Effect of donor age in patients with acute myeloid leukemia undergoing haploidentical hematopoietic cell transplantation vary by conditioning intensity and recipient age.

We investigated the impact of donor age (younger [≤35 years] vs. older [>35 years]) after accounting for other non-HLA and HLA factors on outcomes of patients with acute myeloid leukemia undergoing HLA-haploidentical hematopoietic cell transplantation (n = 790). The effect differed by conditioning-partly related to the differences in the recipient age in myeloablative (MAC; median 46 years) versus reduced-intensity/non-myeloablative conditioning (RIC/NMA; median 61 years) groups. With MAC (n = 320), donor age had no impact on acute graft-versus-host disease (GVHD), but older donors were associated with a significantly higher risk of chronic GVHD (hazard ratio [HR]: 1.6, 95% confidence interval [CI]: 1.10-2.30, p = .02) independent of recipient age and other factors. Donor age had no impact on either relapse or non-relapse mortality (NRM). The impact of donor/recipient age on overall survival changed over time. Older donors were associated with significantly higher late overall mortality (>6 months) in younger recipients (≤ 50 years; HR: 2.2, 95% CI: 1.03-4.6, p = .04) but not older recipients. With RIC/NMA (n = 470), neither recipient's nor donor's age influenced the risk of GVHD. Donor age had no significant impact on the risk of relapse, but older donors were associated with a significantly higher risk of NRM (HR: 1.6, 95% CI: 1.02-2.6, p = .04) independent of recipient age. Older donor age was associated with significantly higher late overall mortality (>9 months) in older recipients (>50 years; HR: 1.66, 95% CI: 1.0-2.67; p = .049) but not in younger recipients. Donor selection based on donor age may require a tailored approach for a particular recipient.

Immunosuppressant adherence in adult outpatient hematopoietic cell transplant recipients.

INTRODUCTION: Medication nonadherence continues to be challenging for allogeneic hematopoietic cell transplant (HCT) recipients. The risk and severity of chronic graft-versus-host disease (GVHD) are associated with low immunosuppressant concentrations (which can be improved with model-informed precision dosing (MIPD)) and with immunosuppressant nonadherence (which can be improved with acceptable interventions). METHODS: With the goals of improving adherence and achieving therapeutic concentrations of immunosuppressants to eliminate GVHD, we characterized the feasibility of using the Medication Event Monitoring (MEMS®) Cap in adult HCT recipients. RESULTS: Of the 27 participants offered the MEMS® Cap at the time of hospital discharge, 7 (25.9%) used it, which is below our a priori threshold of 70%. These data suggest the MEMS® Cap is not feasible for HCT recipients. The MEMS® Cap data were available for a median of 35 days per participant per medication (range: 7-109 days). The average daily adherence per participant ranged from 0 to 100%; four participants had an average daily adherence of over 80%. CONCLUSIONS: MIPD may be supported by MEMS® technology to provide the precise time of immunosuppressant self-administration. The MEMS® Cap was used by only a small percentage (25.9%) of HCT recipients in this pilot study. In accordance with larger studies using less accurate tools to evaluate adherence, immunosuppressant adherence varied from 0% to 100%. Future studies should establish the feasibility and clinical benefit of combining MIPD with newer technology, specifically the MEMS® Button, which can inform the oncology pharmacist of the time of immunosuppressant self-administration.

Allogeneic hematopoietic cell transplantation for blastic plasmacytoid dendritic cell neoplasm: a CIBMTR analysis.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematological malignancy with a poor prognosis and considered incurable with conventional chemotherapy. Small observational studies reported allogeneic hematopoietic cell transplantation (allo-HCT) offers durable remissions in patients with BPDCN. We report an analysis of patients with BPDCN who received an allo-HCT, using data reported to the Center for International Blood and Marrow Transplant Research (CIBMTR). We identified 164 patients with BPDCN from 78 centers who underwent allo-HCT between 2007 and 2018. The 5-year overall survival (OS), disease-free survival (DFS), relapse, and nonrelapse mortality (NRM) rates were 51.2% (95% confidence interval [CI], 42.5-59.8), 44.4% (95% CI, 36.2-52.8), 32.2% (95% CI, 24.7-40.3), and 23.3% (95% CI, 16.9-30.4), respectively. Disease relapse was the most common cause of death. On multivariate analyses, age of ≥60 years was predictive for inferior OS (hazard ratio [HR], 2.16; 95% CI, 1.35-3.46; P = .001), and higher NRM (HR, 2.19; 95% CI, 1.13-4.22; P = .02). Remission status at time of allo-HCT (CR2/primary induction failure/relapse vs CR1) was predictive of inferior OS (HR, 1.87; 95% CI, 1.14-3.06; P = .01) and DFS (HR, 1.75; 95% CI, 1.11-2.76; P = .02). Use of myeloablative conditioning with total body irradiation (MAC-TBI) was predictive of improved DFS and reduced relapse risk. Allo-HCT is effective in providing durable remissions and long-term survival in BPDCN. Younger age and allo-HCT in CR1 predicted for improved survival, whereas MAC-TBI predicted for less relapse and improved DFS. Novel strategies incorporating allo-HCT are needed to further improve outcomes.

