Express Scripts parent company Cigna alleges the Federal Trade Commission ignored more than 3 million pages of documents the pharmacy provided to investigators.

As the FTC has increasingly prodded PBMs over their role in high drug costs, Express Scripts is fighting back by launching a lawsuit against the agency.

Cigna Group’s pharmacy benefit manager Express Scripts on Tuesday sued the U.S. Federal Trade Commission, alleging that the agency’s July report on the PBM industry was biased and defamatory and asking the court to order the FTC to withdraw the report.