Stemcentrx does seem the most reasonable of the three companies I mentioned from a scientific standpoint, but this area is fraught with prior failures[0]. It's just the nature of the industry. Also[1]:
> The company says that they’re doing 150 xenografts a day (!) But their rationale is that trying to culture CSCs in vitro runs the risk of having them change character too much, making any assays using them unreliable. My guess is that they’re right about that, but my worry is that xenograft tumors themselves are already unreliable enough to cause trouble (and I have no idea of what happens to them after you “passage” them through multiple animals). Xenograft models are, of course, well known in oncology drug discovery, but one of the things that’s well known about them is that they’re the pure example of “necessary but nowhere near sufficient”. If your drug fails in a xenograft, it will probably fail in the clinic. But if your drug works in a xenograft, it will probably fail in the clinic, too. The odds get better, but they go from “extremely likely not to work” to “pretty likely not to work”, and you take what you can get in this business.
> So how’s Stemcentrx doing in their cell hunt? They’re not going to tell Technology Review, naturally, but as the article mentions, the entire CSC hypothesis has been taking some hits recently. It’s still very much an open question. How many tumor types are driven by stem cells, whether they can be targeted (and how), how to tell when such an approach is indicated at all – there are a lot of open questions. It seems very likely that there are cell types inside a given tumor population that are more aggressive and likely to spread, but whether that narrows down to a particular stem cell group, I don’t know. What if there are 234 cell types in some particular tumor, and (say) fourteen of them are the ones to really worry about? What then? Will there be a common mechanism to target these, or not?
0: https://www.bostonglobe.com/business/2015/09/28/verastem-sha...
1: http://blogs.sciencemag.org/pipeline/archives/2015/09/09/cha...