Improving availability and safety of unrelated donor transplants

TBI and melphalan followed by allogeneic hematopoietic SCT in children with advanced hematological malignancies

We evaluated the efficacy and safety of the conditioning regimen that consisted of TBI and melphalan (L-PAM), followed by hematopoietic SCT (HSCT) in 23 children with advanced hematological malignancies. The median age at HSCT was 9 (range, 2-15) years. The underlying diseases were ALL in 16 patients (5 in CR2, 3 in CR3, 6 in relapse (RP) and 2 in induction failure (IF)), AML in 4 patients (3 in RP and 1 in IF) and non-Hodgkin's lymphoma in 3 patients (1 in CR3, 1 in CR4 and 1 in RP). The stem cell sources were BM for 19 patients and cord blood for 4 patients. All patients received the conditioning regimen that consisted of TBI 12 or 13.2 Gy and L-PAM 210 mg/m(2). In all, 22 patients engrafted on the median of day 16 (range, 10-23). The regimen was well tolerated and common regimen-related toxicities (RRTs) included grade II stomatitis and grade I hepatic toxicity. The cumulative incidences of RP and TRM were 47.6 and 21.5%, respectively. At a median follow-up of 24.4 months, the probability of disease-free survival was 41.0%. The regimen may provide sufficient anti-leukemic effect without increased RRT for advanced pediatric hematological malignancies.

Rapid transport and infusion of hematopoietic cells is associated with improved outcome after myeloablative therapy and unrelated donor transplant

We evaluated effects of graft transport time on outcomes after transplantation of 938 unrelated donor bone marrow (BM) or 507 peripheral blood progenitor cells (PBPC) in patients with acute or chronic leukemia and myelodysplastic syndrome (MDS). BM grafts were collected at 107 centers and PBPC, 89 centers. Median time from end of collection to infusion was 14 hours for BM and 15 hours for PBPC. Platelet recovery was less likely in BM recipients when the interval from end of collection to receipt at transplant center was >or=20 hours (odds ratio 0.47, P = .010) and when the interval from receipt to infusion was >or=6 hours (odds ratio 0.57, P = .001). Mortality rates were higher in recipients of HLA-matched BM when the interval from end of collection to receipt at transplant center was >or=20 hours (relative risk 2.67, P < .001) after adjustment for other significant prognostic factors. Mortality after HLA-mismatched BM transplants was not associated with transport time. Transport times had no demonstrable effect on outcomes after PBPC transplants. These data support a general review of current transport procedures, especially for BM grafts requiring longer transport time and every effort made to minimize time from collection to infusion.

Bone marrow transplantation in children with severe aplastic anemia using a conditioning regimen containing 3 Gy of total body irradiation, cyclophosphamide with or without antithymocyte globulin

We have employed the 3 Gy total body irradiation (TBI) containing conditioning regimen to bone marrow transplantation (BMT) for severe aplastic anemia (SAA) in pediatric patients irrespective of donor type since March 1986. The outcome of BMT for 17 SAA patients is favorable. Eight patients received BMT from human leukocyte antigen matched-related donors (MRD) and nine received BMT from alternative donors. The conditioning regimen consisted of 3-Gy TBI and cyclophosphamide of 200 mg/kg in the BMT from MRD. In the case of BMT from alternative donor, antithymocyte globulin 10 mg/kg was added to the regimen. Fifteen of 17 patients (88%) engrafted on median of day 18 (range, 11-26) and all 13 evaluable patients showed complete donor chimerism by median 30 (range, 13-47) days after BMT. Fourteen patients have survived with a median follow-up of 67 (range, 2-228) months and the probability of survival was 81.9% (95% CI, 63.3-100%). No late complications including second malignancies caused by TBI have been observed and all three female patients have regular menstruation. In conclusion, TBI of 3 Gy appears to be an appropriate dose regarding to ensure engraftment and avoid the risk of late adverse event for SAA patients.

