Strategies to reduce relapse risk in patients undergoing allogeneic stem cell transplantation for acute myeloid leukaemia.

Allogeneic stem cell transplantation is a centrally important curative strategy in adults with acute myeloid leukaemia; however, relapse occurs in a significant proportion of patients and remains the leading cause of treatment failure. The prognosis for patients who relapse post-transplant remains poor, and the development of new strategies with the ability to reduce disease recurrence without increasing transplant toxicity remains a priority. In this review, within the context of our understanding of disease biology and the graft-versus-leukaemia (GVL) effect, we will discuss established, evolving and novel approaches for increasing remission rates, decreasing measurable residual disease pretransplant, future methods to augment the GVL effect and the opportunities for post-transplant maintenance. Future progress depends upon the development of innovative trials and networks, which will ensure the rapid assessment of emerging therapies in prospective clinical trials.

HLA alleles, haplotypes frequencies, and their association with hematological disorders: a report from 1550 families whose patients underwent allogeneic bone marrow transplantation in Egypt.

HLA alleles are representative of ethnicities and may play important roles in predisposition to hematological disorders. We analyzed DNA samples for HLA-A, -B, -C, -DRB1, and -DQB1 loci, from 1550 patients and 4450 potential related donors by PCR-SSO (Polymerase chain reaction sequence-specific oligonucleotides) and estimated allele frequencies in donors and patients from 1550 families who underwent bone marrow transplantation (BMT) in Egypt. We also studied the association between HLA allele frequencies and incidence of acute myeloid leukemia, acute lymphoblastic leukemia, and severe aplastic anemia. The most frequently observed HLA class I alleles were HLA- A*01:01 (16.9%), A*02:01 (16.1%), B*41:01 (8.7%), B*49:01 (7.3%), C*06:02 (25.1%), and C*07:01 (25.1%), and the most frequently observed class II alleles were HLA-DRB1*11:01 (11.8%), DRB1*03:01 (11.6%), DQB1*03:01 (27.5%), and DQB1*05:01 (18.9%). The most frequently observed haplotypes were A*33:01~B*14:02 ~ DRB1*01:02 (2.35%) and A*01:01~B*52:01~DRB1*15:01 (2.11%). HLA-DRB1*07:01 was associated with higher AML odds (OR, 1.26; 95% CI, 1.02-1.55; p = 0.030). Only HLA-B38 antigen showed a trend towards increased odds of ALL (OR, 1.52; 95% CI, 1.00-2.30; p = 0.049) HLA-A*02:01, -B*14:02, and -DRB1*15:01 were associated with higher odds of SAA (A*02:01: OR, 1.35; 95% CI, 1.07-1.70; p = 0.010; B*14:02: OR, 1.43; 95% CI, 1.06-1.93; p = 0.020; DRB1*15:01: OR, 1.32; 95% CI, 1.07-1.64; p = 0.011). This study provides estimates of HLA allele and haplotype frequencies and their association with hematological disorders in an Egyptian population.

Outcomes of transplant-eligible patients with myelodysplastic syndrome with excess blasts registered in an observational study: The JALSG-CS11-MDS-SCT.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is the sole curative therapy for myelodysplastic syndrome (MDS). However, whether bridging therapy (BRT) including azacitidine (AZA) and combination chemotherapy (CCT) prior to allo-SCT should be performed is unclear. We analyzed BRT and the outcomes of patients with myelodysplastic syndrome with excess blasts (MDS-EB) who were ≤ 70 years old at the time of registration for a prospective observational study to clarify the optimal allo-SCT strategy for high-risk MDS. A total of 371 patients were included in this study. Among 188 patients (50.7%) who were considered for allo-SCT, 141 underwent allo-SCT. Among the patients who underwent allo-SCT, 64 received AZA, 29 received CCT, and 26 underwent allo-SCT without BRT as the initial treatment. Multivariate analysis identified BRT as an independent factor influencing overall survival (AZA vs. without BRT, hazard ratio [HR] 3.33, P = 0.005; CCT vs. without BRT, HR 3.82, P = 0.003). In multivariate analysis, BRT was independently associated with progression-free survival (AZA vs. without BRT: HR, 2.23; P = 0.041; CCT vs. without BRT: HR, 2.94; P = 0.010). Transplant-eligible patients with MDS-EB should undergo allo-SCT when clinically acceptable, and upfront allo-SCT without BRT may be superior to AZA or CCT.

