Because ALPN-202 does not block the mouse PD-1–PD-L1 interaction, we sought to understand how hPD-L1-mediated CD28 costimulation would compare to or work in combination with mPD-1 blockade in two separate tumor models: MC38/hPD-L1 (Fig. 7a) and the more immunotherapy-resistant B16-F10/hPD-L1 (Fig. 7b). Here, CD28 is linked to neoplasm.