[Preprint] Spatial mapping of pediatric brain tumors across diagnoses and relapses

Escudero Morlanes J, Lehto TP, Larsson L, Alonso Galicia L, Mollbrink A, Shamikh A, Basmaci E, Prochazka G, Díaz de Ståhl T, Sandgren J, Taylan F, Tesi B, Nordgren A, Erickson A, Lamb AD, Blomgren K, Nistér M, Lundeberg J, Mirzazadeh R, Kvastad L.

bioRxiv. 2026 Aug 26. Preprint – not peer reviewed. doi: https://doi.org/10.64898/2026.08.25.746606

Abstract. We present a spatial transcriptomic atlas of 19 pediatric brain tumor patients spanning nine major and rare diagnoses, including seven relapses, revealing their spatial cellular and molecular organization. Each tumor section resolves into 2 - 4 recurrent spatial archetypes across 11 biological themes, with some mirroring developmental lineage patterns - for example, oligodendrocyte-lineage programs in pilocytic astrocytomas. Spatially inferred copy-number analysis identifies relapse-associated putative clones. In one rare embryonal tumor, spatial niches in the primary tumor harboring putative clones colocalized with an archetype enriched for nervous system development and glioblast-lineage programs. In one ependymoma and one pilocytic astrocytoma, relapse-associated putative clones preferentially localized to the vasculature, suggesting regrowth during relapse may be seeded by clonal selection of residual tumor cells within specialized microenvironmental niches. This resource provides an open-access spatially resolved map via an interactive viewer to inform research on pediatric brain tumor ecosystems, relapse biology, and therapeutic strategies.