Abstract 6701: 6-color Crystal Digital PCR for the high-plex detection of 10 ESR1 mutations in breast cancer

Abstract

Abstract Introduction. ESR1 mutations have emerged as a key mechanism of resistance to endocrine therapy in estrogen-receptor-positive (ER+) breast cancer, thus detection of ESR1 mutations is crucial to monitor during patient treatment. We evaluated a novel 12plex breast cancer assay for the detection of 10 ESR1 mutations and AKT1 E17K in plasma cell-free DNA (cfDNA) using 6-color Crystal Digital PCRTM (naica® system, Stilla Technologies, France). We further compared the results with our previously reported ESR1 NAPA assay for D538G, Y537S, Y537C and Y537N mutations (Stergiopoulou et al, Cancers, 2021). Patients and Methods. Using the 6-color Crystal Digital PCRTM breast cancer 12plex assay, we analyzed 35 plasma cfDNA samples from ER+ breast cancer patients and 10 plasma cfDNA from healthy donors (HD). We also analyzed the same cfDNA samples using the ESR1 NAPA assay. Results. The Stilla 6-color breast cancer assay revealed in 5/35 (14,3%) ER+ cfDNA samples the AKT1_E17K and ESR1 D538G mutations. ESR1 D538G was detected in 4/35 ER+ cfDNA samples with the ESR1 NAPA assay. Direct comparison between Crystal Digital PCR™ and the ESR1 NAPA assay revealed a high concordance (97.1%) for 34/35 samples tested, for the detection of the D538G mutation, and with a higher sensitivity for the Stilla 6-color breast cancer assay. The ESR1 mutations Y537S, Y537C and Y537N were not detected by either method in any of the plasma-cfDNA samples. No AKT1 E17K or ESR1 mutations were detected in cfDNA from HD plasma. Conclusions. The naica® system 12plex ESR1 assay is quantitative, highly sensitive and easy to perform using plasma-cfDNA samples. The use of highly multiplexed Crystal Digital PCR™ shows great promise for clinical utility for ER+ breast cancer patient monitoring. Key words: Circulating tumor DNA; Crystal Digital PCR™, ESR1 mutations; liquid biopsy; mutation monitoring, 6-color multiplexing; Citation Format: Stavroula Smilkou, Aliki Ntzifa, Dimitra Stergiopoulou, Quentin Blache, Myrtille Remy, Cecile Jovelet, Allison Mallory, Evi Lianidou. 6-color Crystal Digital PCR for the high-plex detection of 10 ESR1 mutations in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6701.