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What: Shares of Spectrum Pharmaceuticals (NASDAQ:SPPI) have lost more than 19% of their value today in the wake of a Friday afternoon court ruling that declared invalid the company's patent claims  on cancer drug Fusilev.

So what: Fusilev  is Spectrum's brand name for levoleucoverin, which is primarily used to counter methotrexate toxicity in chemotherapy patients. Spectrum has been fighting a patent battle against Sandoz Pharmaceuticals, a subsidiary of Novartis, since early 2012  over the rights to produce and market levoleucoverin, which has been known since leucoverin drugs were first developed in the 1950s. Further, the court's decision notes that the patent at issue -- issued in 2002 and initially filed for in 1987 -- describes a method of manufacture for leucoverin that no one, including Spectrum, has ever actually utilized to produce a commercial product.

The court ultimately invalidated Spectrum's patent by drawing on a long history of pharmaceutical leucoverin synthesis, and by noting that Spectrum's license had not resulted in the commercial success that might provide the company with a valid claim.

Now what: This result ought to have been expected by anyone familiar with leucoverin. Even this writer, who admittedly has no chemistry expertise beyond what he learned from watching Breaking Bad, finds it difficult to dispute the court's findings (you can read the full decision here). Nor did it seem likely that a positive judgment would have significantly improved Spectrum's fortunes, as Fusilev sales have not come near to the $204 million  reached in 2012 in the past two years. The drug reached only $68 million in sales in 2013 and only recovered to $76 million in sales  for the first three quarters of 2014.

Still, that $76 million represented 56% of Spectrum's total product sales, and it'll be hard-pressed to recover those sales now that generic competition has been cleared to enter the market. Spectrum took a violent body blow in the courts last week, and it doesn't have much left to help it get off the mat.