Protein / target

Poly [ADP-ribose] polymerase 2

PARP2Q9UGN5Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
9
Approved medicines
30
Clinical trials
Small-molecule tractable
Druggability
Approved Drug

Protein at a glance

Biological role

Poly-ADP-D-ribose modification-dependent protein binding

Strongest disease association

ovarian cancer

Clinical evidence · score 0.60

Therapeutic maturity

Clinically validated target

9 approved medicines against this target

Druggability

Small molecule

Open Targets tractability · Approved Drug

Clinical development

9 approved · 3 in clinical development

30 linked trials

Derived from structured UniProt, Open Targets and literature data on this page.

Protein profile

UniProt 2026_02

Canonical identity and biological annotation from UniProt.

Function

Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a key role in DNA repair (PubMed:10364231, PubMed:25043379, PubMed:27471034, PubMed:30104678, PubMed:32028527, PubMed:32939087, PubMed:34108479, PubMed:34486521, PubMed:34874266). Mediates glutamate, aspartate or serine ADP-ribosylation of proteins: the ADP-D-ribosyl group of NAD(+) is transferred to the acceptor carboxyl group of target residues and further ADP-ribosyl groups are transferred to the 2'-position of the terminal adenosine moiety, building up a polymer with an average chain length of 20-30 units (PubMed:25043379, PubMed:30104678, PubMed:30321391). Serine ADP-ribosylation of proteins constitutes the primary form of ADP-ribosylation of proteins in response to DNA damage (PubMed:32939087). Mediates glutamate and aspartate ADP-ribosylation of target proteins in absence of HPF1 (PubMed:25043379). Following interaction with HPF1, catalyzes serine ADP-ribosylation of target proteins; HPF1 conferring serine specificity by completing the PARP2 active site (PubMed:28190768, PubMed:32028527, PubMed:34108479, PubMed:34486521, PubMed:34874266). PARP2 initiates the repair of double-strand DNA breaks: recognizes and binds DNA breaks within chromatin and recruits HPF1, licensing serine ADP-ribosylation of target proteins, such as histones, thereby promoting decompaction of chromatin and the recruitment of repair factors leading to the reparation of DNA strand breaks (PubMed:10364231, PubMed:32939087, PubMed:34108479). HPF1 initiates serine ADP-ribosylation but restricts the polymerase activity of PARP2 in order to limit the length of poly-ADP-ribose chains (PubMed:34732825, PubMed:34795260). Specifically mediates formation of branched poly-ADP-ribosylation (PubMed:30104678). Branched poly-ADP-ribose chains are specifically recognized by some factors, such as APLF (PubMed:30104678). In addition to proteins, also able to ADP-ribosylate DNA: preferentially acts on 5'-terminal phosphates at DNA strand breaks termini in nicked duplex (PubMed:27471034, PubMed:29361132)

Subcellular location

NucleusChromosome
Domains and Gene Ontology detail (27)

Domains & features

WGRPARP alpha-helicalPARP catalytic

Gene Ontology

  • Cnucleolus
  • Cnucleoplasm
  • Cnucleus
  • Csite of DNA damage
  • Fchromatin binding
  • Fdamaged DNA binding
  • FNAD DNA ADP-ribosyltransferase activity
  • FNAD+ poly-ADP-ribosyltransferase activity
  • FNAD+-protein mono-ADP-ribosyltransferase activity
  • FNAD+-protein-aspartate ADP-ribosyltransferase activity
  • FNAD+-protein-glutamate ADP-ribosyltransferase activity
  • FNAD+-protein-serine ADP-ribosyltransferase activity

583 aa · 66 kDa · 2 isoforms

Biological roles

Reactome v97

What this protein does, drawn together from its UniProt function, Gene Ontology terms and Reactome pathways.

Metabolic enzyme activityGO
View supporting evidence

Metabolic enzyme activity

  • ·NAD DNA ADP-ribosyltransferase activity
  • ·NAD+ poly-ADP-ribosyltransferase activity
  • ·NAD+-protein mono-ADP-ribosyltransferase activity
  • ·NAD+-protein-aspartate ADP-ribosyltransferase activity
View underlying pathways (5)

Concepts derived from UniProt GO Reactome — each badge above shows which sources supported that role.

Interaction neighbourhood

STRING v12.0

Proteins with the strongest functional or physical association. Node size and line weight reflect STRING confidence; hover or select a partner to inspect one association.

HPF1POLBXRCC1LIG3PARGPARP1H2BC11H2AC6XRCC6CASP3PARP2

10 strongest partners — larger node and heavier line mean higher confidence

Functional and physical associations from STRING v12.0. Only associations with this protein are drawn — partner-to-partner links are not part of this evidence.

