Estrogen Receptor-alpha (Phospho-Ser106) ELISA Kit

Background Endocrine therapy (ET) is the mainstay of treatment for hormone receptor-positive human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer; however, adaptive mechanisms emerge in about 25-30% of cases through alterations in the estrogen receptor ligand-binding domain, with a consequent ligand-independent estrogen receptor activity. Epigenetic-mediated events are less known and potentially involved in alternative mechanisms of resistance. The aim of this study was to test the feasibility ofestrogen receptor 1(ESR1) epigenetic characterization through liquid biopsy and to show its potential longitudinal application for an early ET sensitivity assessment. Methods A cohort of 49 women with hormone receptor-positive HER2-negative MBC was prospectively enrolled and characterized through circulating tumor DNA using methylation-specific droplet digital PCR (MS-ddPCR) before treatment start (BL) and after 3 months concomitantly with computed tomography (CT) scan restaging (EV1).ESR1epigenetic status was defined by assessing the methylation of its main promoters (promA and promB). The most established cell-free tumor DNA (ctDNA) factors associated with ET resistance [ESR1and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) mutations] were assessed through next-generation sequencing. Associations were tested through Mann-WhitneyUtest, matched pairs variations through Wilcoxon signed rank test, and survival was analyzed by log-rank test. Results The ET backbone was mainly based on aromatase inhibitors (AIs) (70.83%) in association with CDK4/6 inhibitors (93.75%). Significantly lower promA levels at baseline were observed in patients with liver metastases (P= 0.0212) and in patients withESR1mutations (P= 0.0091). No significant impact on PFS was observed for promA (P= 0.3777) and promB (P= 0.7455) dichotomized at the median while a >= 2-fold increase in promB or in either promA or promB at EV1 resulted in a significantly worse prognosis (respectivelyP= 0.0189,P= 0.0294). A significant increase at EV1 was observed for promB among patients withPIK3CAmutation (P= 0.0173). A trend was observed for promB inESR1wild-type patients and for promA in theESR1mutant subgroup. Conclusion The study proofed the concept of an epigenetic characterization strategy based on ctDNA and is capable of being integrated in the current clinical workflow to give useful insights on treatment sensitivity.

Background One of the major challenges in managing invasive breast cancer (BC) is the lack of reliable biomarkers to track response. Circulating tumor DNA (ctDNA) from liquid biopsy, as a candidate biomarker, provides a valuable assessment of BC patients. In this retrospective study, we evaluated the utility of ctDNA to reflect the efficacy of treatment and to monitor resistance mechanisms. Methods Targeted next-generation sequencing (NGS) of 416 cancer-relevant genes was performed on 41 plasma biopsy samples of 19 HER2+ and 12 HER2- BC patients. Longitudinal ctDNA samples were analyzed in three BC patients over the treatment course for detecting acquired mutations. Results In HER2+ BC patients, ERBB2 somatic copy numbers in ctDNA samples were significantly higher in patients progressed on HER2-targeted therapy than those who were still responding to the treatment. Recurrent acquired mutations were detected in genes including ERBB2, TP53, EGFR, NF1, and SETD2, which may contribute to trastuzumab resistance. In longitudinal analyses, the observed mutation allele frequencies were tracked closely in concordance with treatment responses. A novel ERBB2 p.(Leu869Arg) mutation was acquired in one patient upon resistant to trastuzumab therapy, which was further validated as an oncogenic mutation in vitro and contributed to resistance. In HER2- BC patients with chemotherapy resistance, genetic alterations on TP53, PIK3CA, and DNA damage repair genes were frequently observed. Conclusions In summary, ctDNA monitoring, particularly longitudinal analyses, provides valuable insights into the assessment of targeted therapy efficacy and gene alterations underlying trastuzumab resistance and chemotherapy resistance in HER2+ and HER2- BC patients, respectively.