# TBCRC 048 expansion: olaparib in metastatic breast cancer with germline PALB2 or somatic BRCA

Source: https://onco.cc/key-papers/paper-tung-tbcrc048-expansion-jco-2026/  
OnCo record `paper-tung-tbcrc048-expansion-jco-2026` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Olaparib shrank some metastatic breast cancers with tumour-only BRCA mutations. This does not establish benefit in preventing recurrence after surgery.

## Summary

Phase 2 expansion with 24 germline PALB2 and 30 somatic BRCA1/2 participants. The overall population comprised 42 ER-positive/HER2-negative, seven TNBC and five HER2-positive cancers. Participants received single-agent olaparib until progression. Somatic-BRCA activity was clinically meaningful but missed the prespecified response target.

## Fields

- Kind: Key paper
- Last checked: 2026-10-10
- Journal: Journal of Clinical Oncology
- Year: 2026
- DOI: 10.1200/JCO-25-02075
- Authors: Tung NM, Robson ME, Li T, et al.
- Findings: Somatic BRCA1/2: 11/30 responses, ORR 36.7% (80% CI 24.7 to 50.0), median PFS 5.5 months (90% CI 2.8 to 8.3), median response duration 11.2 months (90% CI 4.4 to not reached).; Germline PALB2: ORR 75% (80% CI 60.2 to 86.3), median PFS 9.4 months (90% CI 8.3 to 13.1).
- What it means: Metastatic single-arm evidence does not supply a somatic-only adjuvant indication or a personal response probability.
- Caveats: Metastatic single-arm evidence does not supply a somatic-only adjuvant indication or a personal response probability.; Only seven participants overall had TNBC; somatic cohort mixed BRCA1 and BRCA2, 15 each.

## Sources

- Primary publication: https://doi.org/10.1200/JCO-25-02075
- PubMed record: https://pubmed.ncbi.nlm.nih.gov/41604601/

## Connected records

- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- targets: [PARP](https://onco.cc/targets/parp/)
- drugs: [Olaparib](https://onco.cc/drugs/olaparib/)
- trials: [Olaparib In Metastatic Breast Cancer](https://onco.cc/trials/nct03344965/)

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