BOSTON, MA, USA I July 15, 2016 I ZIOPHARM Oncology, Inc. (Nasdaq:ZIOP) today issued the following statement regarding the Company’s ongoing multicenter Phase 1 study of Ad-RTS-hIL-12 + orally administered veledimex in recurrent or progressive glioblastoma (GBM) or grade III malignant glioma:

“This Phase I study is being conducted in late-stage, recurrent GBM, so these patients are all, unfortunately, medically fragile. The first two patient deaths, which occurred 6.7 months and 3.9 months after treatment, were unrelated to study drug. A third death has just been reported to us and we are collecting and analyzing information in order to properly and timely report it to the FDA. The cause of death is intracranial hemorrhage, which occurred some time after the patient had been discharged from the treating center. This is an isolated case, and there have been no reported related instances of brain hemorrhage in any pervious cohort or prior studies with Ad-RTS-hIL-12 + veledimex. Enrollment remains open in the study, and we will be discussing with our Safety Review Committee the appropriate course of action. For patients who have experienced multiple recurrences, as these patients have, prognoses are particularly poor. Median follow up in the first dose cohort from our study is now 8 months, in a population with an expected overall survival of 3 to 5 months for patients that have failed temozolomide and bevacizumab, or equivalent salvage chemotherapy. For the patients that remain in follow up in this Phase I study, we believe that preliminary overall survival remains encouraging. The Company expects to provide an update once a course of action has been determined.”

About Glioblastoma

Glioblastoma is an aggressive primary brain tumor affecting approximately 74,000 people worldwide each year.i, ii Recurrent glioblastoma is an aggressive cancer with one of the lowest 3-year survival rates, at 3%, among all cancers.iii For patients who have experienced multiple recurrences the prognosis is particularly poor, with a median overall survival (OS) of 6-7 months, while OS in patients that have failed temozolomide and bevacizumab, or equivalent salvage chemotherapy, is approximately 3-5 months.iv, v

About ZIOPHARM Oncology, Inc.:

ZIOPHARM Oncology is a Boston, Massachusetts-based biotechnology company employing novel gene expression, control and cell technologies to deliver safe, effective and scalable cell- and viral-based therapies for the treatment of cancer. The Company’s immuno-oncology programs, in collaboration with Intrexon Corporation (NYSE:XON) and the MD Anderson Cancer Center, include chimeric antigen receptor T cell (CAR-T) and other adoptive cell-based approaches that use non-viral gene transfer methods for broad scalability. The Company is advancing programs in multiple stages of development together with Intrexon Corporation’s RheoSwitch Therapeutic System® technology, a switch to turn on and off, and precisely modulate, gene expression in order to improve therapeutic index. The Company’s pipeline includes a number of cell-based therapeutics in both clinical and preclinical testing which are focused on hematologic and solid tumor malignancies.

i. Mrugala MM. Advances and challenges in the treatment of glioblastoma: a clinician’s perspective. Discov Med. 2013;15:221-230. http://www.discoverymedicine.com/Maciej-M-Mrugala/2013/04/25/advances-and-challenges-in-the-treatment-of-glioblastoma-a-clinicians-perspective/. Accessed March 24, 2015.

ii. McCubrey JA, LaHair MM, Franklin RA. OSU—0312 in the treatment of glioblastoma. Mol Pharmacol. 2006;70:437-439.

iii. International Agency for Research on Cancer. World Cancer Report. 2003. http://www.iarc.fr/en/publications/pdfs-online/wcr/2003/WorldCancerReport.pdf.

iv. Omuro, A. Glioblastoma and Other Malignant Gliomas. A Clinical Review JAMA. 2013 Nov 6;310(17):1842-50.

v. Iwamoto et al. Patterns or relapse and prognosis after bevacizumab failure in recurrent glioblastoma. Neurology 2009; 73(15):1200-1206

SOURCE: ZIOPHARM Oncology