Immunotherapy for Advanced Conjunctival Squamous Cell Carcinoma: Treatment Failures.

Purpose: To review the treatment response of advanced conjunctival squamous cell carcinoma (SCC) to systemic immune checkpoint inhibitor (ICI) therapy at a single institution.

Methods: A retrospective review of patients treated at a single institution from 2015 to 2024 was conducted to identify those with advanced conjunctival SCC who had been treated with ICI therapy. Advanced disease included patients with orbital invasion of tumors, unresectable disease, or metastatic disease. Computed tomography imaging and tumor mutational burden data were evaluated for all patients.

Results: Five patients with advanced conjunctival SCC were treated with ICIs. All patients had the American Joint Committee on Cancer stage cT3N0M0. All patients had best corrected visual acuity in the affected eye of 20/30 or better at presentation. All patients progressed while on ICIs, with 3 ultimately requiring exenteration at a median time of 6 months from initial diagnosis. One patient had progressive metastatic disease, and one had direct intracranial extension. All patients had low tumor mutational burden.

Conclusions: Unlike prior reports demonstrating complete treatment response while on ICI therapy in patients with advanced conjunctival SCC, the current study demonstrates that 5 of 5 patients had disease progression while on ICI therapy. All patients also had low tumor mutational burden. Tumor mutational burden may be important in predicting disease response to ICI in patients with conjunctival SCC; however, given the small number of patients with conjunctival SCC treated with ICI to date, more data are needed to understand the role of ICIs in conjunctival SCC.