Determinants of Acquired Endocrine Resistance in Metastatic Breast Cancer: A Pilot Study

Sunnybrook Health Sciences Centre20 enrolled

Overview

This is a single-center prospective study involving analysis of circulating tumor DNA (ctDNA) and the gut microbiome in patients with metastatic breast cancer on standard of care endocrine therapy with an aromatase inhibitor in combination with an inhibitor of the cyclin-dependent kinases 4 and 6 (CDK 4/6). Up to 20 patients with Estrogen Receptor positive (ER+), Human Epidermal Growth Factor Receptor 2 negative (HER2-) metastatic breast cancer and Eastern Cooperative Oncology Group (ECOG) performance status 0-1 will be enrolled. This study involves the collection and analysis of patient samples and does not involve therapeutic intervention.

Endocrine therapies have been associated with an overall survival benefit in breast cancer and are the preferred initial treatment approach in patients with ER+, HER2- metastatic breast cancer. Unfortunately, resistance to endocrine therapies eventually develops in the metastatic setting and metastatic breast cancer remains an incurable disease. Endocrine resistance may develop as a result of alterations in estrogen signaling and metabolism pathways, which may be modulated by gut bacteria. In addition, genomic profiling of archival tissues and circulating tumor DNA (ctDNA) in ER+ breast cancer has identified multiple somatic molecular alterations that may mediate response to endocrine therapies. This study is designed to identify markers of endocrine resistance in ctDNA and the gut microbiome in patients with ER+ HER2- metastatic breast cancer.

Study Type

OBSERVATIONAL

Enrollment

Conditions

Metastatic Breast Cancer

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Sign written and voluntary informed consent * Histological confirmation of advanced ER positive and HER2 negative breast cancer. * Adult patients at least 18 years of age * ECOG performance status equal to 0 or 1 * Able to provide written informed consent * Must be willing to provide blood for ctDNA analysis on study enrollment and at specified study time points * Must be willing and able to perform stool sample collection * Patients must be suitable, as per their treating physician, for initiation of first line endocrine therapy with an aromatase inhibitor and a CDK 4/6 inhibitor for metastatic disease Exclusion Criteria: * Prior treatment with CDK 4/6 inhibitors in the neoadjuvant or adjuvant setting * Use of targeted therapies other than endocrine therapies alone in the neoadjuvant or adjuvant setting * Relapse on prior endocrine therapy or within 6 months of discontinuation of prior adjuvant endocrine therapy * History of inflammatory bowel disease, chronic diarrhea or malabsorption syndromes and significant prior bowel resection as judged by the study investigator * Use of immunosuppressants including steroids within the previous 4 weeks of planned Cycle 1 Day 1 treatment

Outcomes

Primary Outcomes

Time to treatment failure

Time from first treatment on study (standard of care aromatase inhibitor and a CDK 4/6 inhibitor) until the date of treatment discontinuation

Time frame: 12 months

Secondary Outcomes

Correlation between specific mutations in ctDNA and in archival tissue samples (where available from prior testing) with time to treatment failure

Identification of mutations in archival tissue samples (where available from prior testing) and sequencing of ctDNA using next generation sequencing panel

Time frame: 12 months

Diversity and composition of the gut microbiome in patients with ER+ HER2- metastatic breast cancer

Analysis of the gut microbiome via 16S rRNA sequencing and metagenomic sequencing of fecal samples at baseline and at development of progressive disease

Time frame: 12 months

Dietary factors and composition of the gut microbiome

Assessment of food intake via dietary questionnaire and correlation with diversity and composition of the gut microbiome

Time frame: 14 days

Overall survival

Time from start of treatment until death

Time frame: 2 years

Determinants of Acquired Endocrine Resistance in Metastatic Breast Cancer: A Pilot Study

Overview

Conditions

Eligibility

Locations (1)

Outcomes

Primary Outcomes

Secondary Outcomes

Central Contacts