BIO2017: After IPO, Full Speed Ahead for San Diego’s Tocagen

Published: Jun 20, 2017

BIO2017: After IPO, Full Speed Ahead for San Diego’s Tocagen June 19, 2017
By Josh Baxt, Breaking News Staff

SAN DIEGO -- Tocagen is one of the many local companies representing San Diego’s bustling life sciences sector here this week at BIO 2017. Part of the gene therapy renaissance, Tocagen is developing a two-part treatment for high-grade gliomas and other cancers.

Gliomas, in particular, are a compelling target.

“Standard treatment for high-grade glioma includes surgical removal of the tumor, radiation and chemotherapy,” said Tocagen CEO Martin Duvall in an email. “However, gliomas have tentacles that spread into surrounding tissues, making surgical removal of all tumor cells nearly impossible. Usually six months or less after primary treatment, the tumor returns. Once a brain cancer returns, patients have a life expectancy of seven to nine months.”

The company’s therapy seeks to convert one of cancer’s strengths – reduced immune response – into a weakness. The first prong is a retrovirus (Toca 511), which selectively implants the gene for cytosine deaminase (a yeast enzyme gene not normally found in people) into cancer cell DNA, turning tumor cells into enzyme factories. Since Toca 511 is a retrovirus, the trait gets passed on to daughter cells.

Once the Toca 511 virus has permeated the tumor, patients are given an antifungal medication called 5-fluorocytosine (Toca FC). The cytosine deaminase converts Toca FC into an anticancer drug (5-FU). Because the enzyme is only produced by cancer cells, the chemotherapy stays localized. In addition to killing tumor cells, the treatment boosts the body’s immune response.

“Together, the Toca 511 and Toca FC combination directly kills cancer cells and immune-suppressive myeloid cells, namely tumor-associated macrophages and myeloid-derived suppressor cells, resulting in activation of the immune system against cancer,” said Duvall.

“Our recently completed upsized initial public offering raised approximately $97.8 million in gross proceeds,” said Duvall. “This substantially increased our financial strength and will help support our ongoing and planned studies of Toca 511 and Toca FC.”

Early results have been encouraging. A Phase I trial of 45 patients with recurrent high-grade glioma extended overall survival to 13.6 months, well beyond the nine-month prognosis.

The company’s recent IPO will support additional trials and other efforts to commercialize the therapy. For now, Tocagen is staying pat with 62 employees, but Duvall notes they plan to gradually grow the company.

Looking beyond glioma, Tocagen is enrolling patients to study the therapy against metastatic colorectal, pancreatic, renal, breast, skin and lung cancers. The company is also planning a Phase Ib trial in 2018 to study the combination against newly-diagnosed high grade gliomas.

“For this patient community, new and effective treatments can’t come soon enough,” said Duvall. “They are happy to find there are options and are very encouraged by the early results our therapy has been showing.”

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