(Reuters) – The U.S. Food and Drug Administration on Friday approved Incyte Corp’s treatment for acute Graft versus Host disease (GvHD), an inflammatory response by the immune system after a bone marrow transplant.

The drug, ruxolitinib, sold under the brand name Jakafi, can now be prescribed to both pediatric patients, aged 12 years or above, and adults who have failed to respond to standard steroid therapy, the company said in a statement.

Jakafi, which has already been approved for treating certain bone marrow and blood disorders in the United States, is the only FDA-approved treatment for GvHD, the company said.

When patients receive genetically incompatible bone marrow transplant for conditions such as blood cancers, donor cells may attack the recipient causing GvHD. When severe and unresponsive to steroids, it is often fatal.

There are two forms of GvHD, acute and chronic, which can affect multiple organ systems, including the skin, gastrointestinal tract and liver. Nearly 5,000 patients have been diagnosed with the acute form of the disease in 2019, according to analytics firm GlobalData.

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The treatment, which is sold by Novartis AG as Jakavi outside the United States, belongs to a class of drugs known as JAK inhibitors, which block inflammation-causing enzymes, known as Janus kinases.

Ruxolitinib is also being tested as a treatment for atopic dermatitis.

Shares of Incyte were up 1.4% at $81.6.

(Reporting by Aakash Jagadeesh Babu and Manojna Maddipatla in Bengaluru; Editing by Shinjini Ganguli and Anil D’Silva)