AbbVie Korea said Thursday its blockbuster biologic Humira gained nationwide reimbursement for treating children and adolescents with severe chronic plaque psoriasis starting Oct. 1.

Humira (ingredient: adalimumab) is a fully human anti-TNF-α monoclonal antibody to treat plaque psoriasis. Also known as the world’s best-selling drug, Humira rang up $16 billion in global sales last year, accounting for about 63 percent of Abbvie’s total revenue.

The insurance coverage will apply to 4- to 17-year-olds who have had severe chronic plaque psoriasis for more than six months or are intolerant to standard therapies such as methotrexate (MTX), cyclosporine and phototherapy.

"With this reimbursement, Humira is now the only biologic approved and reimbursed drug to treat children with this condition starting at four years of age, offering an important new option for physicians treating pediatric plaque psoriasis," said Jin Joo-yea, a medical advisor at AbbVie Korea.

Pediatric plaque psoriasis is a chronic autoimmune disease characterized by rapid and excessive accumulation of skin cells, resulting in thick patches of inflamed, scaly skin. The World Health Organization estimates the condition occurs in less than 1 percent of the pediatric population.

The Korean approval came after the positive results of a multi-site, double-blind phase three study that compared Humira with MTX in 114 pediatric and adolescent patients with the disease, the company said, with the drug being co-sold by Abbvie Korea and Eisai Korea.

Despite losing its patent protection on its substance matter at the end of last year and facing rising competition from biosimilar drugs (including Samsung Bioepis’ Imraldi), experts say Abbvie still has a hold on manufacturing, method of use, and formulation patents that will keep Humira ahead of the pack until at least 2022.

Humira first gained approval 14 years ago and has won approvals in more than 100 countries for 14 indications, the company said.