Replies to post #5277 on Biotech Values

[DewDiligence]

Phase-3 vs phase-2:

[This is a repost of an old message on the BIOM board that is germane to many development-stage biotech companies including, of course, GENR.]

>>
Why phase 3 fails to match phase 2:
by: DewDiligence
09/22/02 02:20 pm
Msg: 104714 of 161130

One reason that phase-3 trials frequently fail to live up to the promise of phase-2 results is an effect I call “Program-survival bias.”

Bad phase-2 trials generally result in clinical programs being canceled (no phase 3), while good phase 2 trials result in continuation to phase 3. Hence the phase-2 data for programs which proceed to phase 3 will have a positive bias, which implies that phase-3 data should on average be weaker than the corresponding phase-2 data.

Although I’ve not seem any formal study of this effect, intuitively, it seems clear to me that it must be a significant factor.
<<

[randychub]

Thanks Poorgrad. That is pretty good data. To bad it did not pan out it would have been nice for those patients.

I guess I fell more confident with tesmilifene because of the number of patients in the first phase 3 trial but I guess you never know what will happen until trials are completed and the FDA gives the final OK.


In the first phase 3 trial for tesmilifene there was 305 patients overall 152 in one arm, 153 in the other arm, which showed a survival benefit of 50%.

There where 191 patients with aggressive breast cancer in the trial (those with mets within 36 months of initial diagnosis). This is the only group being recruited in the 2nd phase 3 trial. In this group the overall survival benefit was 143%.


Randy