severe combined immunodeficiency syndrome a heterogeneous group of congenital disorders which...
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Severe Combined Immunodeficiency Syndrome
• A heterogeneous group of congenital disorders which results in the absence of antigen-specific T and B cell responses
1/50-100, 000 live births
Newborn screening estimate now 1/30-40,000 live birth Athabascan-speaking Native Americans, an incidence of
52/100,000 live births
• Early classification based on presence or absence of adenosine deaminase and the % and absolute numbers of T, B, and NK cells
Genetic mutations associated with SCIDGene Function Phenotype Chromosomal
location Year
Published
ADA Purine salvage enzymeRecycles adenosine and
deoxyadenosine after DNA breakdown
T, B-, NK+ 20q12-13 1972
TCR abn Signaling through TCR Tlo, B+,NK+ 11q23 1987g chain Common g chain
(IL-2,4,6,15,21)T-,B+, NK- Xq13 1993
ZAP 70 Tyrosine Kinase
CD8 def 2q12 1994
Janus kinase- 3 Tyrosine kinase Signaling through gC
T-, B+, NK- 19p13 1995
RAG1, RAG-2•Omenn's syndrome
Recombinase activating genes
initiation of VDJ recombination
T-B-NK+
T+, B-,NK+
11p13 1996
IL7-Ra Cytokine Receptor T-, B+, NK+ 5p13 1998Artemis DNA repair enzyme T-B-NK+ 10p 1998
Mutations associated with SCIDGene GENE
FUNCTIONCommon
PhenotypeChromosoma
l location Year
published
CD45 TYROSINE KINASE
T-,B+,NK low Chr 1 2000
DNA ligase IV DNA REPAIR ENZYME
T(low),B+, NK+
11q23 2001
IL-2R/IL-15b subunit
Cytokine receptor subunit
T (low) B+ NK-
Unk 2001
FOXP3 Mutations
IPEX
T reg deficiency
Immune dysfunction
polyendocrinopathyEnteropathy
X linkedAuto
variants
2001
Adenylate kinase 2
AK2Reticular
dysgenesis
mitochondrial intermembrane
space, stria vascularis region of the inner ear
T-B-NK+/-Absent
neutrophilsDeafness
1p31–p34 2009
Diagnosis and Outcome of infants identified by newborn Screening
Diagnosis Evaluation Treatment Outcome Outcome
#1 ADA deficiencynow 17 months old
34 lymphs/ul PEG ADA Normal T cell function
VaccinatedSuccessfully
#2 X linked+ FHNow 16 months
B+, NK+, T- TCD HLA-MM Related BMT
Normal T cell function
#3 ADA deficiencyNow 16 months old
117 lymphs/ul85% NK, 15% B
PEG ADA Normal T cell function
VaccinatedSuccessfully
#4 Normal NL phenotype NL T cell func NL B cell function
#5 Transient T lymphopeniaNow 9.5 months old
CD3-233/ul T cell numbersNormalized
NL T cell function VaccinatedSuccessfullyIgG3 deficient
#6 T lymphopeniaNL ADA, IL-7R, nl NL CD3 , d eNow almost 9m
CD3:741/ul, inc BCD4:613/ulCD8:117/ul
T cell numbersIncreasing but not normal
NL T cell function VaccinatedSuccessfully
#7 X linked Now 4 months old
B+, NK+, T- TCD HLA –MM RelBMT
3+ m, wellNo GVHD
T cells coming in
#8 Likely X-linkedNL ADA, PNP
3 weeks old
ALC 1450, B 1450/ulNo T, NK 29/ul
Being HLA typed Pre HCT
Laboratory Evaluation
Lymphoid phenotypePHA, MLC, NK functionADA and PNP levelsImmunoglobulin levelsHIV Ab parents, HIV PCR childHLA Class I and Class II expression+/- phenotyping for CD127 (IL-7R)or
CD132 (IL-2g chain) if consistent phenotype
Response to PEG-ADA• 20% show no response• Majority see T cell immune response in
the short term but it wanes with time• B cell immunity, 50% will need continued
IVIG– B cell numbers increase within a few weeks of
therapy– T cell numbers may require several months to
increase
0 5 10 150
100
200
300
400
500
600 #CD3 #CD4 #CD8
#CD56
Age (months)
Cel
ls/u
l
0 5 10 150
100
200
300
400
500
600
#CD3 #CD4 #CD8
#CD56
Age (months)
Cel
ls/u
l
#CD19 B cells
0 5 10 150
500
1000
1500
2000
2500
Age (months)
Cel
ls/u
l
#C19 B cells/ul
0 5 10 150
200
400
600
Age (months)
Cel
ls/u
l
RESPONSE TO PEG-ADA in two infants identified by NBS
0 5 10 150
50000
100000
150000
200000
Age (months)
CP
M
0 5 10 150
50000
100000
150000
200000
250000
PHA responsePatient #2LLN:>109,000
Age (months)
CP
M
