Who Is the Best Hematopoietic Stem-Cell Donor for a Male Patient With Acute Leukemia?

Universal posttransplant cyclophosphamide after allogeneic transplant, a retrospective single institution study

BACKGROUND

The excellent results of posttransplant cyclophosphamide in decreasing graft-versus-host disease (GVHD) after haploidentical (HI) allogeneic transplant have challenged current donor selection algorithms.

PATIENTS AND METHODS

We compared outcomes after matched sibling (MSD) versus alternative donor transplant using identical graft-versus-host disease (GVHD) prophylaxis including posttransplant cyclophosphamide (PTCy. Endpoints included engraftment, time outside of the hospital in the first 100 days after transplant, overall survival (OS), non-relapse mortality (NRM) and percentage of patients disease-free and off immunosuppression (DFOI) at one year and at the last follow-up.

RESULTS

There were significant differences at baseline between matched donor versus HI donor transplants with higher disease-risk index (DRI), more female-to-male donor recipient pairs and a higher percentage of Black patients in the HI group. Engraftment and time out of the hospital favored MSD and matched unrelated donor transplants. Multivariate analysis showed that high DRI and Black race were associated with decreased survival and Black race was associated with a higher NRM.

CONCLUSIONS

With the use of PTCy, our results support current donor selection algorithms. The finding of decreased survival and increased NRM in Black patients requires confirmation in a larger number of patients as well as the development of mitigation strategies.

Prognostic effect of gender on outcome of treatment for adults with acute myeloid leukaemia

There are conflicting reports in the literature suggesting that one gender or the other has a better survival with acute myeloid leukaemia (AML). The present study was done in an attempt to resolve the issue. The effect of gender was examined on 3546 newly diagnosed patients with AML, including 548 patients with acute promyelocytic leukaemia (APL) enrolled in 10 multi-institutional treatment studies from March 1984 to November 2008. Kaplan-Meier estimates were used to estimate event-time distributions for survival and multivariate models were used to examine the gender effect after adjusting for multiple risk factors. P values were based on two-sided tests. Non-APL female patients had a significantly better overall (OS) but not disease-free survival (DFS) than males, irrespective of age, initial white blood cell count, or dose of daunorubicin. No differences were observed for obese or FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD)-positive patients. Female patients with APL had a significantly better OS and DFS than male patients with APL, and differences in survival were greater for patients with t(15;17) + other cytogenetic abnormalities compared with those with t(15;17) only. Gender is an independent prognostic variable in patients with AML. Whether these survival differences are due to hormonal, genetic or pharmacokinetic differences between the sexes or differential toxin exposure such as smoking is unknown. However, the former seems less likely as patient age did not influence the survival advantage for female patients.

[HLA-10/10 matched unrelated donor versus sibling donor hematopoietic stem cell transplantation for adult acute myeloid leukemia]

Objective: To evaluate the outcomes of human leukocyte antigen (HLA) matched unrelated donor hematopoietic stem cell transplantation (MUD-HSCT) for adult acute myeloid leukemia (AML) in a single center. Methods: Consecutive adult AML who received MUD-HSCT in our center from January 2008 to April 2017 were studied retrospectively, comparing with patients undergoing matched sibling donor (MSD) -HSCT in the same period. The rates of overall survival (OS) , disease free survival (DFS) , relapse, non-relapse mortality (NRM) , engraftment, acute and chronic graft-versus-host disease (aGVHD and cGVHD) were analyzed. Results: A total of 247 consecutive cases were enrolled, including 46 patients with MUD-HSCT and 201 with MSD-HSCT. All the patients experienced neutrophil engraftment except for one patient who died early in the MSD group, but the median day of engraftment was longer in the MUD group (15.0 vs 14.0, P=0.017) . The accumulative engraftment rate of platelet was comparable between the two groups (93.5%vs 98.0%, P=0.128) . The accumulative incidences of aGVHD (50.0%vs 46.3%, P=0.421) and cGVHD (37.8%vs 43.0%, P=0.581) were not statistically different between the two groups. Compared with the MSD group, the accumulative NRM rate at+36 months after transplantation was significantly higher in the MUD group (22.0%vs 10.4%, P=0.049) , while the relapse rate was not statistical difference (20.5 vs 28.3%, P=0.189) . Both the 3-year OS (61.6%vs 63.3%, P=0.867) and DFS (57.5%vs 61.6%, P=0.760) were comparable between the two groups. Four independent risk factors were confirmed by the multivariate analysis: patient age ≥45 years old, CR2 or NR before transplantation, a history of extramedullary infiltration and the occurrence of grade Ⅲ-Ⅳ aGVHD. No statistical differences were demonstrated in the survival rate between MUD-and MSD-HSCT in different subgroups. Conclusions: The outcomes, such as GVHD, relapse, OS and DFS, were comparable between MUD-and MSD-HSCT for adult AML, but higher incidence of NRM and longer time to neutrophil engraftment in the MUD group. MUD-HSCT is practical and feasible for adult AML who are lack of MSD.

