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Updated: Aug 22, 2025
Intravitreal Injections in the Ovine Eye
Published on: July 5, 2022
Novel ocular immunotherapy induces tumor regression in an equine model of ocular surface squamous neoplasia
Kathryn L Wotman1, Lyndah Chow2, Brittany Martabano2
1Center for Immune and Regenerative Medicine, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, 80523, USA. Kathryn.Wotman@colostate.edu.
Abstract:
Ocular surface squamous neoplasia (OSSN) is the major cause of corneal cancer in man and horses worldwide, and the prevalence of OSSN is increasing due to greater UVB exposure globally. Currently, there are no approved treatments for OSSN in either species, and most patients are managed with surgical excision or off-label treatment with locally injected interferon alpha, or topically applied cytotoxic drugs such as mitomycin C. A more broadly effective and readily applied immunotherapy could exert a significant impact on management of OSSN worldwide. We therefore evaluated the effectiveness of a liposomal TLR complex (LTC) immunotherapy, which previously demonstrated strong antiviral activity in multiple animal models following mucosal application, for ocular antitumor activity in a horse spontaneous OSSN model. In vitro studies demonstrated strong activation of interferon responses in horse leukocytes by LTC and suppression of OSSN cell growth and migration. In a trial of 8 horses (9 eyes), treatment with topical or perilesional LTC resulted in an overall tumor response rate of 67%, including durable regression of large OSSN tumors. Repeated treatment with LTC ocular immunotherapy was also very well tolerated clinically. We conclude therefore that ocular immunotherapy with LTC warrants further investigation as a novel approach to management of OSSN in humans.
Insights
A novel liposomal TLR complex (LTC) immunotherapy shows promise for treating ocular surface squamous neoplasia (OSSN), a type of corneal cancer. This immunotherapy demonstrated significant tumor response rates and was well-tolerated in horses, suggesting potential for human treatment.
Area of Science:
- Ophthalmology
- Immunology
- Veterinary Medicine
Background:
- Ocular surface squamous neoplasia (OSSN) is a significant cause of corneal cancer in humans and horses, with increasing prevalence linked to UVB exposure.
- Current treatments for OSSN include surgical excision or off-label use of interferon alpha or topical cytotoxic drugs, lacking broad efficacy.
- There is a critical need for a more effective and accessible immunotherapy for OSSN management globally.
Purpose of the Study:
- To evaluate the efficacy of a liposomal TLR complex (LTC) immunotherapy for ocular antitumor activity in a spontaneous equine OSSN model.
- To assess the potential of LTC as a novel treatment for OSSN in humans based on its performance in a relevant animal model.
Main Methods:
- In vitro studies assessed LTC's effect on horse leukocytes, specifically interferon response activation, and its impact on OSSN cell growth and migration.
- A clinical trial involved 8 horses (9 eyes) treated with topical or perilesional LTC for spontaneous OSSN.
- The study monitored tumor response rates and clinical tolerability of repeated LTC treatments.
Main Results:
- In vitro, LTC strongly activated interferon responses in horse leukocytes and inhibited OSSN cell growth and migration.
- The equine trial showed a 67% overall tumor response rate to LTC immunotherapy, including regression of large OSSN tumors.
- Ocular immunotherapy with LTC was clinically well-tolerated in horses with repeated applications.
Conclusions:
- Topical or perilesional LTC immunotherapy demonstrates significant potential for managing ocular surface squamous neoplasia (OSSN).
- The positive results in a horse model suggest that LTC ocular immunotherapy warrants further investigation as a novel treatment for human OSSN.
- LTC represents a promising new therapeutic avenue for corneal cancer, potentially improving outcomes for affected individuals worldwide.
