Preclinical drug screen identifies WEE1 inhibitor and vinca alkaloid as a combination treatment concept for Li-Fraumeni syndrome medulloblastoma

Li-Fraumeni syndrome (LFS) is characterized by constitutional pathogenic TP53 mutation and increased risk of cancer development, including Sonic Hedgehog-activated medulloblastoma (SHH-MB). In LFS patients, radiation and DNA-damaging agents can exhibit lower efficiency and cause secondary malignancies. To identify efficacious, safe chemotherapeutic approaches for LFS-associated SHH-MB, 333 compounds were screened in in vitro TP53^mut brain tumor cell lines. The combination of WEE1 inhibitor adavosertib and vinca alkaloid vincristine demonstrated the highest activity, which was validated in TP53^mut SHH-MB patient-derived organoids. Low genotoxicity of these compounds was determined in vitro in LFS fibroblasts, and in vivo in the LFS mouse model. Despite the drugs’ limited efficacy in the in vivo PDX model, WEE1 knockdown led to significant growth reduction in in vitro and in vivo TP53^mut SHH-MB models. Our findings identify WEE1 as a promising target in LFS SHH-MB, suggesting its inhibition combined with vincristine treatment as a potential chemotherapeutic strategy.