Biosimilar medications are beginning to make gains in the U.S. drug market, with the potential for explosive growth in the future. They currently account for about 1 percent of prescriptions written in the U.S. and 28 percent of drug spending.

An AGA symposium on the final day of DDW^® 2017 examined the advent of biosimilar products in U.S. GI practices. The session’s presenters discussed the terminology used to describe biosimilar agents, considerations when using them in GI practice and what patients should know about these emerging agents.

As defined by the U.S. Food and Drug Administration, biosimilars are biological products that are approved because they are highly similar to an already FDA-approved biological product, known as the biological reference product, and have been shown to have no clinically meaningful differences from the reference product. An interchangeable biological product, in addition to meeting the biosimilarity standard, is expected to produce the same clinical result as the reference product.

“A biosimilar must have the same strength and dosage form — injectable, for example — and the same route of administration as the reference product,” said Gary R. Lichtenstein, MD, AGAF, director of the Inflammatory Bowel Disease Center at the University of Pennsylvania School of Medicine, Philadelphia.

The Biologics Price Competition and Innovation Act of 2009 created an abbreviated licensure pathway for biological products that are demonstrated to be biosimilar to or interchangeable with an FDA-licensed biological product, Dr. Lichtenstein said.

“Biobetter or biosuperior products are a new class of biosimilars that go beyond mimicking the original biologic product to provide improvements in one or various other aspects of their clinical profile through changes in chemistry, alteration in the formulation and innovative delivery,” he added.

Brian G. Feagan, MD, professor of medicine, epidemiology and biostatics at Western University in London, ON, Canada, discussed clinical considerations in the use of biosimilars.

“The FDA, European Medicines Agency and Canada Health have approved biosimilar infliximab for most infliximab indications. However, they have not endorsed switching of drugs for nonmedical reasons,” Dr. Feagan said.

Foreign proteins are immunogenic, and T cells recognize the three-dimensional shape of foreign antigens, he explained, adding that well-designed switching studies are needed to assess the risk of switching drugs. Such trials must assess both the immunogenicity and the protein kinase of biosimilars over at least 18 months, he said.

“Biosimilars cannot be considered generic biologics. They are safe and effective alternatives to innovator products,” Dr. Feagan said. “Agencies in the United States, Canada and Europe have approved the first monoclonal antibody, and more approvals will follow. Interchangeability remains a critical issue in respect to immunogenicity, but will likely prove to be unimportant.”

David T. Rubin, MD, AGAF, the Joseph B. Kirsner professor of medicine and chief of gastroenterology, hepatology and nutrition at the University of Chicago, IL, discussed patient issues surrounding biosimilars.

“The law in at least 12 states specifies that individual patients must be notified that a substitute or switch of medications has been made,” he said. “In some cases, state law requires that the patient consent to the switch before any such switch is made.”

In a survey conducted by the European Federation of Crohn’s and Ulcerative Colitis Associations, 45 percent of respondents said they were currently receiving biological medications for inflammatory bowel disease, and another 36.2 percent had heard of biosimilars, Dr. Rubin said.

Among patients who heard of biosimilars but were not being treated with them, 47 percent worried about the safety profile of the agents, 40 percent worried about their efficacy, 56 percent thought the lower cost of biosimilars should not come before their safety and efficacy, and 66 percent wanted to know in writing whether they were receiving the reference drug or a biosimilar before the drug was administered.

“No biosimilar in the United States currently has interchangeable designation, but switches are occurring,” Dr. Rubin said. “The true cost of biosimilars to insurers will decrease with biosimilar drug entry into U.S. market, but it’s unknown whether patients will save money by switching to a biosimilar.”