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