Non-myeloablative hematopoietic cell transplant for treatment of nonmalignant disorders in children

Hematopoietic stem cell transplantation (HCT) may offer the only curative therapy for certain life-threatening immune deficiency disorders. Conventional HCT poses a risk to patients for severe morbidity, mortality, and late sequelae resulting from myeloablative preparative regimens. This review summarizes the development of nonmyeloablative regimens that have the potential to reduce both short- and long-term risks of HCT. Results of NM-HCT in a small number of patients indicate that this procedure may play an important role in treatment of life-threatening immune deficiencies.

Factors associated with outcome after unrelated marrow transplantation for treatment of acute lymphoblastic leukemia in children

Acute lymphoblastic leukemia (ALL) is the most common indication for transplantation of marrow from unrelated donors in children. We analyzed results of this procedure in children with ALL treated according to a standard protocol to determine risk factors for outcome. From January 1987 to 1999, 88 consecutively seen patients with ALL who were younger than 18 years received a marrow transplant from an HLA-matched (n = 56) or partly matched (n = 32) unrelated donor during first complete remission (CR1; n = 10), second remission (CR2; n = 34), third remission (CR3; n = 10), or relapse (n = 34). Patients received cyclophosphamide and fractionated total-body irradiation as conditioning treatment and were given methotrexate and cyclosporine for graft-versus-host disease (GVHD) prophylaxis. Three-year rates of leukemia-free survival (LFS) according to phase of disease were 70% for CR1, 46% for CR2, 20% for CR3, and 9% for relapse (P <.0001). Three-year cumulative relapse rates were 10%, 33%, 20%, and 50%, respectively, and 3-year cumulative rates of death not due to relapse were 20%, 22%, 60%, and 41%, respectively, for patients with CR1, CR2, CR3, and relapse. Grades III to IV acute GVHD occurred in 43% of patients given HLA-matched transplants and in 59% given partly matched transplants (P =.10); clinical extensive chronic GVHD occurred in 32% and 38%, respectively (P =.23). LFS rates were lower in patients with advanced disease (P <.0001), age 10 years or older (P =.002), or short duration of CR1 (P =.007). Thus, in addition to phase of disease, age and duration of CR1 were predictors of outcome after unrelated-donor transplantation for treatment of ALL in children. Outcome was particularly favorable in younger patients with early phases of the disease.

Absence of major histocompatibility class II expression does not impair hematopoiesis in mice

OBJECTIVE

Major histocompatibility class II (MHC II) molecules are among the earliest antigens to be expressed in hematopoietic progenitor cells; however, the functional role of these molecules in hematopoiesis remains controversial. We examined the role of MHC II antigens during hematopoiesis using a mouse model of MHC II deficiency related to the absence of the critical transcriptional activator, CIITA.

METHODS

Sca-1(-), Sca-1(+)lin(+), and Sca-1(+)lin(-) populations of marrow cells from CIITA(-)(/-) and wild-type mice were analyzed by immunofluorescence for MHC II expression. Hematopoietic capacity was assessed in CIITA(-/-) and wild-type mice by CFU-S, CFU-GM, and radiation sensitivity assays.

RESULTS

Flow cytometric characteristics of hematopoietic progenitors from CIITA(-/-) and wild-type mice were identical except for the absence of MHC II expression in CIITA null mice. There were no significant differences in capacity for hematopoietic reconstitution and clonogenicity as measured by radiation sensitivity, CFU-S, and CFU-GM assays among CIITA(-/-) and wild-type mice.

CONCLUSIONS

These experiments show that downregulation of MHC II gene transcription does not effectively alter normal hematopoiesis, and provide strong evidence that MHC II expression on hematopoietic progenitors is not required for normal hematopoietic development.

Effect of HLA mismatches on the outcome of hematopoietic transplants

Hematopoietic cell transplantation from unrelated volunteer donors for the treatment of hematological malignancy can be optimized by complete and precise matching for HLA class I and II alleles between the donor and recipient. Survival is improved when the donor and recipient are matched for HLA-A, -B, -C, -DRB, -DQB1 and -DPB1 alleles. The risks of clinically severe graft-versus-host disease, graft failure and mortality are increased in the presence of multilocus mismatching. These findings demonstrate that HLA allelic differences are biologically relevant in human transplantation.

