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Hope for Patients With Metastatic Breast Cancer

December 7th, 2021

Rebecca Nagy, Vice President Medical Affairs, Guardant Health, Professor Clinical Internal Medicine, Licensed Genetic Counselor

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For 74% of patients who have metastatic breast cancer, the disease is fatal within five years.1  Comprehensive genomic profiling (CGP) quickly identifies actionable alterations that can inform breast cancer treatment options. Therapies that target specific alterations often extend overall survival time and improve quality of life. By identifying the underpinnings of malignant disease, liquid biopsies continue to pave the way for precision medicine, dramatically changing the landscape of care for advanced cancer patients.2,3

Studies Demonstrate that All Breast Cancer Patients Should be Tested

PlasmaMATCH was the first prospective, multicenter study assessing the feasibility and clinical utility of ctDNA analysis to guide therapy in patients with advanced breast cancer. Conducted at the Institute of Cancer Research London, the study found that Guardant360® detected significantly more targetable alterations than hotspot testing, including over 35 percent more PIK3CA mutations4 that can now be targeted by recently FDA-approved therapies.5 Guardant360 also detected many more ESR1 mutations and found previously-undetected microsatellite instability (MSI) and ERBB2 amplifications and mutations, all of which are clinically actionable.

Aberrant mutations in breast cancer, such as human epidermal growth factor receptor 2 (ERBB2/HER2) are common. Recommended guidelines also include testing for PIK3CA and BRCA1/2, and liquid biopsies such as Guardant360 CDx go beyond the recommendations to test for NTRK1 and MSI as well. Fortunately, a number of approved therapeutics exist that directly target these mutations6-11, including monoclonal antibodies;14-16 PARP inhibitors16,17 that target BRCA1/2-mutated advanced breast cancers; and PI3K inhibitors18 for PIK3CA-mutated late-stage breast cancers. Other targeted therapies being researched include AKT inhibitors,19,20 STAT3 inhibitors,11,22 and anti-androgen therapies.23-26

The use of genomic data to guide cancer treatment has become indispensable. Liquid biopsies such as Guardant360 CDx are increasingly being used to identify treatment-relevant genomic mutations in metastatic breast cancer.

References

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