Immunotherapy with Chemotherapy in Recurrent or Metastatic Maxillary Sinus Squamous Cell Carcinoma: A Real-world Study in China

Background: Patients with Recurrent or Metastatic Maxillary Sinus Squamous Cell Carcinoma (R/M MSSCC) generally have a poor prognosis. Traditional chemotherapy has limited efficacy. In real-world practice, there is no data about the efficacy and safety of immunotherapy combined with chemotherapy in these patients. Objective: This study aimed to evaluate the efficacy and safety of immunotherapy combined with chemotherapy for patients with unresectable R/M MSSCC in a real-world setting. Methods: We included 15 R/M MSSCC patients treated at Beijing Tongren Hospital from January 2021 to December 2024. All patients received PD-1 inhibitors combined with chem-otherapy. We collected and analyzed clinical information and survival data of all patients. discussion: To our knowledge, this represents the first real-world cohort study evaluating PD-1 inhibitor-based chemoimmunotherapy in Chinese patients with recurrent/metastatic maxillary sinus squamous cell carcinoma. Overcoming challenges in prospective research for rare cancers, we observed encouraging clinical activity. Notably, exploratory biomarker analysis suggested that PD-L1 CPS≥20 may identify patients deriving enhanced benefit. Our findings provide preliminary evidence supporting the clinical feasibility of immunotherapy in combination with chemotherapy. Results: The Objective Response Rate (ORR) was 26.7%, and the Disease Control Rate (DCR) was 86.7%. The median Progression-Free Survival (PFS) was 5.1 months (95% CI 0.26-17.27), and the median Overall Survival (OS) was 7.8 months (95% CI 0.44-10.23). Compared with patients with PD-L1 CPS < 20, patients with CPS ≥20 had a longer median PFS (14.1 months vs.3.9 months, p=0.031, HR 0.223, 95%CI 0.040-1.264). The most fre-quent grade 1/2 Adverse Events (AEs) included: loss of appetite (15/15, 100%), alopecia (13/15, 86%), anemia (10/15, 67%), peripheral neurotoxicity (10/15, 67%), and leukopenia (8/15, 53%). Only one person experienced a grade 4 AE, which was chemotherapy-induced neutropenia. The most common immune-related AE was hypothyroidism (3/15, 20%). No serious immune-related adverse events were observed. Discussion: This study shows that PD-1 inhibitors combined with chemotherapy are a fea-sible and promising treatment strategy for recurrent/metastatic MSSCC. Most importantly, the results suggest that PD-L1 CPS has predictive value in this anatomical subtype. Patients with CPS ≥20 showed a significant survival benefit. Conclusion: In real-world practice, PD-1 inhibitors combined with chemotherapy are an effective and safe treatment option for recurrent/metastatic R/M MSSCC.