On November 8, 2019 Tocagen Inc. (Nasdaq: TOCA), a clinical-stage, cancer-selective gene therapy company, reported that the Company presented data from the Toca 6 Phase 1b study of Toca 511 and Toca FC in patients with non-CNS tumors at the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) 34th Annual Meeting in National Harbor, MD and will have two presentations related to brain cancer at the 24th Annual Meeting of the Society for Neuro-Oncology (SNO), to be held Nov. 20-24 in Phoenix (Press release, Tocagen, NOV 8, 2019, View Source [SID1234550838]).

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The SITC (Free SITC Whitepaper) poster titled, "Immunomodulation in peripheral blood and tumor following Toca 511 & Toca FC treatment in patients with solid tumors," was a summary of the results in the Toca 6 Phase 1b, single arm study of Toca 511 and Toca FC in advanced non-CNS solid tumors. The objectives of the study were to assess changes in immune activity of peripheral blood mononuclear cells (PBMCs) relative to baseline following treatment and to evaluate immune cell modulation in the tumor microenvironment from tumor biopsies taken at baseline compared to biopsies collected following treatment.

Data Summary

The Toca 6 Phase 1b, single arm study of Toca 511 and Toca FC in advanced non-CNS solid tumors demonstrated vector deposition, immune activity, a potential signal of clinical activity and a favorable safety profile.

Treatment was generally well tolerated, with predominantly Grade 1 and 2 treatment-related gastrointestinal adverse events. Most patients enrolled (81%) had metastatic colorectal cancer; the median lines of prior chemotherapies was four (1, 12).
Clinical activity was supported by observations of partial response and stable disease. The median overall survival was 9.6 months (95% CI 6.3, 16.4) in this heavily pre-treated population.
Toca 511 and Toca FC was associated with a T-cell mediated immune response in peripheral blood and metastatic tumor in some patients, consistent with the mechanism of action observed in preclinical models.
Peripheral blood T-cells shift from naïve to effector phenotypes indicating that T-cells are encountering their target antigens, potentially including proteins released by tumor cell killing.
Expansion of CD4+ memory T-cells after treatment is consistent with engagement of the adaptive immune system.
Increased post-treatment quantities of B-cells further suggests immune activation during the course of Toca 511 and Toca FC therapy.
Toca 511 and Toca FC led to a decrease of CD11b+ myeloid cells in five of six patients with evaluable colorectal metastasis. This immune fluorescence analysis suggests a decrease in the immunosuppressive myeloid cells, as seen in preclinical models, and potentially makes the tumor and the tumor microenvironment more conducive to immunologic modulation.
"Data from our poster at SITC (Free SITC Whitepaper) are encouraging and support the planned exploration of our Toca regimen in non-muscle invasive bladder cancer," said Marty Duvall, chief executive officer of Tocagen. "In addition, we look forward to presenting Toca 5 analyses at the upcoming SNO conference Toca 5 analyses including subgroups and molecular data in addition to details of the planned NRG Oncology trial in patients with newly diagnosed glioblastoma."

Details of the SNO presentations are as follows. Copies of the presentations will be available on Tocagen’s website following the presentations.

Presentation Type: Plenary Presentation (Abstract: LTBK-08)
Title: Toca 511 & Toca FC Versus Standard of Care in Patients With Recurrent High Grade Glioma
Presenter: Timothy Cloughesy, M.D., director of the University of California, Los Angeles, Neuro-Oncology Program
Date and Time: Friday, Nov. 22, 11:50 a.m. – 12:00 p.m. MST

Presentation Type: Poster Presentation (Abstract: RBTT-11)
Title: NRG Oncology NRG-BN006: A phase II/III randomized, open-label study of Toca 511 and Toca FC with standard of care compared to standard of care in patients with newly diagnosed glioblastoma
Presenter: Manmeet Ahluwalia, M.D., head of operations, Burkhardt Brain Tumor and Neuro-Oncology Center, Cleveland Clinic.
Date and Time: Saturday, Nov. 23, 5:00 p.m. – 7:00 p.m. MST

About Toca 511 & Toca FC
Tocagen’s lead product candidate is a two-part cancer-selective immunotherapy comprising an investigational biologic, Toca 511 (vocimagene amiretrorepvec), and an investigational small molecule, Toca FC (flucytosine, extended-release). Toca 511 is a retroviral replicating vector (RRV) that selectively infects cancer cells and delivers a gene for the enzyme, cytosine deaminase (CD). Through this targeted delivery, infected cancer cells carry the CD gene and produce CD. Toca FC is an orally administered prodrug, 5-fluorocytosine (5-FC), which is converted into an anti-cancer drug, 5-fluorouracil (5-FU), when it encounters CD. 5-FU kills cancer cells and immune-suppressive myeloid cells resulting in anti-cancer immune activation and subsequent tumor killing.