The long-awaited cancer vaccine revolution is getting a little closer to reality.

New data from Moderna Inc. and Merck & Co. suggest that after decades of failures, researchers are finally figuring out the right way to design a vaccine that can teach immune cells how to recognize and combat tumors.

Earlier this month, the companies said that when used in concert with Merck¡¯s cancer immunotherapy Keytruda, Moderna¡¯s mRNA cancer vaccine reduced the risk of certain skin cancers from returning or patient deaths by 44% compared with Keytruda alone.