Top U of M Researcher, Drug Firm Collaborate to Yield Brain Cancer Progress
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Top U of M Researcher, Drug Firm Collaborate to Yield Brain Cancer Progress

Masonic Cancer Center’s Chen and Tocagen Inc. announce ‘impressive’ results.

The newly-appointed head of the University of Minnesota Medical School’s neurosurgery department has unveiled encouraging early results from a research collaboration with a California biotech company seeking to treat aggressive and deadly brain cancer tumors.
Dr. Clark Chen was appointed to the medical school post and named the U’s Lyle French Chair in Neurosurgery in May, relocating his renowned cancer lab from the University of California-San Diego to the U’s Masonic Cancer Center.
Chen came to the U as a nationally recognized brain tumor researcher and surgeon with a dedicated interest in understanding how glioblastomas (highly aggressive and malignant brain cancer tumors) acquire resistance to radiation and chemotherapy.
He is also a consultant to San Diego-based Tocagen Inc. (Nasdaq: TOCA), which is developing virus-based drugs to attack high-grade gliomas (HGGs). Dubbed Toca 511 and Toca FC, the drugs are among the most promising in the emerging field of viral oncology, in which bioengineered viruses are administered to “infect” cancer cells and render them vulnerable to follow-up anti-cancer agents.
HGGs are among the most common and aggressive primary brain cancers, with some 160,000 patients worldwide are expected to be diagnosed in 2017. The two most common forms of HGGs are glioblastoma and anaplastic astrocytoma. With current standard of care, recurrent HGG patients have a median survival of approximately seven to nine months.
Among the well-known victims of glioblastomas are former U.S. Sen. Ted Kennedy and Beau Biden, the son of former U.S. Vice President Joe Biden. U.S. Sen. John McCain has also been diagnosed with aggressive brain cancer. 
But there is now some good news in the fight against such brain cancers. Last week, Chen and Tocagen announced new data from a Phase I clinical showed that more than a quarter of patients with recurrent high-grade glioma remained alive more than three years after initial treatment with Toca 511 and Toca FC.
“Given the deadly nature of this disease, three-year survival is rarely reported in the recurrent setting,” the U of M researcher said in a released statement. “It is notable that the survival benefit was seen across a range of patients and not just limited to patients with specific genetic mutations. This finding indicates that many patients could benefit from this treatment.”
Once glioblastomas recur, the expected survival is typically just months and physicians facing those circumstances are now left with limited treatment options. But the new clinical results for the first time showed some high-grade glioma patients experiencing “complete responses” and living multiple years after receiving Toca 511 and Toca FC.
“The duration of response and the number of patients with durable response or stable disease are impressive in this Phase 1 study, supporting further evaluation of Toca 511 and Toca FC as a potential treatment for recurrent high-grade glioma,” Chen said.
Armed with the positive early results, Tocagen says it is “committing to advancing” the viral therapy through the next two phases of the “Toca 5” clinical trial in an effort to “bring a potentially transformative product to patients as quickly as possible.”