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Major histocompatibility complex class I polypeptide-related sequence A (MICA) is a highly polymorphic ligand of the activating NKG2D receptor on natural killer (NK) cells, γδ-T cells, and NKT cells. MICA incompatibilities have been associated with an increased graft-versus-host disease (GVHD) incidence, and the MICA-129 (met/val) dimorphism has been shown to influence NKG2D signaling in unrelated hematopoietic stem cell transplantation (uHSCT). We investigated the effect of MICA matching on survival after uHSCT. We sequenced 2172 patients and their respective donors for MICA. All patients and donors were high-resolution HLA-typed and matched for 10/10 (n = 1379), 9/10 (n = 636), or 8/10 (n = 157) HLA alleles. Within each HLA match group, cases matched and mismatched for MICA and MICA-129 were analyzed for the end points overall survival (OS), disease-free survival (DFS), nonrelapse mortality (NRM), relapse-incidence (RI), and GVHD. Mismatches at the MICA locus as well as MICA-129 increased with the number of HLA mismatches (MICA mismatched 10/10, 9.2% [n = 127]; 9/10, 22.3% [n = 142]; 8/10, 38.2% [n = 60]; MICA-129 mismatched 10/10, 3.9% [n = 54]; 9/10, 10.2% [n = 65]; 8/10, 17.2% [n = 27]). Adverse OS was observed in the 10/10 match group if MICA-129 was mismatched (10/10, hazard ratio [HR], 1.77; confidence interval [CI], 1.22-2.57; P = .003). MICA-129 mismatches correlated with a significantly worse outcome for DFS in the 10/10 HLA match group (HR, 1.77; CI, 1.26-2.50; P = .001). Higher rates of aGVHD were seen in MICA-129 mismatched cases. Our results indicate that MICA-129 matching is relevant in uHSCT. Prospective typing of patients and donors in unrelated donor search may identify mismatches for MICA-129, and compatible donor selection may improve outcome for this small but high-risk subgroup., (© 2016 by The American Society of Hematology.)

Patients with autoimmune multilineage cytopenias are often refractory to standard therapies requiring chronic immunosuppression with medications with limited efficacy and high toxicity. We present data on 30 patients treated on a multicenter prospective clinical trial using sirolimus as monotherapy. All children (N = 12) with autoimmune lymphoproliferative syndrome (ALPS) achieved a durable complete response (CR), including rapid improvement in autoimmune disease, lymphadenopathy, and splenomegaly within 1 to 3 months of starting sirolimus. Double-negative T cells were no longer detectable in most, yet other lymphocyte populations were spared, suggesting a targeted effect of sirolimus. We also treated 12 patients with multilineage cytopenias secondary to common variable immunodeficiency (CVID), Evans syndrome (ES), or systemic lupus erythematosus (SLE), and most achieved a CR (N = 8), although the time to CR was often slower than was seen in ALPS. Six children with single-lineage autoimmune cytopenias were treated and only 2 responded. Sirolimus was well tolerated with very few side effects. All of the responding patients have remained on therapy for over 1 year (median, 2 years; range, 1 to 4.5 years). In summary, sirolimus led to CR and durable responses in a majority of children with refractory multilineage autoimmune cytopenias. The responses seen in ALPS patients were profound, suggesting that sirolimus should be considered as a first-line, steroid-sparing treatment of patients needing chronic therapy. The results in other multilineage autoimmune cytopenia cohorts were encouraging, and sirolimus should be considered in children with SLE, ES, and CVID. This trial was registered at www.clinicaltrials.gov as #NCT00392951., (© 2016 by The American Society of Hematology.)

The objective was to evaluate the prognostic and predictive impact of allelic ratio and insertion site (IS) of internal tandem duplications (ITDs), as well as concurrent gene mutations, with regard to postremission therapy in 323 patients with FLT3-ITD-positive acute myeloid leukemia (AML). Increasing FLT3-ITD allelic ratio (P = .004) and IS in the tyrosine kinase domain 1 (TKD1, P = .06) were associated with low complete remission (CR) rates. After postremission therapy including intensive chemotherapy (n = 121) or autologous hematopoietic stem cell transplantation (HSCT, n = 17), an allelic ratio ≥ 0.51 was associated with an unfavorable relapse-free (RFS, P = .0008) and overall survival (OS, P = .004); after allogeneic HSCT (n = 93), outcome was significantly improved in patients with a high allelic ratio (RFS, P = .02; OS, P = .03), whereas no benefit was seen in patients with a low allelic ratio (RFS, P = .38; OS, P = .64). Multivariable analyses revealed a high allelic ratio as a predictive factor for the beneficial effect of allogeneic HSCT; ITD IS in TKD1 remained an unfavorable factor, whereas no prognostic impact of concurrent gene mutations was observed. The clinical trials described herein were previously published or are registered as follows: AMLHD93 and AMLHD98A, previously published; AML SG 07-04, ClinicalTrials.gov identifier #NCT00151242., (© 2014 by The American Society of Hematology.)