PHA ResponsePatient #1LLN:>109,000
Tet Diph Pert HIB
Pre 0.81 1.01 6
Post 3.43 1.39 403
PRE1(0.6)3(1.40)4(0.0)14(3.4)19(2.0)23(0.9)6B(1.20) 7F(1.3)18c(0.90)
POST PCV13x3
1(8.1)3(>37.6)4(6.5)14(2.1)19(7.4)23(3.3)6B(11.8)7F(33.9)18C(12.3)
Tet Diph Pert HIB
Pre 1.21 0.6 5 1.61
Post 6.79 >2.5 37 >9
PRE1(0.8)3(>37.5)4(0.5)14(2.1)19(1.2)23(0.6)6B(0.7)7F(4.4)18c(0.6)
POST PCV13x3
1(9.3)3(34.4)4(4)14(1.6)19(6.4)23(1.3)6B(3.9)7F(18.1)18c(6.6)
Response to PEG-ADA
Results of HCT for ADA deficiency
Publication HLA MSIB Alternative donor
Eur Experience*
81%, n=19 29%, n=26
MSKCC none 50%, n=8
Ulm, Munich 100%, n=7 63%, n=8
81-100% 29%-63%
*50% survivors had neurologic deficits
Newborn Screening Allows early identification and treatment of affected infants
EFS if HCT <2 months of age: 90-100% Currently how well young infants tolerate cytoreduction is
unknown How much cytoreduction to ensure B cell engraftment unknown
NBS also uncovers infants who may have transient lymphopenia or immune defects that previously were unrecognized and may or may be associated with an increased risk of infection.
Need to determine best way to inform parentsCurrent literature needs to be translated into multiple languagesAvailable literature for parents is either too simplistic or too complicated
Patient # 1
0 2 4 6 8 100
1000
2000
3000
4000
5000Total lymphs#CD3#CD4#CD8#CD19#CD56
Months of age
Ab
so
lute
nu
mb
er/
ul
Serum Ig levels
0 2 4 6 8 100
200
400
600IgGIgAIgM
Months of age
mg
/dl
Percentage CD4+CD45RA+ cells
0 2 4 60.0
0.2
0.4
0.6
0.8
1.0
Age (months)
Perc
en
tag
e
Absolute numbers of CD4+ CD45RA+ cells
0 2 4 60
500
1000
1500
Age (months)
cell
s/u
l
Normal TRECS
No TRECS
Longitudinal lymphoid phenotype of female child with low-absent TRECS on newborn screen
Lymphoid phenotype and function
Age ALC CD3 CD4 CD8 CD19 CD56
%CD4/CD45RA
PHA OKT3
2 months 1750 228 140 53 735 770
160,143 13, 478
2.5 months 1966 550 354 177 1219 216 0.33 189, 056
3 months 2674 856 508 321 1444 508 0.47
3.9 months 2700 1161 675 459 1269 351 0.72
5. 1 months 4090 2536 1594 900 1268 286 0.79
T Lymphopenia, normal functionNL antibody response
0 1 2 3 4 50
100200300400500600700800900
1000#CD3#CD4#CD8#CD56
Age (months)
Cel
ls/u
l
CD19 Bcells
0 1 2 3 4 50
250
500
750
1000
1250
1500
Age (months)
Cel
ls/u
l
Age at test
PHALLN 109, 576
OKT3LLN 3, 715
CandidaLLN: 6624
Tetanus ToxoidLLN:2417
Vaccine Responses
1.9 m 262881 101032 3283
2.6m 144050 77453
4.2m 100222 1050
5.7m 185539 31749 4673 6614
+ Response to Tetanus, Pertussis, Diphtheria
PCV13, HIB
Longitudinal immune phenotype and function of female infant with low but detectable TRECs on newborn screen
Why do children with SCID ever need cytoreduction
Effect of pre-HCT NK function on engraftment following TCD MM-
related SBA- E- BMT in the absence of cytoreduction
To ensure donor B cell engraftment
To prevent graft rejection in patients with NK activity
via KIR pathways
In pts with ADA deficiency-to ensure 100% donor chimerism including red cell lineage
To prevent T cell mediated graft rejection in those with PHA >5% LLN
PREHCTNKfunction
Engrafted Failed toengraft
Absent 14/14 0/14
Present 1/8 7/8
CHI-SQUARE=17.9, p <.001
Results of unmodified HLA-matched related BMT
• Matched sibling transplant remains the treatment of choice• Cytoreduction or GVHD prophylaxis generally unnecessary• European Experience 1968-1999: 81%, n=104,
– ADA def: 81%, Reticular Dysgenesis: 75%-HLA matched BMT
• Single Center – MSKCC: 1971-2011, 87.5% survival, n=16– Hopital Necker-Enfants Malades 1971-92, 80%
survival, n=30– Univ of Ulm: 81% survival, n=21– DUMC: 1982-98, 100% survival, n=12– Univ of Brescia: >80%, n=35
T and B cell function following unmodified HLA-matched BMT for SCID
Normal T cell numbers rapidly restored 2-4 weeks
Normal T cell mitogen and specific antigen responses restored
