Carbonic Anhydrase IX and Cyclooxygenase-2 Regulation in Renal Cell Carcinoma and Impact on Therapeutic Efficiency of Anti-CAIX CAR T cells.

Background: Clear cell renal cell carcinoma (ccRCC) is the most prevalent of renal cancers, with a 5-year survival rate of less than 10% for metastatic cases. The most efficient current strategies to treat ccRCC in advanced settings slightly increase progression-free survival. Chimeric antigen receptor T cells (CAR T cells) targeting carbonic anhydrase IX (CAIX) have reemerged as a promising alternative to ccRCC treatment based on recent preclinical data. CAIX and cyclooxygenase- 2 (COX-2) are key players in tumor progression across various malignancies, overexpressed in 95% and 50% of ccRCC cases, respectively.

Methods: This study employed in silico analysis to examine the expression of CAIX and COX-2 in ccRCC cell lines. The effects of celecoxib, anti-CAIX monoclonal antibodies, and anti-CAIX CAR T cells were evaluated using immunofluorescence microscopy and flow cytometry techniques.

Results: Herein, we show a positive correlation between CAIX and COX-2 expression in ccRCC cell lines in vitro and in silico. Notably, COX-2 blockade with celecoxib led to a significant downregulation of CAIX expression in ccRCC cell lines. This effect is retroactive since treatment of these ccRCC cells with two different anti-CAIX monoclonal antibodies (mAbs) resulted in the downregulation of COX-2 expression. The association of celecoxib with anti-CAIX CAR T cell therapy impaired their cytotoxic potential over ccRCC in vitro, depending on CAIX cellular density.

Conclusion: These findings suggest a regulatory interaction between CAIX and COX-2 levels, indicating that COX-2 inhibitors may diminish the efficacy of CAIX-targeted therapies and should be avoided in combination treatments.