Risperidone

A newly published case study describes the case of a 57-year old GBM patient, with poor prognosis due to a KPS of only 50 and postoperative neurologic symptoms.  The patient was being treated for schizophrenia at the time of GBM diagnosis with risperidone at a dose of 6-6.5 mg per day.  He ended up going 5.5 years without recurrence, and then lived for an additional year after first recurrence.  This paper posits a possible correlation of his unexpected progression-free survival with his use of risperidone.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066542/

In 2010, Richard Kast published a paper hypothesizing that risperidone, pimozide, and paliperidone could be useful for GBM treatment as 5-HT7 serotonin receptor antagonists.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2990148/

Additionally, risperidone is a potent inhibitor of D2 and D3 dopamine receptors. D2 has been described as a valid target for GBM therapy:

https://www.ncbi.nlm.nih.gov/pubmed/24658464

Finally, a more recent paper by Richard Kast and Marc Halatsch proposing D3 dopamine receptor as a target for GBM therapy.

https://www.ncbi.nlm.nih.gov/pubmed/24242756