HTRA1 and ependymoma: In tumor #2 and relative PDOs, we found a cluster particularly enriched with astroglial/ependymal markers (AQP4, GFAP, ID4, SERPINE2, HTRA1, IGFBP2) linked with ependymoma and brain tumorigenic progression (Chen et al, 2018; Yang et al, 2018; Khan, 2019), and another with a strong link with mesenchymal markers, similar as previously observed (Gillen et al, 2020) (CHI3L1, CAV1, IGFBP5) as predominant.