Antibody, cell-mediated response and infection susceptibility in allogeneic hematopoietic stem cell recipients after COVID-19 mRNA vaccination.

BACKGROUND: Patients undergoing allogeneic stem-cell transplantation (allo-SCT) have reduced responses to vaccines due to immunosuppressive status linked to GvHD prophylaxis and treatment. In our study, we compared humoral responses to anti-SARS-CoV-2 mRNA vaccine, and infection onset, according to patients and transplant features; we also evaluated cellular response in patients without seroconversion. METHODS: We tested antibodies titer after second and third vaccine doses. Antibodies were detected through an immune-enzymatic assay. In a patients' subgroup without seroconversion, we tested cell-mediated responses evaluating interferon-gamma release by T-lymphocytes exposed to virus spike protein. RESULTS: Seroconversion rate increased from 66% at 30 days to 81% at 90 days after the second dose; it was 97% at 150 days after the third dose. We found a significant association between seroconversion after the second dose and two variables: shorter interval between allo-SCT and vaccination; ongoing immunosuppression. Twelve of 19 patients (63%) without antibodies after the second dose did not show cellular responses. Nineteen percent of patients developed SARS-CoV-2 infection after the third dose, with favorable outcome in all cases. Patients within 12 months after allo-SCT showed a significantly higher infection risk. CONCLUSIONS: Our study suggests that an interval shorter than 12 months between allo-SCT and first vaccine dose and/or ongoing immunosuppression were associated with humoral and cellular response deficiency after two doses. Third dose induced an increased and sustained humoral response in the majority of patients. However, patients within 1 year after allo-SCT remained at higher infection risk and may be candidate for prophylaxis with anti-SARS-CoV-2 monoclonal antibodies.

Outcomes of second allogeneic stem cell transplantation and anti-relapse strategies in patients with relapsed/refractory acute myeloid leukemia: A unicentric retrospective analysis.

Second allogeneic stem cell transplantation (allo-SCT2) represents a rescue option for selected patients (pts) with relapsed/refractory (r/r) acute myeloid leukemia (AML). Still, relapse rates post-allo-SCT2 remain high and effective anti-relapse strategies and predictive biomarkers remain to be defined. We here analyzed a cohort of 41 AML patients (pts) undergoing allo-SCT2 in our center. Allo-SCT2 induced a third hematologic complete remission (CR) in 37 pts, at costs of a 36% non-relapse mortality rate. Furthermore, 19 pts eventually relapsed post allo-SCT2. Addressing relapse after allo-SCT2, 14 pts (74%) underwent cell-based anti-relapse strategies, including third allogeneic transplantation (allo-SCT3; 3/14), donor lymphocyte infusions (DLIs) combined with either 5-azacytidin and venetoclax (4/14) or chemotherapeutic agents (7/14). Notably, six of seven pts (86%) who received either allo-SCT3 or a combination therapy of DLIs, 5-azacytidine and venetoclax achieved CR despite poor cytogenetics post-allo-SCT2 (e.g., TP53). Finally, 11 of 41 pts were alive at the last follow-up (seven CR2, three CR3, one partial remission) resulting in estimated 2- and 5-year overall survival of 35% and 25%, respectively.

Allogeneic stem cell transplantation in AML with t(6;9)(p23;q34);DEK-NUP214 shows a favourable outcome when performed in first complete remission.

