An enzyme treatment from Alexion Pharmaceuticals costing 491,992 pounds ($704,630) a year may be worth using in babies with a rare disorder but does not represent good value for all patients, Britain's healthcare cost watchdog said.

Kanuma is designed for treating lysosomal acid lipase (LAL) deficiency, a rare inherited genetic disease in which fats build up in cells. Rapidly progressing LAL deficiency is particularly serious in babies, with survival of less than 12 months.

The National Institute for Health and Care Excellence (NICE), which decides if drugs should be used on the state health service, said in draft guidance on Thursday that more research was needed on the drug's costs and benefits.

Alexion said NICE had failed to recognize the "transformative clinical innovation of Kanuma", adding the drug had shown major survival benefit in babies and significant improvements in children and adults with LAL deficiency.

($1 = 0.6982 pounds)

(Reporting by Ben Hirschler; Editing by David Holmes)