There have been no studies on patient outcome after allogeneic hematopoietic cell transplantation (HCT) in patients with X-linked inhibitor of apoptosis (XIAP) deficiency. To estimate the success of HCT, we conducted an international survey of transplantation outcomes. Data were reported for 19 patients. Seven patients received busulfan-containing myeloablative conditioning (MAC) regimens. Eleven patients underwent reduced intensity conditioning (RIC) regimens predominantly consisting of alemtuzumab, fludarabine, and melphalan. One patient received an intermediate-intensity regimen. Survival was poor in the MAC group, with only 1 patient surviving (14%). Most deaths were from transplantation-related toxicities, including venoocclusive disease and pulmonary hemorrhage. Of the 11 patients who received RIC, 6 are currently surviving at a median of 570 days after HCT (55%). Preparative regimen and HLH activity affected outcomes, and of RIC patients reported to be in remission from HLH, survival is 86% (P = .03). We conclude that MAC regimens should not be used for patients with XIAP deficiency. It is possible that the loss of XIAP and its antiapoptotic functions contributes to the high incidence of toxicities observed with MAC regimens. RIC regimens should be pursued with caution and, if possible, efforts should be made to ensure HLH remission before HCT in these patients.

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans histiocytosis, with noncodified therapeutic management and high mortality. No treatment has yet been shown to improve survival in these patients. We conducted a multicenter prospective observational cohort study to assess whether extraskeletal manifestations and interferon-α treatment would influence survival in a large cohort of ECD patients. To achieve this goal, we thoroughly analyzed the clinical presentation of 53 patients with biopsy-proven ECD, and we performed a survival analysis using Cox proportional hazard model. Fifty-three patients (39 men and 14 women) with biopsy-proven ECD were followed up between November 1981 and November 2010. Forty-six patients (87%) received interferon-α and/or PEGylated interferon-α. Multivariate survival analysis using Cox proportional hazard model revealed that central nervous system involvement was an independent predictor of death (hazard ratio = 2.51; 95% confidence interval, 1.28-5.52; P = .006) in our cohort. Conversely, treatment with interferon-α was identified as an independent predictor of survival (hazard ratio = 0.32; 95% confidence interval, 0.14-0.70; P = .006). Although definitive confirmation would require a randomized controlled trial, these results suggest that interferon-α improves survival in ECD patients. This may be seen as a significant advance, as it is the first time a treatment is shown to improve survival in this multisystemic disease with high mortality.

Donor-derived T cells have been proposed to play a role in pathogenesis of chronic graft-versus-host disease (cGVHD). The impact of ex vivo T-cell depletion (TCD) on cGVHD was analyzed in a randomized multicenter trial involving unrelated donor marrow transplants. A total of 404 patients diagnosed with hematologic malignancies received a total body irradiation-based myeloablative conditioning regimen. GVHD prophylaxis included TCD plus cyclosporine (CSA) or unmodified grafts with CSA plus methotrexate (M/C). Median recipient age was 31.2 years (range, 0.5-55.6 years); median follow-up time since randomization was 4.2 years. The mean number of T cells infused was 1 log lower on the TCD arm. The incidence of cGVHD at 2 years was similar between the TCD and M/C arms, 29% versus 34% (P = .27), respectively. Survival at 3 years from diagnosis of cGVHD was also similar, (TCD 51% versus M/C 58%; P = .29). The proportion of patients with cGVHD who discontinued immunosuppression at 5 years was not different (TCD 72% versus M/C 63%; P = .27), and incidence of serious infections and leukemia relapse were similar on both treatment arms. In spite of a significant reduction of acute GVHD, TCD did not reduce the incidence of cGVHD or improve survival in patients who developed cGVHD.

