Assessment of hypoxia-targeting therapy for gastrointestinal lymphoma in dogs: Preclinical test using murine models.

The transcription factor hypoxia-inducible factor 1α (HIF-1α) is expressed in several cancers under intratumoral hypoxic stress that arises during pathogenic processes, resulting in malignant progression. We previously reported that hypoxic stimulation enhances the growth potential of canine lymphoma cells by activating the HIF-1α signaling pathway. In contrast, evofosfamide (Evo) releases a DNA-alkylating moiety within hypoxic tumor regions, suggesting that Evo could serve as a hypoxia-targeting drug in canine lymphoma. This study aimed to use Evo to evaluate hypoxia-targeted therapy in dogs with gastrointestinal lymphoma (GIL) and investigate how Evo affects antitumor efficacy and adverse events in three type of murine xenograft models using T-cell GIL cells. In vitro tests, the sensitivity to Evo of three T-cell GIL cell lines under hypoxic culture was significantly higher than that under normoxic culture. Our metabolic analysis suggested that the three murine models might have high reproducibility as clinical cases in canine GIL. Our data showed that Evo showed significantly higher tumor growth potential and fewer adverse events in three type of murine models compared to lomustine; CeeNu (CCNU). Additionally, Evo suppressed the expression of HIF-1α protein in tumor tissues, suggesting that it may preferentially target and inhibit tumor cells in a hypoxic region. The evidence presented here supports the favorable preclinical evaluation that Evo may be effective for GIL in dogs.