IFNA1 and neoplasm: We found that the composition of tumours in the xenograft model was relatively uniform with low heterogeneity (Fig. 6a), whereas tumours from PDXs models were more heterogeneous with many histological and genetic features of the primary tumours (Fig. 6b) as observed in many other PDX tumour models.33 Increased stromal cell numbers and necrotic elements were observed in response to IFNα treatment in vivo.