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
Palbociclib	US FDA	—	Efficacy supplement 2026-06-24 (see label)	approved	Jun 24, 2026	openfda
Palbociclib	US FDA	—	Efficacy supplement 2025-09-16 (see label)	approved	Sep 16, 2025	openfda
Palbociclib	US FDA	—	Efficacy supplement 2025-09-16 (see label)	approved	Sep 16, 2025	openfda
Palbociclib	US FDA	—	Efficacy supplement 2025-04-23 (see label)	approved	Apr 23, 2025	openfda
Palbociclib	US FDA	—	Efficacy supplement 2025-04-23 (see label)	approved	Apr 23, 2025	openfda
Palbociclib	US FDA	—	Efficacy supplement 2023-09-06 (see label)	approved	Sep 6, 2023	openfda
Palbociclib	US FDA	—	Efficacy supplement 2023-09-06 (see label)	approved	Sep 6, 2023	openfda
Palbociclib	US FDA	—	Efficacy supplement 2022-12-13 (see label)	approved	Dec 13, 2022	openfda
Palbociclib	US FDA	—	Efficacy supplement 2022-12-13 (see label)	approved	Dec 13, 2022	openfda
Palbociclib	US FDA	Malignant Breast Neoplasm	in combination with inavolisib and fulvestrant for the treatment of adult patients with endocrine-resistant, PIK3CA -mutated, HR-positive, HER2-negative, locally advanced or metastatic breast cancer, as detected by an FDA‑authorized test, following recurrence on or after completing adjuvant endocrine therapy.	approved	Nov 1, 2019	openfda
Palbociclib	US FDA	Malignant Breast Neoplasm	for the treatment of adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer in combination with: o an aromatase inhibitor as initial endocrine-based therapy	approved	Nov 1, 2019	openfda
Palbociclib	US FDA	Malignant Breast Neoplasm	in combination with trastuzumab, with or without pertuzumab, and endocrine therapy for the maintenance treatment of adult patients with HR-positive, HER2‑positive locally advanced or metastatic breast cancer following induction treatment.	approved	Nov 1, 2019	openfda
Palbociclib	US FDA	—	; or o fulvestrant in patients with disease progression following endocrine therapy.	approved	Nov 1, 2019	openfda
Palbociclib	US FDA	—	Efficacy supplement 2019-09-09 (see label)	approved	Sep 9, 2019	openfda
Palbociclib	US FDA	—	Efficacy supplement 2019-04-04 (see label)	approved	Apr 4, 2019	openfda
Palbociclib	US FDA	—	Efficacy supplement 2018-02-06 (see label)	approved	Feb 6, 2018	openfda
Palbociclib	US FDA	—	Efficacy supplement 2017-03-31 (see label)	approved	Mar 31, 2017	openfda
Palbociclib	US FDA	—	Efficacy supplement 2016-02-19 (see label)	approved	Feb 19, 2016	openfda
Palbociclib	US FDA	—	; or o fulvestrant in patients with disease progression following endocrine therapy.	approved	Feb 3, 2015	openfda
Palbociclib	US FDA	Malignant Breast Neoplasm	in combination with trastuzumab, with or without pertuzumab, and endocrine therapy for the maintenance treatment of adult patients with HR-positive, HER2 positive locally advanced or metastatic breast cancer following induction treatment.	approved	Feb 3, 2015	openfda
Palbociclib	US FDA	Malignant Breast Neoplasm	for the treatment of adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer in combination with: o an aromatase inhibitor as initial endocrine-based therapy	approved	Feb 3, 2015	openfda
Palbociclib	US FDA	Malignant Breast Neoplasm	in combination with inavolisib and fulvestrant for the treatment of adult patients with endocrine-resistant, PIK3CA -mutated, HR-positive, HER2-negative, locally advanced or metastatic breast cancer, as detected by an FDA-authorized test, following recurrence on or after completing adjuvant endocrine therapy.	approved	Feb 3, 2015	openfda
Ribociclib	US FDA	Malignant Breast Neoplasm	Early Breast Cancer KISQALI is indicated in combination with an aromatase inhibitor for the adjuvant treatment of adults with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative stage II and III early breast cancer at high risk of recurrence.	approved	Mar 13, 2017	openfda
Sacituzumab Govitecan	US FDA	Malignant Breast Neoplasm	Locally Advanced or Metastatic HR-Positive, HER2-Negative Breast Cancer For the treatment of adult patients with unresectable locally advanced or metastatic hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative (IHC 0, IHC 1+ or IHC 2+/ISH–) breast cancer who have received endocrine-based therapy and at least two additional systemic therapies in the metastatic setting.	approved	Apr 22, 2020	openfda
Tamoxifen	US FDA	—	Efficacy supplement 2018-09-25 (see label)	approved	Sep 25, 2018	openfda
Tamoxifen	US FDA	—	To reduce risk of invasive breast cancer following breast surgery and radiation in adult women with ductal carcinoma in situ (DCIS)	approved	Oct 29, 2005	openfda
Tamoxifen	US FDA	Malignant Breast Neoplasm	For treatment of adult patients with estrogen receptor-positive metastatic breast cancer	approved	Oct 29, 2005	openfda
Tamoxifen	US FDA	Malignant Breast Neoplasm	For adjuvant treatment of adult patients with early stage estrogen receptor- positive breast cancer	approved	Oct 29, 2005	openfda
Tamoxifen	US FDA	Malignant Breast Neoplasm	To reduce the incidence of breast cancer in adult women at high risk	approved	Oct 29, 2005	openfda
Trastuzumab Deruxtecan	US FDA	Malignant Breast Neoplasm	HER2-Low and HER2-Ultralow Metastatic Breast Cancer as monotherapy for the treatment of adult patients with unresectable or metastatic hormone receptor (HR)-positive, HER2-low (IHC 1+ or IHC 2+/ISH-) or HER2-ultralow (IHC 0 with membrane staining) breast cancer, as determined by an FDA-authorized test, that has progressed on one or more endocrine therapies in the metastatic setting.	approved	Dec 20, 2019	openfda
Trastuzumab Deruxtecan	US FDA	Malignant Breast Neoplasm	HER2-Low and HER2-Ultralow Metastatic Breast Cancer as monotherapy for the treatment of adult patients with unresectable or metastatic hormone receptor (HR)-positive, HER2-low (IHC 1+ or IHC 2+/ISH-) or HER2-ultralow (IHC 0 with membrane staining) breast cancer, as determined by an FDA-authorized test, that has progressed on one or more endocrine therapies in the metastatic setting.	approved	Dec 20, 2019	openfda

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)