In 2008 the FDA granted Spectrum Pharmaceuticals company sole right to market a folinic acid isomer which is calls Fusilev (levoleucovorin). The patent expires in 2019. The stock doubled over the last two months and performed in the top 2% of stocks last year, trading more than 1 million shares a day.
Fusilev is used in the treatment of osteosarcoma, an orphan cancer disease that strikes four out of a million children and one out of a million adults. It allows a higher dose of the drug Methotrexate to be used without damaging mucous membranes and bone marrow.
There is less research money allocated to the study of osteosarcoma each year (approximately 30 million dollars) than the yearly profits from Fusilev alone.
Folinic acid is readily available over the counter and is usually considered to be a vitamin. It costs about 10 cents a capsule while its isomer, called Fusilev (and its nearly twin brother leucovorin) costs about 100 dollars per capsule. Isomers have exactly the same chemical formula as other isomers but their structure varies causing them to have different chemical properties (however, the pharmaceutical properties of leucovorin and levoleucovorin appear to be identical.)
On the announcement that an unnamed company planned to market a generic version of Fusilev for a much cheaper price, Spectrum Pharmaceutical stock plunged more than 6% on Friday. Spectrum’s lawyers said that there was little danger that Spectrum’s patent would be challenged successfully.