DESTINY-Breast03 Phase 3 Study Results
Clinical Activity of HER3-DXd Across BC Subtypes
Outcomes (BICR per RECIST 1.1)
Confirmed ORR, % (95% CI³)
HR+/HER2-
(n=113)
HER3-High and -Low
30.1
(21.8-39.4)
TNBC
(n=53)
HER3-High
HER2+
Best overall response, %b
PR
SD
PD
NE
DOR, median (95% CI), mo
30.1
22.6
22.6
(12.3-36.2)
42.9
(n=14)
HER3-High
42.9
(17.7-71.1)
50.4
56.6
50.0
11.5
17.0
7.1
8.0
3.8
0.0
7.2
5.9
8.3
(5.3-NE)
PFS, median (95% CI), mo
6-month PFS rate, % (95% CI)
7.4
(4.7-8.4)
53.5
(43.4-62.6)
14.6
(11.3-19.5)
(3.0-8.4)
5.5
(3.9-6.8)
38.2
(24.2-52.0)
14.6
(11.2-17.2)
(2.8-26.4)
11.0
(4.4-16.4)
51.6
(22.1-74.8)
19.5
(12.2-NE)
OS, median (95% CI), mo
HER3-DXd demonstrated durable antitumor activity across BC subtypes
•
Confirmed ORR for all patients (N=182), 28.6% (95% CI, 22.1%-35.7%); median DOR, 7.0 mo (95% CI, 5.5-8.5 months)
CR, confirmed response; DOR, duration of response; NE, not evaluable; ORR, objective response rate; OS, overall survival; PFS, progression-free survival; PR, partial response; SD, stable disease.
a 95% exact binomial confidence interval (by Clopper-Pearson method).
b No patients had a CR.
ASCO 2022 #1002 Oral
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