Drugs targeting this protein

4

Whether each drug engages this protein directly or through a complex, and how many other targets are recorded for it. Direct binders with few recorded targets are listed first.

talazoparib
Narrow target profileApprovedInhibitor

Poly [ADP-ribose] polymerase 2 inhibitor

Appears in clinical studies involving breast cancer, neoplasm, psoriatic arthritis, prostate cancer

Direct interaction with this protein · 1 of 2 recorded protein targets — narrow recorded profile

niraparib
Narrow target profileApprovedInhibitor

Poly [ADP-ribose] polymerase 2 inhibitor

Appears in clinical studies involving fallopian tube neoplasm, peritoneal neoplasm, ovarian neoplasm, neoplasm

Direct interaction with this protein · 1 of 2 recorded protein targets — narrow recorded profile

olaparib
ApprovedInhibitor

PARP 1, 2 and 3 inhibitor

Appears in clinical studies involving ovarian cancer, ovarian carcinoma, pancreatic neoplasm, prostate carcinoma

Acts on a complex — shared with PARP1, PARP3 · 1 of 3 recorded protein targets — narrow recorded profile

rucaparib
ApprovedInhibitor

PARP 1, 2 and 3 inhibitor

Appears in clinical studies involving ovarian cancer, neoplasm, fallopian tube cancer, primary peritoneal carcinoma

Acts on a complex — shared with PARP1, PARP3 · 1 of 3 recorded protein targets — narrow recorded profile

ChEMBL mechanism, action type and target identity. Open Targets clinical status and indications.

Translational evidence

Open Targets 26

Why this target matters therapeutically — disease associations, drugs in development, tractability and safety, from Open Targets.

Highest-confidence therapeutic associations

Diseases where a drug acting on this target has already reached clinical development.

ovarian cancer0.97

Clinical · overall 0.60

neoplasm0.92

Clinical · overall 0.57

fallopian tube cancer0.91

Clinical · overall 0.55

breast cancer0.90

Clinical · overall 0.56

ovarian carcinoma0.89

Clinical · overall 0.55

Highest overall evidence

Remaining associations by Open Targets' aggregated evidence score.

primary peritoneal carcinoma0.52

Clinical

prostate cancer0.52

Clinical

breast neoplasm0.51

Clinical

ovarian neoplasm0.50

Clinical

peritoneum cancer0.50

Clinical

Show all associations
ovarian cancer0.60
neoplasm0.57
breast cancer0.56
fallopian tube cancer0.55
ovarian carcinoma0.55
primary peritoneal carcinoma0.52
prostate cancer0.52
breast neoplasm0.51
ovarian neoplasm0.50
peritoneum cancer0.50

Open Targets ranks 478 associations for this target and we store the top 10 by aggregated score. The long tail is largely literature co-mention and RNA-expression evidence, not evidence that this target drives those diseases.

Known drugs · 12 total

NIRAPARIBApproval

fallopian tube neoplasm · peritoneal neoplasm · ovarian neoplasm

VELIPARIBApproval

neoplasm · breast cancer · malignant epithelial tumor of ovary

SENAPARIBPhase 3

primary peritoneal carcinoma · fallopian tube cancer · ovarian cancer

OLAPARIBApproval

ovarian cancer · ovarian carcinoma · pancreatic neoplasm

PAMIPARIBApproval

neoplasm · cancer · ovarian cancer

2X-121Phase 2

ovarian cancer · breast cancer · colorectal cancer

NIRAPARIB TOSYLATE MONOHYDRATEApproval

ovarian cancer · fallopian tube cancer · peritoneum cancer

RUCAPARIB CAMSYLATEApproval

ovarian cancer · ovarian neoplasm · ovarian carcinoma

TALAZOPARIBApproval

breast cancer · neoplasm · psoriatic arthritis

E-7016Phase 2

melanoma · glioma

Tractability

SM · Approved DrugSM · Structure with LigandSM · High-Quality LigandSM · Med-Quality PocketSM · Druggable FamilyPR · LiteraturePR · Database UbiquitinationPR · Small Molecule Binder

Clinical trials

30

Trials of drugs that target this protein — reached indirectly through those drugs, so a trial listed here studies the drug, not the protein.

Show remaining trials (24)

ACTIVE_NOT_RECRUITING · via rucaparib · NCT04624178

ClinicalTrials.gov via the drug-target graph.

