Shares of Modena and Merck fell, and the companies' much-anticipated personalized melanoma vaccine data was insufficient to convince investors that a new era of cancer treatment had arrived. The two companies announced in August that this customized vaccine, when used in combination with Merck's best-selling drug Keytruda, can significantly reduce the risk of recurrence of this deadly tumor and has clinical significance. The full test data leaked on Thursday fell short of the high expectations Wall Street had formed earlier this year. Although the experimental results clearly showed that the vaccine was effective, they were not surprising enough to convince the market that Modner and Merck could achieve their more ambitious goal of pioneering a new treatment for many types of cancer. Modena shares plummeted 18%, and Merck fell 1.8%.

Shares of Modena and Merck fell, and the companies' much-anticipated personalized melanoma vaccine data was insufficient to convince investors that a new era of cancer treatment had arrived. The two companies announced in August that this customized vaccine, when used in combination with Merck's best-selling drug Keytruda, can significantly reduce the risk of recurrence of this deadly tumor and has clinical significance. The full test data leaked on Thursday fell short of the high expectations Wall Street had formed earlier this year. Although the experimental results clearly showed that the vaccine was effective, they were not surprising enough to convince the market that Modner and Merck could achieve their more ambitious goal of pioneering a new treatment for many types of cancer. Modena shares plummeted 18%, and Merck fell 1.8%.