2. DR. IRZA WAHID - SpPD KHOM ROICAM 2015 Endocrine Resisten Breast Cancer - Copy

7/25/2019 2. DR. IRZA WAHID - SpPD KHOM ROICAM 2015 Endocrine Resisten Breast Cancer - Copy

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S4.2

Pathophysiology of Hormonal Resistance

Nama : DR. Dr. Irza Wahid, SpPD-KHOM, FINASIM

Posisi : Kepala Sub Bagian Hematologi-Onkologi Medik FK Unand/

RS Dr. M. Djamil Padang

Pendidikan

Dokter Umum FK Unand

Spesialis Penyakit Dalam FK Unand

Konsultan Hematologi-Onkologi Medik , Kolegium Ilmu Penyakit Dalam


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Mechanisms of endocrine resistance in

breast cancer

Dr dr Irza Wahid SpPD KHOM

Division of Haematology Medical Oncology

Internal Medicine Departement Faculty of Medicine, Andalas UniversityGeneral Hos ital of Dr M D amil Padan


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Hormone Receptor-Positive (HR+)

Breast Cancer

Approximately 75% of invasive breast cancers

are classified as HR+1,2

ER signaling leads to

Cell proliferation

Time available for DNA repair

Risk of mutation

HR+ breast cancers are generally slower growing

and have a better prognosis than HR cancers1

ER expression correlates with improved

response to endocrine therapy1

Effectiveness of endocrine therapy is limited by

denovo or acquired endocrine resistance

Multiple mechanisms within the ER pathway

allow development of resistance to endocrine

therapy3

1. Cleator SJ, et al. Clin Breast Cancer. 2009;suppl 1:S6-S17; 2. Milani M, et al. Clin Med Ther. 2009;1:141-156;3. Arpino G, et al. Endocr Rev. 2008;29(2):217-233; 4. www.breastpathology.info. Accessed September 14, 2011.

Images reprinted from NHS Trust, Edinburgh, UK. (www.breastpathology.info)

Staining of ER+ breast cancer nuclei

by immunohistochemistry (IHC)4

A. Strong nuclear staining indicating widespread

expression of ER (Allred score = 8)

B. Weak nuclear staining indicating low to

moderate expression of ER (Allred score = 4)

3


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Estrogen Production

Normal tissue of subcutaneus fat, breast, muscle,bone, ovarium. Conversion of androgen by

aromatase

ER is nuclear receptor encoded by the ESR1 gene

2 distinct transactivation domains : Activation

Function (AF 1 , AF 2)

Estrogen response element (E) Transcriptional

control proliferation, Time available for

DNA repair , Risk of mutation


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Figure 1. Schematic representation of functional domains of humanER & ER.

* The A/B domain at the N-terminal containsAF-1 site.

*The C domain includes the DNA-bindingdomain (DBD) and a dimerization site.

* The D domain contains a nuclear localization signal.* The E/F domain is located at the C-terminal and comprises the ligand binding, as

well as the AF-2 domain, a second nuclear localization signal, and another

dimerization site.

Berrera et al, Int. J. Mol. Sci. 2013


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Dixon JM, New Journal of Science, 2014

Figure 2: Diagram showing local estrogen production via the enzymatic onversion of

androgens to estrogen by aromatase and estrogen receptor signalling in breast cancer.

Estrogen (E), estrogen receptor alpha (ER), estrogen response element (ERE) and

heat-shock proteins (HSP).The targets of commonly used endocrine therapies in the

pathway are shown: aromatase inhibitors (AI), tamoxifen (T) and fulvestrant (F).


