In August, two drug companies reported that an mRNA vaccine combined with an immunotherapy drug substantially reduced the risk of melanoma returning. The news raised hopes that personalized vaccines could one day protect against many types of cancer, not just melanoma.
Days later, however, a German drugmaker said it was ending its colorectal cancer vaccine trial after early data showed the treatment wasn't working. The contrasting outcomes have left experts puzzled about why the approach succeeded in one cancer type but failed in another.
Researchers are now trying to understand which cancers are vulnerable to vaccine-based attacks and which will require more creative strategies. The source also notes that a separate explainer walks through how cancer vaccines rally the body's immune system, offering context for the mixed results.