New Insights Into Multicenter PICU Mortality Among Pediatric Hematopoietic Stem Cell Transplant Patients

OBJECTIVES

Over 2,500 children undergo hematopoietic stem cell transplantation in the United States each year, and up to 35% require PICU support for life-threatening complications. PICU mortality has dropped from 85% to 44%, but interpretation is confounded by significant cohort heterogeneity. Reports conflict regarding outcomes for patients with different underlying hematopoietic stem cell transplantation indications, and the burden of infectious complications for these patients has not been evaluated. We aim to describe infections, critical care interventions, and mortality for pediatric hematopoietic stem cell transplantation patients requiring PICU admission.

DESIGN

A retrospective multicenter cohort analysis.

SETTING

One hundred twelve centers in the Virtual PICU Systems database, January 1, 2009, to June 30, 2012.

PATIENTS

A total of 1,782 admissions for patients who are 21 years old or younger with prior hematopoietic stem cell transplantation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Pediatric Index of Mortality-2, Pediatric Risk of Mortality-3, transplant indication, infections, interventions, and mortality were recorded from admission through PICU death or discharge. Pediatric hematopoietic stem cell transplantation patients comprised 0.7% of all PICU admissions (1,782/246,346), which resulted in 16.2% mortality compared with 2.4% mortality for non-hematopoietic stem cell transplantation admissions (odds ratio, 7.8; 95% CI, 6.8-8.8; p < 0.001). Mortality for admissions with underlying hematologic malignancy (22.7%) was similar to that of admissions with primary immunodeficiency (19.4%; p = 0.41) but significantly greater than admissions with underlying nonmalignant non-primary immunodeficiency hematologic disease (15.4%; p = 0.020), metabolic disorder (8.1%; p < 0.001), or solid malignancy (5.7%; p < 0.001). Infection was documented in 45.7% of admissions with 22.2% mortality; viral and fungal mortality were 28.5% and 33.7%, respectively. Invasive positive pressure ventilation and renal replacement therapy were used in only 34.6% and 11.9% of admissions, with mortality of 42.5% and 51.9%, respectively.

CONCLUSIONS

PICU mortality for pediatric hematopoietic stem cell transplantation patients may be as low as 16.2% but higher for those receiving intubation (42.5%) or replacement therapy (51.9%). Hematologic malignancy and primary immunodeficiency had greater risk for mortality than other transplant indications. Greater understanding of other risk factors affecting mortality and the need for critical care support is needed.

Radiation-sensitive severe combined immunodeficiency: The arguments for and against conditioning before hematopoietic cell transplantation--what to do?

Defects in DNA cross-link repair 1C (DCLRE1C), protein kinase DNA activated catalytic polypeptide (PRKDC), ligase 4 (LIG4), NHEJ1, and NBS1 involving the nonhomologous end-joining (NHEJ) DNA repair pathway result in radiation-sensitive severe combined immunodeficiency (SCID). Results of hematopoietic cell transplantation for radiation-sensitive SCID suggest that minimizing exposure to alkylating agents and ionizing radiation is important for optimizing survival and minimizing late effects. However, use of preconditioning with alkylating agents is associated with a greater likelihood of full T- and B-cell reconstitution compared with no conditioning or immunosuppression alone. A reduced-intensity regimen using fludarabine and low-dose cyclophosphamide might be effective for patients with LIG4, NHEJ1, and NBS1 defects, although more data are needed to confirm these findings and characterize late effects. For patients with mutations in DCLRE1C (Artemis-deficient SCID), there is no optimal approach that uses standard dose-alkylating agents without significant late effects. Until nonchemotherapy agents, such as anti-CD45 or anti-CD117, become available, options include minimizing exposure to alkylators, such as single-agent low-dose targeted busulfan, or achieving T-cell reconstitution, followed several years later with a conditioning regimen to restore B-cell immunity. Gene therapy for these disorders will eventually remove the issues of rejection and graft-versus-host disease. Prospective multicenter studies are needed to evaluate these approaches in this rare but highly vulnerable patient population.

