Developmental biology - Immune Disorders|
Treating 'Bubble Baby' Diseases
An international study identifies ways to improve chances of child survival with a rare immune deficiency...
An international research study has combed through severe combined immune deficiency (SCID) patient records from 1982 to 2012 to identify what improved the chances of survival of children with the rare immune disorder. Published in the journal Blood, the research was led by Elie Haddad MD PhD, a pediatric immunologist at CHU Sainte-Justine and professor at Université de Montréal. The work highlights the urgent need for better treatment strategies for patients suffering from SCIDs.
This deficiency, better known as "bubble baby disease" is a rare syndrome characterized by total non-function of the body's immune system. Children affected have no immune defence and are vulnerable to bacteria, viruses and fungi, with repeated severe infections. Without appropriate treatment, in most cases this disease is fatal within the first months after birth.
SCID can be caused by mutations in various genes involved in the functioning of the immune system. New research shows that the nature of the mutated gene (or genotype) has a significant influence on patients' survival and reconstitution of their immune system after bone marrow transplant.
44 Medical Centres Involved
Funded by the U.S. National Institutes of Health, the Primary Immune Deficiency Treatment Consortium (PIDTC) involves 44 medical centers across North America. The PIDTC conducted this retrospective analysis of 662 patients with SCID who received hematopoietic stem cell transplants as their first therapy - these are stem cells that give rise to blood cells. Data was collected from cases in 33 of the 44 centers.
Results of the study showed survival:
• was higher from a matched sibling donor
• youth and absence of active infection were key
• SCID genotype influenced reconstitution (86%)
Explains Dr. Haddad: "Immune diseases are among the top priorities at CHU Sainte-Justine in terms of care, teaching and research. Although there are only one or two cases of SCID per year in Quebec, having access to such a cohort of patients with this rare disease - and over such a long period - has provided us with significant and unique data advancing our treatment."
Critical Need for Neonatal Screening
"We need to develop patient-specific treatment strategies. There is a critical need for neonatal screening to establish appropriate isolation, implement infection-prevention measures — particularly before transplantation — and ensure rapid referral for bone-marrow transplant or gene therapy after diagnosis."
Elie Haddad MD PhD, Pediatric Immunologist, CHU Sainte-Justine, Professor, Université de Montréal, Canada.
The study also points to the need for close monitoring of immune-system reconstitution after treatment to identify patients with conditions that may require additional intervention and prevent a poor long-term prognosis.
Further studies will be needed to identify patient and transplant-related factors that limit early immune-system reconstitution, and to determine the most appropriate and effective interventions.
Haddad: "In our future research, our objective will be to analyze the late effects of conditioning and the quality of long-term immune-system reconstitution after hematopoietic cell transplant for this deficiency."
• The genetic cause of SCID impacts survival and immune reconstitution, and should be considered in tailoring HCT for individual patients.
• Total and naïve CD4+ cell counts in SCID patients 6 and 12 months post-HCT predict long-term survival and sustained immune reconstitution.
The Primary Immune Deficiency Treatment Consortium (PIDTC) performed a retrospective analysis of 662 patients with severe combined immunodeficiency (SCID) who received a hematopoietic cell transplantation (HCT) as first-line treatment between 1982 and 2012 in 33 North American institutions. Overall survival was higher after HCT from matched-sibling donors (MSDs). Among recipients of non-MSD HCT, multivariate analysis showed that the SCID genotype strongly influenced survival and immune reconstitution. Overall survival was similar for patients with RAG, IL2RG, or JAK3 defects and was significantly better compared with patients with ADA or DCLRE1C mutations. Patients with RAG or DCLRE1C mutations had poorer immune reconstitution than other genotypes. Although survival did not correlate with the type of conditioning regimen, recipients of reduced-intensity or myeloablative conditioning had a lower incidence of treatment failure and better T- and B-cell reconstitution, but a higher risk for graft-versus-host disease, compared with those receiving no conditioning or immunosuppression only. Infection-free status and younger age at HCT were associated with improved survival. Typical SCID, leaky SCID, and Omenn syndrome had similar outcomes. Landmark analysis identified CD4+ and CD4+CD45RA+ cell counts at 6 and 12 months post-HCT as biomarkers predictive of overall survival and long-term T-cell reconstitution. Our data emphasize the need for patient-tailored treatment strategies depending upon the underlying SCID genotype. The prognostic significance of CD4+ cell counts as early as 6 months after HCT emphasizes the importance of close follow-up of immune reconstitution to identify patients who may need additional intervention to prevent poor long-term outcome.
Elie Haddad, Brent R. Logan, Linda M. Griffith, Rebecca H. Buckley, Roberta E. Parrott, Susan E. Prockop, Trudy N. Small, Jessica Chaisson, Christopher C. Dvorak, Megan Murnane, Neena Kapoor, Hisham Abdel-Azim, Imelda C. Hanson, Caridad Martinez, Jack J. H. Bleesing, Sharat Chandra, Angela R. Smith, Matthew E. Cavanaugh, Soma Jyonouchi, Kathleen E. Sullivan, Lauri Burroughs, Suzanne Skoda-Smith, Ann E. Haight, Audrey G. Tumlin, Troy C. Quigg, Candace Taylor, Blachy J. Dávila Saldaña, Michael D. Keller, Christine M. Seroogy, Kenneth B. Desantes, Aleksandra Petrovic, Jennifer W. Leiding, David C. Shyr, Hélène Decaluwe, Pierre Teira, Alfred P. Gillio, Alan P. Knutsen, Theodore B. Moore, Morris Kletzel, John A. Craddock, Victor Aquino, Jeffrey H. Davis, Lolie C. Yu, Geoffrey D. E. Cuvelier, Jeffrey J. Bednarski, Frederick D. Goldman, Elizabeth M. Kang, Evan Shereck, Matthew H. Porteus, James A. Connelly, Thomas A. Fleisher, Harry L. Malech, William T. Shearer, Paul Szabolcs, Monica S. Thakar, Mark T. Vander Lugt, Jennifer Heimall, Ziyan Yin, Michael A. Pulsipher, Sung-Yun Pai, Donald B. Kohn, Jennifer M. Puck, Morton J. Cowan, Richard J. O'Reilly and Luigi D. Notarangelo.
"SCID genotype and 6-month post-transplant CD4 count predict survival and immune recovery," was selected as a "plenary paper," i.e. a study of major scientific importance, and is accompanied by an editorial. Dr. Haddad is a clinician-scientist in clinical immunology at CHU Sainte-Justine and a full professor in the Department of Pediatrics at Université de Montréal; he is also a member of the steering committee of the Primary Immune Deficiency Treatment Consortium. Drs. Hélène Decaluwe, Fabien Touzot and Pierre Teira are among the clinicians at CHU Sainte-Justine also involved in the consortium, which is funded by the U.S. National Institutes of Health.
Return to top of page
Nov 23, 2018 Fetal Timeline Maternal Timeline News News Archive
David Phillip Vetter (September 21, 1971 – February 22, 1984) was an American boy who spent 12 years in isolation to prevent any enviromental exposure that might compromise his severe combined immunodeficiency (SCID), a hereditary disease that dramatically weakens the immune system. Credit: Immune Deficiency Foundation IDF