Prevention of tumor ulceration in mice – Mammary fat pad injection of tumor cells

Background: Syngeneic tumor models are frequently used with subcutaneous injection of tumor cells into mice. Ulceration is a common drawback of these models. For ethical reasons, mice with tumor ulcerations have to be sacrificed early, i.e. tumors cannot grow to their maximum size and the study duration is too short to fully investigate the effects of immuno-oncology drugs on the tumor and its immune cell infiltrates. Moreover, the reduced number of remaining animals without ulceration decreases the statistical significance of the study results. We demonstrate that this challenge can be overcome by syngeneic tumor models in which tumor cells are implanted into the mammary fat pad of mice.