A shareholder has accused pharmaceutical company MEI Pharma Inc. of inflating stock prices by overhyping the trial success of a blood cancer treatment.

The derivative suit filed Wednesday in the U.S. District Court for the District of Delaware by shareholder Peter D’Arcy alleges 10 of the San Diego-based company’s officers and directors intentionally gave investors nonspecific information and failed to disclose the risk factors of Pracinostat, a drug for which an international clinical trial was halted in July just before MEI’s share price dropped more than 18% in a day.