Autotransplantation versus HLA-matched unrelated donor transplantation for acute myeloid leukaemia: a retrospective analysis from the Center for International Blood and Marrow Transplant Research

Most acute myeloid leukaemia (AML) patients lack human leucocyte antigen-identical sibling donors for transplantation. Autotransplants and unrelated donor (URD) transplants are therapeutic options. To compare autologous versus URD transplantation for AML in first (CR1) or second complete remission (CR2), we studied the outcomes of 668 autotransplants were compared with 476 URD transplants reported to the Center for International Blood and Marrow Transplant Research. Proportional hazards regression adjusted for differences in prognostic variables. In multivariate analyses transplant-related mortality (TRM) was significantly higher and relapse lower with URD transplantation. Adjusted 3-year survival probabilities were: in CR1 57 (53-61)% with autotransplants and 44 (37-51)% URD (P = 0.002), in CR2 46 (39-53)% and 33 (28-38)% respectively (P = 0.006). Adjusted 3-year leukaemia-free survival (LFS) probabilities were: CR1 53 (48-57)% with autotransplants and 43 (36-50)% with URD (P = 0.021), CR2 39 (32-46)% and 33 (27-38)% respectively (P = 0.169). Both autologous and URD transplantation produced prolonged LFS. High TRM offsets the superior antileukaemia effect of URD transplantation. This retrospective, observational database study showed that autotransplantation, in general, offered higher 3-year survival for AML patients in CR1 and CR2. Cytogenetics, however, were known in only two-thirds of patients and treatment bias cannot be eliminated.

Optimization of conditioning for marrow transplantation from unrelated donors for patients with aplastic anemia after failure of immunosuppressive therapy

In 87 patients with aplastic anemia who failed to respond to immunosuppressive treatment, we determined the minimal dose of total body irradiation (TBI) required when added to antithymocyte globulin (ATG, 30 mg/kg x 3) plus cyclophosphamide (CY, 50 mg/kg x 4) to achieve engraftment of unrelated donor marrow. TBI was started at 3 x 200 cGy, to be escalated or deescalated in steps of 200 cGy depending on graft failure or toxicity. Patients were aged 1.3 to 53.5 years (median, 18.6 years). The interval from diagnosis to transplantation was 3 to 328 months (median, 14.6 months). Donors were HLA-A, -B, -C, -DR, and -DQ identical for 62 patients, and nonidentical for 1 to 3 HLA loci at the antigen or allele level for 25. The dose-limiting toxicity was diffuse pulmonary injury. The optimum TBI dose was 1 x 200 cGy. Nine patients did not tolerate ATG and were prepared with CY + TBI. Graft failure occurred in 5% of patients. With a median follow-up of 7 years, 38 (61%) of 62 HLA-identical, and 10 (40%) of 25 HLA-nonidentical transplant recipients are surviving. The highest survival rate with HLA-identical transplants was observed at 200 cGy TBI. Thus, low-dose TBI + CY + ATG conditioning resulted in excellent outcome of unrelated transplants in patients with aplastic anemia who had received multiple transfusions.

Which donor should be chosen for hematopoietic stem cell transplantation among unrelated HLA-A, -B, and -DRB1 genomically identical volunteers?

The aim of this study was to identify significant prognostic factors by using unrelated genomically HLA-A, -B and -DRB1-identical donors. Such data could help to choose the best donor. We studied 136 consecutive patients with hematologic malignancies and a median age of 32 years (range, 0-55 years) who received hematopoietic stem cell transplantation. Bone marrow grafts were given to 83 and peripheral blood stem cells to 53 patients. The cumulative incidence of grade II to IV acute graft-versus-host disease (GVHD) was 30% and of chronic GVHD was 54%. At 5 years, the overall transplant-related mortality (TRM) was 34%, and patient survival was 50%. In Cox multivariate analysis, 32 potential risk factors were analyzed. Monoclonal antibody OKT-3 during conditioning was correlated with grade II to IV acute GVHD, chronic GVHD, and TRM. HLA-DP mismatch was associated with poor TRM and poor survival. Cytomegalovirus-seropositive patients with a seronegative donor had a decreased leukemia-free survival. Five-year TRM was 14% with no risk factor, 38% with 1 risk factor, and 87% with 2 risk factors. The 5-year survival was 72%, 48%, and 30% with 0, 1, and 2 risk factors, respectively. We concluded that unrelated hematopoietic stem cell transplantation may be improved if an optimal donor and immunosuppression are chosen.

Availability of unrelated donors for hematopoietic stem cell transplantation for hemoglobinopathies

Hematopoietic stem cell transplantation (HSCT) is the only curative option for patients with hemoglobinopathies. However, fewer than 30% of individuals will have an HLA-identical sibling. Improvement in outcomes after HSCT using unrelated donors (URD), and the development of novel nontoxic preparative regimens may make URD HSCT an option for hemoglobinopathy patients who do not have an HLA-identical sibling donor. The National Marrow Donor Program (NMDP) maintains a Registry of 4 million volunteer donors, and facilitates URD HSCT for patients with life-threatening blood diseases. In light of the increased representation of minorities in the NMDP registry, donor searches were run in April 2001 for a cohort of 272 thalassemia patients and 77 sickle cell disease (SCD) patients for whom searches had been submitted between 1989 and 2001 in order to determine the current likelihood of finding a potential donor of hematopoietic stem cells for hemoglobinopathy patients. About 59.7% SCD patients 80.2% thalassemia patients will find at least one potential 6/6 HLA matched donor or umbilical cord blood (UCB) unit. All patients will find at least one donor or UCB that is a potential 5/6 HLA match. In conclusion the majority of hemoglobinopathy patients will find at least one potential HLA matched unrelated bone marrow donor or UCB.

