Issues in applying multi-arm multi-stage methodology to a clinical trial in prostate cancer: the MRC STAMPEDE trial

Table 4 Impact on patients recruited and trial duration of stopping accrual at a set timepoint

	Median		Arms accruing at Activity Stage					Total		Differences ^b in
Pts/yr	Median FFS (m)	Median OS (m)	1	2	3	4	Year accrual stopped	Pts	Time (m)	Total pts	Time (m)
No arms stop early
500	24	48	6	6	6	6	Uncapped^c	3411	82	0	0
500	24	48	6	6	6	6	7	3411	82	0	0
500	24	48	6	6	6	6	6	3000	83	-411	1
500	24	48	6	6	6	6	5	2500	89	-911	7
One arm is dropped after each Activity Stage
500	24	48	6	5	4	3	Uncapped^c	3133	75	0	0
500	24	48	6	5	4	3	7	3133	75	0	0
500	24	48	6	5	4	3	6	3000	75	-133	0
500	24	48	6	5	4	3	5	2500	80	-633	5
Dropped to 2 arms after Activity Stage I
500	24	48	6	2	2	2	Uncapped^c	2738	66	0	0
500	24	48	6	2	2	2	7^c	2738	66	0	0
500	24	48	6	2	2	2	6	2738	66	0	0
500	24	48	6	2	2	2	5	2500	66	-162	0
Dropped to 2 arms after Activity Stage II
500	24	48	6	6	2	2	Uncapped^c	2983	72	0	0
500	24	48	6	6	2	2	7^c	2983	72	0	0
500	24	48	6	6	2	2	6	2983	72	0	0
500	24	48	6	6	2	2	5	2500	75	-483	3
One arm dropped after each Activity Stage & survival is longer
500	24	60	6	5	4	3	Uncapped	3397	82	0	0
500	24	60	6	5	4	3	7^c	3397	82	0	0
500	24	60	6	5	4	3	6	3000	83	-397	1
500	24	60	6	5	4	3	5	2500	91	897	91
One arm is dropped after each Activity Stage & accrual is slower
350	24	48	6	5	4	3	Uncapped	2702	93	0	0
350	24	48	6	5	4	3	7	2450	94	-252	1
350	24	48	6	5	4	3	6	2100	101	-602	8
350	24	48	6	5	4	3	5^a	n/a	n/a	n/a	n/a

Uncapped means that accrual continues until the point of maturity.
^a Model not provided because Efficacy Stage III would not have been completed by 5 years
^b Differences compared with the uncapped model with the same parameters
^c Recruitment would have been completed at sooner time point ie another model stops accrual sooner eg the first row shows uncapped accrual to be the same as accrual to 7 years because the accrual-to-7-years model stops accrual just before 7 years

ISSN: 1745-6215