Translating in vitro prediction of cytotoxic T cell alloreactivity to hematopoietic stem cell transplantation outcome

INTRODUCTION

Previously we developed a weighted amino acid (AA) mismatch score predictive for cytotoxic T cell (CTL) alloreactivity (in vitro CTLp assay) based on the structure of the HLA class I molecule. The aim of this study is to confirm the clinical relevance of the CTLp assay and to validate the AA mismatch score as an alternative and easy to use tool to predict permissible mismatches in hematopoietic stem cell transplantation (HSCT).

METHODS

We selected patients transplanted with a 9/10 single HLA class I mismatched graft (n=171) at three Dutch HSCT centers. A CTLp assay was performed in 73 donor-recipient pairs. As a control we selected 168 10/10 HLA matched pairs that were matched to the 9/10 single HLA class I mismatched pairs for HSCT year, donor type, patient age and diagnosis.

RESULTS

We observed that pairs with negative a CTLp assay had statistically significant decreased incidence of mortality after HSCT comparable to that of 10/10 HLA matched pairs. However, the weighted AA mismatch score did not significantly predict any HSCT end point of interest.

CONCLUSION

Further investigation is needed to unravel the mechanisms involved in causing the beneficial effect of a negative CTLp assay, before other alternative tools to predict HSCT outcome may be developed.

The impact of frequent HLA haplotypes in high linkage disequilibrium on donor search and clinical outcome after unrelated haematopoietic SCT

The MHC region on chromosome 6 contains a large number of non-HLA genes next to the HLA genes. Matching for HLA in unrelated hematopoietic SCT (HSCT) does not necessarily mean that these non-HLA genes are also matched. We selected 348 Northwest European patients transplanted with an HLA-A-, -B-, -C-, -DRB1-, -DQB1-matched unrelated donor (MUD) between 1987 and 2008. Patients' haplotypes were identified via descend. We were unable to determine the haplotypes of the donor; therefore we used frequent haplotypes (FH) in high linkage disequilibrium (LD) as a proxy for haplotype matching. Presence of a FH in a patient positively affected the probability and speed of identifying a matched unrelated donor. Competing risk survival analysis showed that patients with one or two FH have a statistically significantly decreased probability of developing ≥ grade II acute GVDH (aGVHD) without increased risk of relapse compared to patients without FH (HR (95% CI): 0.53 (0.31-0.91)). This association was strongest for those FH with the highest LD between both HLA-A and -C or -B, and HLA-C or -B and -DRB1 (HR (95% CI): 0.49 (0.26-0.92)). These results extend evidence that non-HLA allele coding regions have a significant impact on development of ≥ grade II aGVHD. We conclude that there is more to successful HSCT than matching for HLA genes.

Hematopoietic stem cell transplantation for advanced myelodysplastic syndrome in children: results of the EWOG-MDS 98 study

We report on the outcome of children with advanced primary myelodysplastic syndrome (MDS) transplanted from an HLA-matched sibling (MSD) or an unrelated donor (UD) following a preparative regimen with busulfan, cyclophosphamide and melphalan. Ninety-seven patients with refractory anemia with excess blasts (RAEB, n=53), RAEB in transformation (RAEB-T, n=29) and myelodysplasia-related acute myeloid leukemia (MDR-AML, n=15) enrolled in the European Working Group of MDS in Childhood (EWOG-MDS) 98 study and given hematopoietic stem cell transplantation (HSCT) were analyzed. Median age at HSCT was 11.1 years (range 1.4-19.0). Thirty-nine children were transplanted from an MSD, whereas 58 were given the allograft from a UD (n=57) or alternative family donor (n=1). Stem cell source was bone marrow (n=69) or peripheral blood (n=28). With a median follow-up of 3.9 years (range 0.1-10.9), the 5-year probability of overall survival is 63%, while the 5-year cumulative incidence of transplantation-related mortality (TRM) and relapse is 21% each. Age at HSCT greater than 12 years, interval between diagnosis and HSCT longer than 4 months, and occurrence of acute or extensive chronic graft-versus-host disease were associated with increased TRM. The risk of relapse increased with more advanced disease. This study indicates that HSCT following a myeloablative preparative regimen offers a high probability of survival for children with advanced MDS.

