A Layperson's Guide to Endocrine (Hormone) Therapy

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Erik Peters
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1 A Layperson's Guide to Endocrine (Hormone) Therapy

2 What we will cover What is the endocrine system Basic definition of endocrine therapy Classes of endocrine drugs How you can utilise endocrine therapy

3 Disclaimer This presentation is solely intended to provide background information on these topics We are not able to recommend any specific therapeutic approach Any decisions about your situation should come following discussions with your medical team

in delivery (depend on blood flow) but prolonged in response compared to the nervous

4 The Endocrine System Messaging system within the body which uses chemicals (hormones) released into the bloodstream to regulate other functions Endocrine messages are slower in delivery (depend on blood flow) but prolonged in response compared to the nervous system. For GCT, the focus is on 2 small glands in the brain, as well as the receptors in ovaries

eventually tells the hypothalamus to stop producing GnRH Source: Hormones of the

5 Brain Controls Signalling GnRH released by hypothalamus stimulates the pituitary gland to produce FSH/LH FSH/LH control estrogen production in the ovary Estrogen eventually tells the hypothalamus to stop producing GnRH Source: Hormones of the Reproductive System

6 Estrogen Plays Many Roles Outside Ovaries Reduce muscle mass Increase fat stores Maintains bone health Reduce LDL (bad cholesterol) Facilitates blood flow and blood pressure And more...

7 Other Ways to Generate Estrogen Steroidgenesis Based on cholesterol Ends with Aromatase

8 Many Ways to Receive Estrogen Signals Estrogen receptors in the cell Travel into nucleus In the cell membrane Cause signal transduction Using indirect receptors e.g. G-Protein receptors

9 Therefore, Not A Simple Target! Diversity and redundancy in production Multiplicity of signalling pathways A natural example of system survival No single point of failure Allows continuation of important functions postmenopause?

10 Endocrine Therapy for GCT What it is Treatment of disease through the use of hormones Attempts to control either the production of estrogen or its ability to interact with tumour cells What it isn't Hormone Replacement Therapy (HRT) Impact of HRT on relapse/progression of GCT is unclear

GnRH Modulators Classes of Endocrine Drugs Agonists work on the pituitary gland receptors Initially they over-stimulate the pituitary causing excess production of FSH/LH

11 GnRH Modulators Classes of Endocrine Drugs Agonists work on the pituitary gland receptors Initially they over-stimulate the pituitary causing excess production of FSH/LH (clinical flare) When the pituitary realizes that it has overproduced it shuts down further production Antagonists rapid shutdown of FSH/LH production No initial surge of FSH/LH

12 Classes of Endocrine Drugs cont'd Estrogen Receptor Modulators Selective Estrogen Receptor Modulator (SERM) Inhibits ER receptors based on the tissue type Exerts an estrogen-like effect for bone and lipid metabolism Competes with estrogen in ovarian tissue (GCT) and shuts down estrogen receptors ER Antagonists Completely inhibit binding of estrogen to its receptor Also called an ER down-regulator

13 Classes of Endocrine Drugs cont'd Aromatase Inhibitors (AI) What is aromatase An enzyme that facilitates biosynthesis of estrogen from other steroids Commonly from testosterone or androgen

14 Aromatase Inhibitors cont'd Steroidal v. Non-steroidal AI Steroidal AI permanently binds to aromatase Non-steroidal AI reversibly binds to the enzyme

15 How Can Endocrine Therapy Be Utilised Monotherapy Sequential application as resistance occurs e.g. RW Carlson and C Henderson, Sequential hormonal therapy for metastatic breast cancer after adjuvant tamoxifen or anastrozole, Brest Cancer Research and Treatment, 2003 Combination therapy With standard chemo or targeted drugs e.g. S Johnston, Integration of endocrine therapy with targeted agents, Breast Cancer Research, 2008 With other ET (estrogen blockade) Possibly AI with ER Antagonist, for example

16 Representative Endocrine Drugs Trade Name Drug Name Class Arimidex Anastrozole AI Aromasin Exemestane AI Cetrotide Cetrorelix Acetate GnRH Antagonist Fareston Toremifene SERM Faslodex Fulvestrant ER Antagonist Femara Letrozole AI Lupron (US), Lucrin, Prostap Leuprorelin Acetate GnRH Agonist Megace Megestrol Acetate GnRH Agonist Nolvadex (US), Genox, Tamofen Tamoxifen Citrate SERM Plenaxis Abarelix GnRH Antagonist Superfact Buserelin GnRH Agonist Trelstar (US), Decapeptyl Triptorelin GnRH Agonist Zoladex Goserelin GnRH Agonist

Lecture 10: Hormonal agents

Lecture 10: Hormonal agents The survival and proliferation (growth) of some cancer cells is dependent on the action of steroid hormones. Early stage breast cancer and early stage prostate cancer are the