Moderna and Merck say their personalized mRNA melanoma vaccine significantly reduced both cancer recurrence and spread in a late-stage trial. The treatment could reach patients as soon as next year if regulators approve it. Reuters reports: Moderna developed the vaccine with Merck and tested it together with immunotherapy drug Keytruda, a widely used treatment for melanoma. [...] This is the first positive late-stage trial result for an mRNA cancer vaccine, which trains a patient's immune system to fight tumors by targeting specific mutations in those cells and the first such study to show that adding a treatment to Keytruda worked better than that therapy alone. Similar approaches are being tested against lung, breast and pancreatic cancers. [...] The cancer treatment combines Merck's Keytruda with a made-to-order mRNA vaccine from Moderna that is based on an analysis of mutations found in the patients' own tumors. The trial enrolled 1,137 high-risk patients with stage IIB-IV melanoma that had been surgically removed. Volunteers were randomized to receive up to nine doses of Keytruda plus the personalized vaccine or Keytruda alone for about one year. The companies said no new safety signals have emerged in the trial. In January, the companies announced results of a mid-stage trial of the treatment showing that it reduced the risk of recurrence or death by 49% after five years. Karen Knudsen, CEO of the Parker Institute for Cancer Immunotherapy, said the Moderna results could signal a new era for treating solid-tumor cancers. "The positive hit here leads us into truly this next phase in immunotherapy," Knudsen said. "This is an auspicious start -- this is where things begin." Moderna shares more than doubled on the news, adding about $30 billion to its market value.

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