Clinical significance of next-generation sequencing in Chinese patients with relapsed/refractory Wilm’s tumor.

Abstract

e22003 Background: Medical advances have been greatly improved in the survival rate for Wilms’ tumor, but the survival is still dismal for relapsed/refractory (R/R) patients. In the present study, we aimed to investigated the genomic profiling and the incidence of germline cancer susceptibility mutations of Chinese patients with R/R WT. Methods: From Jun 18, 2020 to Dec 22, 2020, the tumor specimens with matched blood samples obtained from R/R pediatric WT in Sun Yat-Sen University Cancer Center were performed next-generation sequencing (NGS) using a 539 cancer-related gene panel in a CAP-certified laboratory (Simcere Diagnostic Co, Ltd). Clinical information including age, gender and tumor histology were collected. Somatic and germline variations including single nucleotide variants (SNV), insertion-deletion variants (Indels), copy number variations (CNVs) and fusion, as well as tumor mutational burden (TMB)/microsatellite instability (MSI) were analyzed. IHC staining for PD-L1 expression was performed by FDA-approved VENTANA PD-L1(SP263) assay. Results: Eight patients with R/R WT were enrolled in this study, including 5 males and 3 females, with a median age of 6 years old (range, 3-14). All of the pathology was identified as favorable histology WT (FHWT). Of the specimens, 8 were from pulmonary and 1from peritoneum. We identified 152 reportable molecular aberrations, with a median of 19 (0-24). CNVs accounted for the majority of the total somatic aberrations, followed by SNVs, the percentage was 77% and 22%, respectively. Genes with either CNVs or SNVs were detected in FGFR1 (n=4), ERBB2(n=3), MYCN(n=4), MET(n=2), CDK4/6(n=2), TP53(n=2), CTNNB1(n=2), MYC(n=2), NF1(n=2), MDM4(n=2), CHEK2(n=1), FBXW7(n=1), EGFR(n=1). Notable cancer driver mutations were also characterized, such as the amplifications of ERBB2/MET/EGFR/FGFR1, and the point variations of CHEK2/FBXW7/NF1. Besides, a novel ASB12 intergenic region- AMER1 fusion was identified. Both of the patients available for PD-L1 evaluation showed negative PD-L1 expression on tumor cells. The median TMB was 1.47 (range, 0-7.8). All patients were microsatellite stabilization (MSS). A 4-year-old patient suffering peritoneal relapse harbored a germline pathogenic mutation in FANCA (c.1777-1G>C, intron 19), this locus has never been reported in WT before. Conclusions: We discovered some driver genes mutations which potentially sensitive to the corresponding targeted drugs in Chinese R/R WT patients. Large sample size was needed to provide a better understanding of molecular features in R/R WT patients to achieve precision medicine.