New conditioning regimens are being explored to reduce toxicity and enable allogeneic bone marrow transplantation in patients not eligible for conventional transplantation. We have investigated treosulfan, an alkylating agent, with the aim of developing an efficient and reliable but less-toxic conditioning regimen. A series of 30 patients who were not eligible for standard conditioning therapy received transplants from HLA-matched related (n = 14) or unrelated (n = 16) donors after administration of treosulfan 10 g/m2 intravenously daily for 3 days and fludarabine 30 mg/m2 intravenously daily for 5 days. Patients receiving grafts from unrelated donors also were given rabbit antithymocyte globulin 10 mg/kg intravenously daily for 3 days. All patients achieved prompt neutrophil and platelet recovery. Extramedullary toxicity was generally mild with Common Toxicity Criteria (CTC) grade 3 or 4 attributable to the conditioning seen only with transaminases. Complete donor chimerism was achieved by 90% of the patients. Acute graft-versus-host disease (GVHD) grade III or IV developed in 14% of the patients and chronic GVHD in 39%. An estimated overall survival rate of 73% and an event-free survival rate of 49% have been reached after a median of 22 months (range, 7.4-33.4 months). In summary, the combination of treosulfan and fludarabine is a safe and efficient conditioning regimen.

Allogeneic bone marrow transplantation (BMT) may be curative for more patients than chemotherapy for the child with relapsed acute lymphoblastic leukemia. This study reviewed the outcomes of 363 children with acute lymphoblastic leukemia in second remission who received unrelated donor BMT from 1988 to 2000 in order to define prognostic factors that affect leukemia-free survival (LFS). Median patient age was 9 years (range, 0-19 years), and median follow-up 29 was months (range, 0-125 months). The median duration of first remission was 24 months (range, 0-109 months). Prognostic factors, including age, duration of first remission, HLA matching, and graft-versus-host (GVH) disease, were analyzed using both univariate and multivariate analyses. Overall survival was 38%, and LFS was 36% at 5 years. LFS was significantly worse for patients 15 years or older (log-rank, P =.009). HLA matching was associated with improved LFS. Acute GVH disease developed in 71%, with 29% having grades III-IV. The incidence of chronic GVH disease was 39% for patients who survived more than 80 days and was significantly higher for female patients receiving marrow from female donors (P =.0009). Transplantation-related mortality was 42% and was associated with HLA mismatches, age 15 years and older, and first remission less than 12 months. The 5-year estimate for relapse was 22%, with first remission at least 6 months associated with a lower risk. Results of unrelated donor BMT appear similar to multi-institutional studies of matched related donor BMT, and this approach appears to be curative for many patients. However, innovative approaches are needed for patients with initial remissions of less than 6 months and for older teenagers.

Donor T cells play a pivotal role in facilitating alloengraftment but also cause graft-versus-host disease (GVHD). Ex vivo T-cell depletion (TCD) of donor marrow is the most effective strategy for reducing GVHD but can compromise engraftment. This study examined an approach whereby donor T cells are selectively eliminated in vivo after transplantation using transgenic mice in which a thymidine kinase (TK) suicide gene is targeted to the T cell using a CD3 promoter/enhancer construct. Lethally irradiated B10.BR mice transplanted with major histocompatibility complex (MHC)-incompatible TCD C57BL/6 (B6) bone marrow (BM) plus TK(+) T cells were protected from GVHD after treatment with ganciclovir (GCV) in a schedule-dependent fashion. To examine the effect of GCV treatment on alloengraftment, sublethally irradiated AKR mice underwent transplantation with TCD B6 BM plus limiting numbers (5 x 10(5)) of B6 TK(+) T cells. Animals treated with GCV had comparable donor engraftment but significantly reduced GVHD when compared with untreated mice. These mice also had a significantly increased number of donor splenic T cells when assessed 4 weeks after bone marrow transplantation. Thus, the administration of GCV did not render recipients T-cell deficient, but rather enhanced lymphocyte recovery. Adoptive transfer of spleen cells from GCV-treated chimeric mice into secondary AKR recipients failed to cause GVHD indicating that donor T cells were tolerant of recipient alloantigens. These studies demonstrate that administration of TK gene-modified donor T cells can be used as an approach to mitigate GVHD without compromising alloengraftment.

