Toripalimab-based chemoimmunotherapy for unresectable sinonasal NUT carcinoma of the maxillary sinus: a case report

Background: Nuclear protein in testis (NUT) carcinoma is an extremely rare and highly aggressive epithelial malignancy driven by NUTM1 rearrangements. Sinonasal involvement is uncommon and often presents with non-specific clinical and radiologic features, leading to delayed diagnosis. Optimal management remains undefined, and outcomes are poor when complete resection is not feasible. Case presentation: A 31-year-old man developed progressive numbness and swelling of the left cheek after tooth extraction. Imaging revealed a soft-tissue mass involving the left maxillary sinus with adjacent maxillofacial soft-tissue extension. Endoscopic biopsy demonstrated a poorly differentiated carcinoma with diffuse punctate nuclear NUT expression, high proliferative index (Ki-67 ~50%), and PD-L1 expression in both tumor cells and immune cells. ^18F-FDG PET-CT showed no regional or distant metastases. Given unresectability, the patient received toripalimab (240 mg) combined with docetaxel and cisplatin every 3 weeks. MRI after three cycles showed early radiologic improvement, and further tumor regression was observed after six cycles, consistent with a partial response. The patient subsequently continued on toripalimab-based maintenance therapy with ongoing stable residual disease at the latest follow-up (approximately 5 months after therapy initiation and 6 months from diagnosis). Conclusion: To our knowledge, this is the first reported case of toripalimab-based chemoimmunotherapy demonstrating an early partial response and short-term disease control in unresectable maxillary sinus NUT carcinoma. It supports the potential role of PD-1 blockade integrated with platinum-taxane chemotherapy as a component of multimodal management for sinonasal NUT carcinomas.