Acute myeloid leukaemia (AML) with t(6;9)(p23;q34) is a poor-risk entity, commonly associated with FLT3-ITD (internal tandem duplication). Allogeneic stem-cell tranplantation (allo-SCT) is recommended, although studies analysing the outcome of allo-SCT in this setting are lacking. We selected 195 patients with t(6;9) AML, who received a first allo-SCT between 2000 and 2016 from the EBMT (European Society for Blood and Marrow Transplantation) registry. Disease status at time of allo-SCT was the strongest independent prognostic factor, with a two-year leukaemia-free survival and relapse incidence of 57% and 19% in patients in CR1 (first complete remission), 34% and 33% in CR2 (second complete remission), and 24% and 49% in patients not in remission, respectively (P < 0·001). This study, which represents the largest one available in t(6;9) AML, supports the recommendation to submit these patients to allo-SCT in CR1.

Quantitative PCR Is Faster, More Objective, and More Reliable Than Immunohistochemistry for the Diagnosis of Cytomegalovirus Gastrointestinal Disease in Allogeneic Stem Cell Transplantation.

Diagnosis of gastrointestinal (GI) cytomegalovirus (CMV) disease relies on the presence of GI symptoms and detection of CMV, mainly by immunohistochemistry (IHC), in GI biopsy specimens. Thus, in a symptomatic patient, a positive CMV-IHC result is accepted as a diagnosis of CMV disease. However, a positive CMV-PCR in GI tissue is considered "possible" CMV disease. Therefore, it would be very useful if, in practice, both techniques showed equal sensitivity and reliability. This is because PCR has many practical advantages over IHC for detecting CMV. The aim of this study was to compare quantitative PCR with IHC for the diagnosis of GI CMV disease. A total of 186 endoscopic GI biopsy specimens from 123 patients with GI symptoms after an allogeneic stem cell transplantation (allo-SCT; 2004-2017) were analyzed by IHC and PCR on 113 paraffin-embedded and 73 fresh samples. The results were then compared. Of the patients with macroscopic lesions in the mucosa and CMV-IHC-positive biopsy specimens (eg, "proven" CMV disease, n = 28), all but 1 were CMV-PCR positive. Of the patients without macroscopic lesions in the mucosa and CMV-IHC-positive biopsy specimens (eg, probable CMV disease, n = 4), only 1 was CMV-PCR positive. Eight patients had CMV-IHC-negative/CMV-PCR-positive gut biopsy specimens. These cases fall within the current definition of possible CMV disease. In 6 of these 8 cases (75%), the viral load in GI tissue was very high (>10,000 copies/µg). Taken together, the results from the proven and probable cases revealed that CMV-PCR shows the same sensitivity (100%), specificity (98%), and positive (93%) and negative predictive value (100%) as CMV-IHC. Detection of CMV in fresh GI mucosa by quantitative PCR is as useful as IHC for the diagnosis of GI CMV disease. The results show that quantitative PCR has the same sensitivity, specificity, and positive/negative predictive value as IHC.

Brentuximab vedotin for recurrent Hodgkin lymphoma after allogeneic hematopoietic stem cell transplantation: A report from the EBMT Lymphoma Working Party.

BACKGROUND: The treatment of patients with Hodgkin lymphoma (HL) who develop disease progression after undergoing allogeneic stem cell transplantation (allo-SCT) remains challenging. METHODS: The authors assessed outcomes in 184 adult patients with HL who developed disease recurrence or progression after a matched related or unrelated allo-SCT at European Society for Blood and Marrow Transplantation-participating centers between 2010 and 2014. RESULTS: Eighty patients who received brentuximab vedotin (BV) salvage therapy were compared with 104 patients who did not. Patients in the BV group were younger (median age of 30 years vs 34 years) and were more likely to receive pretransplant BV (65% vs 46%) or posttransplant donor lymphocyte infusion (66% vs 33%). The 2 groups otherwise were comparable. Patients in the BV group received a median of 6 doses of posttransplant BV, resulting in a complete remission rate of 29%, a partial response rate of 45%, and a stable disease rate of 26%. Response to BV after allo-SCT did not appear to be affected by receipt of pretransplant BV. Despite a longer median follow-up for surviving patients in the BV group (33 months vs 23 months; P<.001), approximately 34% of the original BV cohort were alive and in CR at the time of last follow-up versus 18% in the group that did not receive BV (P=.003). The use of BV before donor lymphocyte infusion was found to be associated with the highest probability of being alive and in CR (40%) at the time of last follow-up. Salvage BV appeared to have no effect on chronic graft-versus-host disease or 1-year overall survival from the time of disease recurrence after allo-SCT (76% vs 67%). CONCLUSIONS: BV is a safe and effective salvage therapy for patients with HL who develop disease recurrence or progression after undergoing allo-SCT, even after prior exposure to BV.

