"I seriously doubt any major pharma company is going to be interested in DC based vaccines as they have been an abysmal failure."
I would not characterize it quite like that. I have been in biotech for a very long time and have led many clinical trials including one for a DC therapy, albeit not for GBM. The vaccines do work, but rarely as a monotherapy. It is like hitting the cancer with a fly swatter when the only effective implement is a sledge hammer. If cancers would cooperate by presenting a single antigen, life would be easier and the drugs would be more effective, but that is not reality.
Which leaves DC vaccines as part of a multi-drug combination therapy. It is very difficult to get a pharma company to trial a combination therapy unless they own all of the drug components. Most combination trials are done with already approved drugs in the context of investigator-led trials. The reasons are largely economic; if the market will accept a $50,000 price tag for a combination therapy, how do you reach agreement on how to divide the pie if different companies own the various components. Similarly, does it make sense to invest millions in a combination therapy if the other company can decide to withdraw its drug from the market, change its dosing forms, or alter its formulation which would require starting over.
Those business realities make DC vaccines a non-starter for most, if not all, pharmas. When the business model gets messy things usually end poorly and it has nothing to do with the drug itself. However, that reality does affect valuation quite negatively.