Bone marrow transplantation for children less than 2 years of age with acute myelogenous leukemia or myelodysplastic syndrome

We analyzed results of 40 infants less than 2 years of age who received bone marrow transplants (BMT) between May 1974 and January 1995 for treatment of acute myelogenous leukemia (AML; N = 34) or myelodysplastic syndrome (MDS; N = 6) to determine outcome and survival performance. Among the AML patients, 13 were in first remission, 9 were in untreated first relapse or second remission, and 12 were in refractory relapse. Patients were conditioned with cyclophosphamide in combination with either total body irradiation (TBI; N = 29) or busulfan (N = 11). Source of stem cells included 6 autologous donors, 15 HLA genotypically identical siblings, 14 haploidentical family members, and 5 unrelated donors. Graft-versus-host disease (GVHD) prophylaxis was methotrexate (MTX) for 17, MTX plus cyclosporine (CSP) for 14, or CSP plus prednisone for 3. Incidence of severe (grade 3-4) regimen-related toxicity was 10% and transplant-related mortality was 10%. Acute GVHD (grades II-III) occurred in 39% of allogeneic patients, and chronic GVHD developed in 40%. Relapse, the most significant problem for patients in this study, occurred in 1 MDS patient and 23 AML patients and was the cause of death for 19 patients. The 2-year probabilities of relapse are 46%, 67%, and 92%, respectively, for patients transplanted in first remission, untreated first relapse or second remission, and relapse. One MDS and 8 AML patients received second marrow transplants for treatment of relapse, and 5 of these survive disease-free for more than 1.5 years. All 6 MDS patients and 11 of 34 AML patients survive more than 1.5 years later. The 5-year probabilities of survival and disease-free survival are 54% and 38% for patients transplanted in first remission and 33% and 22% for untreated first relapse or second remission. None of the patients transplanted with refractory relapse survive disease-free. Outcome was significantly associated with phase of disease at transplantation and pretransplant diagnosis of extramedullary disease. Long-term sequelae included growth failure and hormonal deficiencies. Survival performance was a median of 100% (80% to 100%) and neurologic development for all survivors was appropriate for age. This study indicates that infants with AML have similar outcome after BMT compared with older children and that BMT should be performed in first remission whenever possible. In addition, allogeneic BMT provides effective therapy for the majority of infants with MDS.

Optimizing outcome after unrelated marrow transplantation by comprehensive matching of HLA class I and II alleles in the donor and recipient

In unrelated marrow transplantation, the benefit of matching class II HLA-DRB1 and DQB1 alleles of the donor and recipient is well documented. Little is known about the clinical relevance of matching for class I HLA-A, B, and C alleles. We used DNA-amplification methods to identify the HLA-A, B, and C alleles of 300 patients and their donors. The incidence of graft failure was correlated with multiple class I mismatching in the donor. The risk of grades III-IV acute graft-versus-host disease was highest with class II mismatching in the recipient. Mismatching for a single class I or class II allele had no effect on survival, but mortality was increased by mismatching for more than one class I allele and by simultaneous mismatching for class I and class II alleles. We conclude that matching HLA class I and class II alleles of the donor and recipient can improve outcome after unrelated marrow transplantation.

Treatment of severe veno-occlusive disease with defibrotide: compassionate use results in response without significant toxicity in a high-risk population

