Durable tumor regression and restoration of neurologic function after treatment with anti-PD-1 in patients with functionally unresectable cutaneous squamous cell carcinoma with perineural spread into the cavernous sinus

Purpose: To describe tumor response and cranial nerve function outcomes after administration of anti-PD-1 to patients with cutaneous squamous cell carcinoma (CSCC) with perineural spread to cranial nerves (CN) extending into the cavernous sinus. Methods: Electronic patient records from a single institution were queried for patients with CSCC of the head and neck causing diplopia (ICD-10 H53.2) who were treated with anti-PD-1. Data extracted included demographics, duration of anti-PD-1 therapy, immune-mediated adverse reactions, tumor response per adapted RECIST v1.1, and changes in CN function and symptoms (e.g., pain). All patients were prescribed cemiplimab 350 mg IV q3 weeks. Results: Four patients met inclusion criteria. They had varying degrees of pain and sensory deficits in branches of the trigeminal nerve (CN V). One, 2, 3 and 1 patients had baseline involvement of CN III, IV, VI and VII, respectively. MRI confirmed perineural cavernous sinus involvement in all patients. Duration of anti-PD-1 therapy ranged 15–60 weeks. All patients experienced an objective anti-tumor response to anti-PD-1; partial response n = 2, complete response n = 2. At a median follow-up of 22 months, responses were ongoing in all patients. All patients demonstrated improvement in ocular motility deficits and pain with resolution of symptoms in 3 and 1 patients, respectively. Conclusion: Administration of anti-PD-1 to patients with CSCC with perineural spread into the cavernous sinus can generate durable anti-tumor regressions and restore CN function, while sparing the morbidity associated with surgical resection and/or radiotherapy. Our findings add to emerging literature supporting this treatment approach for this patient population.