Shares of Verastem Inc. plummeted 70 percent Monday after the Cambridge biotech reported that its lead drug candidate failed to help patients suffering from a rare form of lung cancer. Verastem, which helped propel the long-running boom in initial public offerings of biotech companies when it went public in early 2012, said Monday it had stopped enrolling patients with malignant pleural mesothelioma – a type of cancer caused by exposure to asbestos – in a clinical study that was widely expected to lead to a new drug application.