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A1. Genomic signalling (classic, direct bind ing)

Estrogen berikatan

dengan ERsitoplasma/nukleus

Kompleks E-ER

menuju nukleus (NISS-

nuclear initiated steroidsign)

Berikatan dengan

Estrogen ResponseElement(ERE) di DNA

Kemudian akan

mengaktifkan faktor

transkripsi


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A2. Genom ic signal (Non Class ic, tethering)

ER dan ER juga

dapat memodulasi

ekspresi gen tanpa

ikatan langsung padaDNA

Ada interaksi dengan

berbagai protein seperti

sp1, faktor transkripsi

fos/jun pada AP1, dan

melalui kompleks NF-

B

Klinge CM. Estrogen receptor interaction with estrogen response element. NucleicAcid Res 2001;29(14):2905-19


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B. Ligand independent receptor activation

The ER signaling pathway is also regulated by membrane RTKs including EGFR, HER2,

and IGF1-R, FGFR. These membrane kinases activate signaling pathways thateventually result in phosphorylation of ER as well as its coactivators and corepressors at

multiple sites to influence their specific functions

Crosstalk between the growth factor receptor and ER pathways has been established

through several other mechanisms . Estrogen can increase the expression of ligands

such as transforming growth factor- (TGF) and IGF1 which can then activate the

growth factor receptor pathway . On the other hand, estrogen signaling downregulates

the expression of EGFR and HER2 while increasing the expression of IGF1- R

Activation of the PI3K/AKT and the p42/44 mitogen-activated protein kinases (MAPK)

pathways by these receptors, in turn, downregulates the expression of ER and PR

Thus, while these RTKs can activate the transcriptional function of ER, they can also

reduce estrogen dependence by downregulating the expression of ER perhaps

contributing to the relative resistance to endocrine therapies in tumors amplified for

HER2 .

Osborne and Schiff. Annu Rev Med. 2011


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C. Non-Genomic signal (MISS)

Membran Intiated Steroid Signaling(MISS), Non-transcriptional mechanisms

Low levels of ER have been found outside the nucleus in the membrane,

cytoplasm, or even in the mitochondria

Some of the non genomic action of estrogen appears to be too rapid for activate

GF receptor signaling, including the PI3K/AKT & Ras/p42,44, MAPK pathways .Thus, ER can alter the expression of genes normally regulated by GF

The stress kinase pathway via p38 and JNK can also modulate ER function by

phosphorylation of ER & its coregulators . The microenvironment and its

associated integrin signaling may exert a similar activity .

Thus, ER activity and signaling is modulated by a variety of pathways which could

also contribute to resistance to ER-targeted therapies, especially when the

pathways display aberrant activity in a cancer cell.y regulated by growth factors

Osborne and Schiff. Annu Rev Med. 2011


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Figure 1 Estrogen receptor action at molecular level. A: Ligand dependent activation: in classic estrogen

signaling, ligand-bound ER activates gene expression either through direct binding of dimeric ER to specific DNAresponse elements in complexes including co-activators, or function as a coregulator through protein protein

interactions with other transcription factors to facilitate binding to serum response elements and activation of

transcription; B: Ligand independent activation: the ER can also be activated by ligand independent fashion, as a

consequence of signaling events downstream of membrane receptor tyrosine kinases (RTKs); C: Non genomic

mechanisms: signaling can be mediated through non-genomic mechanisms by ER that is localized at the cell

membrane or in the cytoplasm. mTOR: Mammalian target of rapamycin; FGFR: Fibroblast growth factor receptor;

IGF-1R: Insulin-like growth factor-1 receptor; EGFR: Epidermal growth factor receptor.

Zhao M et al (2014) . Advances in endocrine-resistant breast cancer


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Endocrine theraphy agent

Anti estrogen

Selective estrogen

receptor modulator

(ESRM) AF1Tamoxifen

Selective estrogen

receptor down regulator(ESRD) AF1, AF2

Fulvestrant

Aromatase inhibitor

Non steroid inhibitor

letrozol,

anastrozol

Steroid inhibitor

exemestane

f


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Endocrine Therapy for HR+

Advanced Breast Cancer

Cytoplasm

Nucleus

LBD

LBD

Cofactor complex

AF1 DBD

DBDAF1

Estrogen

Cell

growth

Estrogen

receptor

Aromatase inhibitors

(AIs)

