Federal regulators are suing to block biotech drug developer Amgen’s more than $26 billion deal for Horizon Therapeutics. The Federal Trade Commission said Tuesday that the deal, announced last December, would give Amgen unfair leverage to block competition for Horizon medications. The FTC said the deal would entrench Horizon’s monopoly position on treatments for thyroid eye disease and chronic refractory gout. An Amgen representative did not immediately return a call from The Associated Press seeking comment. Amgen leaders said in December that the deal would give their company a strong platform to expand into rare disease treatments.