Former U.S. President Jimmy Carter announced that his recent brain scan showed no evidence of cancer, crediting Merck's new immunotherapy drug, Keytruda.

The 91-year old Carter had revealed in August that he was diagnosed with melanoma, with tumors on his brain and liver. He began regular 3-week immunotherapy treatments of Keytruda, as well as radiation therapy.

In September 2014, the FDA granted accelerated approval to Keytruda (pembrolizumab) for treatment of patients with advanced or unresectable melanoma who are no longer responding to other drugs. Earlier this December, the FDA also granted breakthrough therapy designation to Keytruda for the treatment of patients with MSI-H metastatic colorectal cancer.

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