Impact of marrow unrelated donor search duration on outcome of children with acute lymphoblastic leukemia in second remission

Outcomes of strategic alternative donor selection or suspending donor search based on Japan Marrow Donor Program coordination status

In allogeneic hematopoietic stem cell transplantation (allo-HSCT) from unrelated donors, delays in donor search are adversely associated with patient outcome. However, the optimal duration for either waiting for an unrelated donor or selecting alternative sources remains undetermined. Using data from the Japan Marrow Donor Program (JMDP) registry, we retrospectively analyzed 349 adult patients who had searched for unrelated donors. Two hundred and three patients received allo-HSCT from JMDP donors (Group A) with a median of 140 days required to identify a donor, 60 received allo-HSCT from alternative sources (Group B) after a median of 111.5 days at which point either all donor candidates had failed or the patient achieved a second or subsequent complete remission, and 77 suspended allo-HSCT (Group C) after a median of 310 days. The 5-year overall survival (OS) rate in Group A was superior to that of Group C (48.6 vs 38.5%, P = 0.001). Although Group B included more patients with high or very high disease risk index (DRI) at the time of allo-HSCT compared with Group A, the 5-year OS was not significantly different between Groups A and B (48.6 vs 40.9%, P = 0.07), indicating that switching to alternative donors may benefit patients with high DRI.

Concurrent search for unrelated cord and volunteer donor in high-risk acute lymphoblastic leukemia

To assess the effectiveness of the search for an unrelated donor on the outcome of patients with high-risk acute lymphoblastic leukemia, we analyzed prospectively 136 patients who underwent a search for cord blood (CB) and an unrelated volunteer donor (UD) at the same time. The probability of finding a donor was 58.2%, 70.3%, and 75.7% at 3, 6, and 12 months, respectively. The median time to find a donor was 1.8 months for CB and 3.5 months for UD. Of the 99 patients with a donor, 38.4% failed to undergo the transplant because of a relapse observed at a median of 4 months from the start of the search. In univariate analysis, absence of relapse during the search (p < 0.0001) and transplant (p = 0.004) showed a positive impact on long-term survival. In multivariate analysis, relapse during the search remained the key factor affecting survival (p < 0.0001). Since an extension of the search beyond 3 months enables only a slight increase in the probability of finding a donor compared to the increased risk of relapse, the time of the search should not exceed the 3-month time point. The simultaneous search for CB and UD increases the likelihood of performing a timely transplant.

Does high-resolution donor typing of HLA-C or other loci upon registration confer advantages to patients?

Our study compared all requests for confirmatory typing (CT requests) received in our center between May 2007 and December 2009 (n = 134) for donors issued from 3 groups defined by different human leukocyte antigen (HLA) loci typed at different levels of resolution. We observed a significant advantage for volunteers when HLA-C 2-digit typing was available or with HLA-A, -B, -C, -DRB1 4-digit typing compared with generic HLA-A, -B, -DRB1, -DQB1 DNA typing: increased percentage of CT requests (p < 0.001), increased rate of donor selection for donation (p < 0.001), and decreased time frame for donor search (p = 0.025). The time frame for a successful search (donation) is similar among the 3 groups, indicating that the search might be concluded more rapidly when the pathology is clinically active or when the patient is at a high risk of relapse (76% of our cases) or for pediatric patients (24% of our cases), regardless of HLA typing resolution. Improvement of HLA typing for volunteers could be a great advantage for first selection in the absence of emergency or high-risk disease. Knowledge of HLA-C should be used to prioritize the selection of donors for further testing and could allow a better donor selection process, reducing search duration and increasing efficiency. In most cases, 2-digit typing for HLA-C associated with specific tools to estimate the probability of finding a matched donor could be sufficient.

Stem cell source and outcome after hematopoietic stem cell transplantation (HSCT) in children and adolescents with acute leukemia

Allogeneic hematopoietic stem cell transplantation from siblings, unrelated donors or HLA mismatched family members has become an important procedure to offer a chance of cure to children and adolescents with acute leukemia at high risk of relapse and those with certain genetic diseases. Bone marrow (BM) was the only stem cell source for many years. During the past 15 years, peripheral blood stem cells from granulocyte colony-stimulating factor (G-CSF) mobilized healthy donors, or umbilical cord blood from related or unrelated donors, have become available. Each stem cell source has different risks/benefits for patients and donors, the choice depending not only on availability, but also on HLA compatibility and urgency of the HSCT. This review will analyze the advantages and limitations of each of these options, and the main criteria which can be applied when choosing the appropriate stem cell source for pediatric transplant recipients with acute leukemia.

