Replies to post #4633 on Biotech Values

[DewDiligence]

>> I fail to see how a cherry picked set of patients would allow patients vision to improve as they did in that study. If they had wet amd, and their vision improved, it was squalamine that did that was reason <<

If visual-acuity measurements are taken diligently and honestly, there should be no placebo effect in AMD.

At the Macugen panel meeting last August, you may have noticed that there was considerable discussion that the Macugen trial measured visual acuity at a distance of 2 meters rather than the standard distance of 4 meters. Why does this matter as long as all patients were measured the same way? The reason is that, if a patient leans forward in the chair while reading the eye chart, the leaning has a much bigger biasing effect on the result when the reading is taken at 2 meters than it does at 4 meters. I mention this to point out that seemingly minor features of a clinical trial can affect the data to a significant degree.

The possibility of bias is always an issue in an open-label trial, and this is of course the reason the FDA and other regulatory bodies prefer randomized, controlled trials.

Getting back to GENR’s Mexican trial, I agree with you that cherry picking of patients (if that in fact occurred) could not produce a robust response if Squalamine were not working. However, cherry picking of patients could conceivably have magnified the degree of the observed response.

[swampboots]

Randy Re: "I fail to see how a cherry picked set of patients would allow patients vision to improve as they did in that study. If they had wet amd, and their vision improved, it was squalamine that did that was reason. Any arguement there?"

If one has seen many AMD patients, it may be possible to observe a stage when the preception of loss of vision fluctuates the most, unless the endpoint was only an observed measured biological molecular measurable modality. If as I assume, that the test was based only on subjective chart reads, this method could be prone to unintended biases, both in patient selection and posited testing results.
But I do remember something about microscopic vessel observations or am I connecting this with another study????

[rkrw]

I've heard the mexican physician is well respected. However, as a bio investor, it's important to be cautious in interpreting open label studies. Dew has explained the risks very well, selection bias, excellent care, pbo effect, trying harder to read the letters, who knows? Good or bad, the first pbo controlled data is the seminal event for genr.