Clinical Conditions Before Transplantation
Twelve patients with hereditary leukodystrophy were treated by UCBT. Clinical and demographic characteristics of these patients (p1–p12) are summarized in Table 1. Nine (p1–p9 in Table 1) were diagnosed with cerebral ALD and harbored unique maternally inherited ABCD1 mutations (mainly point mutations in exons 1 and 3), and the remaining three (p10–p12) were diagnosed with GLD and harbored inherited GALC gene mutations. The median onset age was 7 years (range, about 3 years to 11.9 years). Ten patients (all except p3 with ALD and p11 with GLD) had neurological symptoms before transplantation, eleven patients (all except p11) had abnormal brain white matter signals on cranial MRI before transplantation, and seven patients (p1, p3, and p5–p9) had adrenal cortex dysfunction and were receiving glucocorticoid replacement therapy. Serum VLCFAs were elevated in all ALD patients and leukocyte galactocerebrosidase activity was reduced in all GLD patients (see Table 1 for details).
Table 1. Baseline clinical characteristic of the 12 patients with heredity leukodystrophy
Patient
|
Sex
|
Onset age
(years)
|
Gene defects
|
Mutations
|
Nervous system
symptom
|
Lesions on cranial MRI
|
Adrenocortical
insufficiency
|
VLCFAs
|
Galactocerebrosidase
(nmol/17h/mg)
|
1
|
Male
|
8.3
|
ABCD1
|
exon1 c.829G > A, p. G277R
|
+
|
+
|
+
|
↑
|
NA
|
2
|
Male
|
7.0
|
ABCD1
|
exon1 c.593G > A, p. T198K
|
+
|
+
|
−
|
↑
|
NA
|
3
|
Male
|
about 3
|
ABCD1
|
exon3 c.1552C > T, p. R518W
|
−
|
+
|
+
|
↑
|
NA
|
4
|
Male
|
5.2
|
ABCD1
|
c.1992-2A > G, p?
|
+
|
+
|
−
|
↑
|
NA
|
5
|
Male
|
about 8
|
ABCD1
|
exon1 c.465delG p. E155Efs*43
|
+
|
+
|
+
|
↑
|
NA
|
6
|
Male
|
4.0
|
ABCD1
|
exon1 c.650A >c p. K217T
|
+
|
+
|
+
|
↑
|
NA
|
7
|
Male
|
6.3
|
ABCD1
|
exon 3–10 del
|
+
|
+
|
+
|
↑
|
NA
|
8
|
Male
|
7.2
|
ABCD1
|
exon 1 c.529C >T p. Q177X
|
+
|
+
|
+
|
↑
|
NA
|
9
|
Male
|
7.7
|
ABCD1
|
exon 10 c.2006A > G p.H669R
|
+
|
+
|
+
|
↑
|
NA
|
10
|
Female
|
7.5
|
GALC
|
exon 8 c.812G > A p. W271X
exon 1 c.136G > T p. D46Y
|
+
|
+
|
NA
|
NA
|
4.76$
(12.89–100.93)
|
11
|
Female
|
–
|
GALC
|
exon 8 c.812G > A p. W271X
exon 1 c.136G > T p. D46Y
|
−
|
−
|
NA
|
NA
|
6.47$
(12.89–100.93)
|
12
|
Male
|
4.3
|
GALC
|
exon 10 c.1090T > G p. L364V
exon 1 c.136G > T p. D46Y
|
+
|
+
|
NA
|
NA
|
2.11$
(12.89–100.93)
|
NA, not applicable; MRI, magnetic resonance imaging; VLCFA, very-long-chain fatty acids
UCBT Data and Conditioning Regimen
Unrelated UCB was provided by the Chinese Cord Blood Bank with HLA matching at a minimum of 7/10 loci (Table 2) according to high-resolution typing identity of A, B, Cw, DRB1, and DQ. The median total nucleated cell (TNC) infused dose was 4.9 × 107/kg (range, 3.0 × 107 to 15.3 × 107/kg), and the median CD34+ cell dose was 1.55 × 105/kg (range, 0.37 × 105 to 19.95 × 105/kg). The conditioning regimen included intravenous busulfan (BU, 12.8 mg/kg to 16 mg/kg), fludarabine (Flu, 150 mg/m2), and cyclophosphamide (CY, 100 mg/kg). Rabbit anti-human thymocyte immunoglobulin (ATG, 5 mg/kg) was used in ten patients. Oral tacrolimus (FK506) was administered starting 4 days before transplantation to prevent graft versus host disease (GvHD). The target concentration of FK506 was 5–10 ng/mL. In addition to FK506, mycophenolate mofetil (MMF) was administered to the patient (p5) receiving UCB with 7/10 HLA matching on the first day post-transplantation. The median age at UCBT was 7.2 years (range, 0.8 to 12.9 years) and median body weight at UCBT was 24.3 kg (range, 8.5 to 38 kg). See Table 2 for details of each procedure.
