Adalimumab-adbm (Cyltezo) has been approved as interchangeable and biosimilar to adalimumab (Humira). This means that Cyltezo can be substituted at the pharmacy for Humira without being specified on the prescription (subject to state pharmacy laws), as it has the same safety and effectiveness as the original biological product. This is similar to the substitution of a generic for a brand-name drug. Interchangeable biosimilar drugs should produce the same clinical result as the original (or reference) drug; there should be no increased risk in terms of safety or diminished efficacy when switching between the two products. Cyltezo is the second drug to be approved as an interchangeable biosimilar; the first was insulin glargine-yfgn (Semglee), which can be substituted for insulin glargine (Lantus). Cyltezo is, however, the first monoclonal antibody to gain such approval.

Cyltezo was originally approved as biosimilar to Humira in August 2017, but not as interchangeable with Humira. According to an article on the website Drug Discovery and Development, Humira is the best-selling drug in the world, with global sales of $20 billion in 2020, $16 billion of which were in the United States.1 According to http://Drugs.com, the average cash price of Humira (without insurance) is $6,240 for two pens, which is a typical month's dose.2 Cyltezo is expected be sold for less than the price of Humira, which should be helpful to patients.

Cyltezo can be used interchangeably with Humira to treat any condition for which Cyltezo is approved. For adults, these include moderately to severely active rheumatoid arthritis, active psoriatic arthritis, active ankylosing spondylitis (an arthritis that affects the spine), moderately to severely active Crohn's disease, moderately to severely active ulcerative colitis, and moderate to severe chronic plaque psoriasis. For pediatric patients, approved uses include moderately to severely active polyarticular juvenile idiopathic arthritis in patients two years of age and older and Crohn's disease in patients six years of age and older.

Cyltezo is given as a subcutaneous injection every other week. The warnings and adverse effects on the labeling are the same as they were before the interchangeable product designation. Both Cyltezo and Humira have boxed warnings of an increased risk of serious infections and malignancies.

Nurses should inform patients who have been receiving Humira that they may instead receive Cyltezo, which is an approved interchangeable biosimilar product, and that this is not a pharmacy error. Nurses should also encourage patients to read the medication guide that comes with each prescription for the most up-to-date information about Cyltezo and its adverse effects.

For full prescribing information for Cyltezo, see http://www.accessdata.fda.gov/drugsatfda_docs/label/2021/761058s008lbl.pdf.

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