Role of transgene regulation in ex vivo lentiviral correction of artemis deficiency

Artemis is a single-stranded endonuclease, deficiency of which results in a radiation-sensitive form of severe combined immunodeficiency (SCID-A) most effectively treated by allogeneic hematopoietic stem cell (HSC) transplantation and potentially treatable by administration of genetically corrected autologous HSCs. We previously reported cytotoxicity associated with Artemis overexpression and subsequently characterized the human Artemis promoter with the intention to provide Artemis expression that is nontoxic yet sufficient to support immunodevelopment. Here we compare the human Artemis promoter (APro) with the moderate-strength human phosphoglycerate kinase (PGK) promoter and the strong human elongation factor-1α (EF1α) promoter to regulate expression of Artemis after ex vivo lentiviral transduction of HSCs in a murine model of SCID-A. Recipient animals treated with the PGK-Artemis vector exhibited moderate repopulation of their immune compartment, yet demonstrated a defective proliferative T lymphocyte response to in vitro antigen stimulation. Animals treated with the EF1α-Artemis vector displayed high levels of T lymphocytes but an absence of B lymphocytes and deficient lymphocyte function. In contrast, ex vivo transduction with the APro-Artemis vector supported effective immune reconstitution to wild-type levels, resulting in fully functional T and B lymphocyte responses. These results demonstrate the importance of regulated Artemis expression in immune reconstitution of Artemis-deficient SCID.

Successful newborn screening for SCID in the Navajo Nation

Newborn screening (NBS) for severe combined immunodeficiency (SCID) identifies affected infants before the onset of life-threatening infections, permitting optimal treatment. Navajo Native Americans have a founder mutation in the DNA repair enzyme Artemis, resulting in frequent Artemis SCID (SCID-A). A pilot study at 2 Navajo hospitals assessed the feasibility of SCID NBS in this population. Dried blood spots from 1800 infants were assayed by PCR for T-cell receptor excision circles (TRECs), a biomarker for naïve T cells. Starting in February 2012, TREC testing transitioned to standard care throughout the Navajo Area Indian Health Service, and a total of 7900 infants were screened through July 2014. One infant had low TRECs and was diagnosed with non-SCID T lymphopenia, while 4 had undetectable TRECs due to SCID-A, all of whom were referred for hematopoietic cell transplantation. This report establishes the incidence of SCID-A and demonstrates effectiveness of TREC NBS in the Navajo.

Chimerism-based pre-emptive immunotherapy with fast withdrawal of immunosuppression and donor lymphocyte infusions after allogeneic stem cell transplantation for pediatric hematologic malignancies

The presence of increasing host chimerism or persistent mixed chimerism (MC) after hematopoietic stem cell transplantation for leukemia in children is a predictor of relapse. To reduce the risk of relapse, we prospectively studied post-transplantation chimerism-based immunotherapy (IT) using fast withdrawal of immunosuppression (FWI) and donor lymphocyte infusions (DLI) in children with early post-transplantation MC. Forty-three children with hematologic malignancies at 2 institutions were enrolled prospectively in this study from 2009 until 2012 and were followed for a mean of 42 (SD, 10) months. Twelve patients (28%) were assigned to the observation arm based on the presence of graft-versus-host disease (GVHD) or full donor chimerism (FDC), and 5 (12%) sustained early events and could not undergo intervention. Twenty-six (60%) patients with MC were assigned to IT with FWI, which started at a median of 49 days (range, 35 to 85 days) after transplantation. Fourteen patients proceeded to DLI after FWI. Toxicities of treatment included GVHD, which developed in 19% of patients undergoing intervention, with 1 of 26 (4%) dying from GVHD and 1 (4%) still requiring therapy for chronic GVHD 21 months after DLI. Patients with MC undergoing IT had similar 2-year event-free survival (EFS) (73%; 95% confidence interval (CI), 55% to 91%) compared with patients who achieved FDC spontaneously (83%; 95% CI, 62% to 100%); however, because 50% of all relapses in the IT occurred later than 2 years after transplantation, the EFS declined to 55% (95% CI, 34% to 76%) at 42 (SD, 11) months. There were no late relapses in the observation group. EFS in the entire cohort was 58% (95% CI, 42% to 73%) at 42 (SD, 11) months after transplantation. Evidence of disease before transplantation remained a significant predictor of relapse, whereas development of chronic GVHD was protective against relapse.

