Dados do Resumo

Título

Circulating tumor DNA (ctDNA) assessment in plasma and urine of non-metastatic renal cell carcinoma patients

Introdução

Plasma circulating tumor DNA (ctDNA) and urine tumor DNA (utDNA) are emerging as valuable tools in cancer care. Early diagnosis of renal cell carcinoma (RCC), especially the aggressive clear cell subtype (ccRCC), significantly improves prognosis. However, recurrence rates post-nephrectomy remain high (over 20% in localized ccRCC). Risk-stratifying biomarkers, such as ctDNA and utDNA, are essential for developing tailored treatment strategies.

Objetivo

Track tumor mutations in ctDNA & utDNA from localized ccRCC patients. Evaluate their potential as risk-stratifying biomarkers for recurrence. Assess ctDNA/utDNA pre-surgery in all RCC patients and longitudinally post-surgery in ccRCC patients. Analyze tumor mutations in the plasma of patient-derived xenograft (PDX) replicates from one aggressive ccRCC patient.

Métodos

RCC patients were recruited from the Oncourology Department of A.C.Camargo Cancer Center. Urine and plasma samples were collected pre-surgery (baseline) and for ccRCC patients 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 4.3 years. A customized 28-gene RCC panel and a commercial 409-gene solid tumor panel were used to identify tumor somatic mutations using Illumina NextSeq 500 and Ion S5 platforms, respectively. Tumor-specific mutations were tracked in DNA from patients’ plasma, urine, and patient-derived xenograft (PDX) plasma using the Personalized amplicon target sequencing (PATS) method on the Ion S5 Plus platform. Samples were considered positive for ctDNA/utDNA when the variant allelic fraction (VAF) of the somatic mutation was greater than 0.5% and at least twice the VAF observed in negative controls.

Resultados

Of 79 RCC patients (58% ccRCC), 57 (72%) had somatic mutations, including 39 (68%) in ccRCC. VHL and PBRM1 were most frequently mutated genes. Baseline ctDNA/utDNA was 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. Baseline ctDNA-positive plasma in ccRCC was associated with disease progression (p=0.0149), tumor staging ≥pT3 (p=0.0005), and reduced progression-free (p=0.0016) and overall (p<0.0039) survival. Baseline ctDNA demonstrated 50% sensitivity and 96% specificity for recurrence. One aggressive ccRCC patient had VHL, BAP1, and FAT1 mutations detected in the tumor and all plasma samples with VAF of 4,0%, 2,67% and 2,31% (baseline) and 5,1%, 2,0% and 2,37% (M1), respectively. PDX experiments revealed that VHL and BAP1 mutations were present in both the PDX tumors and the mouse plasma samples. These mutations were detected at very high levels (VAF >98%) in the mouse plasma, reflecting the aggressive nature of the patient's tumor.

Conclusões

A low proportion of CCR patients had positive ctDNA/utDNA in urine and plasma. Pre-surgery ctDNA detection in plasma may suggest a higher risk of recurrence in ccRCC patients. The way PDX tumors released ctDNA closely resembled what was seen in a ccRCC patient with aggressive disease.

Financiador do resumo

PRONON, INCT

Palavras Chave

Renal cell carcinoma; Liquid Biopsy; PROGNOSTIC