Immunosuppression as a possible risk factor for interferon nonresponse in ocular surface squamous neoplasia

Purpose: The mechanism by which ocular surface squamous neoplasia (OSSN) responds to topical interferon-alpha-2b (IFN2b) is not known. We report the cases of 3 immunosuppressed patients whose tumors did not respond to topical IFN2b therapy. The purpose of this series is to shed light on potential mechanisms of IFN2b in OSSN. Methods: Retrospective case series of 3 immunosuppressed patients whose biopsy-proven OSSN did not respond to topical IFN2b treatment. Results: Three white, immunosuppressed males (mean age 70 years, range 66-76) were diagnosed with OSSN. Topical IFN2b 1 million units/mL was administered 4 times a day and used for a mean of 5 months (range 2-7 mo) without an adequate response. All patients were then switched to 5-fluorouracil. Successful eradication of OSSN was achieved in 2 cases, and improvement of OSSN in another. The latter patient was switched to mitomycin-C with subsequent resolution of OSSN. Conclusions: These cases suggest that an intact immune system may be an important link between IFN2b therapy and tumor resolution. As such, topical IFN2b may not be an optimal choice for patients with underlying immunosuppression. It may be more effective in this patient population to switch to a non-immune-modulating therapy such as 5-fluorouracil or mitomycin-C.