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Updated: Feb 10, 2026

Detection and Monitoring of Tumor Associated Circulating DNA in Patient Biofluids
Published on: June 8, 2019
Identifying Circulating Tumor DNA Mutation Profiles in Metastatic Breast Cancer Patients with Multiline Resistance
Zhe-Yu Hu1, Ning Xie2, Can Tian2
1Hunan Cancer Hospital, and the Affiliated Cancer Hospital of Xiangya Medical School, Central South University, Changsha 410013, China; Department of Breast Cancer Medical Oncology, Hunan Cancer Hospital, Changsha 410013, China; Department of Breast Cancer Medical Oncology, The Affiliated Cancer Hospital of Xiangya Medical School, Central South University, Changsha 410013, China; Central Laboratory, The Affiliated Cancer Hospital of Xiangya Medical School, Central South University, Changsha 410013, China.
Purpose:
In cancer patients, tumor gene mutations contribute to drug resistance and treatment failure. In patients with metastatic breast cancer (MBC), these mutations increase after multiline treatment, thereby decreasing treatment efficiency. The aim of this study was to evaluate gene mutation patterns in MBC patients to predict drug resistance and disease progression.
Method:
A total of 68 MBC patients who had received multiline treatment were recruited. Circulating tumor DNA (ctDNA) mutations were evaluated and compared among hormone receptor (HR)/human epidermal growth factor receptor 2 (HER2) subgroups.
Results:
The baseline gene mutation pattern (at the time of recruitment) varied among HR/HER2 subtypes. BRCA1 and MED12 were frequently mutated in triple negative breast cancer (TNBC) patients, PIK3CA and FAT1 mutations were frequent in HR+ patients, and PIK3CA and ERBB2 mutations were frequent in HER2+ patients. Gene mutation patterns also varied in patients who progressed within either 3 months or 3-6 months of chemotherapy treatment. For example, in HR+ patients who progressed within 3 months of treatment, the frequency of TERT mutations significantly increased. Other related mutations included FAT1 and NOTCH4. In HR+ patients who progressed within 3-6 months, PIK3CA, TP53, MLL3, ERBB2, NOTCH2, and ERS1 were the candidate mutations. This suggests that different mechanisms underlie disease progression at different times after treatment initiation. In the COX model, the ctDNA TP53 + PIK3CA gene mutation pattern successfully predicted progression within 6 months.
Conclusion:
ctDNA gene mutation profiles differed among HR/HER2 subtypes of MBC patients. By identifying mutations associated with treatment resistance, we hope to improve therapy selection for MBC patients who received multiline treatment.
Insights
Tumor gene mutations in metastatic breast cancer (MBC) patients predict drug resistance. Analyzing circulating tumor DNA (ctDNA) revealed distinct mutation patterns across subtypes, aiding in personalized treatment selection for improved outcomes.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- Tumor gene mutations are a significant cause of drug resistance and treatment failure in cancer patients.
- In metastatic breast cancer (MBC), acquired mutations after multiline treatment reduce therapeutic efficacy.
- Understanding these mutation patterns is crucial for predicting disease progression and resistance.
Purpose of the Study:
- To evaluate gene mutation patterns in circulating tumor DNA (ctDNA) of MBC patients.
- To correlate specific mutations with hormone receptor (HR)/human epidermal growth factor receptor 2 (HER2) subtypes.
- To predict drug resistance and disease progression based on identified mutation profiles.
Main Methods:
- Recruited 68 patients with metastatic breast cancer (MBC) who had undergone multiline treatment.
- Analyzed circulating tumor DNA (ctDNA) mutations.
- Compared mutation patterns across different HR/HER2 subgroups and correlated them with treatment response times.
Main Results:
- Baseline ctDNA mutation patterns varied significantly among HR/HER2 subtypes (TNBC, HR+, HER2+).
- Specific mutations like BRCA1/MED12 (TNBC), PIK3CA/FAT1 (HR+), and PIK3CA/ERBB2 (HER2+) were prevalent.
- TERT, FAT1, NOTCH4, PIK3CA, TP53, MLL3, NOTCH2, and ERS1 mutations were associated with disease progression at different time points.
- A ctDNA pattern of TP53 + PIK3CA mutations predicted progression within 6 months in a COX model.
Conclusions:
- ctDNA gene mutation profiles are distinct across HR/HER2 subtypes in MBC.
- Identifying mutations linked to treatment resistance can guide therapy selection.
- This approach may improve treatment strategies for patients with advanced breast cancer receiving multiple treatment lines.
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