Replies to post #3630 on Dendreon Corp fka DNDNQ

[eagle-eye]

Wall,

Can you explain this responce a little more. I am not sure what you mean.

Q: How might slow ramp up on enrollment of 9902B affect the results at the interim and final for an event given trial?

A: There will be a greater effect at the interim look. There will be a lot more censored patients who are more recent enrollees, and this will be a confounding factor.

Thanks.

[iwfal]

Q: What factors led to the relatively poor results of 9902A?

A: Main reason was strong # of bone metastases factor favoring the placebo arm...secondary reason was smaller trial size.


True - but undoubtedly exagerated in the 9902a analysis. E.g. the bone met HR in 9901 was nowhere near as extreme. This is a large part of the reason for the huge change in p value for 02a.

One of the stratification factors in 9902B will be # of bone metastases...this and the much larger size of the trial should help balance out the likelihood of a higher % of placebo crossovers.

If you are doing Cox Regression anyway then randomization strat isn't worth a lot - except that it minimizes the difference between plain Log Rank and the Cox Regression. So the strat doesn't really mean much except that it minimizes the angst where the log rank fails and the CR passes.