Table 2. Basic characteristics of each umbilical cord blood stem cell transplantation procedure
Patient
|
UCBT age (years)
|
UCBT weight (kg)
|
HLA matching
|
TNC/kg
× 107
|
CD34+/kg
× 105
|
Conditioning regimen
|
GvHD prophylaxis
|
1
|
8.8
|
38
|
8/10
|
5.2
|
1.25
|
BU/FLU/CY
|
FK506
|
2
|
7.8
|
25
|
10/10
|
3.4
|
0.37
|
BU/FLU/CY
|
FK506
|
3
|
6.2
|
24
|
8/10
|
4.4
|
0.57
|
ATG+BU/FLU/CY
|
FK506
|
4
|
5.5
|
17.5
|
8/10
|
7.2
|
1.34
|
ATG+BU/FLU/CY
|
FK506
|
5
|
12.9
|
36
|
7/10
|
3.8
|
1.22
|
ATG+BU/FLU/CY
|
FK506/MMF
|
6
|
5.0
|
20
|
8/10
|
6.4
|
3.20
|
ATG+BU/FLU/CY
|
FK506
|
7
|
6.5
|
23.5
|
8/10
|
5.2
|
0.82
|
ATG+BU/FLU/CY
|
FK506
|
8
|
8.2
|
24.5
|
8/10
|
4.6
|
3.29
|
ATG+BU/FLU/CY
|
FK506
|
9
|
8.2
|
38
|
9/10
|
3.0
|
1.76
|
ATG+BU/FLU/CY
|
FK506
|
10
|
8.0
|
22
|
10/10
|
5.3
|
7.32
|
ATG+BU/FLU/CY
|
FK506
|
11
|
0.8
|
8.5
|
9/10
|
15.3
|
19.95
|
ATG+BU/FLU/CY
|
FK506
|
12
|
4.5
|
24.5
|
8/10
|
3.7
|
3.22
|
ATG+BU/FLU/CY
|
FK506
|
UCBT, umbilical cord blood stem cell transplantation; HLA, human leukocyte antigen; ATG, antithymocyte globulin; Bu, Busulphan; Cy, Cyclophosphamide; Flu, Fludarabine; MMF, mycophenolate mofetil
Chimerism and Hematopoietic Reconstitution Post-UCBT
All patients demonstrated complete donor chimerism (CDC) by day +14, and the chimerism was stable during follow-up. The median neutrophil engraftment time was 20 days (range, 12 to 33 days) and the median platelet engraftment time was 29 days (range, 14 to 65 days) after transplantation.
Prognosis and Transplant-related Complications
The median follow-up time after UCBT was 28 months (range, 1 to 73 months). Of the 12 patients treated, two died (both with ADL), one of severe pneumonia complicated by sepsis within one month after UCBT and the other of severe pneumonia due to rapid progression of neurological symptoms five months after UCBT, for an overall survival rate of 81.8%. Four patients (33.3%) developed grade II acute GvHD, and all responded to methylprednisolone therapy. There were no cases of chronic GvHD. Half of the patients developed pulmonary infection after transplantation, including the two fatalities. Four cases developed cytomegalovirus (CMV) viremia, all of which responded to ganciclovir and/or foscarnet as confirmed by negative CMV-DNA tests. Two patients (16.7%) developed delayed hemorrhagic cystitis caused by BK virus infection, and both cases gradually eased after hydration, dieresis, and indwelling catheterization. Two patients (16.7%) developed urinary tract infections after transplantation that were successfully treated with sensitive antibiotics. Finally, one male patient developed autoimmune hemolytic anemia after transplantation that was controlled by plasma exchange, rituximab, and methylprednisolone. However, neurological symptoms deteriorated rapidly. See Table 3 for details of post-UBCT complications and treatments.
