ZIOPHARM Oncology (ZIOP) shares have tumbled in early trading today following a disclosure in its presentation that a patient in its IL-12 glioblastoma clinical trial died from an intracranial hemorrhage 15 days after being treated. A second patient also died, at 3.9 months follow-up. A third death was previously reported due to progressive disease (6.4 months). The two new deaths are not believed to be related to IL-12 therapy.