David Webb

HLH-2004: Diagnostic and therapeutic guidelines for hemophagocytic lymphohistiocytosis

In HLH‐94, the first prospective international treatment study for hemophagocytic lymphohistiocytosis (HLH), diagnosis was based on five criteria (fever, splenomegaly, bicytopenia, hypertriglyceridemia and/or hypofibrinogenemia, and hemophagocytosis). In HLH‐2004 three additional criteria are introduced; low/absent NK‐cell‐activity, hyperferritinemia, and high‐soluble interleukin‐2‐receptor levels. Altogether five of these eight criteria must be fulfilled, unless family history or molecular diagnosis is consistent with HLH. HLH‐2004 chemo‐immunotherapy includes etoposide, dexamethasone, cyclosporine A upfront and, in selected patients, intrathecal therapy with methotrexate and corticosteroids. Subsequent hematopoietic stem cell transplantation (HSCT) is recommended for patients with familial disease or molecular diagnosis, and patients with severe and persistent, or reactivated, disease. In order to hopefully further improve diagnosis, therapy and biological understanding, participation in HLH studies is encouraged. Pediatr Blood Cancer 2007;48:124–131.

Insertional mutagenesis combined with acquired somatic mutations causes leukemogenesis following gene therapy of SCID-X1 patients

X-linked SCID (SCID-X1) is amenable to correction by gene therapy using conventional gammaretroviral vectors. Here, we describe the occurrence of clonal T cell acute lymphoblastic leukemia (T-ALL) promoted by insertional mutagenesis in a completed gene therapy trial of 10 SCID-X1 patients. Integration of the vector in an antisense orientation 35 kb upstream of the protooncogene LIM domain only 2 (LMO2) caused overexpression of LMO2 in the leukemic clone. However, leukemogenesis was likely precipitated by the acquisition of other genetic abnormalities unrelated to vector insertion, including a gain-of-function mutation in NOTCH1, deletion of the tumor suppressor gene locus cyclin-dependent kinase 2A (CDKN2A), and translocation of the TCR-beta region to the STIL-TAL1 locus. These findings highlight a general toxicity of endogenous gammaretroviral enhancer elements and also identify a combinatorial process during leukemic evolution that will be important for risk stratification and for future protocol design.

HLH‐94: A treatment protocol for hemophagocytic lymphohistiocytosis

In January 1995, the Hemophagocytic Lymphohistiocytosis (HLH) Study Group opened its first international treatment study dedicated to the hemophagocytic lymphohistiocytoses. The main intention of the study protocol is to offer affected children therapy with a wellestablished chemotherapeutic regimen (epipodophyllotoxin and corticosteroids) in combinationwith a newer approach, immunotherapy with cyclosporin A. Subsequent bone marrow transplantation (BMT) is recommended to all children with an available donor. The purpose of this communication is to describe this approach to management, that intends to prolong survival and increase the cure rate for children throughout the world with this highly lethal disease [1].

Treatment strategy and long-term results in paediatric patients treated in consecutive UK AML trials.

Between 1988 and 2002, 758 children with acute myeloid leukaemia (AML) were treated on Medical Research Council (MRC) AML 10 and AML 12. MRC AML 10 tested the role of bone marrow transplantation following four blocks of intensive chemotherapy and found that while both allogeneic bone marrow transplant (allo-BMT) and autologous bone marrow transplant (A-BMT) significantly reduced the relapse risk (RR), this did not translate into a significant improvement in overall survival (OS). A risk group stratification based on cytogenetics and response to the first course of chemotherapy derived from MRC AML 10 was used to deliver risk-directed therapy in MRC AML 12. Allo-BMT was limited to standard and poor risk patients and A-BMT was not employed. Instead, the benefit of an additional block of treatment was tested by randomising children to receive either four or five blocks of treatment in total. While the results of MRC AML 12 remain immature, there appears to be no survival advantage for a fifth course of treatment. The 5 year OS, disease-free survival (DFS), event-free survival (EFS) and RR in MRC AML 12 are 66, 61, 56 and 35%, respectively; at present superior to MRC AML 10, which had a 5-year OS, DFS, EFS and RR of 58, 53, 49 and 42%, respectively. MRC AML trials employ a short course of triple intrathecal chemotherapy alone for CNS-directed treatment and CNS relapse is uncommon. Improvements in supportive care have contributed to improved outcomes and the number of deaths in remission fell between trials. Anthracycline-related cardiotoxicity remains a concern and the current MRC AML 15 trial tests the feasibility of reducing anthracycline dosage without compromising outcome by comparing standard MRC anthracycline-based consolidation with high-dose ara-C. MRC studies suggest that the role of allo-BMT is limited in 1st CR and that there may be a ceiling of benefit from current or conventional chemotherapy.

