Merck & Co. Inc. said the European Commission approved Keytruda as an adjuvant treatment — or given after initial therapy — for an advanced form of skin cancer.

The EU regulator gave Keytruda the nod for treating patients with stage 3 melanoma whose cancers have been completely removed through surgery and whose diseases have spread across the lymph nodes.

The approval is based on a phase 3 study, called Keynote-054, which showed that Keytruda reduced the risk of the disease coming back or death by 44% compared to placebo in skin cancer patients. Merck and the European Organisation for Research and Treatment of Cancer jointly conducted the trial, which was also known as EORTC1325.

Keytruda is a checkpoint inhibitor — a tumor-targeting drug that blocks the PD-1 arm on healthy cells from linking up with a partner arm on the surface of cancer cells to spread the disease.

Kenilworth, N.J.-based Merck is also seeking U.S. approval for Keytruda in the same indication. The U.S. Food and Drug Administration is expected to decide on the therapy's approval by Feb. 16, 2019.

Keytruda is already approved in the U.S., EU and elsewhere for multiple cancer indications.

Melanoma is the most serious form of skin cancer and is characterized by the uncontrolled growth of pigment-producing cells. An estimated 287,000 new melanoma cases are expected to be recorded in 2018, resulting in over 60,000 deaths, Merck said in a news release.