Biomarker · Hormone receptor

Estrogen receptor (ER)

Estrogen receptor protein expression measured by immunohistochemistry on tumor tissue; used as a predictive marker for endocrine therapy and as part of breast cancer subtyping.

CI-BIO-00000002ESR1 graph →NCIt C15492

Also calledER · ER-positive · ESR1 expression · estrogen receptor alpha

Derived

Associated cancers (1)

Cancers mapped in ACCEPTED CIViC predictive, prognostic or diagnostic items whose variant (molecular markers) or gene (gene-level markers) is in this biomarker's scope. Counts by type and native level; each row links to the cancer's evidence tab.

Computedrule biomarker-links-v1

Cancer	Items	Predictive	Prognostic	Diagnostic	Levels A / B / C / D / E
Malignant Breast Neoplasm	14	14	—	—	1 / 2 / 1 / 10 / 0

Derived

Drugs with predictive evidence (7)

Therapies named in in-scope PREDICTIVE CIViC items, plus targets of PREDICTS_RESPONSE_TO knowledge edges from in-scope variants. Sensitivity and resistance are counted separately and never merged into a verdict.

Computedrule biomarker-links-v1

Drug	CIViC items	Sensitivity	Resistance	Best level	Edges (S / R)	Cancer context
FulvestrantSmall Molecule	6	5	1	B	5 / 1	Malignant Breast Neoplasm
Hormone Therapy	5	—	5	D	0 / 5	Malignant Breast Neoplasm
TamoxifenSmall Molecule

Curated evidence

Predictive evidence items (15)

ACCEPTED CIViC predictive items in scope, grouped by molecular profile and therapy with native level, direction and cancer context. 50 per page.

civicCuratedShowing 1–15 of 15 evidence items · levels, directions and significance as curated at the source; each row links to its CIViC record.

Therapy	Cancer	Type	Level	Direction · significance	Rating (1–5)	Status	Evidence	Source
ESR1 Mutation1
Elacestrant

Regulatory

Approvals mentioning the linked drugs (186)

Approval records of the derived drug set, plus records whose indication text names this biomarker. Each record names its authority, jurisdiction, indication text and status — a drug approved in one jurisdiction for one indication is not 'approved' in general, and an approval listed here is not necessarily restricted to this biomarker.

Computedrule biomarker-links-v1

Drug	Jurisdiction · authority	Cancer	Indication	Status	Approval date	Source
Fulvestrant	CA Health Canada	—	Marketed in Canada as FULVESTRANT INJECTION (DIN 02558971) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Sep 30, 2025	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as FULVESTRANT INJECTABLE (DIN 02530635) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Sep 12, 2024	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as FULVESTRANT INJECTION (DIN 02536293) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Dec 18, 2023	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as FULVESTRANT INJECTION (DIN 02486792) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Nov 1, 2024	Mar 2, 2022	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as FULVESTRANT INJECTION (DIN 02468549) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Mar 31, 2025	Apr 27, 2020	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as FULVESTRANT INJECTION (DIN 02483610) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Feb 1, 2019	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as TEVA-FULVESTRANT INJECTION (DIN 02460130) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Jan 15, 2019	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as FASLODEX (DIN 02248624) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Jun 14, 2004	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as APO-FULVESTRANT (DIN 02486350) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approved	—	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as ACT FULVESTRANT (DIN 02463075) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince Apr 23, 2020	—	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as FULVESTRANT INJECTION (DIN 02536668) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approved	—	health-canada-dpd
Fulvestrant	CA Health Canada	—	Marketed in Canada as FULVESTRANT INJECTION (DIN 02533111) under ATC L02BA03 FULVESTRANT. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approved	—	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as M-LETROZOLE (DIN 02549972) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Apr 25, 2025	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as AG-LETROZOLE TABLETS (DIN 02543419) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Aug 20, 2024	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as JAMP LETROZOLE TABLETS (DIN 02541912) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Aug 20, 2024	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as LETROZOLE (DIN 02524244) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Jul 18, 2022	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as NRA-LETROZOLE (DIN 02520486) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Mar 25, 2022	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as AG-LETROZOLE (DIN 02374439) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Dormantsince Aug 3, 2026	Feb 3, 2022	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as MINT-LETROZOLE (DIN 02508109) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Jul 20, 2021	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as LETROZOLE (DIN 02504472) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Mar 19, 2021	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as CCP-LETROZOLE (DIN 02459884) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Aug 3, 2023	Jul 24, 2017	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as VAN-LETROZOLE (DIN 02428156) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Aug 7, 2019	Jun 8, 2015	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as NAT-LETROZOLE (DIN 02421585) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Feb 3, 2015	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as RIVA-LETROZOLE (DIN 02398656) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Feb 11, 2014	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as TEVA-LETROZOLE (DIN 02343657) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Jul 8, 2013	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as ZINDA-LETROZOLE (DIN 02378213) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Dormantsince Jul 17, 2018	Jun 18, 2013	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as AURO-LETROZOLE (DIN 02404400) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Apr 24, 2015	Jun 12, 2013	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as LETROZOLE (DIN 02402025) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Feb 14, 2013	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as BIO-LETROZOLE (DIN 02392496) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Feb 12, 2013	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as MAR-LETROZOLE (DIN 02373424) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Jan 8, 2013	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as APO-LETROZOLE (DIN 02358514) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Jun 11, 2012	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as TARO-LETROZOLE (DIN 02372282) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Nov 22, 2022	Oct 4, 2011	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as JAMP-LETROZOLE (DIN 02373009) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Dormantsince Aug 3, 2026	Sep 30, 2011	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as MYL-LETROZOLE (DIN 02372169) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Jun 28, 2016	Sep 8, 2011	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as LETROZOLE (DIN 02348896) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Jun 25, 2014	Aug 29, 2011	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as ACH-LETROZOLE (DIN 02338459) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	May 3, 2010	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as MED-LETROZOLE (DIN 02322315) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Dormantsince May 25, 2018	Apr 28, 2010	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as PMS-LETROZOLE (DIN 02309114) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Apr 28, 2010	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as LETROZOLE (DIN 02348969) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Jun 18, 2018	Apr 28, 2010	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as LETROZOLE (DIN 02347997) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Post Marketsince Dec 10, 2013	Apr 28, 2010	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as SANDOZ LETROZOLE (DIN 02344815) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Apr 27, 2010	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as FEMARA (DIN 02231384) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	approvedsource: Marketed	Aug 18, 1997	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as STASON-LETROZOLE (DIN 02431335) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince Jun 27, 2018	—	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as CO LETROZOLE (DIN 02352052) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince Sep 1, 2017	—	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as LETROZOLE SUN (DIN 02375273) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince Jul 11, 2022	—	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as LETROZOLE TABLETS (DIN 02381958) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince Mar 10, 2023	—	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as PHL-LETROZOLE (DIN 02316366) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince Sep 13, 2017	—	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as DOM-LETROZOLE (DIN 02316374) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince May 30, 2025	—	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as ACCEL-LETROZOLE TABLETS USP (DIN 02406330) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince May 19, 2017	—	health-canada-dpd
Letrozole	CA Health Canada	—	Marketed in Canada as MYLAN-LETROZOLE (DIN 02322544) under ATC L02BG04 LETROZOLE. Indications are not published in the Drug Product Database — see the Health Canada Product Monograph.	withdrawnsource: Cancelled Pre Marketsince Nov 2, 2016	—	health-canada-dpd

