This seems to be an option for everyone with brain metastases (inform your doctor as it is quite new) ) Here are links to research done in Spain in 2017 where patients brain mets improved significantly by taking silibinin :
https://academic.oup.com/annonc/article/28/suppl_5/mdx366.035/4108588 and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5077992/
The results show great improvement - threefold compared to normal situation. It was after WBRT , but it might work on its own according to theoretical part of the research. Dr. Barrera-the head of this research informed me that silibinin was effective on its own in a mice model.
Silibinin (also called silybin) is a major constituent of silymarin - milk thistle extract. In the research they used Legasil - a silibinin extract with increased bioavailability (through Eurosil 85 formulation). Bioavailability could be a problem with regular extracts.
Legasil also contains vitamin E, which according to Mr. Barrera does not probably play any role here.