The U.S. Food and Drug Administration (FDA) has approved the use of Keytruda to treat patients suffering from advanced stages of melanoma, and who are not responding to other medications.

Melanoma is considered the most dangerous form of skin cancer, yet only accounts for less than two percent of all skin cancer cases. Approximately 76,100 new melanomas will be diagnosed by the end of 2014, resulting in approximately 9,710 deaths.

Keytruda is a drug that blocks the cellular pathway which inhibits the body’s immune system from attacking the melanoma cells. The new drug is intended to be used in conjunction with ipilimumab, a type of immunotherapy.

The efficacy of Keytruda was initially established in 173 clinical trials with patients suffering from advanced stages of melanoma. In the half of the trial’s participants who received Keytruda at a dosage of 2 mg/kg, about 24 percent experienced a decrease in the size of their tumors.

In a clinical study analyzing the safety of Keytruda, the most common side effects included fatigue, nausea, cough, itchy skin, rash, joint pain, lack of appetite, diarrhea, constipation and rash.

“Keytruda is the sixth new melanoma treatment approved since 2011, a result of promising advances in melanoma research. Many of these treatments have different mechanisms of action and bring new options to patients with melanoma,” said Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, in a statement.