Table 1.

Characteristics of the Participants at Baseline and after Gene Transfer.^*

Characteristic	Participant Number
	1	2	3	4	5	6	7	8	9	10
At baseline
Age — yr	23	18	46	43	52	21	45	18	37	53
Weight — kg	81.8	55.6	97.9	101.3	87	70.9	87	68.2	82.8	68.1
Factor IX activity — % of normal	<1.0	<1.0	<1.0	1.3	1	<1.0	1.6	<1.0	<1.0	1.7
Factor IX genotype	H221R	G309V	S136Cfs*6	I382F	G396A	W194Stop	C19Y	W194Stop	S365I fs*15	G367R
Cross-reacting material status	+	+	−	+	+	−	+	−	−	+
Factor IX treatment
Use	Prophylactic	Prophylactic	Prophylactic	On demand	On demand	Prophylactic	On demand	Prophylactic	Prophylactic	Prophylactic
Treatment type	EHL-FIX	rFIX	EHL-FIX	NA	NA	rFIX	NA	rFIX	pdFIX	EHL-FIX
Dosing regimen	50 IU/kg weekly	50 IU/kg three times per week	100 IU/kg every 10 days	NA	NA	30 IU/kg twice per week	NA	30 IU/kg twice per week	45 IU/kg weekly	100 IU/kg every 10 days
No. of target joints	0	4	4	2	1	0	2	0	5	0
Infection history
HIV	No	No	Yes	No	No	No	No	No	No	No
Hepatitis C virus	No	No	Yes	No†	Yes	No	Yes	No	Yes	Yes
Hepatitis B virus	No	No	Yes	No	Yes	No	Yes	No	No	Yes
Liver fibrosis (FibroScan result)‡	NA	NA	F2 (8.3 kPa)	NA	F1 (6.4 kPa)	NA	F1 (7.1 kPa)	NA	F1	F1 (7.1 kPa)
AAV neutralizing antibody	<1:1	<1:1	<1:1	<1:1	<1:1	1:1	<1:1	<1:1	<1:1	<1:1
At vector administration
Ratio of full to empty capsids	1:5	1:5	1:4	1:4	1:4	1:5	1:4	1:3	1:3	1:3
After gene transfer
Follow-up — wk	78	52	52	52	52	52	52	37	37	28
Mean steady-state factor IX activity — % of normal	30	36	25	41	36	18	14	27	81	29
Factor IX inhibitor — BU	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
Mean factor IX antigen — % of normal	NA	NA	2.5	NA	NA	1.2	NA	2.2	7.0	NA
AAV capsid immune response — wk after vector infusion	NA	NA	NA	NA	NA	NA	6	NA	4	NA
Thrombin-antithrombin at 52 wk§	2.6	3.6	4.4	2.8	5.9	2.2	3.6	NA	NA	NA
Annualized bleeding rate
Before gene transfer — no. of events/yr	4	3	12	0	10	2	32	0	48	0
After gene transfer — no. of events/yr (% reduction)	0 (100)	0 (100)	4 (67)	0 (100)	0 (100)	0 (100)	0 (100)	0 (100)	0 (100)	0 (100)
Annualized use of factor IX
At 52 wk before gene transfer
No. of infusions	98	159	61	0	10	106	47	104	52	38
Dose — IU/kg	3009	8090	4024	0	911	2990	1761	3050	1884	3362
After gene transfer
No. of infusions (% reduction)	0 (100)	0 (100)	10 (84)	0 (100)	0 (100)	0 (100)	0 (100)	2 (98)	0 (100)	0 (100)
Dose — IU/kg (% reduction)	0 (100)	0 (100)	376 (91)	0 (100)	0 (100)	0 (100)	0 (100)	117 (96)	0 (100)	0 (100)

^*A plus sign indicates positive results, and a minus sign negative results. AAV denotes adeno-associated viral, BU Bethesda titer units, EHL-FIX extended half-life factor IX, HIV human immunodeficiency virus, NA not applicable, pdFIX plasma-derived factor IX, and rFIX recombinant factor IX.

^†Participant 4 was seropositive but did not have history of chronic hepatitis C infection.

^‡Liver fibrosis is assessed on a scale of F0 to F4, with higher stages indicating a greater degree of fibrosis. FibroScan results are on a scale from 2.5 kPa to 75 kPa, with higher values indicating more severe fibrosis.

^§The normal range for thrombin–antithrombin values is 1.0 to 4.1 µg per liter.