Forefront confidence

Synthesis

Our own weighting of the evidence behind each disease association. Human genetics and clinical evidence count for most; literature co-mention counts for little, because two entities sharing an abstract is not evidence that one drives the other.

ovarian cancerModerately supported
0.74
agreement 0.580.89
Clinical97%Literature3%

Open Targets aggregate 0.60 · 2 independent evidence families

neoplasmModerately supported
0.71
agreement 0.560.87
Clinical90%Literature10%

Open Targets aggregate 0.57 · 2 independent evidence families

breast cancerModerately supported
0.69
agreement 0.530.84
Clinical95%Literature5%

Open Targets aggregate 0.56 · 2 independent evidence families

fallopian tube cancerModerately supported
0.68
agreement 0.520.85
Clinical100%

Open Targets aggregate 0.55 · 1 independent evidence family

ovarian carcinomaModerately supported
0.68
agreement 0.520.83
Clinical97%Literature3%

Open Targets aggregate 0.55 · 2 independent evidence families

The evidence agreement range shows how closely the independent evidence families agree — it is not a statistical confidence interval, and nothing here is fitted to outcome data. Derived from Open Targets evidence types under Forefront weighting; the underlying per-type scores are shown above so the calculation can be checked.

What's happening now

26

Recent activity around this target, drawn from one canonical event stream. Every item is reached through 4 drugs that target this protein, so each event is news about that drug rather than about the protein directly.

  1. Trial results posted2026-07-17

    Phase II Study of Rucaparib and Nivolumab in Patients With Leiomyosarcoma

    Results posted · ClinicalTrials.gov · via rucaparib

  2. Trial status changed2026-07-16

    A Pharmacodynamics-Driven Trial of Talazoparib, an Oral PARP Inhibitor, in Patients With Advanced Solid Tumors and Aberrations in Genes Involved in DNA Damage Response

    Status changed to Active, not recruiting · ClinicalTrials.gov · via talazoparib

  3. New publication2025-10-07
    Niraparib and abiraterone acetate plus prednisone for HRR-deficient metastatic castration-sensitive prostate cancer: a randomized phase 3 trial.

    Nature medicine · 2025 · 19 citations · Europe PMC · via niraparib

  4. New publication2025-01-31
    Results of a phase Ib study of olaparib with concomitant radiotherapy in soft-tissue sarcoma: a French sarcoma group study.

    Annals of oncology : official journal of the European Society for Medical Oncology · 2025 · 4 citations · Europe PMC · via olaparib

  5. New publication2023-12-04
    First-line talazoparib with enzalutamide in HRR-deficient metastatic castration-resistant prostate cancer: the phase 3 TALAPRO-2 trial.

    Nature medicine · 2024 · 105 citations · Europe PMC · via talazoparib

  6. New publication2023-11-14
    Olaparib for the Treatment of Patients With Metastatic Castration-Resistant Prostate Cancer and Alterations in <i>BRCA1</i> and/or <i>BRCA2</i> in the PROfound Trial.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2024 · 76 citations · Europe PMC · via olaparib

  7. New publication2023-10-21
    Durvalumab Plus Carboplatin/Paclitaxel Followed by Maintenance Durvalumab With or Without Olaparib as First-Line Treatment for Advanced Endometrial Cancer: The Phase III DUO-E Trial.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2024 · 259 citations · Europe PMC · via olaparib

  8. New publication2023-02-16
    Rucaparib or Physician's Choice in Metastatic Prostate Cancer.

    The New England journal of medicine · 2023 · 332 citations · Europe PMC · via rucaparib

  9. New publication2022-10-10
    Overall survival in the OlympiA phase III trial of adjuvant olaparib in patients with germline pathogenic variants in BRCA1/2 and high-risk, early breast cancer.

    Annals of oncology : official journal of the European Society for Medical Oncology · 2022 · 325 citations · Europe PMC · via olaparib

  10. Safety communication2022-09-26

    Drug Safety Update: Rucaparib (Rubraca▼): withdrawal of third-line treatment indication

    mhra · safety · mhra · via rucaparib

  11. New publication2021-06-03
    Adjuvant Olaparib for Patients with <i>BRCA1</i>- or <i>BRCA2</i>-Mutated Breast Cancer.

    The New England journal of medicine · 2021 · 1,225 citations · Europe PMC · via olaparib

  12. Safety communication2020-10-22

    Drug Safety Update: Niraparib (Zejula▼): reports of severe hypertension and posterior reversible encephalopathy syndrome (PRES), particularly in early treatment

    mhra · safety · mhra · via niraparib

Objective event titles are shown unmodified; the event kind and significance line are derived from structured fields. Forefront AttentionEvent stream aggregating Europe PMC Regulatory filings ClinicalTrials.gov.