Replies to post #4940 on Dendreon Corp fka DNDNQ

[iwfal]

The concern for the interim look is the large percentage (20%) of patients who enrolled in the final 18 months of the enrollment period. These patients, if still alive, will have to be censored at the time of the interim trigger in Sep/Oct 2008. If IMPACT goes like the other Phase III trials, there won't be much separation between the two arms for the first 18 months. The censored patients cloud up the p value.


Add to this that this final 20% is sicker (because of the change in protocol) than the longest enrolled group and I'd guess >30% of the deaths in the interim will be in people who are not benefitting much from the treatment.

[io_io]

<"DNDN has said that if they get better than 0.05 but worse than the interim alpha..... they will submit to the FDA for approval again">



Have they actually COMMITTED to doing that ????

I think that would be asking the FDA to set aside a more fundamental precedent than what was asked earlier this year.


My mind goes off on a tangent.....

.....expressions like "stock-price management" (Elan CEO in reference to NRMX CEO) come to mind.

[steveporsche]

I was playing around with the AC numbers and the really fat separation does not occur until 30 months - even in 02A - and it's nice separation over time that drives p values. Applying the combined numbers to our enrollment estimates gives me 180 deaths a lot earlier than Sept 08. Does anyone have a p-value model for survival curves that I could play with sensitivities on?


alive
9901 6 mos 12 mos 18 mos 24 mos 30 mos 36 mos

Prov 91.5 76.8 67.1 52.4 43.9 34.1
Plac 93.3 66.7 55.6 40.0 24.4 10.7
dif -1.8 10.1 11.5 12.4 19.5 23.4
rat 0.98 1.15 1.21 1.31 1.80 3.19

9902a 6 mos 12 mos 18 mos 24 mos 30 mos 36 mos

Prov 92.3 72.3 52.3 44.6 41.5 31.6
Plac 90.9 69.7 45.5 39.4 27.3 21.2
dif 1.4 2.6 6.8 5.2 14.2 10.4
rat 1.02 1.04 1.15 1.13 1.52 1.49

Comb 6 mos 12 mos 18 mos 24 mos 30 mos 36 mos

91.9 74.6 59.7 48.5 42.7 32.9
92.1 68.2 50.6 39.7 25.9 16.0
dif -0.2 6.3 9.2 8.8 16.9 16.9
rat 1.00 1.09 1.18 1.22 1.65 2.06