# Molecular Features Associated with a High-Risk Clinical Course in Neuroblastomas Initially Diagnosed as Non-High-Risk

## TL;DR

This study finds that certain genetic changes in neuroblastoma tumors at diagnosis can predict which patients will later develop a severe disease course.

## Contribution

The study identifies specific molecular features, like 1p deletion and segmental chromosomal changes, associated with high-risk outcomes in neuroblastoma patients initially classified as non-high-risk.

## Key findings

- Segmental chromosomal changes, especially 1p deletion, are strongly linked to a high-risk clinical course in neuroblastoma patients.
- Alternative lengthening of telomeres and MDM2/CDK4 co-amplification are more common in patients who develop a high-risk disease.
- Gains in 1q, 2p, and 17q, and deletions in 4p and 11q are associated with a worse clinical outcome.

## Abstract

Some children are initially diagnosed with a non-high-risk neuroblastoma but later develop a high-risk clinical course. It is not yet clear why this happens. We examined tumor samples taken at diagnosis to see whether the molecular profile can help to predict which children will develop a high-risk clinical course. We compared tumor samples of non-high-risk neuroblastoma patients who did develop a high-risk clinical course with those who did not. We discovered that segmental chromosomal changes, especially 1p deletion, are associated with a high-risk clinical course. Other genetic changes (activation of alternative lengthening of telomeres, MDM2/CDK4 co-amplification, gains of 1q, 2p, and 17q, and deletions of 4p and 11q) might also be relevant. Larger studies are needed to confirm these findings.

Background/Objectives: Some patients initially diagnosed with non-high-risk neuroblastoma follow a high-risk clinical course and have poor survival compared to those initially diagnosed with high-risk neuroblastoma. We aimed to identify molecular aberrations present at diagnosis that may explain the high-risk clinical course in this patient group. Methods: Data were collected from non-high-risk neuroblastoma patients diagnosed at our center between 2014 and 2021. Segmental chromosomal aberrations (SCAs), gene amplifications and mutations at diagnosis were detected by a single-nucleotide polymorphism array and next-generation sequencing. Telomere maintenance mechanisms (TMMs) were investigated using fluorescent in situ hybridization, whole genome sequencing (WGS) and RNA sequencing. SCA counts were imputed by using multiple imputation. Results: The total cohort included 89 patients. Thirteen patients developed a high-risk clinical course (group A) due to progression (n = 4), local relapse (n = 4), refractory disease (n = 3) or metastases (n = 2). Seventy-six patients followed a non-high-risk clinical course (group B). An SCA profile (≥1 SCA) was present in 76% of patients in group A and only 15% in group B (p = 0.004). 1p deletion was associated with a high-risk clinical course (p = 0.034). Gains of 1q, 2p and 17q, and deletions of 4p and 11q were more common in group A. After imputation, SCA count was associated with a high-risk clinical course (pooled OR 1.256 with 95% CI 1.006–1.568, p = 0.044). Two patients, both group A, exhibited MDM2/CDK4 amplification. Alternative lengthening of telomeres (ALT) was activated in 57% of group A. Conclusions: SCA profile and 1p deletion are associated with a high-risk clinical course. ALT activation, MDM2/CDK4 co-amplification, SCA count, gains of 1q, 2p, and 17q, and deletions of 4p and 11q may also be relevant molecular markers. Larger studies are needed for confirmation of these findings.