The SINTART 2 Study. A phase II non-randomised controlled trial of induction chemotherapy, photon-, proton- and carbon-ion-based radiotherapy integration in patients with locally advanced unresectable sinonasal tumours.

Purpose: Unresectable, locally advanced sinonasal epithelial tumours are rare diseases with poor prognosis. Multimodal approach is widely used, although no standard therapy has been established in prospective trials. This study assessed activity and safety of an innovative integration of multimodality treatment-induction chemotherapy (ICT), surgery and radiotherapy (RT)-modulated by histology and response to ICT.

Methods: Patients with untreated, unresectable sinonasal epithelial tumours with selected histotypes (squamous cell carcinoma, intestinal-type adenocarcinoma, sinonasal undifferentiated and neuroendocrine carcinoma, olfactory neuroblastoma) were enroled in a single-arm, open-label, phase II, multicentre clinical trial. Patients were treated with up to 5 ICT cycles, whose regimen was selected according to histotype. Photon and/or proton/carbon-ion-based RT was employed according to disease site, stage and ICT response. Primary end-point was 5-years progression-free survival (PFS), secondary end-points were overall survival (OS), ICT objective response rate per RECIST 1.1 and safety.

Results: Twenty-five patients were evaluable for primary end-point. Five-year PFS was 26.8% (95% confidence interval [CI]: 12.6-57.1), with a median PFS of 18 months. Five-year OS was 23.8% (95% CI: 9.5-59.3), with a median OS of 27 months. The overall response rate to ICT was 40%. Three-year PFS for patients achieving major volumetric partial response (mPRv) versus non-mPRv was 40% (95% CI: 13.7-100%) versus 23.1% (95% CI: 8.3-64.7%) (P = 0.318) and 3-year OS was 53.3% (95% CI: 21.4-100%) versus 37.7% (95% CI: 20.0-71.0%) (P = 0.114).

Conclusion: Multimodal combination of ICT and innovative RT did not provide a significant improvement in survival rates with respect to previous experiences. This finding underscores the need for future research in this rare disease, still characterised by a heavy burden and poor prognosis. We observed longer survival in subjects achieving response to ICT. The overall treatment safety is acceptable.