NK cells produce high levels of IL-10 early after allogeneic stem cell transplantation and suppress development of acute GVHD.

Natural killer (NK) cells rapidly reconstitute following allogeneic stem cell transplantation (allo-SCT), at the time when alloreactive T cell immunity is being established. We investigated very early NK cell reconstitution in 82 patients following T cell-depleted allo-SCT. NK cell number rapidly increased, exceeding T cell reconstitution such that the NK:T cell ratio was over 40 by day 14. NK cells at day 14 (NK-14) were donor-derived, intensely proliferating and expressed chemokine receptors targeted to lymphoid and peripheral tissue. Spontaneous production of the immunoregulatory cytokine IL-10 was observed in over 70% of cells and transcription of cytokines and growth factors was augmented. NK-14 cell number was inversely correlated with the incidence of grade II-IV acute graft versus host disease (GVHD). These findings reveal that robust reconstitution of immunoregulatory NK cells by day 14 after allo-SCT is an important determinant of the clinical outcome, suggesting that NK cells may suppress the development of the T cell-mediated alloreactive immune response through production of IL-10.

Outcomes of allogeneic stem cell transplantation for DLBCL: a multi-center study from the Kyoto Stem Cell Transplantation Group.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) has been considered as a potentially curative treatment option for refractory or relapsed diffuse large B cell lymphoma (DLBCL) patients. However, there is little information available, especially for Japanese patients and in cord blood transplantation (CBT). We aimed to determine treatment outcomes of allo-SCT for DLBCL in the Kyoto Stem Cell Transplantation Group, a multi-institutional joint research group. Sixty-eight DLBCL patients who underwent their first allo-SCT between 2003 and 2016 were included. The median time from diagnosis to transplantation was 13.5 months. Thirty-one patients were in CR/PR at transplantation. Twenty-seven patients underwent CBT. The median follow-up for survivors was 44.2 months. Four-year overall survival (OS) and relapse-free survival (RFS) rates were 23% (95% CI, 13-35%) and 20% (95% CI, 11-31%), respectively. Cumulative incidences of non-relapse mortality and relapse were 23% and 57%, respectively. Patients in CR/PR at allo-SCT had better OS (4-year, 46% vs 4%, P < 0.001) and RFS (4-year, 36% vs 7%, P = 0.005). The source of the stem cell did not significantly affect OS (4-year, bone marrow vs cord blood vs peripheral blood, 28.6% vs 27.2% vs 6.5%, P = 0.193). In multivariate analysis, non-remission status at SCT associated with inferior OS and RFS. Duration from diagnosis to transplantation of less than 1 year associated with inferior RFS. Allo-SCT, including CBT, may be a promising therapeutic modality for DLBCL patients who have good disease control at transplantation.

Frequency, characteristics, and outcome of PTLD after allo-SCT: A multicenter study from the Spanish group of blood and marrow transplantation (GETH).

