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This is another case where the median overall survival is meaningless and could hide impressive results. Toca 511 and TocaFC is an experimental gene therapy. Toca 511 is a virus that is injected one time. It infects only tumor cells (see https://tocagen.com/our-science/#platform_tech for information on how that magic happens. It is fascinating). When this virus infects a tumor cell, it inserts a gene that codes for a protein called CD. CD can break down the drug Toca FC into a chemotherapy drug 5FU, but only in cells that had the gene inserted. Toca FC is an oral drug which is a reformulation of an old drug approved for fungal infections. After injecting the virus, you wait a few weeks for the virus to spread to most of the tumor cells, then start a round of the oral TocaFC. This drug is harmless to the body except when it comes into contact with the CD protein, which converts the drug to 5FU which kills the nearby cells. This not only kills the tumor cells but exposes the insides of the tumor cells to the immune system to trigger an immune response. You then stop the TOCA FC for a few weeks to allow the virus to infect the remaining cells and repeat the process as long as is needed.
This article reports on the results. This is on 56 recurrent high grade glioma patients - which is medium sized - enough patients to see the trend. They used a comparison to historical controls. The Median overall survival only moved up 2.9 months compared to historical controls (that would be very significant if it was against randomized controls) and the response rate was only 11.3%. Just looking at those numbers, I would usually say it is interesting but needs more research before I would consider using it if I needed it. However, they then go on to say of those 11.3% responders, ALL had complete responses for an extended period of time. This is very impressive. It is rare to get a single complete response in a trial this size, and many times we see a complete response that only last a few months. Seeing about 6 patients our of 56 having a sustained complete response places this treatment among the best options for brain cancer patients.
Disclaimer: The Musella Foundation was an early supporter of this treatment via grants, and Tocagen is a sponsor of our organization