Someone's mad about drug price increases. For once, it's not Bernie Sanders or Hillary Clinton - it's the CEO of a big U.S. biotech company.

Leonard Schleifer, chief executive officer at Regeneron Pharmaceuticals Inc., jumped into the drug pricing debate Thursday at a health-care conference, accusing fellow drug firm executives he shared a stage with of raising prices to cover up a lack of innovation.

"It's ridiculous," Schleifer said. "I hate us also when I see all this stuff."

Ian Read, who leads the drugmaker giant Pfizer Inc., countered with an oft-cited statistic that drug costs as a percentage of health-care expenses haven't changed in two decades, regardless of price increases.

Schleifer's response: "You're not entitled to a fraction of the GDP."

The shouting match was a rare occurrence in an industry that has been trying to show a united front to defend itself from attacks coming from the outside - politicians, patients, and health-benefits managers. In the last 18 months, companies like Mylan NV, the maker of the allergy shot EpiPen, and Valeant Pharmaceuticals International Inc. have emerged as the faces of the public's outrage over drug costs.

"The real reason we're not liked, in my opinion, is because we as an industry have used price increases to cover up the gaps in innovation. That's just a fact," Schleifer said at the Forbes Healthcare Summit in New York.

Ironically, Read and Schleifer sat a few feet from each another on a stage at a panel titled "Restoring Pharma's Reputation." They were joined by David Ricks, incoming CEO of Eli Lilly & Co.; Jim Robinson, head of U.S. operations for Astellas; and Gilead CEO John Milligan.