Co-expression of Foxp3 and Helios facilitates the identification of human T regulatory cells in health and disease.

Foxp3 is regarded as the major transcription factor for T regulatory (Treg) cells and expression of Foxp3 is used to identify and quantitate Treg cells in mouse models. However, several studies have demonstrated that human CD4+ T conventional (Tconv) cells activated in vitro by T cell receptor (TCR) stimulation can express Foxp3. This observation has raised doubt as to the suitability of Foxp3 as a Treg marker in man. Helios, a member of the Ikaros gene family, has been shown to be expressed by 80-90% of human Foxp3+ Treg cells and can potentially serve as a marker of human Treg. Here, we confirm that Foxp3 expression is readily upregulated by Tconv upon TCR stimulation in vitro, while Helios expression is not altered. More importantly, we show that Foxp3 expression is not elevated by stimulation of hTconv in a humanized mouse model of graft versus host disease (GVHD) and in patients with a wide variety of acute and chronic inflammatory diseases including sickle cell disease, acute and chronic GVHD, systemic lupus erythematosus, as well as critical COVID-19. In all patients studied, an excellent correlation was observed between the percentage of CD4+ T cells expressing Foxp3 and the percentage expressing Helios. Taken together, these studies demonstrate that Foxp3 is not induced upon Tconv cell activation in vivo and that Foxp3 expression alone can be used to quantitate Treg cells in humans. Nevertheless, the combined use of Foxp3 and Helios expression provides a more reliable approach for the characterization of Treg in humans.

HLA Class I Genotype Is Associated with Relapse Risk after Allogeneic Stem Cell Transplantation for NPM1-Mutated Acute Myeloid Leukemia.

Mutation-bearing peptide ligands from mutated nucleophosmin-1 (NPM1) protein have been empirically found to be presented by HLA class I in acute myeloid leukemia (AML). We hypothesized that HLA genotype may impact allogeneic hematopoietic stem cell transplantation (allo-HCT) outcomes in NPM1-mutated AML owing to differences in antigen presentation. We evaluated the effect of the variable of predicted strong binding to mutated NPM1 peptides using HLA class I genotypes from matched donor-recipient pairs on transplant recipients' overall survival (OS) and disease-free survival (DFS) as part of the primary objectives and cumulative incidence of relapse and nonrelapse mortality (NRM) as part of secondary objectives. Baseline and outcome data reported to the Center for International Blood and Marrow Transplant Research from a study cohort of adult patients (n = 1020) with NPM1-mutated de novo AML in first (71%) or second (29%) complete remission undergoing 8/8 matched related (18%) or matched unrelated (82%) allo-HCT were analyzed retrospectively. Class I alleles from donor-recipient pairs were analyzed for predicted strong HLA binding to mutated NPM1 using netMHCpan 4.0. A total of 429 (42%) donor-recipient pairs were classified as having predicted strong-binding HLA alleles (SBHAs) to mutated NPM1. In multivariable analyses adjusting for clinical covariates, the presence of predicted SBHAs was associated with a lower risk of relapse (hazard ratio [HR], .72; 95% confidence interval [CI], .55 to .94; P = .015). OS (HR, .81; 95% CI, .67 to .98; P = .028) and DFS (HR, .84; 95% CI, .69 to 1.01; P = .070) showed a suggestion of better outcomes if predicted SBHAs were present but did not meet the prespecified P value of <.025. NRM did not differ (HR, 1.04; P = .740). These hypothesis-generating data support further exploration of HLA genotype-neoantigen interactions in the allo-HCT context.

Impact of Donor Age in Haploidentical-Post-Transplantation Cyclophosphamide versus Matched Unrelated Donor Post-Transplantation Cyclophosphamide Hematopoietic Stem Cell Transplantation in Patients with Acute Myeloid Leukemia.

Haploidentical hematopoietic cell transplantation (HCT) with post-transplantation cyclophosphamide (PTCy) graft-versus-host-disease (GVHD) prophylaxis is associated with inferior overall survival (OS) compared to HLA-matched unrelated donor (MUD) HCT with PTCy prophylaxis in patients receiving reduced-intensity conditioning (RIC). Given prognostic implications of donor age, we investigated the differences in outcomes of patients with acute myeloid leukemia (AML; n = 775) undergoing RIC-HCT with a younger MUD (age <35 years; n = 84) versus a younger haploidentical donor (age <35 years; n = 302) versus an older haploidentical donor (age ≥35 years; n = 389). The older MUD group was excluded from the analysis because of small numbers. The younger haploidentical donor group (median age, 59.5 years) was somewhat younger than the younger MUD group (median age, 66.8 years) and the older haploidentical donor group (median age, 64.7 years). More patients in the MUD group received peripheral blood grafts (82%) compared to the haploidentical donor groups (55% to 56%). In multivariate analysis, compared to the younger MUD group, the younger haploidentical donor group (hazard ratio [HR], 1.95; 95% confidence interval [CI], 1.22 to 3.12; P = .005) and the older haploidentical donor group (HR, 2.36; 95% CI, 1.50 to 3.71; P < .001) had a significantly inferior OS, and the younger haploidentical donor group (HR, 3.72; 95% CI, 1.39 to 9.93; P = .009) and older haploidentical donor group (HR, 6.91; 95% CI, 2.75 to 17.39; P < .001) had a significantly higher risk of nonrelapse mortality. The older haploidentical group had a significantly higher risk of grade II-IV acute GVHD (HR, 2.29; 95% CI, 1.38 to 3.80; P = .001) and grade III-IV acute GVHD (HR, 2.70; 95% CI, 1.09 to 6.71; P = .03). There were no significant differences across the groups in the incidence of chronic GVHD or relapse. Among adult AML patients in CR undergoing RIC-HCT with PTCy prophylaxis, a young MUD may be preferred over a young haploidentical donor.