Human leukocyte antigen (HLA)-identical sibling bone marrow transplantation is an effective treatment for Wiskott-Aldrich syndrome. However, most children with this disease lack such donors and many patients receive transplants from alternative donors. This study compared outcomes of HLA-identical sibling, other related donor, and unrelated donor transplantation for Wiskott-Aldrich syndrome. The outcome of 170 transplantations for Wiskott-Aldrich syndrome, from 1968 to 1996, reported to the International Bone Marrow Transplant Registry and/or National Marrow Donor Program were assessed. Fifty-five were from HLA-identical sibling donors, 48 from other relatives, and 67 from unrelated donors. Multivariate proportional hazards regression was used to compare outcome by donor type and identify other prognostic factors. Most transplant recipients were younger than 5 years (79%), had a pretransplantation performance score greater than or equal to 90% (63%), received pretransplantation preparative regimens without radiation (82%), and had non-T-cell-depleted grafts (77%). Eighty percent received their transplant after 1986. The 5-year probability of survival (95% confidence interval) for all subjects was 70% (63%-77%). Probabilities differed by donor type: 87% (74%-93%) with HLA-identical sibling donors, 52% (37%-65%) with other related donors, and 71% (58%-80%) with unrelated donors (P =.0006). Multivariate analysis indicated significantly lower survival using related donors other than HLA-identical siblings (P =.0004) or unrelated donors in boys older than 5 years (P =.0001), compared to HLA-identical sibling transplants. Boys receiving an unrelated donor transplant before age 5 had survivals similar to those receiving HLA-identical sibling transplants. The best transplantation outcomes in Wiskott-Aldrich syndrome are achieved with HLA-identical sibling donors. Equivalent survivals are possible with unrelated donors in young children.

We analyzed engraftment of unrelated-donor (URD) bone marrow in 5246 patients who received transplants facilitated by the National Marrow Donor Program between August 1991 and June 1999. Among patients surviving at least 28 days, 4% had primary graft failure (failure to achieve an absolute neutrophil count > 5 x 10(8)/L before death or second stem-cell infusion). Multivariate logistic regression analysis showed that engraftment was associated with marrow matched at HLA-A, HLA-B, and DRB1; higher cell dose; younger recipient; male recipient; and recipient from a non-African American ethnic group. More rapid myeloid engraftment was associated with marrow serologically matched at HLA-A and HLA-B, DRB1 match, higher cell dose (in non-T-cell-depleted cases), younger recipient, recipient seronegativity for cytomegalovirus (CMV), male donor, no methotrexate for graft-versus-host disease prophylaxis, and transplantation done in more recent years. A platelet count higher than 50 x 10(9)/L was achieved by 47% of patients by day 100. Conditional on survival to day 100, survival at 3 years was 61% in those with platelet engraftment at day 30, 58% in those with engraftment between day 30 and day 100, and 33% in those without engraftment at day 100 (P <.0001). Factors favoring platelet engraftment were higher cell dose, DRB1 allele match, recipient seronegativity for CMV, HLA-A and HLA-B serologically matched donor, and male donor. Secondary graft failure occurred in 10% of patients achieving initial engraftment, and 18% of those patients are alive. These data demonstrate that quality of engraftment is an important predictor of survival after URD bone marrow transplantation.

The efficacy and toxicity of donor leukocyte infusions (DLI) after unrelated donor bone marrow transplantation (BMT) is largely unknown. We identified 58 recipients of unrelated DLI (UDLI) for the treatment of relapsed disease from the National Marrow Donor Program database. A retrospective analysis was performed to determine response, toxicity, and survival after UDLI and to identify factors associated with successful therapy. UDLI was administered for relapsed chronic myelogenous leukemia (CML) (n = 25), acute myelogenous leukemia (AML) (n = 23), acute lymphoblastic leukemia (ALL) (n = 7), and other diseases (n = 3). Eight patients were in complete remission (CR) before UDLI, and 50 were evaluable for response. Forty-two percent (95% confidence interval [CI], 28%-56%) achieved CR, including 11 of 24 (46%; 95% CI, 26%-66%) with CML, 8 of 19 (42%; 95% CI, 20%-64%) with AML, and 2 of 4 (50%; 95% CI, 1%-99%) with ALL. The estimated probability of disease-free survival (DFS) at 1 year after CR was 65% (95% CI, 50%-79%) for CML, 23% (95% CI, 9%-38%) for AML, and 30% (95% CI, 6%-54%) for ALL. Acute graft-versus-host disease (GVHD) complicated UDLI in 37% of patients (grade II-IV, 25%). A total of 13 of 32 evaluable patients (41%) developed chronic GVHD. There was no association between cell dose administered and either response or toxicity. In a multivariable analysis, only a longer interval from BMT to relapse and BMT to UDLI was associated with improved survival and DFS, respectively. UDLI is an acceptable alternative to other treatment options for relapse after unrelated donor BMT. (Blood. 2000;95:1214-1221)

