aHydroxyprogesterone
Testosterone
Androstenedione
21a-Hydroxylase
aromatase
11-Deoxycorticosterone
11-Deoxycortisol
Estrone
Estradiol
11b-Hydroxylase
Cortisol
Corticosterone
18-Hydroxylase
Aldosterone
Pharmacological Target
Aromatase inhibition within
the breast tumour cell
P-450 Aromatase
+ NADPH-cytochrome P-450 reductase
ANDROGENS
tumour
growth
ESTROGENS
(Testosterone,
androstenedione,
16-OH-testosterone)
(Oestradiol, oestrone)
Aromatase Inhibitors
Sites of peripheral aromatisation
Breast
tumor
Muscle
Fat
Liver
Newer Generation Aromatase Inhibitors
Arimidex
Femara
Type II Non-steroidal
Reversible Binding
Aromasin
Type I Steroidal
Irreversible Binding
Key Clinical Trials Change the
Landscape of Hormonal Therapy
• Anastazole is superior to tamoxifen as first-line
therapy in advanced breast cancer. Bonneterre et al.,
Cancer (2001) 92:2247-2258
• Anastrozole is superior to tamoxifen in as first-line
therapy in early breast cancer. ATAC Trialists’ Group The
Lancet (2002), 359:2131-2139.
• Letrozole after 5 years of tamoxifen therapy
improves disease-free survival. N Engl J. Med.(2003) 349: 19
• Exemestane after 2-3 years tamoxifen is superior to 5
years of tamoxifen treatment in improved diseasefree survival. N. Engl J Med (2004), 350: 1081.