I believe ustekinumab goes after a new target that hasn't previously been used to treat crohns, but a couple companies are working on drugs for it (not 100% certain and don't have time to look up which companies and how many and what target). MLN0002 has the previous knowledge the tysabri works, but _should_ be free of the risks of the side effects, but until enough people take the drug and in various combinations with other therapies, we cannot be certain. The last choice you should ever make (at least in my book) is a permanent surgery leading to an ostomy when you have other options available to you. Even with an ostomy, your lifestyle has to change significantly and you are prone to other issues that can cause pain and discomfort, so it isn't a perfect solution either.
My personal choice would be the open label trial since it sounds like you are in bad shape right now. You need some form of medication more than the chance of getting it. If I were in your shoes, that is how I would chose. The other thing to look at are the trial inclusion/exclusion criteria. What dose of pred do you have to be on before you can enter? For how long? How long do you have to be off other biologics (i.e. remicade/humira)? For how long? A lot of trials are fairly standardized, but you might have to wait 2+ months to enter either trial simply based on your current medications. Also, find out if after 8-12 weeks you get your trial group switched in the double blind random trial. Or if you can be switched to the drug if you are on placebo after 8-12 weeks and your condition is worsening and you would be forced to exit the trial otherwise. These are all very important details about both trials and their design that you should know before entering the trial. Also, depending on your age, do you want to have kids in the next ~2 years? Many drugs request you to not have kids during their duration and for a period after due to the unknown effects on unborn children. If you do have a kid, then you have to be closely monitored (which in some ways helps them to study the drug effects on developing babies, but do you want to take that risk?). I think I covered most of the things I considered when I tried to get into a couple clinical trials. Good luck with your decision and let us know which one you chose.