Hematopoietic stem cell transplantation for leukemia

Leukemia represents the most common pediatric malignancy, accounting for approximately 30% of all cancers in children less than 20 years of age. Most children diagnosed with leukemia are cured without hematopoietic stem cell transplantation (HSCT), but for some high-risk subgroups, allogeneic HSCT plays an important role in their therapeutic approach. The characteristics of these high-risk subgroups and the role of HSCT in childhood leukemias are discussed.

Allogeneic haemopoietic stem cell transplantation in children: what alternative donor should we choose when no matched sibling is available?

Allogeneic haemopoietic stem cell transplantation has provided curative therapy for life-threatening malignant and non-malignant diseases in children for over 40 years. Only 25% of children in whom an allograft is indicated have the ideal option of a human leucocyte antigen-identical sibling donor. Substantial advances in the use of alternative donors (unrelated volunteer donors, haploidentical family donors and unrelated umbilical cord blood donors) now make it possible for almost all children to benefit from this life-saving treatment. Each donor choice is associated with distinct advantages and disadvantages, which have greater or lesser importance in different diseases. We review the current status of alternative donor transplantation for haematological malignancies, primary immunodeficiencies, inherited metabolic disorders and bone marrow failure syndromes and outline the current UK consensus donor selection algorithms for these disease groups.

Transplantation for children with acute lymphoblastic leukemia

EFS for children with ALL continues to increase and is predicted to reach 90% with current therapy. Better understanding of leukemia cell biology and pharmacogenetics has led to the design of more effective treatment and also refined the prognostic features associated with a poor outcome. ALL characterized by the translocation t(9;22) or t(4;11), or by a hypodiploid karyotype or by an incomplete response to induction therapy is likely to relapse. SCT for ALL is largely used to treat patients failing primary chemotherapy but is selectively included as part of initial therapy for children at high risk for relapse. If SCT is going to become the primary therapy for children with ALL in first remission, the regimen-related mortality must approach 0%, and the risk for severe acute and chronic GVHD should be less than 5%. Salvage therapy after ALL relapse remains the major indication for SCT. The time required to find a suitable match has led to the use of cord blood and haploidentical related donors as stem cell sources. For children who relapse, SCT is likely to remain the principal option to promote survival. Efforts to reduce both the risk of relapse and the transplant regimen toxicity, both immediate and delayed, must continue.

Allogeneic hemopoietic stem cell transplantation for childhood acute lymphoblastic leukemia in second complete remission-similar outcomes after matched related and unrelated donor transplant: a study of the Spanish Working Party for Blood and Marrow Transplantation in Children (Getmon)

The authors report the results of 58 children with ALL in 2CR after related (n = 31) or unrelated (n = 27) AHSCT. Characteristics at diagnosis and initial and after relapse antileukemic treatment were similar in the related donor (RD) and the unrelated donor (UD) groups. Conditioning consisted of TBI/CY +/- VP-16 for patients > or = 3 years old (n = 43) and Bu/CY for the rest. Median recipient age was 8 years (range 1-17) in the RD and 9 years (range 3-14) in the UD group. Median follow-up was 54 months (range 24-80) and 52 months (range 22-85) in the RD and the UD groups repectively. The 5-year EFS probability was 43 +/- 9% for the RD group and 36 +/- 9% in the UD group (p = .25). The transplant-related mortality was 16% in the RD and 37% in the UD group (p = .016). In the RD group 36.7% of patients relapsed versus 18.6% in the UD group (p = .05). GvHD associated with organ failure or infection caused most of the transplant-related deaths in both groups. Survivor quality of life for both groups was good (Lansky score < or = 90).

Genetics of Risk Factors for Graft-Versus-Host Disease

Modern understanding of the genetic basis of graft-versus-host disease (GVHD) in allogeneic hematopoietic stem cell transplantation (HSCT) involves knowledge of human leukocyte antigen (HLA), killer immunoglobulin-like receptors (KIR), cytokine genes, and their interactions. Insights into the immunogenetic basis of GVHD come from long-standing clinical experience in the use of myeloablative conditioning regimens and donor bone marrow as the grafting source. Under these circumstances, donor T-cell recognition of host HLA can cause GVHD. The recent elucidation of HLA class I as ligands for natural killer (NK) cell inhibitory KIR demonstrates that GVHD is the result of a complex interplay between the innate and adaptive immune responses. The extent to which T cells and NK cells contribute to clinical GVHD is a function of the host post-conditioning environment, immunosuppressive treatments, and the content of the graft source. The contribution of donor and host genetic differences in cytokine genes in modulating risks of GVHD has recently been recognized.

