Immune reconstitution and survival of 100 SCID patients post-hematopoietic cell transplant: a PIDTC natural history study.

The Primary Immune Deficiency Treatment Consortium (PIDTC) is enrolling children with severe combined immunodeficiency (SCID) to a prospective natural history study. We analyzed patients treated with allogeneic hematopoietic cell transplantation (HCT) from 2010 to 2014, including 68 patients with typical SCID and 32 with leaky SCID, Omenn syndrome, or reticular dysgenesis. Most (59%) patients were diagnosed by newborn screening or family history. The 2-year overall survival was 90%, but was 95% for those who were infection-free at HCT vs 81% for those with active infection (P = .009). Other factors, including the diagnosis of typical vs leaky SCID/Omenn syndrome, diagnosis via family history or newborn screening, use of preparative chemotherapy, or the type of donor used, did not impact survival. Although 1-year post-HCT median CD4 counts and freedom from IV immunoglobulin were improved after the use of preparative chemotherapy, other immunologic reconstitution parameters were not affected, and the potential for late sequelae in extremely young infants requires additional evaluation. After a T-cell-replete graft, landmark analysis at day +100 post-HCT revealed that CD3 < 300 cells/µL, CD8 < 50 cells/µL, CD45RA < 10%, or a restricted Vß T-cell receptor repertoire (<13 of 24 families) were associated with the need for a second HCT or death. In the modern era, active infection continues to pose the greatest threat to survival for SCID patients. Although newborn screening has been effective in diagnosing SCID patients early in life, there is an urgent need to identify validated approaches through prospective trials to ensure that patients proceed to HCT infection free. The trial was registered at www.clinicaltrials.gov as #NCT01186913.

Long-term clinical outcome of patients with severe combined immunodeficiency who received related donor bone marrow transplants without pretransplant chemotherapy or post-transplant GVHD prophylaxis.

OBJECTIVE: To determine long-term health benefits of nonablative bone marrow transplantation for severe combined immunodeficiency (SCID), we investigated our cohort of 161 related donor bone marrow-transplanted patients with SCID. Only 16 (10%) had HLA-identical donors. STUDY DESIGN: All 124 survivors were sent questionnaires about their current clinical statuses. Details from clinic visits were also compiled. One hundred eleven patients (90%) were reached. We compared outcomes of patients transplanted before and after 3.5 months of life and by molecular defect. RESULTS: The overall survival rate was 77%, but the rate for the 48 infants transplanted in the first 3.5 months of life was 94%, compared with 70% for the 113 transplanted after 3.5 months (P = .002). Twenty-eight (76%) of the 37 deceased patients died of viral infections present at diagnosis. One or more clinical problems were reported to have been present in the past 2 years in 71 (64%) of the survivors, although 95 (86%) were considered healthy by their families. CONCLUSIONS: Most patients with SCID transplanted with related donor marrow without pretransplant chemotherapy have done well in the long term, but those transplanted at <3.5 months of age had a superior survival rate, a lower rate of clinical problems, less need for booster transplants, and better nutritional status.