Nonsteroidal AIs

Anastrozole

Letrozole

Steroidal AIs

Exemestane

SOS

EGFR

Shc

RAF PI3K

Akt/

m-TOR

MEK

HER2

P

P P

MAPK

Growth factor

receptor

GRB2

Selective estrogen

receptor modulators

(SERMs)

Tamoxifen

Toremifene

Adapted from Yardley DA, et al. J Clin Oncol. 2011;29(suppl 27). Abstract 268. 13

Estrogen receptor

downregulator

(ERD)

Fulvestrant

RAS


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Endocrine Resistance in HR+Advanced Breast Cancer

Definition of endocrine resistance is evolving

Primary resistance: PD within 6 months

of starting treatment1

Secondary resistance: Initial response with relapse

6 months or later1

Approximately 50% of patients with HR+ advanced

breast cancer do not respond to initial endocrine

therapy2

The majority of patients with HR+ advanced breast

cancer will ultimately progress despite endocrine therapyAbbreviations: HR, hormone receptor; PD, progressive disease.

1. Bachelot T, et al. Breast Cancer Res Treat. 2010;100(suppl 1):Abstract S1-S6; 2. Bedard PL, et al. Breast Cancer Res Treat.2008;108(3):307-317.


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Endocrine Resistance in HR+Advanced Breast Cancer

Clinical

Histopatology

Marker- High expression of cycle machinery genes

Cyclin-D1, Cyclin-E1, CDK4, CDK6

- High expression of antiapoptotic proteins

- Abberant expression of other regulation cycle cell

C-MYC, RB1, p21, P27KIPI

Abbreviations: HR, hormone receptor; PD, progressive disease.

1. Bachelot T, et al. Breast Cancer Res Treat. 2010;100(suppl 1):Abstract S1-S6; 2. Bedard PL, et al. Breast Cancer Res Treat.2008;108(3):307-317.


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Mechanisms of Resistance to Endocrine Therapy

De novoresistance in

breast cancer ischaracterized byloss of ER (theER isoform)

expression andER genemutations suchas deletion andpoint mutation

Patients carryinginactive alleles ofcytochromeP4502D6 (CYP2D6)deficiency cannotconvert tamoxifen toits active metabolite,endoxifen, thereforeare resistant totamoxifen.

By contrast,multiple

mechanismshave beendetected toaccount for the

acquiredresistance toendocrinetherapies


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Studies have suggested that innate

resistance may be linked to lowerlevels of ER, which might suggest that the

drive to proliferation of these cancers is

not as dependent on estrogen as thoseexpressing higher levels of ER.

1 A. Level of estrogen receptors


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1 B. ER Post-translational Modifications.

A number of post-translational modifications of ER have been reported,

including phosphorylation, methylation and sumoylation which influence its

interaction with other members of the ER signalling pathway.

It has been suggested that aberrations in the posttranslational modification of

ER could be linked to endocrine therapy resistance . ER can be phosphorylated

at a serine-118, serine-167 and threonine-311 within the AF1 binding domain aswell as in other domains.

Phosphorylation and activation of ER at key positions can result from a

number of pathways including: the MAPK/ERK pathway in response to

growth factors such as epidermal growth factor (EGF), the PI3K-AKT

pathway in response to insulin-like growth factors and the p38-MAPKpathway in response to stress or various cytokines .

It has been suggested that aberrations in the posttranslational modification of

ER could be linked to endocrine therapy resistance


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1 C. Differential ER Binding

A recent study looked at genome-wide ER binding events in primary breast tumours

of patients sensitive and resistant to tamoxifen and revealed that in tamoxifen-resistant cancers ER is still recruited to the chromatin and binds regulatory regions in

a pattern that is unique to resistant tumours

The resistant phenotype may be due to selection and expansion of a resistant

subpopulation of cells, or alternatively could involve the rapid reprogramming of ER

binding by FOXA1, which has a known role in ER-chromatin interactions in responseto growth stimuli

Forkhead motifs and EREs were found to be enriched within the DNA regions which

showed increased ER binding in tamoxifen-resistant cell lines and in primary tumour

specimens of patients with a poor clinical outcome, providing further evidence for the

FOXA1- mediated reprogramming model of ER binding .

