Shares of Adventrx Pharmaceuticals ( ANX) dove 75% on Monday after the company announced that a phase IIb study on its experimental ANX-510 for metastatic colorectal cancer failed. The biopharmaceutical company's 300-patient midstage trial had researchers administer ANX-510, also known as CoFactor, plus 5-fluorouracil and compare those results with a combination of leucovorin and 5-fluorouracil. Adventrx was looking for an improvement in safety and a reduction of patients with one or more hematological or gastrointestinal adverse events from patients in the ANX-510 arm, but there were no statistically significant differences in either measure. "We will carefully analyze the full set of data and our assumptions underlying the development of CoFactor for the treatment of metastatic colorectal cancer in determining the future of this program," said Evan Levine, chief executive of Adventrx. Shares plunged $1.95 to 63 cents following the news.