Comparison of outcomes of hematopoietic stem cell transplantation without chemotherapy conditioning by using matched sibling and unrelated donors for treatment of severe combined immunodeficiency

BACKGROUND

Patients with severe combined immunodeficiency disease who have matched sibling donors (MSDs) can proceed to hematopoietic cell transplantation (HCT) without conditioning chemotherapy.

OBJECTIVE

We sought to determine whether the results of HCT without chemotherapy-based conditioning from matched unrelated donors (URDs), either from volunteer adults or umbilical cord blood, are comparable with those from MSDs.

METHODS

We performed a multicenter survey of severe combined immunodeficiency transplantation centers in North America, Europe, and Australia to compile retrospective data on patients who have undergone unconditioned HCT from either URDs (n = 37) or MSDs (n = 66).

RESULTS

Most patients undergoing URD HCT (92%) achieved donor T-cell engraftment compared with 97% for those with MSDs; however, estimated 5-year overall and event-free survival were worse for URD recipients (71% and 60%, respectively) compared with MSD recipients (92% and 89%, respectively; P < .01 for both). URD recipients who received pre-HCT serotherapy had similar 5-year overall survival (100%) to MSD recipients. The incidences of grade II to IV acute and chronic graft-versus-host disease were higher in URD (50% and 39%, respectively) compared with MSD (22% and 5%, respectively) recipients (P < .01 for both). In the surviving patients there was no difference in T-cell reconstitution at the last follow-up between the URD and MSD recipients; however, MSD recipients were more likely to achieve B-cell reconstitution (72% vs 17%, P < .001).

CONCLUSION

Unconditioned URD HCT achieves excellent rates of donor T-cell engraftment similar to that seen in MSD recipients, and reconstitution rates are adequate. However, only a minority will have myeloid and B-cell reconstitution, and attention must be paid to graft-versus-host disease prophylaxis. This approach might be safer in children ineligible for intense regimens to spare the potential complications of chemotherapy.

Combined umbilical cord blood and bone marrow from HLA-identical sibling donors for hematopoietic stem cell transplantation in children with hemoglobinopathies

BACKGROUND

It is well established that umbilical cord blood and bone marrow are biologically different stem cell sources.

PATIENTS AND METHODS

We analyzed the feasibility and outcome of hematopoietic stem cell transplantation (HSCT) in 13 children (median age 5.9 years) with hemoglobinopathies after the co- infusion of cord blood (CB) and bone marrow (BM) from the same human leucocyte antigen (HLA) identical sibling donor. We also compared outcomes of children with co-transplantation to outcomes in children with hemoglobinopathies who had received a BM (n = 21) or CB (n = 22) transplant alone.

RESULTS

Compared to CB transplant (CBT) recipients, the co-transplant group had more rapid neutrophil (17 vs. 25 days, P = 0.013) and platelet (29 vs. 48 days, P = 0.009) recovery and less transplant related mortality. Patients who received a co-transplant had a lower incidence of ≥ grade II acute (0% vs. 26.3%) and chronic (0% vs. 21%) graft versus host disease (GVHD) compared to BM transplant (BMT) recipients (P = 0.055 and 0.045, respectively). With a median follow-up of >60 months in each treatment group, the 5-year probability of event free survival (EFS) was 100% in the co-transplant group, 90% after BMT and 86% after CBT (P = 0.42).

CONCLUSION

Co-transplantation of CB and BM from HLA-identical sibling donors appears to be a feasible and effective strategy to further optimize outcomes of HSCT for hemoglobinopathies.

A trial of plerixafor adjunctive therapy in allogeneic hematopoietic cell transplantation with minimal conditioning for severe combined immunodeficiency

For infants with SCID, the ideal conditioning regimen before allogeneic HCT would omit cytotoxic chemotherapy to minimize short- and long-term complications. We performed a prospective pilot trial with G-CSF plus plerixafor given to the host to mobilize HSC from their niches. We enrolled six patients who received CD34-selected haploidentical cells and one who received T-replete matched unrelated BM. All patients receiving G-CSF and plerixafor had generally poor CD34(+) cell and Lin(-) CD34(+) CD38(-) CD90(+) CD45RA(-) HSC mobilization, and developed donor T cells, but no donor myeloid or B-cell engraftment. Although well tolerated, G-CSF plus plerixafor alone failed to overcome physical barriers to donor engraftment.