Dynamical system modeling to simulate donor T cell response to whole exome sequencing-derived recipient peptides: Understanding randomness in alloreactivity incidence following stem cell transplantation

Quantitative relationship between the magnitude of variation in minor histocompatibility antigens (mHA) and graft versus host disease (GVHD) pathophysiology in stem cell transplant (SCT) donor-recipient pairs (DRP) is not established. In order to elucidate this relationship, whole exome sequencing (WES) was performed on 27 HLA matched related (MRD), & 50 unrelated donors (URD), to identify nonsynonymous single nucleotide polymorphisms (SNPs). An average 2,463 SNPs were identified in MRD, and 4,287 in URD DRP (p<0.01); resulting peptide antigens that may be presented on HLA class I molecules in each DRP were derived in silico (NetMHCpan ver2.0) and the tissue expression of proteins these were derived from determined (GTex). MRD DRP had an average 3,670 HLA-binding-alloreactive peptides, putative mHA (pmHA) with an IC50 of <500 nM, and URD, had 5,386 (p<0.01). To simulate an alloreactive donor cytotoxic T cell response, the array of pmHA in each patient was considered as an operator matrix modifying a hypothetical cytotoxic T cell clonal vector matrix; each responding T cell clone’s proliferation was determined by the logistic equation of growth, accounting for HLA binding affinity and tissue expression of each alloreactive peptide. The resulting simulated organ-specific alloreactive T cell clonal growth revealed marked variability, with the T cell count differences spanning orders of magnitude between different DRP. Despite an estimated, uniform set of constants used in the model for all DRP, and a heterogeneously treated group of patients, higher total and organ-specific T cell counts were associated with cumulative incidence of moderate to severe GVHD in recipients. In conclusion, exome wide sequence differences and the variable alloreactive peptide binding to HLA in each DRP yields a large range of possible alloreactive donor T cell responses. Our findings also help understand the apparent randomness observed in the development of alloimmune responses.

What compatibility in 2017 for the haematopoietic stem cell transplantation?

The diversification of potential donors to perform stem cell allografts now enables to propose a compatible graft cell source adapted to the different clinical situations. Transplants with a geno-identical sibling donor, otherwise with the most HLA-compatible unrelated donor, remain the first-line solutions. Alternative transplants allow to graft patients having no donors in international registries, owing to the rarity of their HLA typing. They are carried out with fairly incompatible grafts and are therefore limited by the existence in the recipient of preformed anti-HLA antibodies which predispose to their rejection. The simple prevention of acute Graft-versus-host disease in haplo-identical transplants, as well as the availability of donors, explain why they have very often replaced placental stem cell transplants. These latter remain useful for pediatric patients or in the absence of family donors.

