TABLE 3.

ARIA‐H events from Study 201 core and OLE.

	Core						OLE
	Lecanemab						Lecanemab
ARIA term	Placebo (N = 245) n (%)	2.5 mg/kg Biweekly (N = 52) n (%)	5 mg/kg Monthly (N = 51) n (%)	5 mg/kg Biweekly (N = 92) n (%)	10 mg/kg Monthly (N = 253) n (%)	10 mg/kg Biweekly (N = 161) n (%)	Newly Treated Core Placebo (N = 45) n (%)	Overall (N = 180) n (%)
ARIA‐H	12 (4.9)	3 (5.8)	7 (13.7)	13 (14.1)	24 (9.5)	10 (6.2)	6 (13.3)	26 (14.4)
ApoE4+	9/174 (5.2)	3/38 (7.9)	6/40 (15.0)	13/84 (15.5)	22/225 (9.8)	6/49 (12.2)	5/31 (16.1)	23/125 (18.4)
Homozygous	1/40 (2.5)	0/5 (0)	3/12 (25.0)	1/14 (7.1)	9/60 (15.0)	3/10 (30.0)	2/4 (50.0)	11/28 (39.3)
Heterozygous	8/134 (6.0)	3/33 (9.1)	3/28 (10.7)	12/70 (17.1)	13/165 (7.9)	3/39 (7.7)	3/27 (11.1)	12/97 (12.4)
ApoE4‐	3/71 (4.2)	0/14 (0)	1/11 (9.1)	0/8 (0)	2/28 (7.1)	4/112 (3.6)	1/14 (7.1)	3/55 (5.5)
ARIA‐E and ARIA‐H	1 (0.4)	0 (0)	1 (2.0)	0 (0)	11 (4.3)	6 (3.7)	1 (2.2)	8 (4.4)
ApoE4+	1/174 (0.6)	0/38 (0)	1/40 (2.5)	0/84 (0)	10/225 (4.4)	4/49 (8.2)	1/31 (3.2)	7/125 (5.6)
Homozygous	0/40 (0)	0/5 (0)	1/12 (8.3)	0/14 (0)	5/60 (8.3)	3/10 (30.0)	¼ (25.0)	3/28 (10.7)
Heterozygous	1/134 (0.7)	0/33 (0)	0/28 (0)	0/70 (0)	5/165 (3.0)	1/39 (2.6)	0/27 (0)	4/97 (4.1)
ApoE4‐	0/71 (0)	0/14 (0)	0/11 (0)	0/8 (0)	1/28 (3.6)	2/112 (1.8)	0/14 (0)	1/55 (1.8)
Isolated ARIA‐H (no ARIA‐E)	11 (4.5)	3 (5.8)	6 (11.8)	13 (14.1)	13 (5.1)	4 (2.5)	5 (11.1)	18 (10.0)
ApoE4+	8/174 (4.6)	3/38 (7.9)	5/40 (12.5)	13/84 (15.5)	12/225 (5.3)	2/49 (4.1)	4/31 (12.9)	16/125 (12.8)
Homozygous	1/40 (2.5)	0/5 (0)	2/12 (16.7)	1/14 (7.1)	4/60 (6.7)	0/10 (0)	1/4 (25.0)	8/28 (28.6)
Heterozygous	7/134 (5.2)	3/33 (9.1)	3/28 (10.7)	12/70 (17.1)	8/165 (4.8)	2/39 (5.1)	3/27 (11.1)	8/97 (8.2)
ApoE4‐	3/71 (4.2)	0/14 (0)	1/11 (9.1)	0/8 (0)	1/28 (3.6)	2/112 (1.8)	1/14 (7.1)	2/55 (3.6)