Low-dose fractionated total body irradiation (TBI) adversely affects prognosis of patients with leukemia receiving an HLA-matched allogeneic bone marrow transplant from an unrelated donor (UD-BMT)

The optimal total body irradiation (TBI) regimen for unrelated donor bone marrow transplant (UD-BMT) is unknown. In the present study we analyze the outcomes of two different TBI regimens used in our center for patients with leukemia undergoing an UD-BMT. Between January 1994 and August 2001, 99 consecutive UD-BMT patients entered this comparative study. The conditioning regimen consisted of cyclophosphamide, 120 mg/kg followed by TBI on days -3, -2 and -1. Forty-six patients received TBI 12 Gy (2 Gy, twice a day) in six fractions (HF-TBI) and 53 patients received TBI 9.90 Gy (3.30 Gy per day) fractionated over 3 days (F-TBI). End-points were transplanted-related mortality (TRM), leukemia relapse rate (LRR) and overall survival (OS). At median follow-up of 22 months (58 months for HF-TBI and 17 for F-TBI, respectively), 60 patients were alive (32 in HF-TBI sub-group and 28 in F-TBI one). The actuarial 5-year TRM was 31% for HF-TBI and 41% for F-TBI (P = 0.1), whereas the 5-year LRR was 13% for HF-TBI and 31% for F-TBI (P = 0.04). The actuarial 5-year OS was 68% for patients treated with HF-TBI and 51% for those treated with F-TBI (P = 0.02). At multivariate analysis F-TBI schedule emerged as an adverse predictor for OS (P = 0.04) and LRR (P = 0.03). These data indicate that a lower total dose of TBI appears significantly less effective in leukemia eradication and associated with worse overall survival when compared with a higher dose of radiation.

Genetics of the immune response: identifying immune variation within the MHC and throughout the genome

With the advent of modern genomic sequencing technology the ability to obtain new sequence data and to acquire allelic polymorphism data from a broad range of samples has become routine. In this regard, our investigations have started with the most polymorphic of genetic regions fundamental to the immune response in the major histocompatibility complex (MHC). Starting with the completed human MHC genomic sequence, we have developed a resource of methods and information that provide ready access to a large portion of human and nonhuman primate MHCs. This resource consists of a set of primer pairs or amplicons that can be used to isolate about 15% of the 4.0 Mb MHC. Essentially similar studies are now being carried out on a set of immune response loci to broaden the usefulness of the data and tools developed. A panel of 100 genes involved in the immune response have been targeted for single nucleotide polymorphism (SNP) discovery efforts that will analyze 120 Mb of sequence data for the presence of immune-related SNPs. The SNP data provided from the MHC and from the immune response panel has been adapted for use in studies of evolution, MHC disease associations, and clinical transplantation.

Determinants of survival after human leucocyte antigen-matched unrelated donor bone marrow transplantation in adults

Unrelated donor (URD) bone marrow transplantation (BMT) in adults can be associated with high non-relapse mortality (NRM). Therefore, factors determining survival in 136 human leucocyte antigen (HLA)-A, B, DRB1-matched adult BMT recipients were reviewed. Fifty-four per cent of patients had chronic myelogenous leukaemia (CML) and 36% had acute leukaemia or myelodysplasia. Graft-versus-host disease (GvHD) prophylaxis was either cyclosporin A (CSA)/methotrexate (64%) or T-cell depletion and CSA/corticosteroids (34%). The probability of donor engraftment by d 45 was 97% (95% CI: 94-100). Incidence of grades III-IV acute GvHD was 18% (95% CI: 12-24) at 100 d, and chronic GvHD was 42% (95% CI: 32-52) at 2 years. At 2 years, 14% (95% CI: 8-20) had relapsed. Multiple regression analysis showed that adverse risk factors for survival were non-CML diagnosis, age > 35 years, diagnosis to transplant time of > 18 months [chronic-phase CML (CML-CP) only]; and grades III-IV acute GvHD. Patients <or= 35 years with early CML-CP had a 2 year survival of 77% (95% CI: 54-100), which compared with a survival in advanced CML patients <or=35 years of 67% (95% CI: 37-97) and 37% (95% CI: 20-54) in non-CML patients. Two year survival for patients > 35 years with early CML-CP was 55% (95% CI: 33-77), 40% (95% CI: 19-61) in advanced CML and 14% (95% CI:1-27) in non-CML. Future efforts should focus on improving the outcome for older BMT recipients, especially those with diagnoses other than CML.