Post-transplant lymphoproliferative disorder (PTLD) is an infrequent complication of allogeneic stem cell transplant (allo-SCT). AIMS: To estimate the frequency and management of PTLD in Spain and to identify prognostic factors influencing outcomes. METHODS: Multicenter, retrospective analysis of allo-SCT performed in 14 transplant units over a 15-year period. RESULTS: 102 PTLD were diagnosed among 12 641 allo-SCT, leading to an estimated frequency of 0.8%. PTLD was diagnosed at a median of 106 days after SCT. Eighty-seven cases (85%) were diagnosed between 2007 and 2013. At diagnosis, 22% and 17% of the patients had gastrointestinal tract and CNS involvement. Eighty-seven (85%) received rituximab treatment, alone or in combination with immunosuppression reduction, with an ORR of 50.6%. With a median follow-up for survivors of 58 months, the 2-year overall survival (OS) was 33% and the PTLD-related mortality 45%. Age ≥ 40 years, malignant underlying disease, non-response to rituximab, and severe thrombocytopenia or lymphocytopenia at PTLD diagnosis were associated with worse overall survival. CONCLUSIONS: Only a small proportion of allografted patients were diagnosed a PTLD. Its clinical course was highly aggressive, and prognosis poor, especially in those failing rituximab. The prognostic impact found of the platelet, and lymphocyte count at diagnosis requires further confirmation.

Increased Coexpression of PD-1, TIGIT, and KLRG-1 on Tumor-Reactive CD8+ T Cells During Relapse after Allogeneic Stem Cell Transplantation.

Allogeneic stem cell transplantation (allo-SCT) can be a curative treatment for patients with a hematologic malignancy due to alloreactive T cell responses recognizing minor histocompatibility antigens (MiHA). Yet tumor immune escape mechanisms can cause failure of T cell immunity, leading to relapse. Tumor cells display low expression of costimulatory molecules and can up-regulate coinhibitory molecules that inhibit T cell functionality on ligation with their counter-receptors on the tumor-reactive T cells. The aim of this explorative study was to evaluate immune checkpoint expression profiles on T cell subsets and on cytomegalovirus (CMV)- and/or MiHA-reactive CD8+ T cells of allo-SCT recipients using a 13-color flow cytometry panel, and to correlate these expression patterns to clinical outcomes. MiHA-reactive CD8+ T cells exhibited an early differentiated CD27++/CD28++ phenotype with low KLRG-1 and CD57 expression. These T cells also displayed increased expression of PD-1, TIM-3, and TIGIT compared with total effector memory T cells and CMV-specific CD8+ T cells in healthy donors and allo-SCT recipients. Remarkably, high coexpression of PD-1, TIGIT, and KLRG-1 on MiHA-reactive CD8+ T cells was associated with relapse after allo-SCT. Taken together, these findings indicate that MiHA-specific CD8+ T cells of relapsed patients have a distinctive coinhibitory expression signature compared with patients who stay in remission. This phenotype may serve as a potential monitoring tool in patients. Moreover, these findings suggest that PD-1 and TIGIT play important roles in regulating T cell-mediated tumor control, providing a rationale for immunotherapy with blocking antibodies to treat relapse after allo-SCT.

Deleterious Effect of Steroids on Cytomegalovirus Infection Rate after Allogeneic Stem Cell Transplantation Depends on Pretransplant Cytomegalovirus Serostatus of Donors and Recipients.

This study examined the impact of prednisone (PDN) on cytomegalovirus (CMV) infection after allogeneic stem cell transplantation (allo-SCT) according to donor and recipient CMV serostatus. Seventy-five patients underwent allo-SCT from June 2010 to July 2012. The risk of CMV infection according to donor and recipient serostatus was defined as follows: high risk (HR; D-/R+), intermediate risk (IR; D+/R+ and D+/R-), and low risk (D-/R-). Forty-five patients (60%) developed CMV infection, and 46 patients (61%) received steroids (PDN ≥ 1 mg/kg/day) to treat acute graft-versus-host disease. CMV infection was more common in those treated with steroids than in those not treated with steroids (70% versus 44%, respectively, P < .05). Overall, 40% of patients had recurrent CMV infection (50% PDN versus 24% no PDN, P < .05). Steroids had no impact on the incidence of CMV infection or its recurrence in HR patients; however, steroids did prolong the need for antiviral treatment. The incidence of CMV infection in IR patients was higher in those receiving PDN (80% PDN versus 41% no PDN, P = .01); recurrence rates were also higher (55% PDN versus 18% no PDN, P = .02). We analyzed CMV-specific immune reconstitution in the first 22 patients of the series and observed that patients on steroids had lower levels of CMV-specific lymphocytes TCD8 (P < .05 on days +60, +100, and +180) and that CMV-specific immune reconstitution (defined as lymphocytes CD8/IFN ≥ 1 cell/µL) was achieved later (after day +100 post-SCT) in the steroid group.

