Table 4.

Frequencies at which surrogacy discordance (based on DFS for OS), efficacy, inferiority, or futility were determined at each time point (percentages of the maximum number of desired events for final analysis) for the 25 ACCENT trial comparisons, by endpoint. The total number of trials stopped at each time point are also given for each design (adaptive and O’Brien-Fleming). Trials with futility results at the final checkpoint had insufficient evidence to reject the null hypothesis of no treatment effect after the desired number of events had been observed.

	Endpoint	25% Max Events	50% Max Events	75% Max Events	100% Max Events	Total
Switch S to T		2	0	0	0	2 (8%)
Efficacy	S	5	4	2	0	11 (44%)
	T	2	0	0	0	2 (8%)
Inferiority	S	0	0	0	0	0 (0%)
	T	0	0	0	0	0 (0%)
Futility	S	4	1	0	7	12 (48%)
	T	0	0	0	0	0 (0%)
Adaptive Design Totals	S; T	11 (44%)	5 (20%)	2 (8%)	7 (28%)	25 (100%)
O’Brien-Fleming Totals	S	0	4 (16%)	3 (12%)	1 (4%)	8 (32%)