niraparib
Zejula (niraparib) is an oral PARP inhibitor from GlaxoSmithKline used as maintenance treatment for advanced ovarian, fallopian tube, or primary peritoneal cancer that has responded to platinum-based chemotherapy. It blocks DNA repair enzymes cancer cells depend on, so DNA damage accumulates and the cells die.
This page is based on FDA prescribing information and the EMA medicine record for niraparib, cross-checked with DailyMed, MedlinePlus, and the National Cancer Institute dictionary; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
Every cell suffers small DNA breaks daily, and PARP enzymes are the first responders that patch single-strand damage. Many ovarian cancers have lost their backup repair crew through BRCA mutations. Niraparib removes the first responders; with both crews gone, breaks pile up until the cancer cell's genome falls apart and the cell dies, while healthy cells with an intact backup crew cope.
In simple terms
Niraparib blocks PARP-1 and PARP-2, the enzymes cells use to repair single-strand DNA breaks. When PARP is inhibited, unrepaired breaks accumulate. Cancer cells, particularly those with BRCA mutations or other homologous recombination defects, cannot fix this damage and die, while normal cells retain other repair routes. Taken by mouth, niraparib is used as maintenance therapy to help keep ovarian, fallopian tube, or primary peritoneal cancer from returning after platinum-based chemotherapy has shrunk it.
In depth
Niraparib is an orally bioavailable, hydrated tosylate salt that binds and inhibits PARP-1 and PARP-2, blocking PARP-mediated repair of single-strand DNA breaks. The resulting accumulation of strand breaks promotes genomic instability and apoptosis, with selective toxicity in tumors carrying homologous recombination deficiency such as deleterious BRCA mutations. Companion diagnostics identifying HRD-positive or germline BRCA-mutated disease are used to select patients for maintenance treatment after platinum response.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
How niraparib blocks PARP-1/2 so HRD-deficient tumour cells die
- Niraparib blocks PARP-1 and PARP-2, the enzymes cells use to repair single-strand DNA breaks.
- Niraparib is an orally bioavailable, hydrated tosylate salt that binds and inhibits PARP-1 and PARP-2, blocking PARP-mediated repair of single-strand DNA breaks.
- The resulting accumulation of strand breaks promotes genomic instability and apoptosis, with selective toxicity in tumors carrying homologous recombination deficiency such as deleterious BRCA mutations.
- Companion diagnostics identifying HRD-positive or germline BRCA-mutated disease are used to select patients for maintenance treatment after platinum response.
Target: Poly (ADP-ribose) polymerase 1 and 2 (PARP-1, PARP-2)
Enzymes that detect single-strand DNA breaks and start their repair; blocking them leaves breaks unrepaired, which is especially lethal to cancer cells whose backup repair pathways are already defective.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in United States
FDA- For the maintenance treatment of adults with advanced epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in a complete or partial response to first-line platinum-based chemotherapy and whose cancer is homologous recombination deficiency (HRD)-positive, defined by a deleterious or suspected deleterious BRCA mutation and/or genomic instability, with patients selected by an FDA-authorized companion diagnostic
- For the maintenance treatment of adults with deleterious or suspected deleterious germline BRCA-mutated recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in a complete or partial response to platinum-based chemotherapy, with patients selected by an FDA-authorized companion diagnostic
Approved uses in European Union
EMA- As monotherapy, for the maintenance treatment of adults with advanced epithelial (FIGO Stages III and IV) high-grade ovarian, fallopian tube or primary peritoneal cancer who are in response (complete or partial) following completion of first-line platinum-based chemotherapy
- As monotherapy, for the maintenance treatment of adults with platinum-sensitive relapsed high-grade serous epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in response (complete or partial) to platinum-based chemotherapy
Official sources
The statements on this page trace back to these records.
- Zejula (niraparib) — Summary of product characteristics and package leaflet, English version
European Medicines Agency
- DailyMed: ZEJULA (niraparib) official US label
U.S. National Library of Medicine, DailyMed
- U.S. Food and Drug Administration: niraparib prescribing information
U.S. Food and Drug Administration
- MedlinePlus: niraparib
MedlinePlus, U.S. National Library of Medicine
- National Cancer Institute: niraparib tosylate monohydrate
National Cancer Institute
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.