Biologics are becoming increasingly popular: Their global market is projected to exceed $390 billion by 2020, and by this time biologics will account for up to 28 percent of the growth in prescription drug spending, according to market research firm, IMS Health.

The injected or infused drugs for diseases like cancer and immune system disorders, “manufactured” in living cells, are often complicated to make — and can be quite expensive, costing $100,000 or more annually. Several brand-name biologics have patents that will expire soon. Approximately $71 billion of biologic patent exclusivity in the U.S. is expected to expire by 2020, according to IMS Health.

For these reasons, biosimilars are emerging as viable alternatives to brand-name counterparts.  These products are considered to be a nearly identical copy of the original medication, manufactured by a different company. To date, two biosimilars are approved in the U.S., with nearly 50 distinct biosimilars currently in development. In 2015, the U.S. Food and Drug Administration approved the first biosimilar drug, Novartis’s Zarxio, its version of Amgen’s Neupogen, used to reduce infection risk in patients who’ve had chemotherapy. And a few months later, in early 2016, the FDA approved Inflectra, a biosimilar for Remicade, a treatment used for several indications including rheumatoid arthritis, inflammatory bowel disease and psoriasis.

However, there is concern that the complex manufacturing processes used to develop biosimilars can result in slight changes that alter the medication’s structure, affecting how safe and effective the bisosimilar might be. “The billion-dollar question has been whether these ‘generic biologics’ are the same as the brand-name versions,” said G. Caleb Alexander, MD, of the Bloomberg School, in a news release.

“The same debate occurred with the advent of less complicated generic drugs and now it’s being hashed out all over again with much more at stake — more room for error and more potential for cost savings to the health system.” Estimates say the cost of biosimilars may be 20 percent to 30 percent less than those of biologics.

Dr. Alexander and his colleagues reviewed data from 19 studies conducted through April 2016, which compared biologic and biosimilar versions of tumor necrosis factor-alpha (TNF-α) inhibitors. These treatments suppress the over-activity of the immune system, in rheumatoid arthritis, inflammatory bowel disease and psoriasis. They include well-known treatments, Amgen’s Enbrel, AbbVie’s Humira, and Johnson & Johnson’s Remicade.

Their findings, published in the Annals of Internal Medicine, suggest that these biosimilar forms of TNF-α inhibitors are just as safe and effective as their biologic counterparts.

A caveat of the study is that the research only focused on TNF-α inhibitors, and did not review other biosimilars and biologics, such as insulin and cancer treatments.

Nevertheless, the analysis shines a light on an important up-and-coming sector of the pharmaceutical market. By competing with biologic medications across a range of therapy areas, biosimilars may offer more alternatives in treatment options.

Although the first biosimilar was only recently approved in the U.S., biosimilars certainly aren’t new to countries like Europe and India. Europe’s first biosimilar was approved and marketed in 2006, and in these last 10 years, the country has approved more than 20 biosimilar medications. India approved its first biosimilar in 2000 and currently has more than 25 approved biosimilars. Australia currently has 11 biosimilar approvals, and Japan has seven.