Screened selection design for randomised phase II oncology trials: an example in chronic lymphocytic leukaemia

Table 3 Sample size and overall probability of correctly selecting a superior arm in SSD for different response rates based on 1 million replications

Scenario	Undesirable rate, p0	Desirable rates		n	Nominal alpha (exact alpha)	Nominal beta (exact beta)	First segment (Simon’s 2 stage)		Overall probability of correctly selecting a superior arm
		pA^*	pB				r1/n1	r/n
1	1%	20%	35%	29	0.05 (0.026)	0.05 (0.049)	0/14	1/29	0.900
2	5%	20%	35%	29	0.2 (0.169)	0.06 (0.059)	0/18	2/29	0.901
3	10%	30%	45%	35	0.2 (0.187)	0.05 (0.049)	2/19	4/35	0.903
4	15%	30%	45%	35	0.2 (0.197)	0.15 (0.122)	5/28	6/35	0.903
5	20%	40%	55%	37	0.18 (0.177)	0.05 (0.048)	3/19	9/37	0.902
6	25%	40%	55%	37	0.2 (0.191)	0.14 (0.138)	4/22	11/37	0.902
7	30%	50%	65%	36	0.2 (0.160)	0.07 (0.070)	5/21	13/36	0.901
8	35%	50%	65%	36	0.2 (0.198)	0.2 (0.191)	9/24	14/36	0.900
9	40%	60%	75%	32	0.2 (0.159)	0.1 (0.100)	8/21	15/32	0.900
10	45%	60%	75%	32	0.2 (0.198)	0.21 (0.204)	12/25	16/32	0.900
11	50%	70%	85%	26	0.2 (0.161)	0.13 (0.128)	7/16	15/26	0.904
12	55%	70%	85%	26	0.2 (0.194)	0.23 (0.230)	10/20	16/26	0.903
13	60%	80%	95%	16	0.2 (0.163)	0.21 (0.209)	4/8	11/16	0.904
14	65%	80%	95%	16	0.2 (0.191)	0.36 (0.357)	7/10	11/16	0.901

p0 : response proportion of a poor drug.
pA : response proportion of Arm A.
pB : response proportion of Arm B.
alpha : probability of rejecting p ≤ p0 when this is true (exact alpha provided in parenthesis).
beta : probability of rejecting p ≥ pA^* when this is true (exact beta provided in parenthesis).
pA is taken as the minimum response rate of a good drug.
n1 : no. of subjects required for Stage 1 in Simon’s 2 stage.
r1 : maximum number of successes in which will terminate trial.
r : maximum number of successes at the end of Stage 2 not to warrant further investigation.

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