This question is specifically asked within the Project called "Treatment of Melanoma Brain Metastases."
Because neurological tissues as well as many forms of skin malignancies will tend to express at least some significant CB1 and CB2 receptors, perhaps using moderate dosing of a safe agonist like Delta 9-THC may be useful? And consider including evaluation of equivalent to 100-300 mg or oral CBD for humans as well as this is becoming very common among patients.
I work with both brain cancer patients (mostly Glioblastoma) and many breast cancer patients and they had already chosen to integrate cannabis extracts into their therapies. Because CBD and THC cross the BBB, and does not appear toxic to healthy normal cells, it may be reasonable to consider exploring this with research. I do have one interesting patient who reported using these compounds to treat her ER-PR-HER2+ brain metastases with tremendous success in only 3 months. The Herceptin and Perjeta she was on are too large to cross the BBB, so the situation is dire for her otherwise. Best wishes and thank you for your project!