Among primary + recurrent MCT tumors, which treatment group showed significantly shorter survival in high Beclin-1 vs low Beclin-1 expression?

• A. Chemotherapy treated dogs that also had other treatment modalities
• B. Radiation
• C. Toceranib (± other modalities)
• D. Toceranib alone

Answer: (A)

Beclin-1 is a key regulator of autophagy, a process that can help cancer cells survive under therapeutic stress. In canine mast cell tumors, the level of Beclin-1 expression can influence how tumor cells cope with treatment, especially when multiple therapies are used together. Among tumors that were primary or recurrent, the group treated with chemotherapy plus other modalities showed that dogs with high Beclin-1 had significantly shorter survival than those with low Beclin-1. This suggests that robust autophagy, indicated by high Beclin-1, may enable tumor cells to withstand the combined assault of chemotherapy and additional treatments, leading to poorer outcomes. In other treatment contexts, the Beclin-1–related survival difference was not observed, implying the prognostic impact of Beclin-1 expression depends on the treatment setting and the role autophagy plays in those therapies.