Tracking endocrine resistance in estrogen-receptor positive breast cancer in ctDNA.

• DOI: 10.1200/jco.2019.37.15_suppl.e14550
• Publication Date: 2019-05-27T16:00:33Z
• Authors: Magdalena Meissner; Rachel Butler; Angela Claire Cas...; Margherita Carucci; Tracie-Ann Madden; Sacha Jon Howell; Robert Hugh Jones
• Keywords: Fulvestrant; Liquid biopsy; Targeted Therapy

e14550 Background: Endocrine therapy is the standard of care treatment for patients with estrogen-receptor positive advanced breast cancer, owing to improved tolerability and comparable efficacy that cytotoxic chemotherapy. Half such cancers will progress through first line (primary endocrine resistance) half after an initial period disease control (secondary or acquired resistance). A significant challenge test identify biomarkers which can guide likely success as a single agent in combination small molecule inhibitors.This particularly challenging where metastatic deposits reside at sites biopsy difficult. Potential indicative resistance have been identified be detected circulating tumour DNA (ctDNA). CtDNA shed from tumours detectable cancer patient’s bloodstream. Information on mutational profiles oncologist selection targeted addition hormonal therapy. Methods: We analysed formalin-fixed paraffin-embedded(FFPE) samples longitudinal liquid biopsies 19 who were treated fulvestrant novel inhibitor PIK3CA/AKT pathway next-generation sequencing using 44-gene panel. Mutations this technique tracked during course droplet-digital PCR(ddPCR). Results: 57 tested panel; FFPE matched ctDNA obtained prior progression. PIK3CA, AKT1, ESR1and TP53 genes trackable ddPCR. The association between dynamics outcome presented. Conclusions: Multiple mutations enable early detection failure ctDNA. Investigating clinical utility paramount.