Table 3. Outcomes and complications of UCBT
Patient
|
Engraftment
|
Chimerism
|
Neutrophil engraftment day
|
Platelet engraftment day
|
GvHD
|
Complication
|
Outcome
(months post-UCBT)
|
1
|
Engrafted
|
CDC
|
19
|
22
|
I
|
Pulmonary fungal infection
|
Alive (73)
|
2
|
Engrafted
|
CDC
|
32
|
-
|
-
|
Severe pneumonia, septic shock
Gastrointestinal hemorrhage
|
Died (1)
|
3
|
Engrafted
|
CDC
|
33
|
37
|
I
|
None
|
Alive/well# (41)
|
4
|
Engrafted
|
CDC
|
21
|
26
|
II
|
Urinary tract infection
Pneumonia, CMV viremia
|
Alive (38)
|
5
|
Engrafted
|
CDC
|
22
|
43
|
II
|
Severe pneumonia (Klebsiella pneumoniae, Candida tropical)
Septic shock
CMV viremia
|
Died (5)
|
6
|
Engrafted
|
CDC
|
12
|
14
|
I
|
Severe pneumonia (Acinetobacter baumannii)
CMV viremia
AIHA
|
Alive (30)
|
7
|
Engrafted
|
CDC
|
18
|
29
|
II
|
Hemorrhagic cystitis
|
Alive (26)
|
8
|
Engrafted
|
CDC
|
24
|
35
|
I
|
None
|
Alive (21)
|
9
|
Engrafted
|
CDC
|
19
|
29
|
II
|
Hemorrhagic cystitis,
Pneumonia
|
Alive (18)
|
10
|
Engrafted
|
CDC
|
16
|
17
|
I
|
Urinary tract infection
|
Alive (46)
|
11
|
Engrafted
|
CDC
|
25
|
37
|
I
|
None
|
Alive/well# (37)
|
12
|
Engrafted
|
CDC
|
14
|
65
|
I
|
CMV viremia
|
Alive (20)
|
AIHA, autoimmune hemolytic anemia; CDC, complete donor chimerism; # Nervous system asymptomatic
Comparison of Neurologic Function Score, Performance Status, and Loes Score Pre-UCBT and Post-UCBT
Neurologic function, PS, and Loes scores were evaluated before and regularly after transplantation. Eight patients with ALD (all except p3) and two patients with GLD (all except p11) demonstrated neurological impairments of varying severity before transplantation (NFS range, 1–17 points), and two of these patients (both with ALD) died after UCBT. Eleven patients (all except p2) were followed-up for at least three months after transplantation, and all showed varying degrees of neurologic symptom aggravation. In patient 6, neurologic symptoms deteriorated markedly after transplantation (6 points before transplantation to 9 points three months after transplantation to 24 points six months after transplantation) due to severe autoimmune hemolytic anemia, and there was no significant recovery during follow-up. Among the remaining seven patients (p1, p3, p4, p6–p9), the NFS of p1 was similar to pre-UBCT baseline at 5 years follow-up (Figure 1 for details). All other ALD cases demonstrated different degrees of brain damage before transplantation as measured by Loes scoring of magnetic resonance images, and most exhibited further increases in brain lesion severity after UCBT with stabilization by nine months post-treatment.
Two female patients (p10 and p11) with GLD were siblings. The neurological symptoms of the elder sibling (p10) progressed slowly before and after transplantation as evidenced by stable NFS and PS. Similarly, the younger sibling (p11) had no imaging lesions or nervous system involvement before or after UCBT. Another male (p12) with GLD was also neurologically stable before and after UCBT, although the Loes score increased slightly after transplantation. The changes in Loes scores for each patient throughout the treatment period are shown in Figure 2. Finally, the PS of six patients (p3, p7, p8, p10, p11, and p12) was stable after UCBT, while all other patients demonstrated different degrees of PS deterioration (Table 4).
Table 4. Performance status scores of patients with heredity leukodystrophy pre-UCBT and post-UCBT
Patient
|
PS pre-UCBT
|
PS post-UCBT&
|
1
|
70
|
50
|
2
|
80
|
0
|
3
|
100
|
100
|
4
|
50
|
40
|
5
|
60
|
0
|
6
|
50
|
40
|
7
|
100
|
100
|
8
|
80
|
80
|
9
|
50
|
40
|
10
|
80
|
80
|
11
|
100
|
100
|
12
|
80
|
80
|
performance status scores (PS) by Lansky 14; &at last follow-up
Changes in Lipid Metabolism
The serum VLCFA concentrations of most surviving ALD patients (except p4) were measured regularly following treatment. Both absolute C26:0 concentration and the C26:0/C22:0 ratio were significantly reduced one year post-UCBT (Figure 3), indicating partial restoration of ABCD1 activity.