How GI-6301 works
GI-6301 is a type of immunotherapy called a cancer vaccine. It acts indirectly on the cancer by stimulating the immune system to target and kill tumor cells.
Certain immune cells, called dendritic cells (DCs), can identify and process antigens (foreign substances associated with an infection or disease, such as particular protein) and alert another type of immune cell, called T-cells, to their presence. This triggers a targeted immune response against cells expressing that particular antigen, by stimulating the production of cytotoxic (cell-killing) T-cells against the antigen.
GI-6301 is a vaccine targeting a protein called brachyury produced using Inovio’s Tarmogen platform. This protein is expressed in a wide range of cancers and can be involved in the spread of the cancer to different parts of the body. Brachyury is also expressed in chordoma, a rare type of bone cancer.
GI-6301 is a heat-inactivated yeast cell modified to produce brachyury. After injection, GI-6301 is recognized by the immune system and engulfed by dendritic cells. The yeast cell is then destroyed, and the brachyury protein inside it processed by the DCs and used to activate T-cells to target the cancer cells. This process aims to reduce the number of tumor cells.
GI-6301 in clinical trials
An open-label Phase 1 clinical trial (NCT01519817) testing the safety and efficacy of GI-6301 was carried out by the National Cancer Institute (NCI) at a single site in Maryland. The trial recruited 34 people with advanced cancers, including 11 chordoma patients, who have tried and failed other treatment options. It consisted of an initial dose escalation, followed by a regular monthly dosing. Patients were monitored for up to four years for adverse events.
Results showed that GI-6301 successfully induced an immune response in the majority of patients after six vaccinations. The treatment was also well-tolerated, with the most common adverse events being mild/moderate injection site reactions.
The NCI is now recruiting patients with chordoma for a Phase 2 clinical trial (NCT02383498) assessing overall response rate to GI-6301, compared to placebo, for up to three years. This single-site study is also taking place at the National Institutes of Health center in Bethesda, Maryland.
GI-6301 is administered as an injection under the skin.
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