Dados do Resumo

Título

Living biobank of pediatric solid tumors: establishment and validation of the PDX models for precision medicine research.

Introdução

Pediatric cancers present significant challenges with around 12,000 new cases diagnosed annually in children and adolescents in Brazil. The five-year survival rate for some of these cancers remains below 70%, due in part to the lack of accurate diagnosis for certain tumor types and the limited effectiveness of conventional treatments. Traditional research models often fail to recapitulate the full complexity of these tumors. Therefore, patient-derived xenograft (PDX) models present a valuable alternative by offering a more precise representation of pediatric tumors. In this way, to establish a biobank of pediatric solid tumors with PDX models, we can achieve a more precise understanding of tumor behavior and treatment responses

Objetivo

To present comprehensive data on the establishment of biobank from pediatric solid tumors, highlighting histopathological and molecular validation of PDX models.

Métodos

125 tumor specimens from pediatric patients were collected (biopsy or surgery) at Boldrini Children's Hospital, following approval from the Institutional Ethics Committees (CAAE: 44219021.6.0000.5376). The consent form was obtained from all patients involved in the present study. A total of 596 NOD/SCID/IL2Rg (NSG) mice (6-8 weeks old) were used in the study (CEUA-0017-2021/0). Tumor fragments (5x5 mm) were implanted subcutaneously with a 1:1 mix of cell culture medium and GeltrexTM to generate the 1st PDX generation. Up to three mice per tumor sample were used, with humane endpoints applied for pain/distress. Tumors were harvested by euthanasia and stored for: living biobank, histopathology e molecular analyses (RT-PCR and RNA-seq). For the 2nd PDX generation, reimplants were made in at least 3 animals for tumor expansion with the same protocol. PDX data was registered in RedCaP web platform.

Resultados

The primary samples were derived from 33 tumor types, with 17 successfully engrafted in NSG mice. Among the patients, 88% are alive, and 70.4% had prior treatment before xenotransplantation; no correlation was found between prior treatment and engraftment success. Of 125 implanted samples, 44% successfully engrafted in the 1st generation of PDX, increasing to 86% in the 2nd generation, indicating tumor adaptation. Although the lifespan was reduced in the 2nd generation, no significant differences were observed among different tumor types. However, when analyzed individually, Ewing's sarcoma, myeloid sarcoma, synovial sarcoma, hepatoblastoma, malignant teratoma, neuroblastoma, and Hodgkin's lymphoma showed significant reduction in lifespan.Histopathological analysis showed high concordance, except for one hepatoblastoma case. RT-PCR detected gene fusions in PDX models: 7/8 synovial sarcomas were positive for SS18-SSX1 (t(X;18)), 1/5 rhabdomyosarcomas for PAX3-FOXO1 (t(2;13)), and 4/4 Ewing's sarcomas for t(11;22) (EWSR1-FLI1). RNA-sequencing identified additional patient-specific fusions, confirming PDX models recapitulate patient tumor profiles accurately.

Conclusões

The successful establishment of PDX models highlights their value for cancer research. Tumor-specific gene fusions confirm their accuracy in replicating patient tumor profiles, supporting personalized treatments and enhancing our understanding of tumor biology.

Financiador do resumo

PRONON: SIPAR - 25000.211368/2019-41.

Palavras Chave

PDX; Pediatric Cancer; Solid Tumors