These findings suggest that ER may have an important role to play in tamoxifen

resistance by binding to a distinct set of regulatory elements giving rise to a unique

gene expression profile which promotes tumour progression and confers resistance

to therapy.


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1 D. Activating Mutations in ER

A recent clinical sequencing study in patients with advanced ER-positive breast

cancer identified a D538G mutation within ER in endocrine therapy resistant patients

causing a change from aspartic acid to glycine at position 538 within the ligand

binding domain.

Importantly, the mutation was found in distant metastatic sites but not in the primary

tumour. The D538G mutant ER was found to confer constitutive ligand-independent

transcriptional activity which mimicked that of estrogen bound wild-type ER with

reduced tamoxifen binding affinity.

Overexpression of mutant ER was found to enhance proliferation

and confer resistance to tamoxifen

Similar studies have also identified additional ER mutations in the ligandbinding

domain which also result in constitutive activity and may represent potential

mechanisms foracquired endocrine therapy resistance


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1 E. ER-Independent Signalling

It should be noted that the estrogen receptor exists as two distinct isoforms: ER(ER) and ER. The exact role of ER is not clear, however studies have shown

that tamoxifen can bind ER and that tamoxifen-bound ER can activate AP1

regulated genes, possibly by altering the balance of associated coactivators and

corepressors at the promoter site.

Increased ER expression has been reported in tamoxifen resistant breast cancersand data from a recent study suggested that the ratio of ER to ER may be

important in predicting response to tamoxifen and anastrozole in the neoadjuvant

setting

Alternative mechanisms involve expression of truncated isoforms of ER such as ER

36 or other estrogen-related receptors such as estrogen-related receptor

gamma (ERR), associated with reduced response to tamoxifen

Resistance related to ERR overexpression might suggest an important role for

this molecule in an alternative estrogen signalling pathway


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Estrogen signalling via the ER has been shown to upregulate

the expression of the PR and thus the majority of ER +

patients are also PR +.

Tumours which are ER + and PR - display a poorer response

to endocrine therapy and a more aggressive phenotype than

ER +/ PR + tumours,

Some reports have shown that the ER +/PR + population hasa significantly better prognosis compared with the ER + / PR -

2. Progesterone receptors


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3. EPIGENETICS AND ENDOCRINE RESISTANCE

Epigenetics is defined as reversible changes in gene expression

without change in the DNA sequence. There is increasing evidence that epigenetic modification plays a

potential role in the development of endocrine resistance in breast

cancer.

The epigenetic regulation of ER is mediated though the recruitmentof multimolecular complexes containing HDAC1, DNMT1 and other

co-repressors to the promoter region. Methylation of the gene

encoding ER- is one of the mechanisms of loss of ER expression

in ER negative breast cancer cell.

The epigenetic silencing of ER target genes is crucial to the

development of ER independent growth and endocrine treatment

resistance.


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4. Crosstalk with Growth Factor Signalling Pathways

Receptor tyrosine kinases (RTKs) HER2

Receptors for epidermal growth factor (EGFR)

Mitogen actifated protein kinase (MAPK)

Insulin-like growth factor 1 (IGF1)

PI3K-AKT-mTOR Pathway


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Figure 2. Pathways involved in endocrine resistance. (a) While tamoxifen (T), aromataseinhibitors (AIs), or fulvestrant (F) inhibit estrogen (E) signalization, GFR pathways promote ER phosphorylation,

transcription factors (TFs), and their coactivators (CoA) in a ligand-independent manner. E-ER complex outside

the nucleus can interact with GFRs, Src, CoA and matrix metalloproteinases that release heparin-binding-EGF; (b)

