A clinical-stage, cancer-selective gene therapy company Tocagen has announced its randomised, controlled Phase 2/3 clinical trial, Toca 5, has begun patient enrolment in South Korea.

The study is ongoing in the US, Canada and Israel.

This trial compares a cancer-selective virus, Toca 511 (vocimagene amiretrorepvec), in combination with Toca FC (extended-release 5-fluorocytosine), to standard of care in patients with first or second recurrence of glioblastoma or anaplastic astrocytoma who are undergoing resection.

Toca 511 encodes a prodrug activator enzyme, CD. Its selective delivery to cancer cells means that the infected cells carry the CD gene and produce CD protein. Toca FC is an orally administered, proprietary extended-release formulation of 5-fluorocytosine (5-FC), a prodrug that is inactive as an anti-cancer drug.

Sungkyunkwan University School of Medicine Samsung Medical Center department of neurosurgery professor Do Hyun Nam said: “Brain tumours are among the deadliest of all cancers and there are very few treatment options available.

“Data from Phase 1 studies of this investigational agent showed very promising safety, survival and durable tumour response data so we are excited to continue evaluation of this therapy in the Toca 5 trial.”

Sungkyunkwan University School of Medicine enrolled the first patient in South Korea.

Seoul St. Mary’s Hospital neurosurgery professor Sin-Soo Jeun is the principal investigator for the Toca 5 clinical trial in South Korea.

The primary endpoint for the Toca 5 clinical trial is overall survival, while secondary endpoints include objective response rate.

Investigators may select chemotherapy (lomustine or temozolomide) or antiangiogenic therapy (bevacizumab) for the control arm.

"Brain tumours are among the deadliest of all cancers and there are very few treatment options available."

High-grade gliomas are among the most common and aggressive primary brain cancers.

The two most common forms of high-grade glioma are glioblastoma and anaplastic astrocytoma.

Standard treatment for newly diagnosed high-grade glioma includes safe surgical removal of as much of the tumour as possible, followed by radiation therapy and chemotherapy.

The tumour typically recurs despite these treatments.

Image: Sagittal MRI displaying tumour in a patient with glioblastoma. Photo: courtesy of Christaras A/Wikipedia