A trial of alemtuzumab adjunctive therapy in allogeneic hematopoietic cell transplantation with minimal conditioning for severe combined immunodeficiency

For infants with SCID the ideal conditioning regimen before allogeneic HCT would omit cytotoxic chemotherapy to minimize short- and long-term complications. We performed a prospective pilot trial with alemtuzumab monotherapy to overcome NK-cell mediated immunologic barriers to engraftment. We enrolled four patients who received CD34-selected haploidentical cells, two of whom failed to engraft donor T cells. The two patients who engrafted had delayed T-cell reconstitution, despite rapid clearance of circulating alemtuzumab. Although well-tolerated, alemtuzumab failed to overcome immunologic barriers to donor engraftment. Furthermore, alemtuzumab may slow T-cell development in patients with SCID in the setting of a T-cell depleted graft.

Newborn screening for severe combined immunodeficiency in 11 screening programs in the United States

IMPORTANCE

Newborn screening for severe combined immunodeficiency (SCID) using assays to detect T-cell receptor excision circles (TRECs) began in Wisconsin in 2008, and SCID was added to the national recommended uniform panel for newborn screened disorders in 2010. Currently 23 states, the District of Columbia, and the Navajo Nation conduct population-wide newborn screening for SCID. The incidence of SCID is estimated at 1 in 100,000 births.

OBJECTIVES

To present data from a spectrum of SCID newborn screening programs, establish population-based incidence for SCID and other conditions with T-cell lymphopenia, and document early institution of effective treatments.

DESIGN

Epidemiological and retrospective observational study.

SETTING

Representatives in states conducting SCID newborn screening were invited to submit their SCID screening algorithms, test performance data, and deidentified clinical and laboratory information regarding infants screened and cases with nonnormal results. Infants born from the start of each participating program from January 2008 through the most recent evaluable date prior to July 2013 were included. Representatives from 10 states plus the Navajo Area Indian Health Service contributed data from 3,030,083 newborns screened with a TREC test.

MAIN OUTCOMES AND MEASURES

Infants with SCID and other diagnoses of T-cell lymphopenia were classified. Incidence and, where possible, etiologies were determined. Interventions and survival were tracked.

RESULTS

Screening detected 52 cases of typical SCID, leaky SCID, and Omenn syndrome, affecting 1 in 58,000 infants (95% CI, 1/46,000-1/80,000). Survival of SCID-affected infants through their diagnosis and immune reconstitution was 87% (45/52), 92% (45/49) for infants who received transplantation, enzyme replacement, and/or gene therapy. Additional interventions for SCID and non-SCID T-cell lymphopenia included immunoglobulin infusions, preventive antibiotics, and avoidance of live vaccines. Variations in definitions and follow-up practices influenced the rates of detection of non-SCID T-cell lymphopenia.

CONCLUSIONS AND RELEVANCE

Newborn screening in 11 programs in the United States identified SCID in 1 in 58,000 infants, with high survival. The usefulness of detection of non-SCID T-cell lymphopenias by the same screening remains to be determined.

Transplantation outcomes for severe combined immunodeficiency, 2000-2009

BACKGROUND

The Primary Immune Deficiency Treatment Consortium was formed to analyze the results of hematopoietic-cell transplantation in children with severe combined immunodeficiency (SCID) and other primary immunodeficiencies. Factors associated with a good transplantation outcome need to be identified in order to design safer and more effective curative therapy, particularly for children with SCID diagnosed at birth.

METHODS

We collected data retrospectively from 240 infants with SCID who had received transplants at 25 centers during a 10-year period (2000 through 2009).