Novel prognostic subgroups in childhood 11q23/MLL-rearranged acute myeloid leukemia: results of an international retrospective study

Translocations involving chromosome 11q23 frequently occur in pediatric acute myeloid leukemia (AML) and are associated with poor prognosis. In most cases, the MLL gene is involved, and more than 50 translocation partners have been described. Clinical outcome data of the 11q23-rearranged subgroups are scarce because most 11q23 series are too small for meaningful analysis of subgroups, although some studies suggest that patients with t(9;11)(p22;q23) have a more favorable prognosis. We retrospectively collected outcome data of 756 children with 11q23- or MLL-rearranged AML from 11 collaborative groups to identify differences in outcome based on translocation partners. All karyotypes were centrally reviewed before assigning patients to subgroups. The event-free survival of 11q23/MLL-rearranged pediatric AML at 5 years from diagnosis was 44% (+/- 5%), with large differences across subgroups (11% +/- 5% to 92% +/- 5%). Multivariate analysis identified the following subgroups as independent prognostic predictors: t(1;11)(q21;q23) (hazard ratio [HR] = 0.1, P = .004); t(6;11)(q27;q23) (HR = 2.2, P < .001); t(10;11)(p12;q23) (HR = 1.5, P = .005); and t(10;11)(p11.2;q23) (HR = 2.5, P = .005). We could not confirm the favorable prognosis of the t(9;11)(p22;q23) subgroup. We identified large differences in outcome within 11q23/MLL-rearranged pediatric AML and novel subgroups based on translocation partners that independently predict clinical outcome. Screening for these translocation partners is needed for accurate treatment stratification at diagnosis.

Chemoimmunotherapy for hemophagocytic lymphohistiocytosis: long-term results of the HLH-94 treatment protocol

Hemophagocytic lymphohistiocytosis (HLH) used to have a dismal prognosis. We report the final results of HLH-94, the largest prospective diagnostic/therapeutic HLH study so far. The treatment includes immunosuppressive and cytotoxic therapy aiming at clinical remission, followed by HSCT in patients with familial, persistent, or recurrent disease. Altogether, 249 patients fulfilled inclusion criteria and started HLH-94 therapy (July 1994-December 2003); 227 (91%) were followed-up for ≥ 5 years. At 6.2 years median follow-up, estimated 5-year probability of survival was 54% ± 6%. Seventy-two patients (29%) died before HSCT, 64 within 1 year, 97% of whom had active disease. In 124 patients who underwent HSCT, 5-year survival was 66 ± 8%; tendency to increased survival (P = .064) in patients with nonactive disease at HSCT. Patients with familial disease had a 5-year survival of 50% ± 13%; none survived without HSCT. Patients deceased during the first 2 months more often had jaundice, edema, and elevated creatinine. Forty-nine patients (20%) were alive without signs of HLH activity and off-therapy > 1-year without HSCT; they presented at older age (P < .001), were more often female (P = .011), and less often had CNS disease (P < .001) or hepatomegaly (P = .007). To conclude, HLH-94 chemoimmunotherapy has considerably improved outcome in HLH. Collaborative efforts are needed to further reduce early mortality, HSCT-related mortality, and neurologic late effects.

Adolescents with acute lymphoblastic leukaemia: Outcome on UK national paediatric (ALL97) and adult (UKALLXII/E2993) trials

Adolescents with acute lymphoblastic leukaemia (ALL) have languished in the shadow of success of the outcome of therapy in childhood ALL. Their treatment has always been incorporated into either paediatric or adult clinical trials depending on the mode of referral and hence there is a need to address an age and risk specific strategy for improving the outcome of this neglected group of patients. This article has summarised the recent and updated retrospective comparative analysis of adolescents treated on the Medical Research Council (MRC) trials. This analysis adds further emphasis to the treatment approach and the merits and limitations of treatment of adolescents on paediatric and adult trials.

