A federal judge has declined to toss out a lawsuit in which Aetna alleged the maker of a highly addictive opioid-based painkiller duped the insurance company into paying reimbursements for off-label uses.

In an Aug. 23 ruling, U.S. District Judge Cynthia Rufe of the Eastern District of Pennsylvania denied defendant Insys Therapeutic's request to dismiss the case.

Insys, the manufacturer of the fentanyl drug Subsys, used most commonly for cancer patients, encouraged doctors to prescribe the painkiller for uses other than those approved by the U.S. Food and Drug Administration, Aetna alleged. The insurance company claimed Insys raked in the cash—to the tune of $300 million from 2012 to 2014—by defrauding insurers into providing coverage for the off-label prescriptions, according to Rufe's opinion.

The drugmaker argued that Aetna could not prove that Insys was unjustly enriched by its alleged behavior. Rufe, however, said that was not so.

“Insys argues that Aetna has failed to allege that it conferred a benefit on Insys to Aetna's detriment. The complaint alleges that Aetna paid for prescriptions of Subsys based on misrepresentations made by Insys concerning the indication for which the drug was prescribed and that Insys gained sales revenue and market share as a result of these prescriptions. Courts have found similar facts to satisfy the benefit element of an unjust enrichment claim under Pennsylvania law,” Rufe said.

“Significantly, Pennsylvania law does not require that the alleged benefit in an unjust enrichment claim be conferred directly by the plaintiff upon the defendant,” Rufe continued, “so long as the benefit is not too attenuated to support equitable relief. While Insys contends that it only received payment for services and products that it provided, and that an equitable remedy is not justified in light of the tort remedies available to plaintiffs to redress their losses, these are arguments more appropriately addressed on a full factual record.”

Insys also argued against Aetna's claim for punitive damages, but since Rufe declined to dismiss the plaintiff's common-law fraud claim, she allowed the punitive damages claim to proceed as well.

Lastly, Insys asked the court to strike certain passages from the complaint, namely those pertaining to the national opioid epidemic and the FDA commissioner's statements on the impact of off-label promotion of drugs on public health, along with other official statements.

“These background facts provide context to the alleged events,” Rufe said. “At the pleadings stage, it is premature to assess whether these alleged facts would be sufficiently prejudicial or confusing to warrant exclusion at later stages of the case. Thus, Insys's motion to strike will be denied without prejudice, and defendants may raise the same concerns later, if warranted, in a motion in limine or as otherwise appropriate.”

Aetna is represented by Christina McPhaul of Lowey Dannenberg in White Plains, New York, and Insys is represented by Scott Etish of Gibbons in Philadelphia. Neither responded to requests for comment.