Actually, they DID collect clinical response data even though it was a Phase Ib trial. Specifically, as the NYT piece mentions, they measured both cognitive function (via the mini-mental state exam aka MMSE and the clinical dementia rating scale aka CDR) and plaque removal (using one of Lilly's imaging agent) in relation to dosage. The data shows consistently improving cognitive function and plaque removal as dosage increases (albeit at the cost of additional side effects).

Now this is certainly atypical for Phase 1b data but it does (to some extent) justify Biogen increasing in almost $10B in market cap. In fact, the Phase 1b data is compelling enough that Biogen is going straight to Phase III trials.

While it is healthy to be skeptical about early trial results and subsequent market movement, I think it's clearly misplaced here.

I see where you're coming from, but I'm going to have to disagree somewhat...

This kind of report is aimed at influencing the stockmarket, not at reporting success or failure of a particular therapy.

It's both. A company is required/expected to publicly release material information that could influence the stock price. The clinical data also supports whether or not the molecule "passed" this phase of study.

there was no test to determine the effect of aducanumab on Alzheimer's disease.

There is no reason why you can't have efficacy endpoints in your phase 1 study. The endpoints tested in this study are indicators of progression of Alzheimer's disease.

That said (and others here have pointed it out), this is a VERY small study. There have been numerous other examples of Alzheimer's therapy that have show promise in early trials and so far, they have all turned out to be duds. I hope that's not the case here.

Lack of statistical power. Phase I enrol too few subjects for efficacy. The reason they do a Phase I is to determine it would be safe to do a larger trial.

Source: I used to work for the company that is most likely to have done any MRI analysis for this study. We did Phase I/II/III and they are very different beasts.

A small study will lack statistical power to detect small effect sizes, but a small study could still detect a large effect.

The point of statistical tests is to assess the accuracy of a prediction. These trials were not designed to predict/test the efficacy of the drug, therefore no conclusion regarding efficacy can be drawn.

It is of course possible that there was a real effect, and that this is reflected in the data gathered, however to determine if that is the case another trial has to be performed.

I'm pretty sure if they add efficacy endpoints to Phase I, it becomes a Phase I/Phase II and the efficacy is for Phase II. The other problem with efficacy in Phase I is that alzheimer's efficacy is not measured over such short time frames.

> This kind of report is aimed at influencing the stockmarket

The fact that it talks about the Phase I trial exceeding Wall Street expectations makes that pretty clear.

IMO what you said might mislead inexperienced people about a Phase I trial. It's entirely true, but people might not realise there are usually some previous experiments (e.g. in animal models) suggesting that the drug will be efficacious.