Table 3.

Treatment Effect and Interaction Between Treatment Effect and TOP2A Amplification Based on the BCIRG-006 Validation Set Trial

Regimen	TOP2A						Interaction Test P
	Nonamplified (n = 1,904)			Amplified (n = 1,044)
	Hazard Ratio	95% CI	P	Hazard Ratio	95% CI	P
ACT v ACTH	0.53	0.40 to 0.69	< .001	0.80	0.51 to 1.25	.34	.117
ACT v TCH	0.57	0.44 to 0.74	< .001	0.92	0.60 to 1.42	.65	.063
ACT v ACTH + TCH	0.55	0.44 to 0.68	< .001	0.85	0.59 to 1.25	.41	.045

NOTE. The BCIRG-006 study compared two different experimental trastuzumab plus chemotherapy regimens with chemotherapy alone. The control chemotherapy alone arm (ACT) consisted of doxorubicin and cyclophosphamide followed by docetaxel. Patients in the first experimental arm of anthracycline-containing chemotherapy (ACTH) received the same chemotherapy with the addition of trastuzumab beginning with the first docetaxel. A second, nonanthracycline experimental arm (TCH) consisted of docetaxel plus carboplatin concurrently with trastuzumab.

Abbreviations: BCIRG, Breast Cancer International Research Group; ACT, doxorubicin, cyclophosphamide, docetaxel; ACTH, doxorubicin, cyclophosphamide, docetaxel, and trastuzumab; TCH, docetaxel, carboplatin, and trastuzumab.