Obvious caveat: You REALLY want to research this in-depth to see if there's any basis to it, but I recently came across the fact that Hymecromone(4-methylumbelliferone) is an inhibitor of Hyaluronic Acid synthesis, which is a part of extracellular matrix, and necessary for cell proliferation, that is currently being investigated for a large range of different cancers, with positive effects in most(mostly animal models and in vitro studies).

I first discovered it when searching for bladder cancer therapies[1][2]

A cursory search seems to say that HA does in fact play a role in GBM[3], and that 4MU appears to reduce GBM cell proliferation[4] though it looks at a different mechanism.

In fact, there seems to be a review of its potential for treating brain cancers specifically[5]

As far as I can tell, it's a commonly prescribed drug for bile acid related issues that rarely has any side effects or risks. It appears to be safe, and to improve outcomes across many types of cancers

[1] https://www.auajournals.org/doi/full/10.1016/j.juro.2014.02....

[2] https://pmc.ncbi.nlm.nih.gov/articles/PMC11081427/

[3] https://link.springer.com/chapter/10.1007/978-94-007-7602-9_...

[4] https://www.sciencedirect.com/science/article/pii/S235230422...

[5] https://www.researchgate.net/profile/Yasser-Mustafa-3/public...