Cancer Gene Therapy Company Raises $85M in IPO

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13 April 2017. A developer of cancer immunotherapies that transfer gene treatments into patients with brain tumors is raising $85 million in its initial public stock offering. Tocagen Inc., in San Diego, issued 8.5 million shares priced at $10.00. At the 4:00 pm ET closing bell today, shares of Tocagen, with the Nasdaq symbol TOCA, traded at $11.90, a 19 percent increase; the Nasdaq overall closed down 0.53 percent.

Tocagen, founded in 2007, is developing treatments for cancer that harness gene therapies to kill cancer cells and free the immune system to clear the tumor from the patient. The company’s technology, first developed by Noriyuki Kasahara at University of Miami medical school, delivers gene therapies with benign viruses called retroviral replicating vectors; Kasahara is a scientific advisor to Tocagen. The viruses penetrate the cancer cells, then replicate in the tumor to infect more tumor cells, but ignore surrounding cells and tissue.

The company’s lead products, code-named Toca 511 and Toca FC, are designed initially to treat gliomas, brain cancers affecting glial cells that support the neurons or nerve cells sending electronic signals. Gliomas can impair brain functions, and one type of glioma known as glioblastoma multiforme is particularly aggressive, with few treatment options and a poor prognosis.

Toca 511 uses retroviral replicating vectors to deliver genes from yeast that carry instructions to produce an enzyme called cytosine deaminase. This enzyme, not produced in humans, is spread through the tumor with the benign viruses to kill cancer cells.

The companion Toca FC therapy contains a compound called 5-fluorocytosine, a legacy anti-fungal drug, that can cross the blood-brain barrier. When exposed to brain tumor cells infected with cytosine deaminase — delivered by Toca 511 — 5-fluorocytosine metabolizes into 5-fluorouracil, a chemotherapy drug treating a wide range of solid tumor cancers. Fluorouracil kills cancer cells that Toca 511 may have missed, but also myeloid cells and tumor associated macrophage cells suppressing the immune system. By removing these suppressor cells, immune system T-cells are released to kill any residual cancer cells and clear the tumor from the brain.

Tocagen tested Toca 511 and Toca FC in an early-stage clinical trial among 45 patients with gliomas that showed the treatments were well tolerated, but also extended the patients’ survival to nearly 14 months, compared to 7 months for glioma patients not taking part in the study. An intermediate- and late-stage trial of the treatments among brain tumor patients is now underway. The company is also testing the therapies in an early-stage trial among individuals with metastatic colorectal, pancreatic, breast, lung, melanoma, and renal cancers.

More from Science & Enterprise:

• Prodrugs Designed to Better Target Cancer Therapies
• Enhanced Gene Therapy Boosts Anti-Tumor Response
• Biotechs License Solid Tumor Therapy in $2.1B Deal
• Immunotherapy Biotech Raises $102 Million in IPO
• Safer Engineered-Cell Cancer Immunotherapy Designed

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