CD274 and angiosarcoma: Motivated by a strong correlation between IHC-detected PD-L1 expression and patient response rates,23,24 some approaches directly target PD-L1 status prediction for lung-, head and neck- and breast cancer entities.25, 26, 27, 28, 29, 30 However, the adaptation of these approaches to Angiosarcoma PD-L1 status prediction is hindered by two factors: First, the rarity of Angiosarcoma entails that there is relatively little annotated training data available, which has been shown to be detrimental to model performance in a wide range of diverse application scenarios.