Intra-Tumor Genetic Heterogeneity in Wilms Tumor: Clonal Evolution and Clinical Implications

Area of Science:

• Oncology
• Genetics
• Pediatric Cancer Research

Background:

• The evolution of pediatric solid tumors, particularly Wilms tumors (WT), remains poorly understood.
• Conflicting evidence exists regarding intra-tumor genetic heterogeneity (ITGH) in pediatric solid tumors.
• Current clinical trials often use single-sample profiling for prognostic biomarkers like 1q+ in WT, potentially missing critical genetic diversity.

Purpose of the Study:

• To investigate the extent of ITGH and evolutionary trajectories in pediatric Wilms tumors.
• To evaluate the adequacy of single-sample tumor profiling for genetic biomarker assessment.
• To inform rational clinical trial design for pediatric cancer risk stratification.

Main Methods:

• Multisampled 20 Wilms tumor (WT) cases.
• Assessed genome-wide allele-specific copy number aberrations (CNA) and loss of heterozygosity (LOH).
• Utilized Illumina CytoSNP12v2.1 arrays, a custom analysis pipeline, and the MEDICC algorithm to infer tumor evolution.

Main Results:

• WT exhibits significant ITGH and diverse evolutionary paths.
• The 1q+ biomarker is heterogeneous in most tumors, with variable timing, requiring at least three samples for >95% detection.
• Somatic 11p15 LOH is consistently an early event; evidence suggests dual tumor origins in some unilateral and bilateral WT cases.
• Subclonal genetic changes correlate with differential chemotherapy response.

Conclusions:

• Pediatric Wilms tumor evolution is characterized by substantial ITGH and complex trajectories.
• Current single-sample biomarker strategies are insufficient for accurate risk stratification in WT.
• Tumor multisampling is essential for reliable ITGH and evolutionary assessment in clinical trial design.