Because the rules for companies that want to produce competing drugs, or "biosimilars," are so complicated, "only 12 of those products have biosimilars currently in development," Burton said. "Let me be clear: 9 of 10 brand biologic drugs that will lose patent protection over the next 10 years do not have competitors in development."

The lack of competition will hurt patients' access to important prescription drugs, and it will also increase costs for employer health plans and Medicare plans, Burton said.

Biologics basics: One of the best known biologics, insulin, has been around for more than 100 years.

Some of the other well-known biologics are powerful, relatively new anti-inflammatory drugs like Humira, which can help patients with everything from severe arthritis to ulcerative colitis.

Related: Why does insulin cost so much? Big Pharma isn't the only player driving prices

The hearing did not include any representatives from brand-name biologics developers or manufacturers.

Makers of brand name biologics have argued in the past that developing and producing biologics is difficult and expensive. They've said that many of the current rules are necessary to promote patient safety and to reward pharmaceutical companies for cost, time, complexity and failure risk associated with creating new biologics.

But, from an employer's perspective, better access to more affordable biologics could help workers get easier access to medications that would ease their pain and improve their ability to work.

The walls against competition: Reasons for the lack of competition for biologics include tough, sometimes redundant product approval rules at the Food and Drug Administration, Burton said.

He said other problems include "patent thickets," or large, complicated collections of technology patents affecting the same biologic drug or biologic drug production process.

Humira, for example, is in the middle of a thicket of more than 100 patents.

"That's going to be challenging for a biosimilar to overcome through patent litigation," Burton said.

Health insurers and pharmacy benefit managers contribute to the problem by using pricing and rebate arrangements that favor the original brand name drug or very expensive biosimilars over much more affordable biosimilars, he said.

When biosimilars for Humira showed up, for example, some had a list price that was 80% lower than Humira's list price, but the biosimilars ended up with a market share of just 2% after a year.

"The reason is because the big three PBMs were not touching it," Burton said.

Providing better coverage for the Humira competitors would have hurt their revenue from the rebates and fees related to Humira, Burton said.

The future: Rep. Vern Buchanan, R-Fla., the health subcommittee chairman, said Congress needs to help eliminate the barriers keeping biosimilars out of the market.

Congress can help by updating drug reimbursement system rules, supporting efforts to promote biosimilar awareness, and make sure that PBMs have financial incentives to help patients get access to affordable biosimilars, Buchanan said.

The House is now considering three bills that mention biosimilars, including one that would create a biosimilars production tax credit and a bill that would require PBMs working with the Medicare Part D prescription drug program to provide detailed reports about prescription fills involving biological drugs and biosimilar products.