The effect of donor/recipient histocompatibility on relapse in patients receiving T-cell-depleted (TCD) grafts for chronic myelogenous leukemia (CML) was evaluated. Specifically, we sought to determine whether TCD results in an attenuation of the graft-versus-leukemia (GVL) effect on recipients of unrelated marrow grafts similar to that observed in HLA-identical sibling marrow transplantations. This question was addressed by comparative analysis of the relapse rates in marrow grafts who otherwise received identical preparative regimens and graft-versus-host disease (GVHD) prophylaxis schedules (T-cell depletion with T10B9 monoclonal antibody and complement plus posttransplant cyclosporine) and by serial molecular analyses using the polymerase chain reaction (PCR) to detect the bcr/abl RNA transcript in patients transplanted with unrelated donor grafts. Patients transplanted with advanced disease (accelerated phase or blast crisis) had equally high relapse rates, regardless of whether they received HLA-identical sibling (56%;95% confidence interval [CI], 29% to 82%) or unrelated marrow grafts (8%; 95% CI, 0% to 28%) had a significantly lower incidence of relapse than did patients transplanted with HLA-identical marrow grafts (47%; 95% CI, 23% to 71%; P = .002). Because all patients were similarly treated, these data indicate that the lower relapse rate in these unrelated patients was caused by an augmented GVL effect that was most likely attributable to increased HLA disparity between donor and recipient. The probability of developing both acute and chronic GVHD was significantly increased in chronic-phase recipients of unrelated marrow grafts, suggesting that the enhanced GVL effect was at least partly GVHD-associated. The lack of such a finding in advanced disease patient receiving unrelated marrow grafts raises the possibility that clinically significant GVL effect after TCD marrow transplantation was limited and confined to patients with more indolent disease. Serial PCR analyses for the presence of the bcr/abl RNA transcript showed that the vast majority of patients transplanted in chronic phase with unrelated marrow grafts were persistently PCR-negative, indicating that the GVL effect was durable in these patients. Most of these patients were observed to become PCR negative within 1 to 2 months after transplantation, showing that early eradication of leukemia was possible with TCD marrow grafts. This study shows that the use of unrelated marrow grafts compensates for reduced GVL reactivity associated with TCD in patients transplanted for CML. Furthermore, these data indicate that, in selected patient populations with CML, TCD can be used to reduce GVHD without a commensurate compromise in the GVL effect.

Between January 1988 and March 1993, 48 patients received T-cell-depleted marrow grafts from unrelated donors as treatment for chronic myelogenous leukemia (CML). The median age of the population was 31.7 years (range 5.4 to 53) with 17 of 48 patients greater than 40 years of age. Twenty-seven patients were transplanted in chronic phase, 17 in accelerated phase, and 4 in blast crisis. All patients received a standardized preparative regimen of cyclophosphamide, high-dose cytosine arabinoside, methylprednisolone, and total body irradiation. Marrow grafts were depleted of mature T cells with the alpha beta T-cell receptor antibody T10B9 as graft-versus-host disease (GVHD) prophylaxis. All patients also received posttransplant cyclosporine therapy. Twenty-eight of 48 patients were mismatched with their donors for one or more HLA-A, B, DR, or DQ loci by either serology or high-resolution oligonucleotide genotyping. Nine of 28 were mismatched at multiple HLA loci. Durable engraftment was achieved in 94% (45/48) of patients. The actuarial probability of developing grades II to IV and grades III to IV acute GVHD were 39.6% (95% confidence interval (CI) 26.9 to 53.0) and 8.3% (95% CI 6.1 to 10.9) for the entire cohort. There was no difference in the incidence of grades II to IV acute GVHD between patients receiving matched (36.8%) or mismatched (41.4%) marrow grafts (P = .77). The actuarial probability of relapse at 2 years was 8.8% (95% CI 2.1 to 21.6) for the entire cohort and 18% (95% CI 4 to 41) for patients transplanted in either the accelerated or blast crisis phase (advanced disease). One cytogenetic relapse has occurred among patients transplanted in the chronic phase. The probability of disease-free survival at 2 years was 52% (95% CI 24 to 70) for patients transplanted in chronic phase and 46% (95% CI 25 to 73) for patients transplanted with advanced disease. No difference in disease-free survival was observed between patients receiving matched (49%) or mismatched (51%) marrow grafts (P = .90). This study shows that patients receiving unrelated T-cell-depleted marrow grafts for CML can achieve durable engraftment with a low incidence of severe GVHD and apparent preservation of graft-versus-leukemia reactivity. These data also suggest that T-cell depletion may allow patients who might otherwise experience unacceptable toxicity from GVHD-related complications caused by older age or increased HLA disparity to benefit from unrelated marrow grafts.

