Immunotherapy for the Treatment of Perineural Spread in Cutaneous Head and Neck Squamous Cell Carcinoma: Time to Rethink Treatment Paradigms

Background: Immune checkpoint inhibitors have shown promising antitumour activity. Application in head and neck cutaneous squamous cell carcinoma (cSCC) large nerve perineural spread (PNS) is limited.

Methods: Retrospective review of 13 patients with PNS receiving anti-PD-1 therapy from September 2017 to May 2021 is presented. Primary endpoints were objective response (complete or partial response) and median time to progression, determined by Head and Neck Multi-Disciplinary Team (MDT) and independent radiology review of magnetic resonance imaging (MRI) and/or computed tomography/positron emission tomography (CT/PET).

Results: Objective response was observed in 9/13 patients (69%), with complete response in 6 (46%) and partial response in 3 patients (23%). Median time to response was 2.1 months (IQR 1.8-2.7 months). There were 3 (23%) patients with progressive disease, with median time to progression of 3.5 months. There were no grade 3-4 treatment related adverse events.

Conclusions: This case series supports developing evidence for anti-PD-1 checkpoint inhibitor therapy for perineural spread, supporting future prospective clinical trials in this patient population.