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PARP inhibitor

PARP inhibitor

Overview

Poly(ADP-ribose) polymerase (PARP) inhibitors are a class of targeted anticancer agents that exploit defects in DNA damage repair pathways, particularly homologous recombination (HR). PARP enzymes play a central role in detecting and repairing single-strand DNA breaks; when inhibited, unresolved breaks collapse replication forks into double-strand breaks. In tumor cells already harboring deficiencies in HR — such as those with loss-of-function mutations in BRCA1 or BRCA2 DNA repair associated genes — this dual impairment of repair pathways leads to synthetic lethality, resulting in selective cancer cell death while largely sparing normal cells. olaparib, one of the earliest and most clinically validated agents in this class, exemplifies the mechanism and has been approved across multiple HR-deficient tumor types including ovarian, breast, and prostate cancers.

The therapeutic utility of PARP inhibitors is closely tied to the concept of BRCAness — a broader genomic phenotype characterized by deficient homologous recombination repair (HRD), even in the absence of germline BRCA mutations. The presence of PTEN loss and other HR pathway alterations has been associated with sensitivity to this drug class. Understanding and expanding the HRD-positive patient population, overcoming intrinsic and acquired resistance, and identifying synergistic combination strategies represent the principal frontiers of contemporary PARP inhibitor research.

Recent Publications Focus

Below is a summary of the newest research publications targeting PARP inhibitor (sorted by publication date).

  • 2026-06-04 — Triple-negative breast cancer nanotherapy and PARP inhibitor resistance

    • A study in ACS Applied Bio Materials described a manganese oxide-based multifunctional nanoplatform for synergistic therapy of triple-negative breast cancer. The publication specifically noted that TNBC has low bioavailability and high resistance to poly(ADP-ribose) polymerase inhibitors, highlighting PARP inhibitor resistance as a major therapeutic barrier in this disease.
    • The work used manganese oxide-based nanoparticles and manganese(II,III) oxide in ovarian and breast cancer models, indicating interest in combination or platform-based strategies to overcome resistance rather than PARP inhibition alone.

  • 2026-07-01 — PARP inhibitor rechallenge plus bevacizumab in recurrent ovarian cancer

    • Clinical Cancer Research reported on maintenance PARP inhibitor rechallenge combined with bevacizumab in patients with platinum-sensitive, recurrent ovarian cancer who had previously been treated with a PARP inhibitor.
    • This study directly addressed the clinical question of whether PARP inhibitor rechallenge can remain effective after prior exposure, and whether adding bevacizumab may improve maintenance outcomes in this setting.

  • 2026-06-01 — Prior PARP inhibitor exposure and platinum chemotherapy efficacy

    • An International Journal of Clinical Oncology propensity score-matched analysis evaluated the efficacy of platinum-based chemotherapy in platinum-sensitive recurrent ovarian cancer among patients with and without prior PARP inhibitor exposure.
    • The study design used propensity score-matched analysis to compare outcomes, reflecting ongoing concern that prior PARP inhibitor treatment may alter later sensitivity to platinum-based chemotherapy.

  • 2026-05-27 — PARP inhibitor resistance driven by genomic instability and stromal signaling

    • A Science Translational Medicine paper investigated how genomic instability drives POSTN+ myofibroblasts through a STING-WNT axis to promote immunosuppression and PARP inhibitor resistance in ovarian cancer.
    • The study linked STING signaling, WNT3a/7a, and Wnt/β-catenin signaling to a tumor microenvironment program involving cancer-associated fibroblast-like stromal cells, suggesting that genomic instability can paradoxically convert immune activation into immune suppression and thereby limit PARP inhibitor efficacy.

  • 2026-05-08 — AURKA inhibition induces functional BRCAness and sensitizes prostate cancer

    • In JCI Insight, VIC-1911, an Aurora kinase A inhibitor, was reported to induce mitotic defects and functional BRCAness, sensitizing prostate cancer to PARP inhibition.
    • The study found synergistic effects on prostate cancer cell growth in vitro and xenograft tumor growth in vivo when VIC-1911 was combined with PARP inhibitors, supporting a strategy of pharmacologically creating homologous recombination repair vulnerability.

  • 2026-04-28 — PARP inhibitor-treated prostate cancer cells and LINE-1 transcription

    • Cancer Letters reported that M1C mediates LINE-1 transcription in PARP inhibitor-treated prostate cancer cells.
    • The publication focused on advanced castration-resistant prostate cancer, noting that responsiveness to PARP inhibitors is generally restricted to settings with homologous recombination defects. This work adds mechanistic context to how prostate cancer cells respond transcriptionally during PARP inhibitor treatment.

  • 2026-04-22 — Comparative outcomes in prostate cancer treatment subgroups

    • An International Journal of Cancer study on combined immunotherapy and targeted therapy in prostate cancer reported that the androgen receptor signaling inhibitor subgroup exhibited longer survival than the PARP inhibitor subgroup.
    • While not a mechanistic study, this comparison places PARP inhibitor-based treatment within the broader landscape of prostate cancer targeted therapy and suggests differences in clinical benefit across treatment classes.

  • 2026-06-01 — Review of metastatic castration-resistant prostate cancer strategies

    • A review in International Journal of Oncology summarized novel therapeutic strategies for metastatic castration-resistant prostate cancer beyond androgen receptor pathway inhibition.
    • The review identified PARP inhibitors as an option for tumors with homologous recombination repair deficiencies, reinforcing the biomarker-driven role of this therapy in prostate cancer.

  • 2026-04-01 — Genomic instability subtypes in hereditary breast cancer

    • Experimental & Molecular Medicine described four disease subtypes underlying genomic instability in hereditary breast cancers.
    • Functional analysis in cell lines suggested sensitivity to poly(ADP-ribose) polymerase inhibitors and cytotoxic chemotherapy in HRD and CN tumors, whereas immune features in MUT tumors supported vulnerability to immunotherapy. This supports the concept that PARP inhibitor responsiveness is enriched in homologous recombination-deficient disease contexts.

Overall, these publications emphasize that PARP inhibitor activity is strongly shaped by DNA repair defects, especially homologous recombination deficiency, and that resistance can emerge through tumor-intrinsic and microenvironmental mechanisms. Current research is focused on rechallenge strategies, combination therapy with bevacizumab or platinum-based chemotherapy, synthetic lethal sensitization using agents such as Aurora kinase A inhibitors, and resistance biology involving STING signaling, WNT/β-catenin signaling, and stromal remodeling in ovarian cancer and prostate cancer.

Background PMIDs

  • [PMID 42240069]
  • [PMID 41690451]

Method PMIDs

  • [PMID 41915443]

Target PMIDs

  • [PMID 41609513]
  • [PMID 41882282]
  • [PMID 42202048]
  • [PMID 42017392]
  • [PMID 41992975]
  • [PMID 41991965]
Content is generated using Large Language Models (LLMs) and may contain errors or hallucinations. Experts periodically review it to verify accuracy and maintain database integrity.