So can someone explain this one for me? Halozyme has a hyaluoronidase enzyme (PEGPH20) that they’re developing as a therapeutic agent. The idea is that it’s going to be an add-on with other cancer therapeutic combinations, and would increase the exposure of the tumor cells to the actual chemotherapies by breaking down hyaluronan (hyaluronic acid) around the tumor tissue and its associated blood vessels. Fine – this is not a ridiculous idea, and is worth testing.
Tested it they have, in a recent trial of pancreatic cancer with Abraxane (paclitaxel, or taxol) and gemcitabine. And the headlines say things like “Halozyme’s pancreatic cancer drug succeeds” and “Halozyme jumps on positive late-stage pancreatic cancer data”. And from that sort of coverage, you’d expect that the data were, y’know, positive. But this morning, the company released more information, and various biotech observers on Twitter began to roll their eyes.
Here, via AndyBiotech, is the survival curve for the Abraxane/gemcitabine group versus the group with PEGPH20 added. Right. The “positive data” are basically one point along in the trial where the treatment group looked better than the standard of care. But that disappears – check in a couple of months later, and everything looks identically bad. I realize that for pancreatic cancer the standard for “positive data” might be a bit low, since it’s very hard to get anything to work (you wonder what these curves would look like for untreated patients, to be honest). In that later stages of the trial, there are actually more people left alive in the standard-of-care group than there are in the experimental one. The numbers are so small that that’s probably meaningless, but then so is the earlier “effect” that the company is touting. As bio_closeau pointed out as well, this was an open-label trial, and has its own further problems because of that.
This is cherry-picking no matter how you look at it, and Adam Feuerstein was right to call it “shameful conduct” to press-release it the way the company did. But hey, the stock bounced (or it has so far this morning), and that’s what matters, right?
Update: as pointed out in the comments, the primary endpoint for this trial was progression-free survival, and I’m giving Halozyme grief here over their overall survival data instead. Fair enough – but it should be noted that they just barely made significance even for the primary endpoint. And if this drug (or any oncology drug) is going to progress, it’s going to need to show a benefit in overall survival, because (as has been the case for some years), in the end, if progression-free survival means “you die just as quickly, but with fewer tumors”, then odds are that no one cares. I still have a lot of trouble seeing this trial as good news, although I will freely admit that the stock market is disagreeing with me on that. For one of several counterarguments, see here.