Cidofovir for adenovirus infections after allogeneic hematopoietic stem cell transplantation: a survey by the Infectious Diseases Working Party of the European Group for Blood and Marrow Transplantation

Adenovirus is an important cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation and there is no established therapy. Cidofovir has in vitro efficacy against adenovirus. We performed a retrospective analysis of 45 patients treated with cidofovir for adenovirus from 10 centers. In total, 16 patients had definite adenovirus disease, 13 probable disease, and 16 asymptomatic infections. A total of 31 (69%) patients were successfully treated with cidofovir, 10 failed, and four were not evaluable owing to early death from other causes. Cidofovir therapy was successful in 10 patients with adenovirus disease, 10 patients with probable disease, and in 10 patients with asymptomatic infections. The overall survival at 28 days and 6 months after initiation of cidofovir therapy was 76 and 46%, respectively. Of the patients, 18 developed toxicity associated with cidofovir: 14 developed renal toxicity and four other types of toxicities. We conclude that cidofovir may be useful against adenovirus after allogeneic hematopoietic stem cell transplantation but additional studies are needed.

Two consecutive immunophenotypic switches in a child with immunogenotypically stable acute leukaemia

A 12-year-old girl presented with a CD33+ precursor B-acute lymphoblastic leukaemia (ALL) and seemed to respond well to ALL treatment. However, 2 weeks after diagnosis her leucocyte count rose rapidly with a predominance of myeloid blasts with M5b morphology and CD19+ myeloid immunophenotype. Acute myeloid leukaemia (AML) treatment was started and remission was achieved after one course of chemotherapy; the AML treatment was continued for 6 months. Two months after cessation of chemotherapy, the patient developed a bone marrow relapse, this time with an undifferentiated blast morphology and a precursor B immunophenotype. Molecular analysis of the immunoglobulin and T-cell receptor genes showed several clonal gene rearrangements at diagnosis: two IGH, two IGK and two TCRD gene rearrangements. All rearrangements were also detected during the AML phase of the disease, suggesting a phenotypic shift of the same leukaemia. At relapse, 8 months later, all rearrangements were preserved except for one TCRD (Vdelta2-Ddelta3) rearrangement. The first phenotypic shift in the genotypically stable leukaemia was remarkably fast. The most probable explanation for our observations is an oncogenic event in an undifferentiated haematopoietic progenitor clone, with a highly versatile phenotype.

Extramedullary infiltrates at diagnosis have no prognostic significance in children with acute myeloid leukaemia

This retrospective study was designed to review the relative frequency and prognostic significance of extramedullary infiltrates in children with acute myeloid leukaemia (AML). The registration data and initial discharge summaries were reviewed for all children diagnosed with AML, and registered by the Dutch Childhood Leukaemia Study Group (DCLSG). Between 1972 and 1998, 477 children were diagnosed with AML. Of these patients, 120 (25.1%) had extramedullary leukaemia (EML) at diagnosis. Four categories of EML were found: skin, soft tissue or bone, gingival infiltration and central nervous system (CNS) involvement. Patients who presented with gingival infiltrates, were older than those without EML or those in the other EML subgroups, had a high initial WBC count and a high proportion of M4/M5 morphological variants. This type of presentation could indicate a special biological entity. Univariate analysis of prognostic factors in patients treated after 1985 with intensive protocols showed that initial WBC count and the presence of favourable cytogenetic findings were significant. The presence of EML at diagnosis had no significant effect on event-free survival. In a stepwise multiple regression analysis only favourable cytogenetic findings remained significant.

[Congenital amegakaryocytic thrombocytopenia: indication for allogeneic stem cell transplantation]

In two neonates, girls, persistent thrombocytopenia was found, which afterwards proved to be caused by a megakaryocytosis. Congenital amegakaryocytic thrombocytopenia is a rare bone marrow failure in young children that is defined as thrombocytopenia with absent or markedly decreased megakaryocytes in the bone marrow. Untreated, amegakaryocytic thrombocytopenia progresses to marrow failure with pancytopenia. Allogeneic stem cell transplantation offers the only possibility for cure, and is successful in approximately half of the patients. Both patients were treated by stem cell transplantation, the one with a matched unrelated donor, the second with stem cells from her HLA-identical sister. The first patient died, the second recovered with a normal number of circulating thrombocytes of donor origin.