Donor Cell-Derived Hematologic Neoplasms after Hematopoietic Stem Cell Transplantation: A Systematic Review.

Development of de novo hematologic malignancies in donor cells after allogeneic stem cell transplantation (allo-SCT) provides a useful in vivo model to study the process of leukemogenesis. A systematic analysis of the cases reported in the literature was performed to identify risk factors and mechanisms involved in the pathogenesis of donor cell-derived hematologic neoplasms (DCHN) and leukemogenic transformation. Relevant data were extracted from 137 cases. Cases of DCHN show a wide heterogeneity with regard to recipient/donor age, sex mismatch, and conditioning regimen. Some characteristics, such as the type of primary disease, the type of hematologic malignancy of the DCHN, and the stem cell source used in the transplant procedure, differ from those expected. Mechanisms involved in the pathogenesis of DCHN are complex, and several hypotheses have been proposed, such as pre-existing hematologic neoplasms or premalignant clones in the donor, decreased immune surveillance, and damage to bone marrow microenvironment in the recipient. Most likely several if not all these mechanisms play a role in DCHN development. Novel approaches, such as next-generation sequencing to study consecutive samples after allo-SCT in these patients, appear to be promising to decipher the mechanisms of leukemogenesis.

Overall survival with ponatinib versus allogeneic stem cell transplantation in Philadelphia chromosome-positive leukemias with the T315I mutation.

BACKGROUND: Effective treatment options for patients with chronic myeloid leukemia (CML) or Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) who have the threonine to isoleucine mutation at codon 315 (T315I) are few. The objective of this study was to compare overall survival (OS) between patients with CML and those with Ph+ ALL who received treatment with ponatinib versus allogeneic stem cell transplantation (allo-SCT). METHODS: A post hoc, retrospective, indirect comparison of OS among patients who received single-agent ponatinib in the Ponatinib Ph+ ALL and CML Evaluation (PACE) trial with those who underwent allo-SCT as reported to the European Bone Marrow Transplant registry, stratified by CML disease phase and Ph+ ALL, was conducted. Kaplan-Meier survival curves and multivariate Cox proportional-hazards models were used to compare OS between intervention groups, adjusting for time from diagnosis to intervention, age, sex, and geographic region; 24-month and 48-month OS rates and median OS were reported. RESULTS: After adjustment for potential confounders, 24-month and 48-month OS rates were significantly higher in patients with chronic-phase CML (CP-CML) who received ponatinib compared with those who underwent allo-SCT (24 months: 84% vs 60.5%, respectively; P = .004; 48 months: 72.7% vs 55.8%, respectively; P = .013), with a hazard ratio (HR) of 0.37 (95% confidence interval [CI], 0.16-0.84; P = .017). In patients who had accelerated-phase CML, OS rates were not significantly different between the groups (HR, 0.90; 95% CI, 0.20-4.10; P = .889). In patients who had blast-crisis CML and those with Ph+ ALL, ponatinib was associated with shorter OS compared with allo-SCT (blast-crisis CML: HR, 2.29 [95% CI, 1.08-4.82; P = .030]; Ph+ ALL: HR, 2.77 [95% CI, 0.73-10.56; P = .146]). CONCLUSIONS: Although allo-SCT remains an important treatment option for patients with T315I-positive advanced CML and Ph+ ALL, ponatinib represents a valuable alternative for patients with T315I-positive CP-CML. Cancer 2017;123:2875-80. © 2017 American Cancer Society.