Hepatic veno-occlusive disease (VOD) is the most common of the regimen-related toxicities accompanying stem cell transplantation (SCT). Despite aggressive therapies, including the combination of tissue plasminogen activator (t-PA) and heparin, severe VOD is almost uniformly fatal. Defibrotide (DF) is a polydeoxyribonucleotide with activity in several vascular disorders and, unlike t-PA and heparin, produces no systemic anticoagulant effects. Nineteen patients who developed severe VOD after SCT were treated with DF on a compassionate-use basis. Patients had clinically established VOD and met risk criteria predicting progression and fatality. At the initiation of DF, all 19 patients had evidence of multiorgan dysfunction; median bilirubin was 22.3 mg/dL, 12 patients had renal insufficiency (5 dialysis dependent), 14 required oxygen supplementation, and encephalopathy was present in 8 patients. Beginning a median of 6 days after diagnosis of VOD, DF was administered intravenously in doses ranging from 5 to 60 mg/kg/d for a planned minimum course of 14 days. In no case was DF discontinued for attributable toxicity. No severe hemorrhage related to DF administration was observed. Resolution of VOD (bilirubin <2 mg/dL with improvement in other symptoms and signs) was seen in 8 patients (42%). Six of 8 responders survived past day +100, contrasted with the 2% predicted survival reported in comparable patients. The observed response rate, survival to day +100, and absence of significant DF treatment-associated toxicity are compelling and warrant further evaluation.

Legionellosis in a bone marrow transplant center

We reviewed 10 cases of culture proven legionellosis that occurred at a marrow transplant center (Fred Hutchinson Cancer Research Center, Seattle, WA, USA) over a 6-year period ending in 1993. Infections were caused by four species of Legionella with no apparent clustering of cases. Detection of Legionella using direct fluorescent antibody assays proved unreliable due to the high proportion of rare Legionella species isolated. The clinical presentation, course and outcome of patients varied and did not correlate with underlying disease, type of transplant, transplant day or engraftment status. However, five of the seven patients infected with non-pneumophila species recovered from their pneumonia compared to none of the three patients infected with L. pneumophila. Persistent or relapsed infection after 3 weeks of appropriate therapy was documented in one case suggesting that prolonged antibiotic treatment is indicated in these patients.

Oerskovia xanthineolytica infection of a prosthetic joint: case report and review

Oerskovia spp. are gram-positive, Nocardia-like bacilli which inhabit the soil and rarely cause human infections. Previously reported cases of Oerskovia infection have been characterized by a nonaggressive course and an association with foreign bodies. We report the first case of a patient with a prosthetic joint infection due to Oerskovia xanthineolytica. Our patient presented with a prolonged, indolent course and was thought to have aseptic loosening of his prosthesis until the time of surgery. He was cured of his infection by removal of the prosthesis, antibiotic therapy, and delayed reimplantation. Review of the previous 10 reported cases of Oerskovia infection in humans supports the recommendation that foreign-body-associated infections should be treated with a strategy that includes removal of the foreign material.

Differential transcription elements direct expression of HLA-DQ genes

Regulation of class II MHC gene expression, including the HLA-DQ genes, is primarily at the level of transcription. Locus-specific control of DQ gene transcription is both tissue-specific and developmentally regulated and relies on complex mechanisms involving specific DNA-protein interactions. Electrophoretic mobility shift and DNase I protection assays demonstrate the presence of unique nuclear protein interactions with the consensus W and Y box elements in the DQB1 promoter region in DQ-negative cell lines. Based on these and other recent studies, a multistage model of DQ gene regulation is outlined to account for specific patterns of DQ gene expression.

Analysis of differential HLA-DQB expression in autologous B cell lines

Class II major histocompatibility complex genes are differentially expressed during cellular activation and differentiation, often in a locus-specific manner. We investigated the differential expression of the HLA-DQB gene, using B cell lines LAZ221 and LAZ388: LAZ221, derived from an early B cell leukemia, expresses HLA-DR but not HLA-DQ: LAZ388, the autologous Epstein-Barr virus-transformed B cell line, expresses both DR and DQ. Transfection experiments demonstrate differential function of class II gene upstream regulatory regions in the two lines, which correlates with differential class II gene expression. Using gel retardation and DNase I footprint assays, we demonstrate that absence of DQB gene expression is associated with characteristic nuclear protein-binding interactions in the proximal DQB gene upstream regulatory region. These interactions are visualized as DNA-protein complexes that are seen with nuclear proteins from the DQ-negative cell line, LAZ221, and involve consensus promoter Y box and W box elements, as well as novel upstream sites. Transcriptional regulatory proteins that differ in these autologous B cell lines may be stage-specific factors involved in the developmental regulation of HLA genes.