RT Journal Article SR Electronic T1 574 Minimally invasive NGS approach for the detection and follow-up of endometrial cancer patients JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP A187 OP A188 DO 10.1136/ijgc-2024-ESGO.354 VO 34 IS Suppl 1 A1 Arozamena, Carlos Casas A1 Lande, Karin Teien A1 Cueva, Juan A1 Vilar, Ana A1 Arias, Efigenia A1 Sampayo, Victoria A1 Colás, Eva A1 Cabrera, Silvia A1 Gil-Moreno, Antonio A1 Abal, Miguel A1 Lindemann, Kristina A1 Sørlie, Therese A1 Muinelo-Romay, Laura YR 2024 UL http://ijgc.bmj.com/content/34/Suppl_1/A187.3.abstract AB Introduction/Background Background: Minimally invasive biomarkers are a necessity in in a clinical oncology setting the clinical context. In this regard endometrial carcinomas (EC) are lacking. Although usually associated with a good prognosis, advanced EC patients show extremely poor clinical outcomes. Especially relevant in this clinical context is the lack of methods that allow for a proper and dynamic monitoring follow-up in EC. The aim of the present study is to evaluate the value of a minimally invasive NGS approach on longitudinal samples from advanced EC patients.Methodology Peripheral blood samples (n=32) from 18 patients with EC disease were collected at surgery (n=12), at progression disease (PD) (n=10) after first line systemic treatment and at sequential progressions (n=10). Total cfDNA was isolated from 5mL of plasma using QIAamp DNA Circulating Nucleic Acid Kit. Isolated cfDNA was quantified using Qubit and integrity using the TapeStation. After quality control the cfDNA was sequenced using the Oncomine™ Pan-Cancer cell free assay with an input ranging from 4.63 to 58.24ng (Median=20.23ng).Results Overall, 71.88% of samples (23/32) showed at least one pathogenic mutation with the variant allelic frequency ranging from 0.1% to 67.89% (Median=1.53%). Most patients presented mutations in TP53, PIK3CA and/or GNAS. Importantly, ctDNA dynamics reflect disease evolution with levels of ctDNA increasing with the development of PD. The study of longitudinal cfDNA samples with the NGS panel in EC allowed us to understand how the mutational landscape of patients behaves throughout time, with the arisen of novel mutations not found on the baseline samples, that may derive from treatment pressure.Conclusion The study of longitudinal cfDNA samples with the NGS cell-free panel represents a comprehensive strategy for a non-tumour informed characterization of endometrial tumours that reflects the clinical evolution and even allows for the identification of novel mutations that could be used as actionable targets.Disclosures The authors declare no conflict of interests.