Complete Metabolic Remission in Metastatic BCOR-Altered Undifferentiated Round Cell Sarcoma Following Sequential Multimodal Therapy With Vincristine-Doxorubicin-Cyclophosphamide (VDC) Chemotherapy and Pazopanib Maintenance: A Case Report

BCOR-altered undifferentiated round cell sarcomas (URCS) represent a rare entity with limited epidemiological data and variable reported outcomes, contributing to the absence of standardised therapeutic strategies. We report a 27-year-old woman with metastatic BCOR-altered URCS of the scapular region who achieved a durable complete metabolic remission following a sequential multimodal treatment strategy. The patient initially received one cycle of adriamycin-ifosfamide-mesna (AIM), which was discontinued due to toxicity, followed by five cycles of vincristine-doxorubicin-cyclophosphamide (VDC), resulting in a near-complete metabolic response. This was followed by consolidation with intensity-modulated radiotherapy (52 Gy in 26 fractions). Maintenance therapy with a reduced dose of oral pazopanib 400 mg daily, based on prior reports and tolerability considerations, was administered for 12 months. Serial fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) imaging confirmed a sustained complete metabolic remission beyond 18 months with minimal toxicity. This case highlights the marked chemosensitivity of BCOR-altered URCS to anthracycline-vinca-based chemotherapy and suggests a potential role for vascular endothelial growth factor (VEGF)-directed maintenance therapy in sustaining remission.