ESR1 mutations kit performance with SensID ESR1 reference set 1% AF.

Abstract

e13087 Background: Oestrogen receptor 1 (ER/ ESR1) mutations have arisen as crucial biomarkers for endocrine therapy resistance in ER positive metastatic breast cancer. Detecting these mutations is key for understanding acquired resistance during treatment. Current clinical trials, exploring ESR1 mutation prevalence during various treatments, often use expensive and time-consuming next-generation sequencing (NGS)-based assays or digital PCR (dPCR) assays that require specialist equipment. The APIS ESR1 Mutations Kit offers a cost effective, rapid, and highly sensitive (≤ 1% MAF) alternative to NGS, and dPCR assays. This targeted, qPCR-based assay detects eleven ESR1 mutations across ESR1 exons 5 (E380Q), 7 (S463P) and 8 (P535H, L536R/Q/H/P, Y537C/S/N and D538G). Designed for circulating-free DNA (cfDNA) samples, it reduces the need for invasive procedures in clinical settings, providing researchers in both centralised and decentralised laboratory settings the flexibility to explore ESR1 mutations with precision. Here, we demonstrate the performance of the APIS ESR1 Mutations Kit using the first commercially available cfDNA reference set (SensID ESR1 Reference Set 1% AF cfDNA) for nine ESR1 mutations (Table). Methods: The SensID ESR1 standards were assessed with the APIS ESR1 Mutations Kit. All vials were diluted with nuclease-free water to 3 ng/µL, resulting in 15 ng total input per reaction. Samples were run according to the APIS ESR1 Mutations Kit handbook. All PCR runs were performed using a QuantStudio 5 Dx (ThermoFisher) instrument. Results: The APIS ESR1 Mutations Kit successfully detected all ESR1 mutations, with expected target calls for the nine mutations at 1% MAF. No false positive results for the remaining mutation targets were observed. Similarly, no false positives for any mutation targets were reported for vial 5, containing the wildtype (WT) sample, reaffirming the kit’s accuracy in distinguishing WT and mutant samples. Conclusions: The ESR1 Mutations Kit demonstrated highly sensitive and specific detection of the SensID ESR1 Reference Set 1% AF cfDNA, confirming the kit’s LoD of ≤ 1% MAF with externally validated samples. [Table: see text]