Another week, another U.S. medical breakthrough. The latest in the annals of American innovation is a new cystic-fibrosis gene therapy that will help patients with the debilitating disease live comfortably for decades longer. Remember this the next time politicians, on the left or right, complain about greedy drug companies.

Cystic fibrosis is caused by a genetic defect that results in excess mucus production in the lungs, digestive tract and other parts of the body. The disease affects about 30,000 Americans and can lead...