# Case Report: Individualized circulating tumor DNA monitoring guides olaparib adjuvant therapy: an early-stage breast cancer case with somatic BRCA2 mutation

## TL;DR

A breast cancer patient with a BRCA2 mutation had successful treatment guided by ctDNA monitoring, showing how personalized DNA tracking can help tailor therapies.

## Contribution

Demonstrates the clinical utility of ctDNA monitoring in guiding olaparib therapy for early-stage BRCA2-mutated breast cancer.

## Key findings

- ctDNA monitoring detected MRD positivity before imaging showed recurrence.
- Resuming olaparib therapy after MRD detection led to negative MRD status.
- Imaging showed no recurrence despite MRD detection.

## Abstract

Circulating tumor DNA (ctDNA) has demonstrated a strong predictive capacity for recurrence in early-stage breast cancer compared with imaging examinations. However, there remains a paucity of robust clinical evidence to guide the adjustment of adjuvant therapy based on minimal residual disease (MRD) status in early-stage breast cancer.

A 69-year-old female patient with early-stage triple-negative breast cancer (TNBC) with somatic BRCA2 mutations exhibited an exceptional response to adjuvant therapy with olaparib. Personalized ctDNA monitoring, utilizing a tumor-informed approach, was employed alongside imaging examinations and tumor biomarker testing to monitor tumor recurrence. MRD positivity was detected at four months and approximately one-month post-treatment discontinuation. Resumption of olaparib therapy resulted in a negative MRD status, while imaging examinations consistently demonstrated no evidence of recurrence in the patient.

This report underscores the potential benefit of olaparib for early-stage TNBC patients with somatic BRCA2 mutations and the utility of serial ctDNA monitoring for tailoring individualized treatment strategies.