135P Influence of next generation sequencing on sarcomas management in the real-world setting in Oman: Retrospective single institution analysis

Next-generation sequencing (NGS) has the potential to refine sarcoma diagnosis and identify actionable biomarkers. However, its impact on the management of real-world sarcoma patients is less studied. We conducted a retrospective analysis to evaluate the frequency of actionable variants and NGS-induced diagnostic and therapeutic modifications in unselected sarcoma patients at a Cancer Center in Oman. Subjects of any age with sarcomas of any grade who underwent NGS at SQCCCRC between January 2022 and October 2023 were eligible. Relevant clinical and molecular information was retrieved from medical records and quantitatively described. Actionable variants were graded according to OncoKB Levels. Changes in diagnosis and treatment plans after NGS were recorded. We included 63 patients with a median age of 35 years, of whom 50.8% were female. The most prevalent sarcoma subtypes were Ewing sarcoma (15.9%), Gastrointestinal Stromal Tumor (GIST) (14.3%), and leiomyosarcoma (11.1%). Whole exome sequencing and targeted sequencing were used in 61% and 39% of cases, respectively. Actionable variants of OncoKB Level 1 were identified in 19.1%, Levels 2/3 in 0%, and Level 4 in 12.7%. We observed NGS-induced changes in diagnosis in 9.5% of patients and treatment modifications in 12.7%; 4.8% resulting from diagnosis changes and 7.9% based on actionable biomarkers. Excluding GIST, OncoKB Level 1 biomarkers were found in 4/54 (7.4%) patients, and Level 4 in 7/54 (13%) patients. Biomarker-based treatment changes occurred in 2/54 (3.7%) patients. NGS was useful in refining diagnoses. Actionable biomarkers were identified in a significant proportion of sarcomas. However, in non-GIST sarcomas, we observed less biomarker-induced treatment changes.