Ruddle, R. | Search bioRxiv

bioRxiv2026

Cellular uptake of folate-olaparib conjugates via folate receptor-mediated endocytosis: Potential for selective delivery of DNA damage response inhibitors into tumour cells

The folate receptor (FR) is overexpressed in a range of human tumours including ovarian cancer cells. We propose that the overexpression of the FR on the surface of ovarian tumour cells could be exploited for the selective delivery of a DNA damage response inhibitor (DDRi) in the form of an intact folate drug conjugate (FDC). This approach would improve the therapeutic index of the parent DDRi facilitating combination studies of the DDRi-based FDC with DNA damaging chemotherapy. FR-mediated cellular uptake of the proposed folate drug conjugates is requisite for FDC selective delivery into tumours. In this study, we synthesised a series of olaparib-based folate conjugates that maintained the biochemical PARP1 inhibition associated with olaparib and showed binding affinity for the folate receptor. Significantly, we identified compounds 10b and 11 that selectively enter FR overexpressing tumour cells via folate receptor-mediated endocytosis in their intact form and engage with their target as demonstrated by the potent inhibition of PARylation (KB cells, PARylation IC50 = 5.7 and 3.9 nM; respectively).

biochemistry↗

bioRxiv2026

Combination of ALK2 and cholesterol targeting agents exploits linked genetic and metabolic dependencies in diffuse midline glioma

Diffuse midline glioma is an epigenetically driven disease defined by alterations targeting the histone post-translational modification H3K27me3 resulting in epigenetic rewiring and imposing unique metabolic dependencies. ACVR1-mutations arise in ~25% of DMG H3K27-altered patients and impart a selective dependency on the kinase it encodes (ALK2), however ALK2 inhibitors show modest single-agent efficacy in vivo. In an attempt to better understand the cellular consequences of ALK2 inhibition to identify mechanistically-driven drug combinations, integrated multi-omics analysis was performed and revealed a novel role for ALK2 in cholesterol homeostasis while CRISPR and high-throughput drug screens identified hits targeting cholesterol metabolism as sensitisers to ALK2i. In vivo assessment of ALK2i plus clinically well-tolerated statins revealed a significant increase in the median survival compared to vehicle. Forced differentiation of DMG cells from an oligodendrocyte precursor-like to an astrocyte-like cell-state and led to a significant decrease in ALK2i sensitivity and synergy with statins, which was phenocopied when DMG cells were co-cultured with normal astrocytes. We identify a previously unappreciated role for ALK2 signalling in cholesterol homeostasis, showing cell-state dependency, and identify a rational combinatorial strategy for clinical translation.

cancer biology↗