RESULTS

Survival at 5 years, freedom from immunoglobulin substitution, and CD3+ T-cell and IgA recovery were more likely among recipients of grafts from matched sibling donors than among recipients of grafts from alternative donors. However, the survival rate was high regardless of donor type among infants who received transplants at 3.5 months of age or younger (94%) and among older infants without prior infection (90%) or with infection that had resolved (82%). Among actively infected infants without a matched sibling donor, survival was best among recipients of haploidentical T-cell-depleted transplants in the absence of any pretransplantation conditioning. Among survivors, reduced-intensity or myeloablative pretransplantation conditioning was associated with an increased likelihood of a CD3+ T-cell count of more than 1000 per cubic millimeter, freedom from immunoglobulin substitution, and IgA recovery but did not significantly affect CD4+ T-cell recovery or recovery of phytohemagglutinin-induced T-cell proliferation. The genetic subtype of SCID affected the quality of CD3+ T-cell recovery but not survival.

CONCLUSIONS

Transplants from donors other than matched siblings were associated with excellent survival among infants with SCID identified before the onset of infection. All available graft sources are expected to lead to excellent survival among asymptomatic infants. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Primary Immune Deficiency Treatment Consortium (PIDTC) report

The Primary Immune Deficiency Treatment Consortium (PIDTC) is a network of 33 centers in North America that study the treatment of rare and severe primary immunodeficiency diseases. Current protocols address the natural history of patients treated for severe combined immunodeficiency (SCID), Wiskott-Aldrich syndrome, and chronic granulomatous disease through retrospective, prospective, and cross-sectional studies. The PIDTC additionally seeks to encourage training of junior investigators, establish partnerships with European and other International colleagues, work with patient advocacy groups to promote community awareness, and conduct pilot demonstration projects. Future goals include the conduct of prospective treatment studies to determine optimal therapies for primary immunodeficiency diseases. To date, the PIDTC has funded 2 pilot projects: newborn screening for SCID in Navajo Native Americans and B-cell reconstitution in patients with SCID after hematopoietic stem cell transplantation. Ten junior investigators have received grant awards. The PIDTC Annual Scientific Workshop has brought together consortium members, outside speakers, patient advocacy groups, and young investigators and trainees to report progress of the protocols and discuss common interests and goals, including new scientific developments and future directions of clinical research. Here we report the progress of the PIDTC to date, highlights of the first 2 PIDTC workshops, and consideration of future consortium objectives.

The natural history of children with severe combined immunodeficiency: baseline features of the first fifty patients of the primary immune deficiency treatment consortium prospective study 6901

The Primary Immune Deficiency Treatment Consortium (PIDTC) consists of 33 centers in North America. We hypothesized that the analysis of uniform data on patients with severe combined immunodeficiency (SCID) enrolled in a prospective protocol will identify variables that contribute to optimal outcomes following treatment. We report baseline clinical, immunologic, and genetic features of the first 50 patients enrolled, and the initial therapies administered, reflecting current practice in the diagnosis and treatment of both typical (n = 37) and atypical forms (n = 13) of SCID. From August 2010 to May 2012, patients with suspected SCID underwent evaluation and therapy per local center practices. Diagnostic information was reviewed by the PIDTC eligibility review panel, and hematopoietic cell transplantation (HCT) details were obtained from the Center for International Blood and Marrow Transplant Research. Most patients (92 %) had mutations in a known SCID gene. Half of the patients were diagnosed by newborn screening or family history, were younger than those diagnosed by clinical signs (median 15 vs. 181 days; P = <0.0001), and went to HCT at a median of 67 days vs. 214 days of life (P = <0.0001). Most patients (92 %) were treated with HCT within 1-2 months of diagnosis. Three patients were treated with gene therapy and 1 with enzyme replacement. The PIDTC plans to enroll over 250 such patients and analyze short and long-term outcomes for factors beneficial or deleterious to survival, clinical outcome, and T- and B-cell reconstitution, and which biomarkers are predictive of these outcomes.

