Mitigating Antibody-Drug-Conjugate Chemotherapy-Associated Corneal Toxicity

Antibody-drug conjugates (ADC) have emerged as promising chemotherapeutic agents for multiple types of cancer. Various ADC are associated with significant off-target corneal toxicity attributed to the non-specific corneal uptake of ADC by macropinocytosis. The overall goal of this study was to develop an unbiased high-content imaging approach with Dextran-Texas Red, allowing the quantification of macropinocytosis-mediated cellular uptake. ADC-mediated cytotoxicity and cell cycle arrest were quantified to determine the feasibility of repurposing imipramine, an FDA-approved macropinocytosis inhibitor, as a therapeutic strategy to combat ADC-mediated ocular toxicity. EIPA significantly reduced fluorescence intensity and immunopositive area by ~80%. Imipramine resulted in a significant reduction of fluorescence intensity, suggestive of MPC inhibitory activity, but the level of reduction was ~20%. Belantamab mafodotin exerted dose-dependent cytotoxicity, consistent with previous reports. Although imipramine reduced MPC-mediated uptake, none of the concentrations tested were able to reduce MPC by >20%. Based on cytotoxicity and cell cycle studies, this inhibitory effect was insufficient to protect HCE-T cells from belantamab mafodotin-induced toxicity. This study optimized and standardized the method for quantification of MPC using DTR uptake in human corneal epithelial cells. This enhancement ensures consistent and reliable results, and further provides a baseline for further investigation. To our knowledge, this work represents the first study of imipramine in ocular systems, or human corneal epithelial cells and provides support for the feasibility of using imipramine as new therapeutic strategy to reduce off-target ocular toxicity associated with ADC.