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Endocrine Abstracts (2024) 101 PS3-24-09 | DOI: 10.1530/endoabs.101.PS3-24-09

1University of Milan, Department of Medical Biotechnology and Translational Medicine, Milan, Italy; 2Gustave Roussy, Service D’oncologie Endocrinienne, Département D’imagerie, Villejuif, France; 3Gustave Roussy, Département de Biologie et Pathologie Médicale, Villejuif, France; 4Gustave Roussy, Département D’anesthésie, Chirurgie et Radiologie Interventionelle, Villejuif, France; 5Gustave Roussy, Département D’innovation Thérapeutique et Essais Précoces, Villejuif, France; 6Gustave Roussy, Service de Médecine Nucléaire, Département D’imagerie, Villejuif, France; 7Gustave Roussy, Département de Médecine, Gustave Roussy, Villejuif, France and Faculté de Médecine Paris-Saclay Université, Le Kremlin-Bicêtre, France


Objective: Molecular profile can assist differentiated thyroid cancer (DTC) treatment at a metastatic stage. We aim at describing the clinical usefulness of a circulating free DNA “liquid biopsy” (LB) analysis in terms of informative results and actionable targets identified.

Methods: We analyzed all the LB results of locally advanced or metastatic DTC patients performed in a single referral center between January 2021 and January 2024. Cell free DNA (cfDNA) from a peripheral blood sample was analyzed with a 324 genes panel (FoundationOne®CDx) by NGS with turnaround time of about 4 weeks. The results were discussed in a dedicated molecular tumor board.

Results: A cohort of 76 DTC patients (median age 63 years, 24-88) had 86 LB samples analyzed. Most of the patients were radioiodine refractory (65/76 patients, 85.5%) including 10 patients with unresectable primary tumor. LB found sufficient cfDNA for the test in 81 samples (94.2%) form 73 patients. One or more molecular alterations were found in 42 patients (57%). The most frequent DTC molecular drivers observed were: RAS in 10 (24%, NRAS n = 6, KRAS n = 1, HRAS n = 3), BRAF in 2 (5%, one BRAF V600E and one BRAF insertion), KRAS and BRAF fusion in one case, RET fusion in 2 (5%), RB1 in 2 (5%), ATM, EGFR, NOTCH3, NTRK3 fusion, PTEN in 1 patient each. Mutation associated to late DTC molecular events were: TP53 in 18 patients (associated to a driver in 13 cases), TERT in 11 patients (always associated to a thyroid cancer driver), NF1 in 3 cases (always associated to a thyroid cancer driver), AKT1 in 2 patients (associated to a driver in 1 case), PIK3C2G in 1 case. Median tumor mutation burden tested on LB was 1.26 Muts/Mb (0.00-10.12). Actionable molecular targets were ESCAT1 in 4 cases, ESCAT2 in 8 cases, ESCAT3 in 7 cases. In 31 patients (42,5%) a molecular alteration known on tumor tissue was not found on LB, BRAFV600E in 20 cases. Of these 20 patients, 8 were under active systemic treatment (including 5 with anti-BRAF treatment) at the moment of LB and in 3 patients the size of the metastases was ≤1 cm.

Conclusion: LB is a minimally invasive technique capable of providing rapidly a comprehensive molecular profile, opening molecular driven treatment options. BRAFV600E is frequently missed by LB in DTC, a role of systemic treatment at the moment of LB sampling and small tumor volume might play a role in this observation.

Volume 101

46th Annual Meeting of the European Thyroid Association (ETA) 2024

European Thyroid Association 

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