Allogeneic hematopoietic stem cell transplantation for non-Hodgkin's lymphomas: a retrospective analysis of 77 cases.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is a therapeutic option for relapsed, advanced, and otherwise incurable non-Hodgkin's lymphomas (NHL) suggested by the existence of a graft-versus-lymphoma effect. The main complications are graft-versus-host disease and infections. We performed a retrospective analysis of patients with NHL, who received an allo-SCT between January 1995 and December 2014. The parameters that had an impact on overall survival were age ≤60 years old, chemosensitive disease pre-allo-SCT, and indolent NHL histology. The parameters that had an impact on progression-free survival were age ≤60 years old and chemosensitive disease pre-allo-SCT. Only aggressive NHL histology and refractory disease pre-allo-SCT showed an increased risk of death in the multivariate model. The use of allo-SCT for young patients with multiple relapsed chemosensitive indolent NHL is a suitable option. Despite poor prognosis, young aggressive NHL patients can be considered for allo-SCT provided they have chemosensitive disease.

Long-lasting HHV-6 reactivation in long-term adult survivors after double umbilical cord blood allogeneic stem cell transplantation.

Higher incidence of human herpesvirus 6 (HHV-6) infection has been documented after umbilical cord blood allo-transplant in adults. Here we demonstrate that HHV-6 reactivation persists for a very long time in half of the patients after this type of graft. Long-term immune reconstitution does not explain this event, which remains to be explained.

MRD detection of leukemia relapse using HLA typing by FACS in combination with FISH after mismatched allogeneic stem cell transplantation.

Loss of mismatched HLA is a cause of relapse following HLA-mismatched allo-SCT. We directly detected the loss of mismatched HLA alleles in relapsed leukemic cells at a MRD level using HLA typing by multicolor FACS (HLA-Flow) in combination with FISH in the BM of two patients with MLL-AF9-positive AML, at 6 and 10 months after mismatched allo-SCT. HLA-Flow with FISH analysis detected relapsed leukemic cells not expressing a mismatched HLA allele and harboring the MLL rearrangement. Simultaneously, real-time quantitative RT-PCR detected a low copy number of MLL-AF9 transcripts, consistent with MRD detection. HLA-Flow with FISH is a powerful method for detecting molecular relapse after mismatched allo-SCT and provides important information on the HLA expression status of the relapsed leukemic cells to help determine the next intervention.

Comparison of allo-SCT, auto-SCT and chemotherapy for the treatment of patients with low- or intermediate-risk acute myeloid leukemia: a network meta-analysis.

BACKGROUND: The therapeutic status of allogeneic stem cell transplantation (allo-SCT) as a post-remission treatment for patients with high-risk acute myeloid leukemia (AML) was well-accepted. However, the optimal treatment for patients with low/favorable- or intermediate-risk AML who achieve complete remission has remained controversial. Therefore, we conducted a network meta-analysis to discuss this disputed problem. METHODS: We compared the effects of treatment strategies including allo-SCT, autologous stem cell transplantation (auto-SCT) and consolidation chemotherapy (CT) for patients with low/favorable- or intermediate-risk AML. The pooled HRs and 95% CIs for overall survival and disease-free survival were estimated with Stata12 and R software. Thirty clinical studies with 6682 patients were included in the meta-analysis. RESULTS: The results indicated that the treatment outcome of allo-SCT was the best, followed by auto-SCT, and CT was likely the worst in the total AML patients. In patients with low/favorable-risk AML, the treatment outcome of auto-SCT was likely ranked first, followed by allo-SCT, and CT was the worst. In patients with intermediate-risk AML, the treatment outcome of haploidentical stem cell transplantation (haplo-SCT) was the best, followed by allo-SCT (excluding haplo-SCT), and auto-SCT and CT were the worst. However, the median age of the haplo-SCT group was much younger than that of the control group, which may be one of the reasons for the better prognosis of the haplo-SCT group. CONCLUSIONS: Patients with low/favorable- and intermediate-risk (non-high-risk) AML should prioritize allo-SCT if they are eligible for transplantation, and auto-SCT is optional. However, in the subgroup analysis, auto-SCT was the optimal treatment choice for patients with low/favorable-risk AML, and allo-SCT was the priority selection for patients with intermediate-risk AML, especially young patients. These findings could provide references for clinical practice.