Abstract Diffuse midline gliomas (DMGs) are highly aggressive central nervous system tumors primarily affecting children and young adults. They are characterized by rapid progression, with a median overall survival of 9-15 months. Approximately 80% of DMG cases harbor the H3K27M mutation, and the disease is marked by substantial intra-tumoral heterogeneity, with multiple cellular states co-existing within the same tumor. Most tumor cells closely resemble oligodendrocyte precursor cells (OPC-like) while others share similarities with astrocytes (AC-like), oligodendrocytes (OC-like) or mesenchymal (MES-like) cells. Although new therapies, like the newly accelerated FDA-approved dordaviprone (ONC201), show promise for progressive H3K27M-mutant DMG patients, benefits in diffuse intrinsic pontine glioma (DIPG) remain limited, particularly when used as a monotherapy. Given the role of intra-tumoral heterogeneity in treatment resistance, we investigated how distinct cellular states respond to dordaviprone and may impede therapeutic efficacy. Immunocompetent DMG-PPK mice (PdgfraD842V/Trp53DN/H3f3aK27M mutations) were treated with dordaviprone (125mg/kg, b.i.w.) in acute (1 week) or chronic (3 weeks) settings and compared to sham-engrafted and vehicle controls. Single-cell RNA sequencing revealed that OC-like populations were sensitive to dordaviprone, whereas MES-like cells became more prevalent after acute treatment and exhibited strong activation levels for mitogen-activated protein kinase (MAPK) signalling pathway. Spatial transcriptomics (Xenium Prime 5K) confirmed the shift in tumor cell populations with a reduction in OC-like cells, strictly following acute dordaviprone treatment. This change in cellular state highlights that some populations, such as MES-like cells, appear more resistant, while OC-like cells emerge as sensitive in both single-cell and spatial analyses. These data suggest that the acute phase of treatment provides a window of opportunity where tumor population complexity is reduced, potentially exposing transient therapeutic vulnerabilities, like MAPK pathway activation. These findings support the development of rational combination approaches to overcome mechanisms of resistance and enhance the therapeutic efficacy of dordaviprone.
Dubois et al. (Tue,) studied this question.