Former President Jimmy Carter is doing well on treatments for melanoma, with no evidence it’s spread any further, the Carter Center said Tuesday.

Carter, 91, has been getting treatment for melanoma that had spread to his liver and brain, but has stayed active and said he feels well.

“President Carter has received good news from his Winship Cancer Institute doctors,” the Carter Center, a nonprofit organization he set up after leaving the presidency, said in a statement.

“They tell him that recent tests have shown there is no evidence of new malignancy, and his original problem is responding well to treatment. Further tests will continue.”

Carter’s being treated with a newly approved immune system drug called Keytruda, which has been shown to have significant effects in some cases of melanoma.