B cell function returns by one year post transplant pre HCT 1-29d 30-59d 60-89d
0
500
1000
1500
2000 Pt #1
Pt #2
Pt #3
Pt #4
What about patients who lack HLA matched sibling donor
TCD HLA Mismatched BMT Depending on efficiency of T cell depletionCurrent outcomes: 70-80%, and if HCT <2 months:
90-100%Low incidence of GVHDParent readily available
Probability of Overall Survival after Unrelated Donor Transplants for SCID, 1990-2004, n=200
Pro
bab
ilit
y
Years
0 1 2 3 4 50.0
0.2
0.4
0.6
0.8
1.0
Overall survival, 60% (95% CI 52-67) @ 5 years
No significant advantage over parental T cell depleted HLA non-identical marrow grafts when comparable preparative regimens are used
Potential risk of infectious complications due to time needed to procure a donor
Increased Risk of GVHD
Probability of Overall Survival after Unrelated Donor Transplants for SCID, 1990-2004, n=200
Pro
bab
ilit
y
Years
0 1 2 3 4 50.0
0.2
0.4
0.6
0.8
1.0
Overall survival, 60% (95% CI 52-67) @ 5 years
No significant advantage over parental T cell depleted HLA non-identical marrow grafts when comparable preparative regimens are used
Potential risk of infectious complications due to time needed to procure a donor
Increased Risk of GVHD
Probability of Overall Survival after Unrelated Donor Cord Blood Transplants for SCID, 1990-
2005, n=76, CIBMTR
Pro
bab
ilit
y o
f su
rviv
al
Years Post HCT
0 1 2 3 4 50.0
0.2
0.4
0.6
0.8
1.0
Overall survival, 57% (95% CI 44-69) @ 5 years
CIBMTR data, 2007
Immediately available unlike MUD HCTViral naïve, CMV seronegativeLess acute and chronic GVHD despite 1-2 Ag MMNo clear advantage over HLA MM-Rel HCT Higher risk of GHVD, appox 25% aGVHD, 13% chronic
Immune Function
• 50% of children have normal T cell function in the first 6 months post BMT
• 80% have normal T cell function by 6 to 12 months post BMT
• However, without cytoreduction, lack of donor B cell engraftment, IVIG dependent
Recovery of T cells post SBA- E- parental BMT for SCID
0-1m
1-2m
2-3m
3-4m
4-5m
5-6m
6-9m
9-12m
12-18m
18-24
m
24-3
6m
36-4
8m
48-6
0m
60-72m
72-84m
10
100
1000
10000
SCID, with cytoreduction
SCID, without cytoreduction
Months post Mis-related parental TCD BMT for SCID
Med
ian
CD
3+ c
ell c
oun
t
Recovery of CD4+ T cells post SBA- E- parental BMT for SCID
0-1m
0-3m
3-6m
6-9m
9-12
m
12-1
8m
18-2
4m
24-3
6m
36-4
8m
48-6
0m
60-7
2m
72-8
4m
84-9
6m0
400
800
1200
1600
2000SCID, with cytoreduction
SCID, without cytoreduction
Months post Mis-related parental TCD BMT for SCID
Med
ian
CD
4+ c
ell c
oun
t
0
100
200
300
400
500
600
700
800
CD
4+
RA
+ T
ce
lls
pe
r µ
l
HLA MATCHED SIBLING HLA MM RELATED HLA MM RELATED No cytoreduction With cytoreduction
Numbers of circulating naive CD4+ T cells post HCT For SCID
Comparison of the percentage of children with normal PHA post SBA- E- BMT for SCID: With and Without pre-
transplant cytoreduction
0-6m6-12m
12-18m18-24m
24-36m36-48m
48-60m60-72m
0
20
40
60
80
100
Median serum IgG Levels post Mis-matched TCD BMT for SCID
0-6M 6-12M 12-18M 18-24M 24-36M 36-48M0
200
400
600
800
1000
1200CYTONON-CYTO
Median serum IgA Levels post Mis-matched TCD BMT for SCID
0-6m 6-12m 12-18m 18-24m 24-36m 36-48m0
50
100CYTONON-CYTO
Conclusions and Future directions
The majority of children with SCID can be cured by a HCT providing it is performed early
Primary immunodeficiency Treatment Consortium (PIDTC) Retrospective study to determine variables associated with
outcome Prospective study to determine outcome of patients identified
through newborn screeningHCTGene therapyPEG-ADA
Trial under development to determine lowest amt of cytoreduction to ensure T and B cell engraftment
Need to determine the best way to inform parents of NBS which require further evaluation
Need to develop ways to promptly direct parents to centers which can quickly evaluate and treat children with PID