Tocagen, a clinical-stage, cancer-selective gene therapy company, has announced the FDA granted Toca 511 & Toca FC Breakthrough Therapy designation for the treatment of patients with recurrent high grade glioma (HGG). Toca 511 & Toca FC is currently under evaluation in an international, randomized phase II/III clinical trial, which is designed to serve as a potential registrational study. The trial involves patients with first or second recurrence of glioblastoma or anaplastic astrocytoma who are undergoing resection. Enrollment in the phase II portion of the trial has completed and top-line results are anticipated in the first half of 2018.

The Breakthrough Therapy designation application was based on data from three phase I, ascending-dose clinical trials involving 126 patients with recurrent brain cancer. The clinical data includes results published in Science Translational Medicine, including safety data, patient survival data and durable, complete or partial tumor shrinkage determined by independent radiology review. In addition, preclinical information was provided supporting a novel immunological mechanism of action involving the depletion of immune-suppressive myeloid cells in the tumor microenvironment. The FDA previously granted Fast Track designation to Toca 511 & Toca FC for the treatment of recurrent HGG. 

"Receiving Breakthrough Therapy designation from the FDA for recurrent HGG, the first time it has been granted for this type of brain cancer, highlights the urgent need for new treatment options for this deadly disease," said Marty Duvall, chief executive officer of Tocagen. "Based on the encouraging safety and efficacy data we have seen to date, advancing the development of Toca 511 & Toca FC continues to be our team's top priority. We look forward to working closely with the FDA to expedite development and review of the product candidate and related activities."

Breakthrough Therapy designation from the FDA indicates preliminary clinical evidence demonstrates the drug may have substantial improvement on one or more clinically significant endpoints over available therapy. Breakthrough Therapy designation intensifies FDA involvement to ensure an efficient drug development program and is an organizational commitment from the FDA to involve their senior managers.

HGGs are among the most common and aggressive primary brain cancers. The total number of patients with HGG expected to be diagnosed in 2017 is about 160,000 worldwide and about 14,000 in the U.S. The two most common forms of HGG are glioblastoma and anaplastic astrocytoma. Standard treatment for newly diagnosed HGG includes safe surgical removal of as much of the tumor as possible followed by radiation therapy and chemotherapy. However, HGG recurs in most patients even after maximal treatment. After recurrence, median survival is typically seven to nine months.