Table 3.

Median Endoxifen Concentrations for the Three CYP2D6 Genotype Groups and Change Over Time (EM patients no change in dose; IM and PM patients increased tamoxifen dose)

Genotype Category	No. Evaluable at Baseline	Median Endoxifen Baseline* (ng/mL)	No. Completing Protocol-Driven Therapy	Median Endoxifen Baseline (ng/mL)	Median Endoxifen 4 Months Later† (ng/mL)	Intrapatient Change From Baseline (ng/mL)		P‡
						Median	Interquartile Range
EM	32	34.9	29	34.3	29.2	−1.5	−28 to 11.2	.25
IM	74	19.8	51	18.5	21.8	+7.6	−0.6 to 23.9	< .001
PM	11	4.6	9	4.2	12.9	+6.1	2.6 to 12.5	.020

Abbreviations: EM, extensive metabolizer; IM, intermediate metabolizer; PM, poor metabolizer.

^*Medians of the three groups are significantly different from each other with EM v IM: P = .0054; EM v PM: P < .001; IM v PM: P < .001.

^†Represents aggregate data within genotype groups, not intrapatient data.

^‡Relates to the median intrapatient change from baseline.