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Table 2 Progression-free survival by HER2 expression subgroups

From: Relationship between tumor biomarkers and efficacy in MARIANNE, a phase III study of trastuzumab emtansine ± pertuzumab versus trastuzumab plus taxane in HER2-positive advanced breast cancer

  Trastuzumab + taxane (Control) T-DM1 T-DM1 + pertuzumab
(T-DM1) (T-DM1 + P)
No. patients / No. patients with PFS event Median PFS (mo) No. patients / No. patients with PFS event Median PFS (mo) HR vs. trastuzumab + taxane (97.5% CI)a No. patients / No. patients with PFS event Median PFS (mo) HR vs. trastuzumab + taxane (97.5% CI)a HR vs. T-DM1 + placebo (97.5% CI)a
All patientsb  
 IHC 3+ 333/209 14.4 340/215 14.6 0.93 331/195 16.7 0.83 0.90
(0.75–1.16) (0.67–1.04) (0.72–1.12)
 IHC 2+ 27/19 12.6 25/20 7.3 1.13 29/20 8.3 1.25 0.98
(0.55–2.32) (0.61–2.59) (0.48–2.02)
IHC 2+/3+ patients combinedc
 Focal IHC 2+/3+ (10–29%)d 14/8 12.4 12/10 6.4 1.51 15/12 7.5 1.41 1.00
(0.52–4.40) (0.50–3.94) (0.38–2.65)
 Heterogeneous IHC 2+/3+ (30–79%) 35/27 10.6 37/25 8.3 1.04 33/20 6.3 1.11 0.91
(0.57–2.17) (0.46–1.78)
(0.55–1.94)
 Homogeneous IHC 2+/3+ (≥80%) 311/193 14.6 316/200 14.7 0.92 312/183 17.8 0.82 0.89
(0.65–1.04) (0.71–1.13)
(0.74–1.16)
IHC 3+ patients only
 Focal IHC 3+ (10–29%)d 9/5 8.3 11/7 8.3 1.20 8/7 4.2 5.11 2.28
(0.32–4.50) (0.99–26.40) (0.60–8.71)
 Heterogeneous IHC 3+ (30–79%) 44/29 10.5 45/34 10.0 1.15 29/16 17.8 0.79 0.65
(0.65–2.03) (0.39–1.60) (0.33–1.29)
 Homogeneous IHC 3+ (≥80%) 280/175 14.6 284/174 15.2 0.89 294/172 17.7 0.82 0.92
(0.70–1.14) (0.65–1.05) (0.73–1.17)
  1. aUnstratified hazard ratiob Five patients with IHC 0/1+ and five patients with unknown IHC status are not included in this table
  2. cCategories were based on IHC subgroup and then combined
  3. dCompared with the overall population, samples with focal HER2 expression were more likely to express mutated PIK3CA and lower levels of HER2 mRNA
  4. CI confidence interval, HER2 human epidermal growth factor receptor 2, HR hazard ratio, IHC immunohistochemistry, NE not estimable, P pertuzumab, PFS progression-free survival, PIK3CA phosphoinositide 3-kinase catalytic subunit alpha, T-DM1 trastuzumab emtansine