To determine if cell membrane phenotypes change under the selective pressures of therapy we have conducted a prospective study of 54 children with lymphoid malignancies of T-like, B-like, common, and null cell types. Membrane phenotypes were determined at diagnosis in all patients and again 1-24 mo later in 18 children who either failed induction therapy or had one or more relapses. In 7 patients the cells tested were from relapse sites different than those of the original diagnoses. The data indicate that at relapse most children with lymphoid neoplasias had the same cell membrane phenotype as established at diagnosis, and suggest that the site of relapse did not affect the expression of cell surface markers. However, there were three exceptions: (1) a child initially diagnosed as having null cell acute lymphocytic leukemia had 90% T-antigen-positive blasts in her second-relapse bone marrow; (2) only membrane IgM was present on relapse blasts from a B-cell lymphoma that had both membrane IgM and IgD before initiation of treatment; (3) at diagnosis, bone marrow blasts from a child with T-like leukemia expressed both T antigen and E receptors, but at relapse, bone marrow and pleural fluid cells expressed only T antigens. We postulate that these phenotype shifts may be due to selective effects of therapy on cells at different stages of differentiattion.

Differential interference contrast (DIC) microscopy (Nomarsky optics) readily demonstrates the formation of "pits" or crater-like depressions in red cell membranes of splenectomized individuals. Splenic reticuloendothelial dysfunction characteristic of many patients with sickle cell disease (SCD) can be demonstrated by technetium spleen scans, but this technique is expensive, requires injection of radioactive material into children, and is cumbersome to perform at regular intervals. However, pit formation in red cells, which also appears to reflect splenic dysfunction, can readily be quantitated in a finger-stick blood sample using DIC microscopy. In this study, the degree of red cell pitting was compared with results of technetium spleen scans and measurements of Howell-Jolly bodies in individuals with sickle cell disease. The average pitted cell percentage in the control population was 0.5% +/- 0.5 (range 0.0-2.6) and 30.5% +/- 13.9 in the SCD population (range 2.4-71.1) (less than 0.001). Of the individuals studied with SCD, 12 also had technetium (99mTc) sulfur colloid scans and measurements of Howell-Jolly bodies. The percentage of Howell-Jolly bodies was low and did not correlate well with the degree of splenic visualization. However, there was an excellent correlation between pit count and splenic dysfunction as measured by spleen scan. Determination of red cell pitting, therefore, appears to offer a simple means for clinical evaluation of splenic reticuloendothelial function in patients with SCD.

The frequency of three serologically defined HLA-D region antigens--DR, MB, and MT--was determined in a group of 74 children with non-T, non-B acute lymphocytic leukemia (ALL). Statistically, there were no significant differences in the frequency of any antigen in these ALL patients as compared with a panel of 85 normal controls. However, significant differences in HLA-DR frequencies were observed between patients who relapsed or who remained disease-free during a 30-mo period of chemotherapy. An increased incidence of relapse was associated with DR5, while disease-free remission during chemotherapy was associated with DR7. Life table analysis also demonstrated that DR5 was significantly associated with a decrease in disease-free survival in these patients. These data suggest that HLA-associated genetic factors may influence the responses of ALL patients to chemotherapy.