Former President Jimmy Carter revealed Tuesday that he has received the second of four planned doses of a cancer drug. Speaking at the annual A Conversation With the Carters event with his wife, Rosalynn, Carter said he hadn’t experienced any “ill effects” from his treatment with Keytruda, a recently approved immune system-boosting drug. The 90-year-old told a crowd of more than 400 that he also had no further planned radiation treatments. Carter revealed cancer had spread to his brain nearly a month ago. Doctors found four spots of melanoma on his brain shortly after he had a mass removed from his liver.