Introgen's Data-Mining Misleads

My critique last Saturday of Introgen Therapeutics(INGN Quote) sparked some sharp negative reaction by readers, mainly from those believing strongly in the potential of the company's Advexin cancer drug.

So let's take a closer look at the available data and, as a related byproduct, the difference between clinical data that are collected and analyzed prospectively vs. the same done retrospectively.

It's an important distinction that has a big impact on the quality of data and the subsequent conclusions you can make. This issue comes up often in biotech investing, so it's a good topic to explore that's applicable well beyond Introgen.

Introgen and its supporters believe that Advexin works because of clinical data from a phase II study announced in the past year that purports to show a survival benefit in a subset of patients with head and neck cancer who are given Advexin. Introgen's stated plan is to use this survival data to seek FDA approval of the drug before the end of the year.

But here's why I'm so bearish on Introgen: The survival benefit from the phase II trial was culled retrospectively -- in other words, after the trial's prestated endpoints were analyzed.

There's nothing wrong with data-mining, per se, except when you do it to spin a negative trial into a positive one. That's when retrospective data analysis becomes misleading and wrong, which is what Introgen has done with Advexin.