Dados do Resumo

Título

GENOMIC CHARACTERIZATION AND AGGRESSIVE BEHAVIORS OF PATIENT-DERIVED RENAL CELL CARCINOMA XENOGRAFTS: A PLATFORM FOR BIOMARKER PROFILING

Introdução

Renal cell carcinoma (RCC) accounts for up to 90% of all renal tumors, with 30% of patients having metastases at diagnosis, while 20-50% of those treated for localized, curable disease have recurrence. A better understanding of RCC biology is necessary to define the most efficient and personalized treatment or to develop better antineoplastic drugs. Patient-derived xenografts (PDX) have emerged as one of the most promising approaches for this.

Objetivo

Thus, this project aimed to develop a PDX RCC platform to identify new biomarkers for monitoring and therapeutic targeting of RCC.

Métodos

The samples used in the present study were obtained from surgical resections of 85 patients at the A.C.Camargo Cancer Center. Tumor fragments were implanted orthotopically (in the renal capsule) into immunodeficient NOD Scid Gamma (NSG) mice. The animals were monitored by palpation, and when the tumors showed signs of growth, the animals were anesthetized, the tumor removed and serially passed (P2). Tumor fragments were cryopreserved, and part was submitted to histological analysis (immunohistochemistry), and sequencing of genomic targets.

Resultados

A total of 24 RCC PDX models were developed, of which, 19 cases are clear cell renal carcinoma (79.2%), 4 cases are papillary renal carcinoma (16.6%), and 1 case of unclassifiable renal carcinoma (4.2%). A case of clear cell RCC PDX recapitulated the phenotype of the extension of the vena cava tumor thrombus that had been previously diagnosed in the patient, and the formation of metastases. Five cases (5/24; 20%) showed ectopic growth, four cases of clear cell renal carcinoma and one case of unclassifiable renal carcinoma. A case (1/24; 4%) of clear cell renal carcinoma showed viability after cryopreservation, maintaining the same tumor growth kinetics and the same histological and immunohistochemical phenotype. The overall catch rate was 28%, and the time to observe tumor growth ranged from 1 to 13 months). Patients whose tumor fragments were grafted had worse overall survival (OS) than those whose tumor fragments were not grafted (p = 0.09). The data also suggested a similar trend of association with metastasis-free survival (MFS) (p = 0.2). Furthermore, most of the tumors that generated PDX are from patients with high pathological staging (pT3 + pT4 = 58.3%). However, we managed to generate PDX models of patients with low pathological staging (pT1 + pT2 = 41.7%). Patients with tumors of high pathological staging and high histological grade are promising for the establishment of the RCC PDX model (p = 0.01). The characterization by immunohistochemistry indicates that PDXs preserve CCR phenotypes, including the expression of PAX8, Alpha-methyl CoA racemase (AMCR), Carbonic Anhydrase IX (CAIX) and Cytokeratin 7 (CK7). The most frequently mutated genes were VHL (50% - 6/12), and PBRM1 (41.7% - 5/12), followed by SETD2 (25% - 3/12), BAP1 and KDM5C (both 16.7% - 2/12), and ARID1A (8.3% - 1/12), indicating that all PDXs preserved RCC identity, and major molecular alterations.

Conclusões

These findings suggest that tumor engraftment capacity may identify patients at higher risk of recurrence or death. That the orthotopic RCC xenograft model represents a suitable tool to study RCC biology, identify biomarkers and test therapeutic candidates.

Palavras Chave

Patient-derived xenografts; Genetic vulnerabilities; Renal cell carcinoma