Patients who suffer from the most common form of lupus have a new treatment option, an AstraZeneca drug that is now the first new therapy for the autoimmune disorder since a GlaxoSmithKline medicine cleared the regulatory bar a decade ago.

FDA approval of the AstraZeneca drug, anifrolumab, covers adults with moderate to severe systemic lupus erythematosus who are also receiving standard treatment that includes anti-inflammatory and immunosuppressing medications. AstraZeneca will market its new drug under the name “Saphnelo.”

The cause of lupus isn’t known but the inflammatory disorder disproportionately affects women. The condition is more common in African-American, Hispanic, and Asian people compared to other racial groups. The most common form of the disease is systemic lupus erythematosus, which affects organs throughout the body and accounts for about 70% of lupus cases, according to the Lupus Foundation of America. Cutaneous lupus is limited to the skin while drug-induced lupus is caused by certain prescription medications and disappears within months of discontinuing the culprit medication.

Saphnelo is an antibody designed to bind to part of the type I interferon receptor. Doing so stops biologic activity of type I interferon, a chain of amino acids that plays a role in how lupus develops. The company says its drug also causes the internalization of the receptor, which in turn reduces the levels of cell surface receptors available to bind to type I interferon. The AstraZeneca drug is the first FDA-approved lupus therapy that works this way.

In 2011, the FDA approved GlaxoSmithKline’s Benlysta, an antibody that interferes with a way that B cells, a type of immune cell, survives. The GSK drug doesn’t block B cells directly, but instead blocks a protein that promotes their survival. GSK reported that 2020 sales of Benlysta were £719 million (more than $605.7 million). That total includes the subcutaneous version, which accounted for £354 million (about $298.2 million) in sales.

The most common side effects reported in clinical trials testing Saphnelo included cold symptoms, upper respiratory tract infections, bronchitis, infusion-related reactions, herpes zoster, and cough. The drug’s label warns that serious and sometimes fatal infections have developed in patients treated with drugs that suppress the immune system, including Saphnelo. The label also cautions that immunosuppressants raise the risk of cancer, though the impact of the AstraZeneca drug on cancer is not known.

Saphnelo is currently being reviewed by regulators in Europe and Japan. A Phase 3 study evaluating a subcutaneously injected version of the drug has started. AstraZeneca also plans to test the drug in additional Phase 3 studies for lupus that affects the kidneys, the skin, and muscles.

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