Abstract 1415: Reduction in photoimmunotherapy-induced edema with COX-2 inhibition: Combatting clinically relevant adverse events without compromising efficacy
Authors: Ma Gina , Gordon Myra , Lapetoda Jason , Lozano Abram , Amantea Christopher M. , Osada Takuya , Thorne Amy H. 
Published: March 2024

ASP-1929 photoimmunotherapy (PIT), an investigational drug-device combination, consists of an epithelial growth factor receptor (EGFR)-targeting drug, cetuximab, conjugated to a light-activatable dye, IRDye® 700DX, and a laser light. Localized illumination results in rapid and selective tumor necrosis in the preclinical setting, and early clinical studies demonstrate a manageable safety profile in patients with head and neck squamous cell carcinoma. In the ongoing clinical trials, however, edema is a commonly reported adverse event and laryngeal edema, requiring prophylactic tracheostomy, has been noted in some patients. Thus, a critical need exists to provide clinicians with tools to manage ASP-1929 PIT-associated edema to ensure optimal patient outcome. To evaluate edema following cancer-targeted PIT, we developed a mouse tumor model and used it to characterize the mechanism of edema development and evaluate various methods for edema reduction. Briefly, cohorts of mice bearing syngeneic LL/2 tumors engineered to express Ephrin A2 (EphA2) were administered an anti-EphA2 antibody conjugated to IR700 (conjugate) or saline control. Light was applied 24h following administration and edema was measured by caliper. In control mice, light alone did not generate edema; however, mice treated with conjugate plus light showed a light-dose dependent increase in edema volume which peaked at 6h post light delivery. We next evaluated a series of inflammatory cytokines and immune cell populations in the blood and tumor region at the onset (2h), peak (6h), and resolution (24h) of PIT-induced edema. We found a striking increase in neutrophils (500-fold greater than control mice, n=10, p&lt;0.0001) in the blood at the peak of edema formation coinciding with a significant increase in IL-6 (n=5, p&lt;0.001) and IL-10 (n=5, p&lt;0.05), indicating the onset of a heightened inflammatory response. To combat the edema formation, we next evaluated the effect of various anti-inflammatory drugs commonly used in the clinical setting. Cohorts of mice were administered conjugate plus light in the presence or absence of steroids or the selective COX-2 inhibitor meloxicam. Results show there is no reduction in edema by steroids regardless of timing of administration. Conversely, the addition of meloxicam resulted in a significant reduction in edema at all time points and light doses evaluated: 40-50% reduction at both 2h and 6h post-PIT when administered prophylactically and 25% reduction at 6h post-PIT when administered post-light (all settings, n=10, p&lt;0.0001). Importantly, we found the reduction in edema with meloxicam was not associated with a loss of therapeutic benefit based on measurement of tumor growth. In conclusion, the use of COX-2 inhibitors may be directly translated to the clinic for the benefit of patients receiving ASP-1929 PIT and should undergo further evaluation.

Citation Format: Gina Ma, Myra Gordon, Jason Lapetoda, Abram Lozano, Christopher M. Amantea, Takuya Osada, Amy H. Thorne. Reduction in photoimmunotherapy-induced edema with COX-2 inhibition: Combatting clinically relevant adverse events without compromising efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1415.