I think this is isn't quite so likely, but for the first time in the history of the universe, I disagree in a way that makes me more bullish than you.
First of all, they do not have adequate data from the pre-clinical studies to determine that colorectal is most likely to benefit. I think they chose it on the premise that if it works with any of them it's likely to work (at least to some extent) with all of them, they couldn't get pre-approved and be able to pay for reasonably sized phase 2 in all of them (not at the time), so they chose the most financially promising and diversely applicable/data-extensible indication (knowing that if results in phase 1 are great or it passes phase 2, getting usage and approvals of other indications will be far easier). Regarding inoperable solid tumors, colorectal is the hugest population except for breast (mostly limited to females, and many other treatment options both approved and in trials), prostate (males, and other treatment options though perhaps not as good for latest stages), and lung (lots of competition but also declining rates in the developed world due to smoking awareness - it's increasing in the countries that can't afford treatment thanks to everything from wood-burning stoves to increases in cigarette consumption by the budding middle class - anyway, it's perceived as preventable and has a downward trajectory and has a very diverse array of subtypes some of which might react differently than others making it less predictable and harder to screen/enroll).
They know that if for some strange reason based on ample phase 1 data it works great in another indication (like pancreatic) and poorly in colorectal, they won't have any trouble with the FDA changing the indication to be both safer/conservative and more beneficial at the expense of monetary potential (the FDA would love this), but by picking one now their best case scenario is sailing straight through into a very lucrative market.
Now to the bullish part - you have to ask yourself, WHY do a phase 3? When you have to (because there are good alternatives and marginal p2 efficacy), obviously you do it. However, if the data is so good as to warrant an immediate upgrade, based on TUMOR REGRESSION, in an indication with little hope (the latest and greatest combination therapies disclosing results in 2013 still show rapid progression, not-nearly-complete response rates, and unlike dcvax some really serious side-effects), why would the company want to waste money and why would the FDA want to waste time (especially after past scandals and massive policy changes to favor advancement)? If the data is not that good, they likely want to do a phase 2 because with a relatively small investment and short timeline they can figure things out like the most responsive subgroups and potentially the most optimal dosing schedule (could involve an amendment of the protocol with fda, but not an upgrade to registration and phase 3 so quicker and easier to allow). If the data is that good, they know the FDA can and will grant accelerated approval to save tens of thousands of lives every year. So why do a phase 3? They'll learn everything they need to when they do surveillance studies post-marketing and perhaps a blinded phase 3 comparing generation 2 dcvax to generation 3 dcvax to see which is more effective, since results are likely to be less obvious than comparing an effective therapy to a nonexistent therapy....
Obviously this is all highly speculative - we're not even done with phase 1 yet. I'm just saying, as long as we're dreaming about awesome results, let's look at the whole picture including the choice of regression rather than PFS as an endpoint (making it significantly more likely to be approved out of a successful phase 2).
I mentioned earlier side-effects in dcvax-direct versus current options and figure that could probably use some elaboration. With, say, FOLFOXIRI (that's a combination of 4 chemos for those who haven't heard of it) plus avastin, you're getting an intravenous injection, and a lot of it at that. The lucky patients get diarrhea and vomiting. The not so lucky patients get a thromboembolism (can be fatal depending on where the clot goes). Also, pretty much everybody is getting neutropenia as their immune systems are wiped out so even while they're surviving the cancer they might just die of a simple bacterial infection instead. With dcvax-direct, the injection is intratumoral which should make embolisms far less likely (assuming competent treatment), and instead of weakening your immune system, you're strengthening it. So even if it's only a little more effective than current SoC, the FDA might love it anyway due to the safety profile.
Your last line pretty much says it all - due to the safety profile and orphan status, the FDA can accommodate NWBO, but accommodation does not have to mean inviting them to take more time and spend more money. Does that sound right?
(and to finish up this nauseatingly bullish post, I just want to point out that my belief is this stock may be headed down to 1 or up to 100, with little room in between. this series of hypotheticals is all about the 100-400 scenario but I haven't forgotten that the 1-dollar scenario is still in play and neither should anyone else)
