Adding an experimental mRNA-based vaccine from Moderna and Merck & Co. reduced the risk that the most deadly skin cancer would spread by 65% over treatment with an immunotherapy alone in a midstage trial, the companies reported on Monday.

With this and earlier data, Moderna is considering seeking faster approval from regulators for the treatment, the company told investors after having presented the results at the American Society of Clinical Oncology meeting in Chicago.

"Some of the residual uncertainty seems to be going away on that potential (option)," said Moderna President Stephen Hoge.