# TRITON2: rucaparib in men with metastatic castration-resistant prostate cancer harbouring a BRCA1 or BRCA2 alteration

Source: https://onco.cc/key-papers/paper-abida-triton2-rucaparib-brca-jco-2020/  
OnCo record `paper-abida-triton2-rucaparib-brca-jco-2020` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The trial that got rucaparib approved for prostate cancer. In 115 men with a BRCA fault whose cancer had already been through hormone drugs and chemotherapy, around half had their tumours shrink or their PSA halve.

## Summary

Wassim Abida and the TRITON2 investigators treated men with metastatic castration-resistant prostate cancer and a deleterious BRCA1 or BRCA2 alteration with rucaparib 600 mg twice daily, after progression on one or two androgen receptor-directed therapies and one taxane. The efficacy and safety populations comprised 115 men.

The result supported accelerated approval in the United States in May 2020, on a single-arm response rate, three years before TRITON3 provided the randomised confirmation. Response rates were similar whether the BRCA alteration was germline or somatic and whether it was BRCA1 or BRCA2, although prostate-specific antigen responses were higher with BRCA2. That germline and somatic alterations behave the same is the practical reason tumour sequencing, not just a blood test for inherited faults, belongs in this disease.

## Fields

- Kind: Key paper
- Last checked: 2026-09-25
- Also known as: TRITON2; Abida 2020 rucaparib
- Tags: prostate-evidence
- Journal: Journal of Clinical Oncology
- Year: 2020
- DOI: 10.1200/jco.20.01035
- Authors: Abida W, Patnaik A, Campbell D, et al.
- Findings: Confirmed objective response rate by independent radiology review 43.5 percent (95 percent confidence interval 31.0 to 56.7; 27 of 62 patients with measurable disease) and by investigator assessment 50.8 percent (38.1 to 63.4; 33 of 65).; Confirmed prostate-specific antigen response rate, a decrease of 50 percent or more, 54.8 percent (45.2 to 64.1; 63 of 115 patients).; Objective response rates were similar for germline and somatic BRCA alterations and for BRCA1 and BRCA2 alterations; a higher prostate-specific antigen response rate was observed with BRCA2.; The most frequent grade 3 or higher treatment-emergent adverse event was anaemia, in 29 of 115 patients (25.2 percent).; Patients had progressed after one to two lines of next-generation androgen receptor-directed therapy and one taxane-based chemotherapy.
- What it means: The trial behind the second PARP inhibitor licensed in prostate cancer, and the evidence that a somatic BRCA alteration predicts response as well as an inherited one. Together with TOPARP-A it is why tumour as well as germline sequencing is recommended in metastatic disease.
- Caveats: Single-arm with a response endpoint, which supported accelerated rather than full approval; the randomised confirmation came from TRITON3 in 2023.; Restricted to BRCA1 and BRCA2; the wider homologous recombination repair gene set behaves differently and mostly worse.; Anaemia of grade 3 or higher in a quarter of patients is a meaningful burden in a population that is often already anaemic from bone disease and androgen deprivation.

## Sources

- J Clin Oncol 2020: https://doi.org/10.1200/jco.20.01035
- PubMed: https://pubmed.ncbi.nlm.nih.gov/32795228/
- ClinicalTrials.gov NCT02952534: https://clinicaltrials.gov/study/NCT02952534
- Abida et al., J Clin Oncol 2020: TRITON2, rucaparib in 115 men with BRCA-altered metastatic castration-resistant prostate cancer: https://doi.org/10.1200/JCO.20.01035
- RUBRACA prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0295d202-1cfe-7659-e063-6294a90a476e

## Connected records

- key papers: [PROfound: olaparib for metastatic castration-resistant prostate cancer with homologous recombination repair gene alterations](https://onco.cc/key-papers/paper-profound-nejm-2020/), [TOPARP-A: DNA-repair defects and olaparib in metastatic prostate cancer](https://onco.cc/key-papers/paper-mateo-toparp-a-olaparib-dna-repair-nejm-2015/), [TRITON3: rucaparib or physician's choice in metastatic castration-resistant prostate cancer](https://onco.cc/key-papers/paper-fizazi-triton3-rucaparib-nejm-2023/)
- roadmaps: [Prostate cancer roadmap: from Huggins and the discovery that a cancer can depend on a hormone, through the PSA epidemic and what it cost, the androgen receptor drugs, the DNA repair subset and PSMA, to a 2032 registry watch](https://onco.cc/roadmaps/prostate-roadmap/)
- cancers: [Metastatic castration-resistant prostate cancer](https://onco.cc/cancers/prostate-mcrpc/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- fronts: [Targeted Therapy](https://onco.cc/fronts/targeted-therapy/)
- technologies: [Comprehensive genomic profiling](https://onco.cc/technologies/cgp/), [PARP inhibitors](https://onco.cc/technologies/parp-inhibitor/)
- targets: [BRCA1 / BRCA2 (HRD)](https://onco.cc/targets/brca/), [PARP](https://onco.cc/targets/parp/)
- drugs: [Rucaparib](https://onco.cc/drugs/rucaparib/)
- companies: [Clovis Oncology](https://onco.cc/companies/clovis-oncology/)
- pathways: [Base excision repair, PARP & alkylation damage](https://onco.cc/pathways/base-excision-repair-parp/), [Double-strand break repair: HR versus end joining](https://onco.cc/pathways/homologous-recombination-repair/), [Synthetic lethality: paired dependencies](https://onco.cc/pathways/synthetic-lethality-map/)
- terms: [Genome-wide loss of heterozygosity (gLOH)](https://onco.cc/terms/genome-wide-loss-of-heterozygosity/), [Germline BRCA mutation (gBRCA)](https://onco.cc/terms/gbrca-mutation/), [Germline vs somatic mutations](https://onco.cc/terms/germline-vs-somatic/), [Homologous recombination deficiency (HRD)](https://onco.cc/terms/hrd/), [PSA (prostate-specific antigen)](https://onco.cc/terms/psa/), [PSA50 / PSA90 response](https://onco.cc/terms/psa50/), [Synthetic lethality](https://onco.cc/terms/synthetic-lethality/)
- bottlenecks: [Biomarkers are not validated or standardised](https://onco.cc/bottlenecks/b-biomarker-validation/), [Regulatory divergence between regions](https://onco.cc/bottlenecks/b-regulatory-fragmentation/)
- journals: [Journal of Clinical Oncology](https://onco.cc/journals/jco/)
- ideas: [Test every man for DNA repair faults on the day his prostate cancer is found to have spread, not three treatments later](https://onco.cc/ideas/idea-prostate-hrr-testing-at-metastatic-diagnosis/)
- biomarkers: [Homologous recombination repair gene mutation in prostate cancer](https://onco.cc/biomarkers/hrr-gene-mutation/), [Tumour (somatic or germline) BRCA1/2 mutation and HRR gene alterations](https://onco.cc/biomarkers/brca-somatic/)

---
JSON: https://onco.cc/api/v1/entities/paper-abida-triton2-rucaparib-brca-jco-2020.json