Effect of weight and maturation on busulfan clearance in infants and small children undergoing hematopoietic cell transplantation

Little information is currently available regarding the pharmacokinetics (PK) of busulfan in infants and small children to help guide decisions for safe and efficacious drug therapy. The objective of this study was to develop an algorithm for individualized dosing of i.v. busulfan in infants and children weighing ≤12 kg, that would achieve targeted exposure with the first dose of busulfan. Population PK modeling was conducted using intensive time-concentration data collected through the routine therapeutic drug monitoring of busulfan in 149 patients from 8 centers. Busulfan PK was well described by a 1-compartment base model with linear elimination. The important clinical covariates affecting busulfan PK were actual body weight and age. Based on our model, the predicted clearance of busulfan increases approximately 1.7-fold between 6 weeks to 2 years of life. For infants age <5 months, the model-predicted doses (mg/kg) required to achieve a therapeutic concentration at steady state of 600-900 ng/mL (area under the curve range, 900-1350 μM·min) were much lower compared with standard busulfan doses of 1.1 mg/kg. These results could help guide clinicians and inform better dosing decisions for busulfan in young infants and small children undergoing hematopoietic cell transplantation.

The missing vital sign

The author catalogues the challenges to family, friends, and herself of managing her 10 month old son’s long hospital stay as he received a transplant to cure Wiskott-Aldrich syndrome

Unresolved issues in hematopoietic stem cell transplantation for severe combined immunodeficiency: need for safer conditioning and reduced late effects

In this review we discuss recent outcomes of hematopoietic cell transplantation (HCT) for patients with severe combined immunodeficiency (SCID), including survival, T- and B-cell reconstitution, and late effects, particularly those related to genotype, use of conditioning regimen, and use of alternative donors. We identify the following issues that require additional data, which can be obtained through cooperative studies: outcomes of patients with SCID who did not receive conditioning before alternative donor HCT; outcomes of patients with SCID who did not receive graft-versus-host disease prophylaxis after T cell-replete HCT; late effects of HCT for patients with SCID, including neurocognitive outcomes, growth, and development; and their relationship to genotype and use of alkylating agents for conditioning. Careful follow-up of outcomes of all newborns receiving diagnoses based on newborn screening programs for SCID is essential because data are scarce on the effects of conditioning regimens in very young patients. A consensus on the definition of T- and B-cell recovery, criteria for additional "boosts," pharmacokinetic data of chemotherapy agents used in young children, and uniformity of the use of various chemotherapy agents are needed to compare results among institutions. Finally, development of new nontoxic conditioning regimens for HCT that can be safely used in very young children is required.

Haploidentical related-donor hematopoietic cell transplantation in children using megadoses of CliniMACs-selected CD34(+) cells and a fixed CD3(+) dose

We conducted a prospective phase II trial utilizing the CliniMACs system to perform CD34(+)-cell selection of PBSCs from haploidentical donors to evaluate engraftment and hematoimmunological reconstitution. In total, 21 children with hematological malignancies or nonmalignant conditions underwent conditioning with 1200 cGy TBI, thiotepa, fludarabine and Thymoglobulin. Patients received megadoses of CD34(+) cells (median: 22 × 10(6)/kg) with a fixed dose of 3 × 10(4)/kg CD3(+) cells/kg, and engraftment occurred in 90% with prompt recovery of neutrophils and platelets. Grade II acute GVHD (aGVHD) was seen in 32% (95% confidence interval (CI), 15-54%) of evaluable patients, there was no grade III-IV aGVHD, and chronic extensive GVHD was seen in 35% (95% CI, 17-59%) of patients. The estimated 2-year EFS was 62% (95% CI, 48-83%) with a median survivor follow-up of 49 months (range: 18-119 months). Patients with nonmalignant diseases had an estimated 2-year EFS of 100% (95% CI, 56-100%) and patients with malignancies in remission had an estimated 2-year EFS of 56% (95% CI, 22-89%). Megadose CD34(+) cells with a fixed CD3(+) cell dose from haploidentical related donors resulted in good outcomes for pediatric patients with nonmalignant diseases and those with malignant diseases transplanted in remission.

