The United Kingdom’s price watchdog wants to know why Alexion’s rare disease-drug, Soliris, costs so much. PharmaLive reports that the agency wants to know what the company spends on manufacturing and R&D as part of its review process.

The rare-disease medication treats the inflammatory condition atypical hemolytic uremic syndrome and is available in the UK under a special agreement that allows it to be used prior to approval.

The drug costs around $200,000, per patient, per year in the US, and the regulator expects the drug would cost around $96,000 for the first year on its formulary, only to rise to $133,000 in five years.