OR32-06 Circulating Tumor DNA Analysis in Adrenocortical Carcinoma - A First Retrospective Cohort Study

Abstract Disclosure: V. Balderrama Brondani: None. L.P. Marcal: None. M.J. Moussa: None. A.Y. Shah: None. P.H. Graham: None. J. Varghese: None. C. Jimenez: None. M.T. Campbell: None. M.A. Habra: None. Background: Circulating tumor DNA (ctDNA) analysis has been used to assess the treatment response and monitor residual disease in patients with cancer. Adrenocortical carcinoma (ACC) is a rare malignancy with a high recurrence rate. There is a lack of data on ctDNA analysis as a surveillance tool in patients with ACC in the real-world scenario. Objective: To provide first data about ctDNA analysis in a cohort of ACC patients and to correlate results with disease burden judged by imaging studies. Methods: This is a single institution, retrospective study of ACC patients who had ctDNA testing at any point in their disease. ctDNA was assessed using a clinically validated, personalized, tumor-informed ctDNA assay (Signatera, Natera, Inc.) for detection and quantification. Clinical and tumor data were collected from medical records. We assessed the correlation between ctDNA status (detected versus non-detected) and ACC disease status (using concurrent imaging study in a period of <45 days apart from ctDNA evaluation) at any time point of disease. Results: Sixteen patients (9 male, 56%) were included with a median age of 55 years (range 23-76). Eleven patients (69%) were hormonally active at the time of diagnosis (8 cortisol-producing and 3 other non-cortisol producing tumors). A total of 69 tests were evaluated from 16 patients, with a median of 4 tests/patient (IQR range 1-5 tests). Four (25%) patients had ctDNA testing at ACC diagnosis, and 12 (81%) were tested during cancer recurrence or progression of disease. Fifty-four (78%) tests detected ctDNA, and all patients had at least one test detecting ctDNA. Fifty (72%) tests were compared to the available concurrent imaging study, and from this group, 47 (94%) test results were in accordance with the imaging study evaluation. Only 3 (6%) tests had undetectable ctDNA in the presence of metastatic ACC. Conclusion: ctDNA analysis is a promising test for monitoring ACC. Further studies are urgently needed to clarify factors impacting the quantification of ctDNA and to determine which patients with ACC benefit from this new approach in clinical practice. Presentation: Monday, July 14, 2025