Association between pretransplant Thymoglobulin and reduced non-relapse mortality rate after marrow transplantation from unrelated donors

A matched cohort study was designed to test the efficacy of polyclonal rabbit antiserum specific for human T cells (Thymoglobulin), administered in vivo on days 1-5 (2 mg/kg/day) before T cell-replete unrelated donor marrow transplantation. Thymoglobulin was given to 52 leukemic patients at Huddinge Hospital. Control patients matched for diagnosis, disease stage, age and treated with a similar regimen, apart from the omission of Thymoglobulin, were selected in Seattle during the same period (n = 104). All received conditioning with cyclophosphamide and TBI. In the study group all patients received 10 Gy single dose TBI, while the controls were given 12-14.4 Gy fractionated TBI. GVHD prophylaxis was cyclosporine and methotrexate. Patients were treated for grade I acute GVHD in the study group, and for grade II GVHD in the control group. Multivariable analyses were adjusted for patient and donor age and CMV serology, HLA matching, donor gender and marrow cell dose. Non-relapse mortality was lower in the study patients (hazard ratio = 0.30, 95% CI 0.12-0.75, P value = 0.005). The 5-year cumulative incidence of non-relapse mortality was 19% in the study cohort, and 35% in the control cohort. Overall mortality was also lower in study patients (hazard ratio 0.51, 95% CI 0.27-0.97, P value = 0.03). No significant difference in the risk of relapse was seen (P = 0.63). This suggests that Thymoglobulin during conditioning may reduce non-relapse mortality after unrelated donor marrow transplantation.

Hematopoietic stem cell transplantation: current status of old issues

Since 1968 hematopoietic stem cell transplantation (HSCT) has progressed from an experimental to standard therapeutic procedure. There are many obstacles to the successful outcome of HSCT procedures. Some of these obstacles are lack of healthy histocompatible donors, graft versus host disease, graft rejection and infections. Many advances have been made to overcome these obstacles with significant success. However, these issues and associated problems continue to persist at different levels as the field evolves with expanding indications for HSCT, use of alternative sources for hematopoietic stem cells and alternative transplant procedures. Newer interventions have allowed us to overcome some of these obstacles.

Chronic myelogenous leukaemia--new therapeutic principles

The deregulated tyrosine kinase activity of the BCR-ABL fusion protein is the cause of malignant transformation in almost all cases of chronic myelogenous leukaemia (CML), making BCR-ABL an ideal target for pharmacological inhibition. Signal transduction inhibitor (STI571) (formerly CGP57 148B), is an ABL specific, tyrosine kinase inhibitor. In preclinical studies, it has been shown to selectively kill BCR-ABL expressing cells, both in-vitro and in vivo. The results of clinical studies to date are highly encouraging and STI571 promises to be an important addition to the therapy of CML.

Unrelated donor marrow transplantation for acute myeloid leukemia: an update of the Seattle experience

Between 1985 and 1998, 161 patients with primary acute myeloid leukemia (AML) received T-replete bone marrow transplantation (BMT) from unrelated donors in Seattle. Median age was 30 (range 1-55) years. Conditioning for BMT consisted of cyclophosphamide and total body irradiation in 154 (96%) cases and graft-versus-host disease prophylaxis was the standard methotrexate and cyclosporine combination in 134 (83%) cases. Median post-transplant follow-up was 2.9 years. Leukemia-free survival (LFS) at 5 years was 50+/-12% for transplants during first complete remission (n = 16), 28+/-8% during second CR (n = 40), 27+/-17% during subsequent CR (n = 8), 7+/-3% during relapse (n = 81) and 19+/-10% during primary induction failure (n = 16). The cumulative incidences of relapse were 19%, 23%, 25%, 44% and 63%, for the five groups, respectively. Transplantation during remission, a marrow cell dose above 3.5 x 10(8)/kg, and cytomegalovirus seronegative status before BMT in both patient and donor were favorable prognostic factors. Adults in any CR who received a marrow cell dose above 3.5 x 10(8)/mg had a LFS of 54+/-9% at 5 years. These data extend our previous findings on the association between a high marrow cell dose and improved survival and support the use of unrelated donor BMT for treatment of patients with high risk AML when a family match is not available.