Role of active follow-up for early diagnosis of relapse after elective end of therapies

OBJECTIVE

To evaluate the role of active follow-up for the detection of relapses occurring after completion of therapy in children with cancer.

METHODS

The clinical records of all children who had a cancer relapse more than 3 months after the end of therapies in the period 1985-2000 were reviewed. Relapses were defined "diagnosed at a scheduled visit" or "at an unscheduled visit" based upon how the visit that lead to the suspected diagnosis was scheduled. Information was collected on how the first suspicion of relapse was made. Survival after relapse was calculated, by type of visit and tumor type.

RESULTS

Among 739 children who completed therapy for a malignant tumor in first complete remission (CR), 101 relapses [74 after solid tumors (ST), 27 after leukemia/lymphoma (L)] occurred after a median time of 12 months (range 3-87). Fifty-one (50.5%) first relapses were diagnosed during a visit scheduled because of symptoms (36 ST, 15 L), and 50 relapses (49.5%) at a regularly scheduled visit (38 ST, 12 L). Overall, 75% of relapses were first suspected on clinical basis, 16% via imaging, and only 9% via lab tests. Survival more than 10 years from first relapse was 25.7% (SE: 0.05%), with no significant differences between relapses diagnosed at a scheduled visit (20.5%), or at an unscheduled visit (32.1%; P = 0.826). Children with L had a better overall survival (OS, 70.6%) as compared to those with ST (9.2%, P < 0.001), probably because of a more extensive use of stem cell transplantation (SCT) as part of the salvage regimens.

CONCLUSIONS

Scheduled follow-up programs failed to detect relapses in 50% of cases presented here. Survival after relapse is not affected by whether relapse was detected at a scheduled or an unscheduled visit.

The Role of Cytotoxic Therapy with Hematopoietic Stem Cell Transplantation in the Therapy of Acute Lymphoblastic Leukemia in Children: An Evidence-Based Review

Evidence supporting the role of hematopoietic stem cell transplantation (SCT) in the therapy of acute lymphoblastic leukemia (ALL) in children is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the treatment recommendations. Treatment recommendations based on the evidence are presented in a table in this review (Summary of Treatment Recommendations Made by the Expert Panel for Pediatric Acute Lymphoblastic Leukemia) and were reached unanimously by a panel of ALL experts. The priority areas of needed future research in pediatric ALL are unrelated marrow or blood donor versus unrelated cord blood donor allogeneic SCT; alternative, nonfamily allogeneic donor versus autologous SCT; better methods for identifying high-relapse-risk patients; assessments of the effect of current chemotherapy regimens on early relapse; and use of pre-SCT detection of minimal residual disease to predict post-SCT outcomes.

Human leukocyte antigen matching in unrelated donor hematopoietic cell transplantation

Hematopoietic cell transplantation (HCT) from unrelated donors is a curative therapy for many malignant and nonmalignant blood disorders. The success of unrelated HCT is influenced by the degree of human leukocyte antigen (HLA) compatibility between the donor and patient. When donor matching for HLA alleles is feasible, overall transplant outcome is superior. The presence of donor-recipient mismatching is associated with increased risk of post-transplant complications including graft rejection, acute and chronic graft-versus-host disease (GVHD), and mortality; these risks are increased with multiple HLA mismatches. For the majority of patients who lack HLA-matched unrelated donors, current research is focused on the identification of permissible HLA mismatches. The influence of nongenetic factors on the tolerability of HLA mismatching has recently become evident, demonstrating a need for the integration of both genetic and nongenetic variables in donor selection.

How to improve the search for an unrelated haematopoietic stem cell donor. Faster is better than more!

Many patients do not reach haematopoietic stem cell transplantation. Shortage of unrelated donors (UDs) is still seen as the main cause. However, with a worldwide UD pool containing more than 8 million donors, it is possible that other impediments are becoming more important. We analysed 549 UD searches for Dutch patients, performed between 1987 and 2000, in order to find the reasons for failure or success to reach transplantation. Between 1996 and 2000, 59% of the patients of Northwest European origin received a graft from an UD with a median time span of 4.4 months from the start of the search. In all, 11% of the patients lacked a compatible donor, while 30% became medically unfit for transplantation. This is in contrast to the patients of non-Northwest European origin for whom UD shortage is still the most important impediment; only 32% were transplanted while 50% lacked a compatible donor. We conclude that the shortage of donors is no longer the biggest constraint in unrelated stem cell transplantation for patients of Northwest European origin. It may be more effective to optimize the chance on transplantation by making the search process more efficient.