The U.S. Food and Drug Administration (FDA) and several pharmaceutical companies have been working to boost drug development and approval for rare diseases, according to Market Watch.

In the U.S., there are more than 7,000 rare diseases, and only about 5% to 6% of those diseases have FDA-approved treatments, according to Lucy Vereshchagina, Vice President at the Pharmaceutical Research and Manufacturers of America (PhRMA).

Vereshchagina told Market Watch, “[There’s] a huge unmet medical need that exists in our country. It just tells you how challenging it is to develop these medicines.”

There are a few challenges, such as small size clinical trials, delayed diagnoses, lack of data, and variability within diseases.

Heidi Ross of the National Organization for Rare Disorders said, “Establishing appropriate efficacy endpoints in rare diseases is often challenging because of a lack of regulatory precedent, small trial populations, and limited understanding of a disease’s natural history.”

Jamie Sullivan of the EveryLife Foundation for Rare Diseases said, “Many rare diseases are hard to diagnose. And the diagnostic odyssey leads to progression of disease before you can intervene and you can join a trial.”

The Rare Disease Endpoint Advancement (RDEA) program, a new FDA program, aims to bolster clinical trials for rare diseases by increasing collaboration between the agency and key industry players.

The RDEA pilot was proposed as part of the FDA performance goals outlined amid the reauthorization process of the Prescription Drug User Fee Act (PDUFA), according to Market Watch.

Pfizer has recently said in an emailed statement that it is supportive of the PDUFA agreement, urging Congress to pass the bill before it expires at the end of September.

The company said, “Through support for gene therapy development, application of digital health technologies in clinical research, and use of innovative trials designs and real-world evidence, PDUFA VII will help to accelerate the development of modern medicines for rare diseases.”

“Pfizer’s experience with FDA’s existing real-time review program in oncology has been positive and we look forward to the expansion of the Split-Time Application Review (STAR) program to rare diseases, as well as to partnering with FDA to further develop rare disease study endpoints,” it added.

Novartis also said in an email that it “supports the PDUFA VII goals letter as negotiated between FDA and industry, and [welcomes] new regulatory initiatives that further advances innovative product development and enables earlier patient access.”

Due to PDUFA’s success, similar user fee programs were established for generic drugs, biosimilars and medical devices, per Market Watch.

If Congress fails to reauthorize the user fee programs before they expire at the end of September, “the agency’s processes for reviewing drug applications … will come to a screeching halt,” said Jeremy Sharp, managing director at lobbying company Waxman Strategies.

“They’ll still have the appropriated dollars to do it,” added Sharp, who is a former deputy commissioner at the FDA. “But at the end of the day, those dollars are not enough to keep the program operating at current levels.”