Long-term survival and late deaths after hematopoietic cell transplantation for primary immunodeficiency diseases and inborn errors of metabolism

It is uncertain whether late mortality rates after hematopoietic cell transplantation for severe combined immunodeficiency (SCID), non-SCID primary immunodeficiency diseases (non-SCID PIDD), and inborn errors of metabolism (IEM) return to rates observed in the general population, matched for age, sex, and nationality. We studied patients with SCID (n = 201), non-SCID PIDD (n = 405), and IEM (n = 348) who survived for at least 2 years after transplantation with normal T cell function (SCID) or >95% donor chimerism (non-SCID PIDD and IEM). Importantly, mortality rate was significantly higher in these patients compared with the general population for several years after transplantation. The rate decreased toward the normal rate in patients with SCID and non-SCID PIDD beyond 6 years after transplantation, but not in patients with IEM. Active chronic graft-versus-host disease at 2 years was associated with increased risk of late mortality for all diseases (hazard ratio [HR], 1.87; P = .05). In addition, late mortality was higher in patients with non-SCID PIDD who received T cell-depleted grafts (HR 4.16; P = .007) and in patients with IEM who received unrelated donor grafts (HR, 2.72; P = .03) or mismatched related donor grafts (HR, 3.76; P = .01). The finding of higher mortality rates in these long-term survivors for many years after transplantation confirms the need for long-term surveillance.

Busulfan, fludarabine, and alemtuzumab as a reduced toxicity regimen for children with malignant and nonmalignant diseases improves engraftment and graft-versus-host disease without delaying immune reconstitution

For children receiving allogeneic hematopoietic stem cell transplants (HSCTs), the toxicity of the conditioning regimen and graft failure remain challenges. We previously reported that targeted i.v. busulfan, fludarabine, and rabbit anti-thymocyte globulin (rATG) decreased toxicity but had a graft failure rate of 21%. To improve the engraftment rate, we replaced ATG with alemtuzumab, a monoclonal Ab targeting CD52. Thirty-five children with malignant and nonmalignant diseases were enrolled in this phase II prospective study. Twelve children had HLA-matched related donors (MRDs), 16 had 10 of 10, and 7 had 9 of 10 HLA allele-matched unrelated donors (MUDs). Thirty-one of 34 evaluable patients (91%) achieved a durable engraftment. All 3 patients who rejected had a nonmalignant disease and received a MUD transplantation (2 mismatched at 1 antigen). Three patients died of a transplantation-related complication (9% ± 5.2%). Seven patients had disease relapse or progression, 2 of whom died. At a median follow-up of 35 months (range, 15-85 months), the event-free survival (EFS) was 61% ± 9.0% and the overall survival (OS) was 78% ± 7.5%. The median time to neutrophil recovery, B cell, and T cell reconstitution were 16 days, 3 months, and 6 months, respectively. At 1 year, the median donor chimerism in whole blood, CD3, CD14/15, and CD19 subsets were 97%, 87%, 100%, and 99%, respectively. Six patients (17% ± 6.6%) developed acute graft-versus-host disease (aGVHD), only 2 of which were >grade II. Two patients (8% ± 5.4%) progressed to chronic GVHD (cGVHD). These results suggest that replacement of rATG with alemtuzumab may improve engraftment as well as decrease cGVHD rates without resulting in delays in immune reconstitution.

Genotype, phenotype, and outcomes of nine patients with T-B+NK+ SCID

There are few reports of clinical presentation, genotype, and HCT outcomes for patients with T-B+NK+ SCID. Between 1981 and 2007, eight of 84 patients with SCID who received and/or were followed after HCT at UCSF had the T-B+NK+ phenotype. One additional patient with T-B+NK+ SCID was identified as the sibling of a patient treated at UCSF. Chart reviews were performed. Molecular analyses of IL7R, IL2RG, JAK3, and the genes encoding the CD3 T-cell receptor components δ (CD3D), ε (CD3E), and ζ (CD3Z) were carried out. IL7R mutations were documented in four patients and CD3D mutations in two others. Three patients had no defects found. Only two of nine patients had an HLA-matched related HCT donor. Both survived, and neither developed GVHD. Five of seven recipients of haploidentical grafts survived. Although the majority of reported cases of T-B+NK+ SCID are caused by defects in IL7R, CD3 complex defects were also found in this series and should be considered when evaluating patients with T-B+NK+ SCID. Additional genes, mutations in which account for T-B+NK+ SCID, remain to be found. Better approaches to early diagnosis and HCT treatment are needed for patients lacking an HLA-matched related donor.