Cytogenetics of childhood Acute Myeloid Leukemia: United Kingdom Medical Research Council treatment trials AML 10 and 12

PURPOSE Karyotype is an independent indicator of prognosis in acute myeloid leukemia (AML) that is widely applied to risk-adapted therapy. Because AML is rare in children, the true prognostic significance of individual chromosomal abnormalities in this age group remains unclear. PATIENTS AND METHODS This cytogenetic study of 729 childhood patients classified them into 22 subgroups and evaluated their incidence and risk. RESULTS Rearrangements of 11q23 were the most frequent abnormality found in approximately 16% of patients, with 50% of these in infants. The outcome for all patients with 11q23 abnormalities was intermediate; no difference was observed for those with t(9;11)(p21-22;q23). The core binding factor leukemias with the translocations t(8;21)(q22;q22) and inv(16)(p13q22) occurred at incidences of 14% and 7%, respectively, predominantly in older children, and their prognosis was favorable. An adverse outcome was observed in patients with monosomy 7, abnormalities of 5q, and t(6;9)(p23;q34). Abnormalities of 3q and complex karyotypes, in the absence of favorable-risk features, have been associated with an adverse outcome in adults, but the results were not significant in this childhood series. However, the presence of 12p abnormalities predicted a poor outcome. CONCLUSION Because the spectrum of chromosomal changes and their risk association seem to differ between children and adults with AML, biologic differences are emerging, which will contribute to the redefinition of risk stratification for different age groups in the future.

Haematopoietic stem cell transplantation in haemophagocytic lymphohistiocytosis.

Haemophagocytic lymphohistiocytosis (HLH) poses major therapeutic challenges, and the primary inherited form, familial haemophagocytic lymphohistiocytosis (FHL), is usually fatal. We evaluated, including Cox regression analysis, survival in 86 children (29 familial) that received HLH‐94‐therapy (etoposide, dexamethasone, ciclosporin) followed by allogeneic stem cell transplantation (SCT) between 1995 and 2000. The overall estimated 3‐year‐survival post‐SCT was 64% [confidence interval (CI) = ±10%] (n = 86); 71 ± 18% in those patients with a matched related donor (MRD, n = 24), 70 ± 16% with a matched unrelated donor (MUD, n = 33), 50 ± 24% with a family haploidentical donor (haploidentical, n = 16), and 54 ± 27% with a mismatched unrelated donor (MMUD, n = 13). After adjustment for potential confounding factors, estimated odds ratios (OR) for mortality were 1·93 (CI =0·61–6·19) for MUD, 3·31 (1·02–10·76) for haploidentical, and 3·01 (0·91–9·97) for MMUD, compared with MRD. In children with active disease after 2‐months of therapy (n = 43) the OR was 2·75 (1·26–5·99), compared with inactive disease (n = 43). In children with active disease at SCT (n = 37), the OR was 1·80 (0·80–4·06) compared with inactive disease (n = 49), after adjustment for disease activity at 2‐months. Mortality was predominantly transplant‐related. Most HLH patients survived SCT using MRD or MUD, and survival with partially mismatched donors was also acceptable. Patients that responded well to initial pretransplant‐induction therapy fared best, but some persisting HLH activity should not automatically preclude performing SCT.

Nonmyeloablative stem cell transplantation for congenital immunodeficiencies

The optimal approach for stem cell transplantation in children with immunodeficiency has yet to be determined. Conditioning therapy is necessary for reliable engraftment and full immune reconstitution; however, the beneficial effect of cytoreductive conditioning is counterbalanced by increased short- and long-term treatment-related toxicity. Whether bone marrow transplantation with a nonmyeloablative preparative regimen was sufficient for the establishment of donor immune reconstitution, with the resultant correction of disease phenotype, was investigated. Eight patients with severe immunodeficiency states underwent T-cell replete bone marrow transplantation from a human leukocyte antigen-matched unrelated (n = 6) or sibling (n = 2) donor with nonmyeloablative conditioning using a fludarabine-melphalan-anti-lymphocyte globulin-based regimen. All patients had severe organ dysfunction that precluded transplantation with conventional conditioning. All patients were engrafted with predominantly donor hematopoiesis, and the duration of neutropenia was brief. Significant acute graft-versus-host disease (GVHD) did not develop, but one patient had limited chronic GVHD. One patient died of disease recurrence, and 3 have stable, mixed chimerism. At a median follow-up of 1 year, all patients have had good recovery of CD3(+) T-cell numbers, and 6 of 7 evaluable patients have normal phytohemagglutinin stimulation indices. The rate of immune reconstitution is comparable with that of historical controls undergoing standard myeloablative protocols. Two patients with CD40 ligand deficiency now show significant expression, and a patient with adenosine deaminase deficiency has improved deoxy adenosine triphosphate metabolites. In summary, it has been demonstrated that nonmyeloablative stem cell transplantation permits rapid engraftment from both sibling and unrelated donors with minimal toxicity even in the presence of severe organ dysfunction. If long-term immune reconstitution of patients treated with this protocol is demonstrated, it is believed this approach might offer significant advantages compared with standard protocols by combining adequate immune reconstitution with reduced short- and long-term toxicity. (Blood. 2000;96:1239-1246)