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Updated: Jun 18, 2026
Detection of Rare Mutations in CtDNA Using Next Generation Sequencing
Published on: August 24, 2017
Evaluation of endocrine resistance using ESR1 genotyping of circulating tumor cells and plasma DNA
Tilak K Sundaresan1,2,3, Taronish D Dubash1,3, Zongli Zheng1,4,5,3
1Cancer Center, Massachusetts General Hospital, Bldg 149, 13th Street, Charlestown, MA, 02129, USA.
Purpose:
Therapeutic efficacy of hormonal therapies to target estrogen receptor (ER)-positive breast cancer is limited by the acquisition of ligand-independent ESR1 mutations, which confer treatment resistance to aromatase inhibitors (AIs). Monitoring for the emergence of such mutations may enable individualized therapy. We thus assessed CTC- and ctDNA-based detection of ESR1 mutations with the aim of evaluating non-invasive approaches for the determination of endocrine resistance.
Patients And Methods:
In a prospective cohort of 55 women with hormone receptor-positive metastatic breast cancer, we isolated circulating tumor cells (CTCs) and developed a high-sensitivity method for the detection of ESR1 mutations in these CTCs. In patients with sufficient plasma for the simultaneous extraction of circulating tumor DNA (ctDNA), we performed a parallel analysis of ESR1 mutations using multiplex droplet digital PCR (ddPCR) and examined the agreement between these two platforms. Finally, we isolated single CTCs from a subset of these patients and reviewed RNA expression to explore alternate methods of evaluating endocrine responsiveness.
Results:
High-sensitivity ESR1 sequencing from CTCs revealed mono- and oligoclonal mutations in 22% of patients. These were concordant with plasma DNA sequencing in 95% of cases. Emergence of ESR1 mutations was correlated both with time to metastatic relapse and duration of AI therapy following such recurrence. The Presence of an ESR1 mutation, compared to ESR1 wild type, was associated with markedly shorter Progression-Free Survival on AI-based therapies (p = 0.0006), but unaltered to other non-AI-based therapies (p = 0.73). Compared with ESR1 mutant cases, AI-resistant CTCs with wild-type ESR1 showed an elevated ER-coactivator RNA signature, consistent with their predicted response to second-line hormonal therapies.
Conclusion:
Blood-based serial monitoring may guide the selection of precision therapeutics for women with AI-resistant ER-positive breast cancer.
Insights
Monitoring ESR1 mutations in blood via circulating tumor cells (CTCs) and DNA (ctDNA) can guide endocrine resistance treatment in ER-positive breast cancer patients, improving therapeutic selection.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- Estrogen receptor (ER)-positive breast cancer treatment efficacy is limited by acquired ESR1 mutations, leading to resistance against aromatase inhibitors (AIs).
- Monitoring for ESR1 mutations can enable personalized therapy selection for patients with metastatic breast cancer.
- Non-invasive detection methods are crucial for evaluating endocrine resistance and guiding treatment strategies.
Purpose of the Study:
- To assess the efficacy of circulating tumor cell (CTC) and circulating tumor DNA (ctDNA) based detection of ESR1 mutations.
- To evaluate non-invasive approaches for determining endocrine resistance in ER-positive breast cancer.
- To explore alternate methods for assessing endocrine responsiveness through RNA expression in CTCs.
Main Methods:
- Prospective study of 55 women with hormone receptor-positive metastatic breast cancer.
- Isolation of CTCs and development of a high-sensitivity method for ESR1 mutation detection.
- Parallel analysis of ESR1 mutations using multiplex droplet digital PCR (ddPCR) on ctDNA and examination of platform agreement.
- Single CTC isolation and RNA expression analysis to explore endocrine responsiveness.
Main Results:
- High-sensitivity ESR1 sequencing from CTCs identified mutations in 22% of patients, concordant with ctDNA sequencing in 95% of cases.
- Emergence of ESR1 mutations correlated with time to metastatic relapse and duration of AI therapy post-recurrence.
- ESR1 mutations were associated with shorter Progression-Free Survival on AI therapies but not on non-AI therapies.
- AI-resistant CTCs with wild-type ESR1 showed an elevated ER-coactivator RNA signature, suggesting response to second-line hormonal therapies.
Conclusions:
- Blood-based serial monitoring of ESR1 mutations can effectively guide the selection of precision therapeutics.
- This approach is valuable for managing AI-resistant ER-positive breast cancer.
- Non-invasive detection of ESR1 mutations offers a promising strategy for personalized endocrine therapy.
