ETA2024 Poster Presentations Anaplastic thyroid cancer (10 abstracts)
1Istituto Auxologico Italiano Irccs, Università Degli Studi di Milano, Department of Biotechnology and Translational Medicine, University of Milan, Milan, Italy, Milano, Italy; 2Service Doncologie Endocrinienne, Département Dimagerie, Gustave Roussy, Villejuif, France; 3Département de Biologie et Pathologie Médicale, Gustave Roussy, Villejuif, France; 4U1015 Myeloid Cell Development Laboratory, Gustave Roussy, Villejuif, France; 5Département Danesthésie, Chirurgie et Radiologie Interventionelle, Gustave Roussy, Villejuif, France; 6Département Dinnovation Thérapeutique et Essais Précoces, Gustave Roussy, Villejuif, France
Introduction: ATC is the most aggressive thyroid cancer with a median overall survival of 6-12 months. The early detection of targetable molecular alterations (MAs) and matched targeted therapies might improve the prognosis.
Objectives: To evaluate the clinical applicability of liquid biopsy (LB) for the molecular profiling of ATCs.
Methods: This monocentric study retrospectively analysed consecutive ATC patients seen from January 2021 to July 2023. Circulating free DNA (cfDNA) was assessed with FoundationOne®CDx assay within the STING trial (NCT04932525). Tissue molecular profile (TMP) was analysed by various routine NGS targeted panel. All patients underwent BRAFV600E status assessment by immunohistochemistry (IHC).ResultsThirty-three patients (19 females), median age 74, with de novo ATC in 17%, mixed in 24% and transformed in 24%, at stages IVA (6%), IVB (18%), IVC (76%) were included. The median turnaround time for LB was 12 days (range 7-19). ATC-related MAs were identified in 82% of TMPs and in 81% of LBs. The most frequent cfDNA MAs found were: TP53 (55%), TERT promoter (36%), RAS (30%), BRAF (24%), NF1 (15%), RB1 (12%), TSC1 (12%), FGFR2 (9%), BRCA2 (9%), TSC2 (9%), PTEN (9%) and PI3KCA (9%). MTOR pathway alterations were mutually exclusive and present in 13 (39%) cases. ATC-related MAs were identified in TMP only (and not in LB) in 4 cases including 2 BRAFV600E, 1 AFAPL12-BRAF fusion and 1 NRASQ61R, whilst MAs were identified exclusively in 5 cases in LB only including 1 RB1, 2 TERT promoter, 2 TP53, 1 BRAFV600E + HRASG12S, 1 BRAF L485_P4 L485_P490>FN and 1 FGFR2 mutations. Almost all LB (5/6) that did not identify any ATC-related driver were sampled during or post-treatment. BRAFV600E mutation assessment was positive by TMP, IHC and cfDNA in 9 (27%), 8 (24%), and 7 cases (21%), respectively. There were 5 discordant cases: 3 patients had a BRAF V600E mutation in the TMP (n = 3) +/- IHC (n = 1) and not in cfDNA and responded to Dabrafenib + Trametinib (DT), with a progression-free survival of 5, 6 and 15 months, respectively. One patient had a BRAF L485_P4 L485_P490>FN and one patient had BRAFV600E + HRASG12S mutations in cfDNA (and not at IHC and in TMP) and they did not respond to DT.
Conclusions: Liquid biopsy is an effective tool with a rapid turnaround time for the molecular profiling of ATC, especially when performed at the baseline, before any treatment.