ESR1 L536Q2
Hormone Therapy	Malignant Breast Neoplasm	Predictive	D	Supports Resistance	3	accepted	EID242 MCF7 cell lines harboring the L536Q mutation in the ligand-binding domain of ESR1 have shown resistance to hormone therapy. PMID 24185512 · Toy et al., 2013 · Open in CIViC	civic
Fulvestrant + TamoxifenSubstitutes	Malignant Breast Neoplasm	Predictive	D	Supports Sensitivity Response	5	accepted	EID290 Using an estrogen response element (ERE)-luciferase reporter system co-transfected with one of five ESR1 mutants, the L536Q ligand binding domain mutation was shown to result in constitutive activity … (full text at CIViC) PMID 24185510 · Robinson et al., 2013 · Open in CIViC	civic

ESR1 D538G3
Hormone Therapy	Malignant Breast Neoplasm	Predictive	D	Supports Resistance	3	accepted	EID243 MCF7 cell lines harboring the D538G mutation in the ligand-binding domain of ESR1 have shown resistance to hormone therapy. PMID 24185512 · Toy et al., 2013 · Open in CIViC	civic
Letrozole + PalbociclibCombination	Malignant Breast Neoplasm	Predictive	C	Does Not Support Sensitivity Response	2	accepted	EID4814 In a study of 16 patients with metastatic breast cancer (NCT02142868) treated with palbociclib in combination with letrozole, patients with ESR1 mutations (5/16), including ESR1 D538G (n=2), detected … (full text at CIViC) PMID 28978004 · Gyanchandani et al., 2017 · Open in CIViC	civic
Fulvestrant + TamoxifenSubstitutes	Malignant Breast Neoplasm	Predictive	D	Supports Sensitivity Response	5	accepted	EID291 Using an estrogen response element (ERE)-luciferase reporter system co-transfected with one of five ESR1 mutants, the N538G ligand binding domain mutation was shown to result in constitutive activity … (full text at CIViC) PMID 24185510 · Robinson et al., 2013 · Open in CIViC	civic

ESR1 Y537C2
Hormone Therapy	Malignant Breast Neoplasm	Predictive	D	Supports Resistance	3	accepted	EID244 MCF7 cell lines harboring the Y537C mutation in the ligand-binding domain of ESR1 have shown resistance to hormone therapy. PMID 24185512 · Toy et al., 2013 · Open in CIViC	civic
Fulvestrant + TamoxifenSubstitutes	Malignant Breast Neoplasm	Predictive	D	Supports Sensitivity Response	5	accepted	EID292 Using an estrogen response element (ERE)-luciferase reporter system co-transfected with one of five ESR1 mutants, the Y537C ligand binding domain mutation was shown to result in constitutive activity … (full text at CIViC) PMID 24185510 · Robinson et al., 2013 · Open in CIViC	civic

ESR1 Y537N2
Hormone Therapy	Malignant Breast Neoplasm	Predictive	D	Supports Resistance	3	accepted	EID245 MCF7 cell lines harboring the Y537N mutation in the ligand-binding domain of ESR1 have shown resistance to hormone therapy. PMID 24185512 · Toy et al., 2013 · Open in CIViC	civic
Fulvestrant + TamoxifenSubstitutes	Malignant Breast Neoplasm	Predictive	D	Supports Sensitivity Response	5	accepted	EID293 Using an estrogen response element (ERE)-luciferase reporter system co-transfected with one of five ESR1 mutants, the Y537N ligand binding domain mutation was shown to result in constitutive activity … (full text at CIViC) PMID 24185510 · Robinson et al., 2013 · Open in CIViC	civic

Associated cancers (1)

Drugs with predictive evidence (7)

Predictive evidence items (15)

Approvals mentioning the linked drugs (186)

Active trials (177)

Linked publications (6)