Psoriasis patients will soon have another weapon to fight their autoimmune disorder, which affects up to 7.5 million Americans.

On Wednesday, the U.S. Food and Drug Administration (FDA) approved Cosentyx (secukinumab) to treat plaque psoriasis.

Plaque psoriasis, the most common type of psoriasis, results in patches of thick, red skin and silvery scales. The most commonly affected areas of the body are the elbows, knees, scalp, face, and folds in the skin. Psoriasis patches occur when the body’s immune system attacks healthy skin by mistake, causing excess skin cell production.

“Plaque psoriasis can cause significant skin irritation and discomfort for patients, so it is important to have a variety of treatment options available,” Dr. Amy Egan, deputy director of the Office of Drug Evaluation III in the FDA’s Center for Drug Evaluation and Research, said in a press statement.

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How Cosentyx Works

In four clinical trials with a total of 2,403 patients taking either Cosentyx or a placebo, more than 80 percent of patients taking Cosentyx saw 75 percent or more of their symptoms disappear. After three months, more than 65 percent of patients taking the drug rated their psoriasis symptoms at a 0 or 1 on a disease assessment scale, meaning that their skin was totally or almost totally clear.

Symptoms began to clear up in as little as three weeks and stayed at bay for up to a year.

“The results seen from these clinical trials are increasing the efficacy bar compared to the data seen with previous psoriasis medications,” Dr. Mark Lebwohl, Sol and Clara Kest Professor of Dermatology and Chair of the Kimberly and Eric J. Waldman, Department of Dermatology at the Icahn School of Medicine at Mount Sinai, told Healthline. “This is the best data we have for any drug for long-term therapy of this chronic disease.”

Cosentyx works by targeting the protein interleukin (IL)-17A and stopping it from triggering an inflammatory response from the immune system. The IL-17A pathway is a relatively new discovery, and Cosentyx is the only approved drug that targets it.

Researchers at Mount Sinai first developed the drug, and they received the FDA’s approval with “tremendous excitement.”

One of the researchers, Dr. Andrew F. Alexis, Chair of the Dermatology Department at Mount Sinai St. Luke's and Mount Sinai Roosevelt, called the approval a “significant advancement in the treatment of psoriasis.”

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“Targeting IL-17A with secukinumab represents a new breakthrough in reducing the inflammatory response associated with psoriasis,” he told Healthline. “This will broaden the treatment options for the millions who suffer from moderate to severe plaque psoriasis.”

The New Drug on the Block

Marketed by Novartis, the drug will compete against other systemic therapies, such as AbbVie’s Humira (adalimumab) and Amgen’s Enbrel (etanercept). Researchers say the drug will be available to patients in as little as a few weeks.

Cosentyx is delivered by injection under the skin. Treatments are given on a weekly basis for five weeks and then once every four weeks thereafter.

The drug is meant for patients who are healthy enough to have systemic therapy or phototherapy.

Unlike earlier treatments, Cosentyx produces fewer side effects, the most common of which are allergic reactions, diarrhea, and upper respiratory infections.

The FDA warns that doctors should be cautious about prescribing Cosentyx to people with recurring infections and to patients with Crohn’s disease.

Read More: New Drug for Plaque Psoriasis Shows Promise in Clinical Trials »