On March 27, 2019 Tocagen Inc. (Nasdaq: TOCA), a clinical-stage, cancer-selective gene therapy company, reported three presentations of updated clinical and preclinical data at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2019, to be held March 29-April 3 in Atlanta and the 2019 American Association of Neurological Surgeons (AANS) Annual Meeting, to be held April 13-17 in San Diego (Press release, Tocagen, MAR 27, 2019, View Source;p=RssLanding&cat=news&id=2392515 [SID1234534696]).

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The clinical data includes details of immunologic trends in patients with recurrent high-grade glioma (rHGG) from a Phase 1 study of Toca 511 (vocimagene amiretrorepvec) and Toca FC (flucytosine, extended-release). Additionally, new preclinical data will be presented demonstrating increased survival from the combination of Toca 511 and flucytosine with either temozolomide or cyclophosphamide.

Summaries are provided below; full posters or presentations will be placed on Tocagen’s website following the presentation.

Details of the AACR (Free AACR Whitepaper) presentation are as follows:

Presentation Type: Poster (Abstract: 4771)
Title: The addition of Toca 511 and 5-FC to temozolomide improves response in a temozolomide-resistant murine glioblastoma model and correlates with Toca 511 dose
Presenter: Maria E. Rodriguez-Aguirre
Date and Time: Wednesday, April 3, 8:00 a.m.-12:00 p.m. ET
Summary:

This study aimed to assess the interaction of temozolomide with escalating doses of Toca 511 in an orthotopic temozolomide-resistant murine glioma model.
Even with lympho-depleting temozolomide treatment, survival was prolonged with moderate levels (30-50 percent) of tumor transduction of Toca 511 with 5-FC but not with lower transduction rates (10 percent).
Data from this study may inform the evaluation of Toca 511 & Toca FC in combination with temozolomide in patients with newly diagnosed glioblastoma (GBM).
Details of the AANS presentations are as follows:

Presentation Type: E-Poster displayed online (Abstract: 2120)
Title: Immune Monitoring of High-Grade Glioma Patients in a Phase 1 Clinical Trial of Toca 511 and Toca FC
Presenter: Steven Kalkanis, M.D.
Summary:

Human immune monitoring results from a Phase 1 clinical trial of Toca 511 & Toca FC support an immune-related mechanism of action for the regimen.
Univariate comparisons and multivariate models revealed pre-treatment tumor infiltrating cell subsets quantified via deconvolution of RNA sequencing data were associated with both objective responses and survival.
Post-treatment serum cytokine time-course results suggest that differences in temporal modulations are associated with both objective response and survival.
These results indicate the value of evaluating potential biomarkers of patient outcomes in the ongoing randomized Toca 5 Phase 3 trial in patients with recurrent HGG.
Presentation Type: Oral (Abstract: 481)
Title: Toca 511 and 5-FC in Combination with Metronomic Cyclophosphamide Reduces Treg Cells and Enhances Therapy Efficacy in a Preclinical Murine Model
Presenter: David Piccioni, M.D., Ph.D.
Date and Time: Wednesday, April 17, 4:49-4:52 p.m. PT
Summary:

This study aimed to determine if the addition of metronomic cyclophosphamide would provide therapeutic benefit when combined with Toca 511 and 5-FC (5-fluorocytosine) in a preclinical, subcutaneous glioma model.
The addition of metronomic cyclophosphamide improved tumor control and survival, and led to a superior CD8+/Treg ratio in the peripheral blood.
Results support the further evaluation of Toca 511 & Toca FC with metronomic dosing of cyclophosphamide and potentially other chemotherapeutics.
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.