Stress may trigger signalization leading to ER and its coregulators phosphorylation; (c) Notch regulates the

migration and invasion of breast cancer cells. E inhibits this pathway while T activates it; (d) High levels of CoA,

low levels of corepressors (CoR) and altered expression of miRNAs (e) have been implicated in endocrine

resistance development. Berrera et al, Int. J. Mol. Sci. 2013

Historic Timeline of Therapies for HR+


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Historic Timeline of Therapies for HR+

Advanced Breast Cancer

Oopho-

rectomy2,3

Abbreviations: AI, aromatase inhibitor; ERDs, estrogen receptor downregulator; HR+; hormone receptor positive; SERMS, selective estrogen receptor

modulators.* Marginal improvement over lower dose fulvestrant.

1. http://www.advancedbreastcancercommunity.org/treatment/drugs.htm; 2. Beatson CT. Lancet. 1896;2:104-107; 3. Beatson CT. Lancet. 1896;2:162-165;4. Cohen MH, et al. Oncologist. 2001;6:4-11; 5. Faslodex [package insert]. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2011.

SERMS4

Tamoxifen

Toremifene

AIs4

Anastrozole

Letrozole

Exemestane

ERDs5

Fulvestrant

27

ERDs5

High-doseFulvestrant*

1896 1977 1990s 2002 2010

Targeting

mechanisms

of endocrine

resistance

2012EndocrineTherapy

Chemo-

therapy 1990s1980s 2000s

Others1

Capecitabine

Gemcitabine

Ixabepilone

Eribulin

Nab-

paclitaxel

Taxanes1

Paclitaxel

Docetaxel

Anthracyclines1

Doxorubicin

Epirubicin
http://www.advancedbreastcancercommunity.org/treatment/drugs.htmhttp://www.advancedbreastcancercommunity.org/treatment/drugs.htm


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Figure 3: Summary of resistance in breast cancer showing the clinical manifestations of

resistance in the neoadjuvant and adjuvant settings, the clinical need to accurately identify high

risk patients, an overview of some of the best described resistance mechanisms and potential

treatments and therapeutic strategies currently under investigation to combat resistance.



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Endocrine Therapy Everolimus: Positive Results

29

Reprinted from Prat A and Baselga J. Nat Clin Pract Oncol.

2008;5(9):531-542.

Dual Inhibition of E2 and MTORBOLERO-2: AI +/ mTOR Inhibitor

(Progression-free Survival)

Reprinted from Baselga J, et al. N Engl J Med. 2012;366(2):109-119.

Copyright 2011 Massachusetts Medical Society. All rights reserved.

Update presented by Hortobagyi GN. SABCS 2011. Abstract S3-7.


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TAMRAD Time to Progression and Overall Survival

Time, mo

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.70.8

0.9

1.0

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

ProbabilityofSurvi

val

HR = 0.53 (95% CI = 0.35,

0.81)

Exploratory log-rank P =

.0026

TAM + Everolimus: 8.6 months

TAM: 4.5 months

Abbreviations: CI , confidence interval; HR, hazard ratio; TAM, tamoxifen.

Adapted from Bachelot T, et al. SABCS 2010. Abstract S1-6.

HR = 0.32 (95% CI = 0.15,

0.68)

Exploratory log-rank P =

.0019

Time, mo

0.0

0.10.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 6 12 18 24 30

Pr

obabilityofSurviva

l

TAM + Everolimus: not reached

TAM: 32.9 mo

3 9 15 21 27

Time to

Progression(Secondary Endpoint)

Overall Survival(Secondary Endpoint)


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Conclusions

Breast cancer is a heterogeneous disease

Gene profiling and sequencing would help to

assess better the prognosis and to discover targets(evolving field)

Multiple mechanisms within the ER pathway

allow development of resistance to endocrine thy . Endocrine agents (Tamoxifen, AI) + Everolimus

improve the outcome of HR+ patients

31


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T H A N K Y O U

2. DR. IRZA WAHID - SpPD KHOM ROICAM 2015 Endocrine Resisten Breast Cancer - Copy

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