Abstract A052: Circulating tumor DNA (ctDNA) in plasma and urine of renal cell carcinoma patients with localized disease
Authors: Kerekes Miguez Ana Carolina , Job e Meira Isabella Tanus , Bezerra Stephania Martins , de Oliveira Beserra Adriano , Henriques da Costa Walter , Goss dos Santos Tiago , de Cassio Zequi Stenio , Torrezan Giovana Tardin , Carraro Dirce Maria 
Published: November 2024

Abstract
Introduction: Circulating tumor DNA (ctDNA) is increasingly valuable in cancer care. Early diagnosis of renal cell carcinoma (RCC) significantly improves prognosis. Clear cell RCC (ccRCC), the most prevalent and aggressive subtype, often leads to recurrence in over 20% of localized cases post-nephrectomy. Thus, risk-stratifying tools are crucial for tailored treatment strategies. In this study, we tracked tumor mutations in DNA from plasma (ctDNA) and urine (utDNA) in patients with localized ccRCC to explore their potential as risk-stratifying biomarkers for recurrence. We evaluated ctDNA/utDNA pre-surgery in all RCC patients and conducted longitudinal assessments post-surgery in ccRCC patients. Additionally, for one ccRCC patient with aggressive disease, we analyzed tumor mutations in the plasma of patient- derived xenograft (PDX) replicates. Methodology: RCC patients were recruited from A.C.Camargo Cancer Center. Urine and plasma samples were taken pre-surgery (BL-baseline), and for ccRCC patients, samples were collected at 6-8 weeks and 6, 18 and 30 months post- surgery (M1, M2, M3 and M4, respectively). Patients were monitored for recurrence for up to 6,3 years. We used a customized 28-gene RCC panel and a commercial 409-gene solid tumor panel to identify tumor somatic mutations using Illumina NextSeq 500 and Ion S5 platforms, respectively. Tumor specific mutations were tracked in DNA from patient plasma and urine, and PDX plasma, using the PATS (Personalized amplicon target sequencing) method on Ion S5 Plus platform. Results: Out of 79 RCC patients (58% ccRCC), 57 (72%) had tumor somatic mutations, including 39 (68%) in ccRCC. VHL and PBRM1 were the most frequently mutated genes. Baseline ctDNA/utDNA were analyzed in 51 RCC patients, with 18% (13% plasma, 12% urine) positivity in RCC and 19% (12% plasma, 12% urine) in ccRCC. During ccRCC monitoring, ctDNA/utDNA was positive only in M1 and M3, with 9% (9% plasma, 0% urine) and 18% (12% plasma, 6% urine), respectively. ctDNA-positive baseline plasma was associated to disease progression (p=0.0155) and tumor staging ≥pT3 (p=0.002); these patients also experienced reduced progression-free (p=0.004) and overall (p98%, resembling the patient’s tumor aggressiveness. Conclusions: ccRCC tumors release low levels of tumor DNA in urine and plasma. Pre-surgery plasma positivity for ctDNA appears to indicate a higher risk of recurrence in ccRCC patients. The ctDNA release of PDX tumors replicated that observed in one ccRCC patient with aggressive disease.
Citation Format: Ana Carolina Kerekes Miguez, Isabella Tanus Job e Meira, Stephania Martins Bezerra, Adriano de Oliveira Beserra, Walter Henriques da Costa, Tiago Goss dos Santos, Stenio de Cassio Zequi, Giovana Tardin Torrezan, Dirce Maria Carraro. Circulating tumor DNA (ctDNA) in plasma and urine of renal cell carcinoma patients with localized disease [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A052.