Health-care companies rose after a breakthrough at the intersection of vaccines and oncology.

An experimental mRNA-based vaccine succeeded in preventing cancer from coming back or spreading in a study of high-risk melanoma patients, Moderna and its partner Merck said Wednesday, paving the way for a potentially new life-extending treatment for the thousands of people diagnosed with the deadly skin cancer each year.

Moderna shares more than doubled while Merck's rose by 10%.

Shares of obesity-drug maker Eli Lilly continued a recent rally.