Efficiency of high-dose cytarabine added to CY/TBI in cord blood transplantation for myeloid malignancy

Cord blood transplantation (CBT) is an effective therapeutic option for adults with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) after the conventional cyclophosphamide and total body irradiation (CY/TBI) regimen, but posttransplant relapse is still of high importance. High-dose cytarabine (HDCA) can be added to CY/TBI for an intensified regimen; however, its additional effects have not yet been completely elucidated. Therefore, we conducted a cohort study to compare the prognosis of HDCA/CY/TBI (n = 617) and CY/TBI (n = 312) in CBT for AML/MDS, using a Japanese transplant registry database. The median age was 40 years, and 86.2% of the patients had AML; high-risk disease was observed in 56.2% of the patients. The median follow-up period after CBT was approximately 3.5 years. Overall survival was significantly superior in the HDCA/CY/TBI group (adjusted hazard ratio [HR], 0.56; 95% confidence interval [CI], 0.45-0.69; P < .01), and tumor-related mortality was lower (HR, 0.50; P < .01). The incidence of grade II to IV acute graft-vs-host disease (aGVHD) and chronic GVHD was significantly higher in the HDCA/CY/TBI group (HR, 1.33 and 2.30, respectively), but not grade III to IV aGVHD. Incidence of infectious episodes showed no significant difference. Nonrelapse mortality was not increased by the addition of HDCA. Higher-dose CA (12 rather than 8 g/m(2)) was more effective, particularly in patients at high-risk for disease. This study is the first to show the superiority of HDCA/CY/TBI to CY/TBI in CBT for AML/MDS. A large-scale prospective study is warranted to establish new conditioning regimens including HDCA administration.

Anti-CMV-IgG positivity of donors is beneficial for alloHSCT recipients with respect to the better short-term immunological recovery and high level of CD4+CD25high lymphocytes

Hematopoietic stem cell transplantation from anti-cytomegalovirus immunoglobulin G (anti-CMV-IgG) positive donors facilitated immunological recovery post-transplant, which may indicate that chronic CMV infection has an effect on the immune system. This can be seen in the recipients after reconstitution with donor lymphocytes. We evaluated the composition of lymphocytes at hematologic recovery in 99 patients with hematologic malignancies post hematopoietic stem cell transplantation (HSCT). Anti-CMV-IgG seropositivity of the donor was associated with higher proportions of CD4+ (227.963 ± 304.858 × 106 vs. 102.050 ± 17.247 × 106 cells/L, p = 0.009) and CD4+CD25high (3.456 ± 0.436 × 106 vs. 1.589 ± 0.218 × 106 cells/L, p = 0.003) lymphocytes in the blood at hematologic recovery. The latter parameter exerted a diverse influence on the risk of acute graft-versus-host disease (GvHD) if low (1.483 ± 0.360 × 106 vs. 3.778 ± 0.484 × 106 cells/L, p < 0.001) and de novo chronic GvHD (cGvHD) if high (3.778 ± 0.780 × 106 vs. 2.042 ± 0.261 × 106 cells/L, p = 0.041). Higher values of CD4+ lymphocytes in patients who received transplants from anti-CMV-IgG-positive donors translated into a reduced demand for IgG support (23/63 vs. 19/33, p = 0.048), and these patients also exhibited reduced susceptibility to cytomegalovirus (CMV), Epstein-Barr virus (EBV) and/or human herpes 6 virus (HHV6) infection/reactivation (12/50 vs. 21/47, p = 0.032). Finally, high levels (³0.4%) of CD4+CD25high lymphocytes were significantly associated with better post-transplant survival (56% vs. 38%, four-year survival, p = 0.040). Donors who experience CMV infection/reactivation provide the recipients with lymphocytes, which readily reinforce the recovery of the transplanted patients' immune system.

Alternative Donor Allogeneic Hematopoietic Cell Transplantation for Acute Myeloid Leukemia

Allogeneic hematopoietic cell transplantation (alloHCT) provides a potentially curative therapy for patients with high-risk or chemorefractory acute myeloid leukemia (AML). Historically, the applicability of alloHCT has been limited as only 30%-35% of patients have human leukocyte antigen (HLA)-matched siblings and outcomes using other donor types have been markedly inferior due to excess toxicity, graft failure, graft-versus-host disease (GVHD), and consequently non-relapse mortality. Advances in HLA typing, GVHD prophylactic approaches, and other transplantation techniques have successfully addressed these historical challenges. Herein, we review recent alloHCT studies using volunteer unrelated donors, umbilical cord blood units, or HLA-haploidentical donors, specifically focusing on studies that compared outcomes between donor sources. Although none are randomized and most are retrospective, these analyses suggest that current outcomes for AML patients using most alternative donor types are comparable to those seen using HLA-matched siblings.