Immune Checkpoint Inhibitors for Advanced Periocular/Orbital Squamous Cell Carcinoma of Cutaneous Origin: Durable Responses in a Retrospective Cohort

PURPOSE: This study's purpose was to investigate the outcomes of immune checkpoint inhibitor (ICI) treatment of periocular cutaneous squamous cell carcinoma with orbital invasion. METHODS: A retrospective review was performed of 19 patients with biopsy-confirmed, advanced periocular cutaneous squamous cell carcinoma with orbital invasion treated with ICIs at a single institution. Tumors of conjunctival, sinonasal, lacrimal sac, or indeterminate origin were excluded. Demographic and clinical features at presentation, duration (number of cycles) of ICI, and treatment response were analyzed. RESULTS: Nineteen patients with periocular cutaneous squamous cell carcinoma with orbital invasion treated with ICI were identified. The median age at diagnosis was 74 (interquartile range, 67-78) years. Most patients were non-Hispanic White (95%, n=18) and male (68%, n=13). Eight patients (42%) had AJCC T4 disease. Median presenting logMAR visual acuity in the affected eye was 0.3 (0.2-0.8). Eighteen patients (95%) had orbital involvement, and 14 (74%) had perineural involvement. Thirteen (68%) were treated with cemiplimab and 5 (26%) with pembrolizumab, and 1 was transitioned to cemiplimab after progression on pembrolizumab. Patients received a median of 9 (interquartile range, 6-15) cycles. Nine patients (47%) had complete response, 6 (32%) had a partial response, 3 (16%) remained stable, and only 1 (6%) progressed on ICIs. No tumors recurred nor required exenteration by the end of the study period. The median follow-up time was 35 (interquartile range, 19-53) months. CONCLUSIONS: Immunotherapy demonstrated excellent, sustained clinical outcomes in periocular cutaneous squamous cell carcinoma with orbital invasion with low morbidity and mortality. A disease control rate of over 90% was achieved and sustained at a median follow-up of almost 3 years.