It was never marketed for medical use due to safety problems but is currently used in scientific research.
Some of the safety liabilities that lead to its discontinuation for the treatment of insomnia has led to its potential repurposing in the field of oncology. Specifically, ritanserin acts as a potent inhibitor of diacylglycerol kinase alpha (DGKα). As such, it may be used to treat certain types of glioblastoma[6][7] and melanoma. It has also been used as a reference compound to identify putatively more selective and potent DGKα inhibitors to treat these forms of cancer as well as possibly others.[8]
Additionally, ritanserin blocks c-RAF activation and induces apoptotic cell death of non–small cell lung cancer and small cell lung cancer cells.[9]
^Cite error: The named reference Elks2014 was invoked but never defined (see the help page).
^Paiva T, Arriaga F, Wauquier A, Lara E, Largo R, Leitao JN (1988). "Effects of ritanserin on sleep disturbances of dysthymic patients". Psychopharmacology. 96 (3): 395–9. doi:10.1007/BF00216069. PMID3146774. S2CID19232592.