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Molecular Characterization Informs Prognosis in Patients With Localized Ewing Sarcoma: A Report From the Children's
Riaz Gillani1,2,3,4, David S Shulman1,2,3, Natalie J DelRocco5,6
1Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA.
Summary
This study identified STAG2 mutations as a key molecular marker for relapse risk in localized Ewing sarcoma (EWS). Patients with STAG2 mutations face a significantly higher risk of relapse, highlighting its prognostic value in EWS treatment.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Localized Ewing sarcoma (EWS) treatment response varies, with discrete subgroups linked to resistance remaining challenging to identify.
- Molecular characterization of EWS is crucial for understanding treatment outcomes and developing targeted therapies.
Purpose of the Study:
- To molecularly characterize patients with localized EWS within the Children's Oncology Group (COG) biology study AEWS18B1-Q.
- To identify discrete subgroups associated with treatment response and resistance in localized EWS.
Main Methods:
- Analysis of clinical and molecular features from localized EWS patients on frontline COG trials.
- Sequencing for canonical fusions, copy number alterations (CNAs), and mutations in TP53 and STAG2 from FFPE or frozen tissue.
- Evaluation of STAG2 protein expression and association of molecular features with cumulative incidence of relapse.
Main Results:
- EWS canonical fusions were found in 80.3% of 351 patients; TP53 and STAG2 mutations occurred in 5.1% and 7.6%, respectively.
- Recurrent CNAs were present in 63.1% of patients.
- Univariate analysis showed increased relapse risk with TP53 mutation, STAG2 mutation, and recurrent CNAs. STAG2 mutation was the sole significant prognostic molecular biomarker in multivariable analysis.
Conclusions:
- This prospective study validates molecular prognostic features in localized EWS patients receiving standard care.
- STAG2 mutations identify patients with a high risk of relapse in localized Ewing sarcoma, confirming its prognostic significance.
