Complex sentence: There is no convincing evidence from randomized controlled trials in the scientific literature that antineoplastons are useful treatments of cancer, and the U.S. Food and Drug Administration (FDA) has not approved these products for the treatment of any disease.
Split into simpler sentences: There is no convincing evidence from any randomized controlled trial that antineoplastons are useful for the treatment of cancer. The U.S. Food and Drug Administration (FDA) has not approved antineoplastons for the treatment of any disease.