TT took 20 odd years to materialise as an FDA approved drug for the vet, dogs only, market and still only on phase I/II human trials. We should know from experience how long this takes. Promising doesn't mean much, and I bet Qbiotics almost came a cropper a few times along the way even with a seemingly miracle drug that was much touted in the media. Advantage for the biologics TT and its EBC 1013 analogue, is that they are relatively simple well defined naturally derived molecules that have specific but widespread applications (with tumours) proven to be well tolerated with low toxicity to humans, and are very effective and work with incredible rapidly. Already been posted that TT being injectable is seen to be advantageous, particularly when treating solid tumours. And hey, it has a distal/ abscopal effect that's being patented and to be pedantic, it is tumour agnostic. Just consider the package that we know is TT, and still to discover more about its mode of action which could then broaden its applications.. Still took 20 odd years for TT to be approved to treat MCTs for dogs.