Haematopoietic stem cell transplantation for amegakaryocytic thrombocytopenia

Congenital amegakaryocytic thrombocytopenia (CAT), a rare syndrome with failure of megakaryopoiesis, cannot be cured by immunoglobulins, steroids or cyclosporin, but only by allogeneic bone marrow transplantation (BMT). We report on eight patients with CAT, all of whom were dependent at the time of BMT on platelet transfusion. Sources of haematopoietic progenitor cells were bone marrow (n = 5), peripheral stem cells (n = 2) and cord blood (n = 1). Seven patients engrafted. Both patients with matched unrelated donor transplants died, six patients are well with stable platelet counts 3-27 months after transplantation. BMT represents a curative option for CAT. The benefit of using alternative marrow donors should be carefully evaluated.

Autologous haemopoietic stem-cell transplantation in four patients with refractory juvenile chronic arthritis

BACKGROUND

Autologous haemopoietic stem-cell transplantation (AHSCT) had been described as a possible treatment for severe autoimmune disease refractory to conventional treatment. We report the first four children with severe forms of juvenile chronic arthritis (JCA) treated with AHSCT.

METHODS

We studied three children with systemic JCA and one child with polyarticular JCA. Unprimed bone marrow was taken 1 month before AHSCT. T-cell depletion of the graft was done with CD2 and CD3 antibodies. We used a preparative regimen of antithymocyte globulin (20 mg/kg), cyclophosphamide (200 mg/kg) and low-dose total body irradiation (4 Gy). Methotrexate and cyclosporin were stopped before AHCST, prednisone was tapered after 2 months.

FINDINGS

Our patients showed a drug-free follow-up of 6-18 months with a marked decrease in joint swelling, pain, and morning stiffness. Erythrocyte sedimentation rate, C-reactive protein, and haemoglobin returned to almost normal values within 6 weeks. Despite T-cell depletion there was a rapid immune reconstitution in three out of four children. Two patients developed a limited varicella zoster virus eruption, which was treated by aciclovir.

INTERPRETATION

AHSCT for severe JCA was well tolerated and induced a remission of disease in four children with JCA that was resistant to conventional treatment. Prolonged prednisone-free growth catch-up and general well-being is a major therapeutic gain in such children. The actual follow-up is too short, however, for us to conclude that these children are completely cured of their disease.

Hepatic veno-occlusive disease in pediatric stem cell recipients: successful treatment with continuous infusion of prostaglandin E1 and low-dose heparin

Limited data exist on therapeutic options for established hepatic veno-occlusive disease (VOD) in pediatric patients after stem cell transplantation (SCT). In this report, we present data on the successful treatment of VOD in three children following allogeneic SCT and report the duplex ultrasound criteria for the confirmation of the diagnosis and for the evaluation of the treatment progress. All patients were <2 years at the time of transplantation and had received preparative regimens containing busulfan and cyclophosphamide. There were no known pretransplant risk factors for VOD. Allogeneic stem cell transplantation was performed from a sibling donor for CMML and from unrelated donors for Wiskott-Aldrich syndrome and familial hemophagocytic lymphohistiocytosis (FHL). The onset of first clinical symptoms of VOD (as defined by the Seattle and Baltimore criteria) was relatively late in all three patients (days +19, +20, and +25, respectively). Time from onset of first symptoms until confirmation of diagnosis by serial duplex ultrasound examination was 4-11 days. Duplex ultrasound criteria are as follows: complete change of direction of blood flow in the portal vein, decrease of flow in the hepatic veins, and development of collateral circulation. Treatment was initiated upon confirmation of VOD by continuous infusion of prostaglandin E1 (initial dose 0.075 microg/kg/h) in addition to low-dose heparin (100 units/kg/d). Treatment was continued at the maximum tolerated dose of 0.3-0.5 microg/kg/h of PGE1. After 9, 14, and 25 days of treatment respectively, normal portal vein flow was restored and treatment could be discontinued. All three patients are alive and well without apparent sequelae.