Mutational analysis of disease relapse in patients allografted for acute myeloid leukemia

Disease relapse is the major cause of treatment failure after allogeneic stem cell transplantation (allo-SCT) in acute myeloid leukemia (AML). To identify AML-associated genes prognostic of AML relapse post–allo-SCT, we resequenced 35 genes in 113 adults at diagnosis, 49 of whom relapsed. Two hundred sixty-two mutations were detected in 102/113 (90%) patients. An increased risk of relapse was observed in patients with mutations in WT1 (P = .018), DNMT3A (P = .045), FLT3 ITD (P = .071), and TP53 (P = .06), whereas mutations in IDH1 were associated with a reduced risk of disease relapse (P = .018). In 29 patients, we additionally compared mutational profiles in bone marrow at diagnosis and relapse to study changes in clonal structure at relapse. In 13/29 patients, mutational profiles altered at relapse. In 9 patients, mutations present at relapse were not detected at diagnosis. In 15 patients, additional available pre–allo-SCT samples demonstrated that mutations identified posttransplant but not at diagnosis were detectable immediately prior to transplant in 2 of 15 patients. Taken together, these observations, if confirmed in larger studies, have the potential to inform the design of novel strategies to reduce posttransplant relapse highlighting the potential importance of post–allo-SCT interventions with a broad antitumor specificity in contrast to targeted therapies based on mutational profile at diagnosis

Posttransplant MRD and T-cell chimerism status predict outcomes in patients who received allografts for AML/MDS

Allogeneic stem-cell transplant allows for the delivery of curative graft-versus-leukemia (GVL) in patients with acute myeloid leukemia/myelodysplasia (AML/MDS). Surveillance of T-cell chimerism, measurable residual disease (MRD) and blast HLA-DR expression may inform whether GVL effectiveness is reduced. We report here the prognostic impact of these biomarkers in patients allografted for AML/MDS. One hundred eighty-seven patients from FIGARO, a randomized trial of reduced-intensity conditioning regimens in AML/MDS, were alive and relapse-free at the first MRD time-point and provided monitoring samples for flow cytometric MRD and T-cell chimerism, requested to month+12. Twenty-nine (15.5%) patients had at least 1 MRD-positive result posttransplant. MRD-positivity was associated with reduced overall survival (OS) (hazard ratio [HR], 2.18; P = .0028) as a time-varying Cox variable and remained significant irrespective of pretransplant MRD status in multivariate analyses (P < .001). Ninety-four patients had sequential MRD with T-cell chimerism results at months+3/+6. Patients with full donor T-cell chimerism (FDTC) had an improved OS as compared with patients with mixed donor T-cell chimerism (MDTC) (adjusted HR=0.4; P = .0019). In patients with MDTC (month+3 or +6), MRD-positivity was associated with a decreased 2-year OS (34.3%) vs MRD-negativity (71.4%) (P = .001). In contrast, in the group with FDTC, MRD was infrequent and did not affect the outcome. Among patients with posttransplant MRD-positivity, decreased HLA-DR expression on blasts significantly reduced OS, supporting this as a mechanism for GVL escape. In conclusion, posttransplant MRD is an important predictor of the outcome in patients allografted for AML/MDS and is most informative when combined with T-cell chimerism results, underlining the importance of a GVL effect in AML/MDS

Safety and efficacy of autologous haematopoietic stem-cell transplantation with low-dose cyclophosphamide mobilisation and reduced intensity conditioning versus standard of care in refractory Crohn's disease (ASTIClite): an open-label, multicentre, randomised controlled trial

Background: A previous controlled trial of autologous haematopoietic stem-cell transplantation (HSCT) in patients with refractory Crohn's disease did not meet its primary endpoint and reported high toxicity. We aimed to assess the safety and efficacy of HSCT with an immune-ablative regimen of reduced intensity versus standard of care in this patient population. Methods: This open-label, multicentre, randomised controlled trial was conducted in nine National Health Service hospital trusts across the UK. Adults (aged 18–60 years) with active Crohn's disease on endoscopy (Simplified Endoscopic Score for Crohn's Disease [SES-CD] ulcer sub-score of ≥2) refractory to two or more classes of biological therapy, with no perianal or intra-abdominal sepsis or clinically significant comorbidity, were recruited. Participants were centrally randomly assigned (2:1) to either HSCT with a reduced dose of cyclophosphamide (intervention group) or standard care (control group). Randomisation was stratified by trial site by use of random permuted blocks of size 3 and 6. Patients in the intervention group underwent stem-cell mobilisation (cyclophosphamide 1 g/m2 with granulocyte colony-stimulating factor (G-CSF) 5 μg/kg) and stem-cell harvest (minimum 2·0 × 106 CD34+ cells per kg), before conditioning (fludarabine 125 mg/m2, cyclophosphamide 120 mg/kg, and rabbit anti-thymocyte globulin [thymoglobulin] 7·5 mg/kg in total) and subsequent stem-cell reinfusion supported by G-CSF. Patients in the control group continued any available conventional, biological, or nutritional therapy. The primary outcome was absence of endoscopic ulceration (SES-CD ulcer sub-score of 0) without surgery or death at week 48, analysed in the intention-to-treat population by central reading. This trial is registered with the ISRCTN registry, 17160440. Findings: Between Oct 18, 2018, and Nov 8, 2019, 49 patients were screened for eligibility, of whom 23 (47%) were randomly assigned: 13 (57%) to the intervention group and ten (43%) to the control group. In the intervention group, ten (77%) participants underwent HSCT and nine (69%) reached 48-week follow-up; in the control group, nine (90%) reached 48-week follow-up. The trial was halted in response to nine reported suspected unexpected serious adverse reactions in six (46%) patients in the intervention group, including renal failure due to proven thrombotic microangiopathy in three participants and one death due to pulmonary veno-occlusive disease. At week 48, absence of endoscopic ulceration without surgery or death was reported in three (43%) of seven participants in the intervention group and in none of six participants in the control group with available data. Serious adverse events were more frequent in the intervention group (38 in 13 [100%] patients) than in the control group (16 in four [40%] patients). A second patient in the intervention group died after week 48 of respiratory and renal failure. Interpretation: Although HSCT with an immune-ablative regimen of reduced intensity decreased endoscopic disease activity, significant adverse events deem this regimen unsuitable for future clinical use in patients with refractory Crohn's disease. Funding: Efficacy and Mechanism Evaluation Programme, a Medical Research Council and National Institute for Health Research partnership

Fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin with gemtuzumab ozogamicin improves event-free survival in younger patients with newly diagnosed aml and overall survival in patients with npm1 and flt3 mutations

Purpose To determine the optimal induction chemotherapy regimen for younger adults with newly diagnosed AML without known adverse risk cytogenetics. Patients and Methods One thousand thirty-three patients were randomly assigned to intensified (fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin [FLAG-Ida]) or standard (daunorubicin and Ara-C [DA]) induction chemotherapy, with one or two doses of gemtuzumab ozogamicin (GO). The primary end point was overall survival (OS). Results There was no difference in remission rate after two courses between FLAG-Ida + GO and DA + GO (complete remission [CR] + CR with incomplete hematologic recovery 93% v 91%) or in day 60 mortality (4.3% v 4.6%). There was no difference in OS (66% v 63%; P = .41); however, the risk of relapse was lower with FLAG-Ida + GO (24% v 41%; P < .001) and 3-year event-free survival was higher (57% v 45%; P < .001). In patients with an NPM1 mutation (30%), 3-year OS was significantly higher with FLAG-Ida + GO (82% v 64%; P = .005). NPM1 measurable residual disease (MRD) clearance was also greater, with 88% versus 77% becoming MRD-negative in peripheral blood after cycle 2 (P = .02). Three-year OS was also higher in patients with a FLT3 mutation (64% v 54%; P = .047). Fewer transplants were performed in patients receiving FLAG-Ida + GO (238 v 278; P = .02). There was no difference in outcome according to the number of GO doses, although NPM1 MRD clearance was higher with two doses in the DA arm. Patients with core binding factor AML treated with DA and one dose of GO had a 3-year OS of 96% with no survival benefit from FLAG-Ida + GO. Conclusion Overall, FLAG-Ida + GO significantly reduced relapse without improving OS. However, exploratory analyses show that patients with NPM1 and FLT3 mutations had substantial improvements in OS. By contrast, in patients with core binding factor AML, outcomes were excellent with DA + GO with no FLAG-Ida benefit

A study of regulatory T cells in allogeneic haematopoietic stem cell transplantation

Allogeneic haematopoietic stem cell transplantation (alloHSCT) is an established therapy for many haematological disorders. Unfortunately, the new donor-derived immune system may damage host cells (graft-versus-host disease (GvHD)), causing significant morbidity and mortality. Since regulatory T cells (Tregs) can modulate immune responses, it was hypothesised that Treg numbers in the haematopoietic stem cell grafts and/or peripheral blood may influence the development of GvHD and other transplant-related complications. In this project, a prospective observational clinical study of putative Tregs in human alloHSCT was performed in Oxford. Flow cytometry and methylation-specific qPCR assays were developed to quantify putative Tregs and lymphocyte populations within the grafts and post-transplant blood samples. Although low CD4(+)CD25(+)FOXP3(+)CD127(-/dim) T-cell numbers were not associated with increased incidence of GvHD, low proportions of CD25(+)FOXP3(+)CD127(-/dim) cells in the graft (as a percentage of total CD4(+) T cells) were independently associated with poor engraftment, increased non-relapse mortality and inferior overall survival. Similarly, falling CD4(+)CD25(+)FOXP3(+)CD127(-/dim) T-cell counts over the first three months post-transplant were associated with higher non-relapse mortality and inferior overall survival. In view of these novel findings, strategies that increase CD4(+)CD25(+)FOXP3(+)CD127(-/dim) T cells in alloHSCT may improve clinical outcomes. One possible route for increasing Tregs is through cellular therapy. This project therefore tested the hypothesis that CD4(+)CD25(+)FOXP3(+) Tregs can be produced in vitro from conventional CD4(+) T cells. In the presence of TGFβ and Azacitidine, FOXP3 was expressed in the majority of activated CD4(+) T cells. These cells also had a demethylated FOXP3 TSDR enhancer which is specific to natural Tregs. However, most of these cells produced pro-inflammatory cytokines, for example, TNFα. Therefore, under these conditions, FOXP3 expression was not sufficient to produce a Treg phenotype. It is proposed that current focus for generating Tregs for human clinical trials should be directed towards improving isolation and expansion of ex vivo isolated Tregs.This thesis is not currently available in ORA