Posttransplantation cyclophosphamide expands functional myeloid-derived suppressor cells and indirectly influences Tregs.

Posttransplantation cyclophosphamide (PTCy), given on days +3 and +4, reduces graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (HCT), but its immunologic underpinnings are not fully understood. In a T-cell-replete, major histocompatibility complex-haploidentical murine HCT model (B6C3F1→B6D2F1), we previously showed that PTCy rapidly induces suppressive mechanisms sufficient to prevent GVHD induction by non-PTCy-exposed donor splenocytes infused on day +5. Here, in PTCy-treated mice, we found that depleting Foxp3+ regulatory T cells (Tregs) in the initial graft but not the day +5 splenocytes did not worsen GVHD, yet depleting Tregs in both cellular compartments led to fatal GVHD induced by the day +5 splenocytes. Hence, Tregs were necessary to control GVHD induced by new donor cells, but PTCy's impact on Tregs appeared to be indirect. Therefore, we hypothesized that myeloid-derived suppressor cells (MDSCs) play a complementary role. Functionally suppressive granulocytic and monocytic MDSCs were increased in percentages in PTCy-treated mice, and MDSC percentages were increased after administering PTCy to patients undergoing HLA-haploidentical HCT. PTCy increased colony-stimulating factors critical for MDSC development and rapidly promoted the generation of MDSCs from bone marrow precursors. MDSC reduction via anti-Gr1 treatment in murine HCT did not worsen histopathologic GVHD but resulted in decreased Tregs and inferior survival. The clinical implications of these findings, including the potential impact of expanded MDSCs after PTCy on engraftment and cytokine release syndrome, remain to be elucidated. Moreover, the indirect effect that PTCy has on Tregs, which in turn play a necessary role in GVHD prevention by initially transplanted or subsequently infused T cells, requires further investigation.

Haploidentical vs matched unrelated donors for patients with ALL: donor age matters more than donor type.

Haploidentical hematopoietic cell transplantation (HCT) with posttransplant cyclophosphamide (PTCy) graft-versus-host-disease (GVHD) prophylaxis yields a similar overall survival (OS) to HLA-matched unrelated donor (MUD) HCT with conventional prophylaxis. Given the prognostic implications of donor age, we investigated the impact of donor age (younger [<35 years, n = 868] vs older [≥35 years, n = 418]) and donor type (haploidentical [n = 373] vs MUD [n = 913]) on OS in adult patients with acute lymphoblastic leukemia (ALL). Older donor age was independently associated with significantly poor OS, whereas donor type was not. Next, we directly compared the outcomes of a younger haploidentical donor (n = 187) vs an older MUD (n = 232). In this cohort, more patients in the haploidentical group had B-cell immunophenotype (89% vs 77%, respectively, P < .001), poor cytogenetics (61% vs 51%, respectively, P = .44), Philadelphia chromosome-negative (53% vs 48%, respectively, P = .38), received bone marrow graft (42% vs 16%, respectively, P < .001), and reduced-intensity conditioning (45% vs 23%, respectively, P < .001). In the multivariate analysis, the older MUD group was associated with a significantly higher risk of chronic GVHD, higher nonrelapse mortality (NRM), lower relapse, and poorer OS. Despite a higher risk of relapse, younger donor haploidentical HCT with PTCy prophylaxis may be preferred over older MUD HCT with conventional prophylaxis in patients with ALL due to lower NRM and better OS. Further analysis comparing the effect of donor age in haploidentical PTCy vs MUD PTCy is warranted.

The incidence and impact of clostridioides difficile infection on transplant outcomes in acute leukemia and MDS after allogeneic hematopoietic cell transplant-a CIBMTR study.

Clostridioides difficile infection (CDI) is common after allogeneic hematopoietic cell transplantation (alloHCT). The determination of incidence, risk factors, and impact of CDI on alloHCT outcomes is an unmet need. The study examines all patients aged 2 years and older who received first alloHCT for acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), or myelodysplastic syndrome (MDS) between 2013 and 2018 at US centers and reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) data registry. In total, 826 patients with CDI and 6723 controls from 127 centers were analyzed. The cumulative incidence of CDI by day 100 was 18.7% (99% CI: 15-22.7%) and 10.2% (99% CI: 9.2-11.1%) in pediatric and adult patients, respectively, with a median time to diagnosis at day +13. CDI was associated with inferior overall survival (OS) (p = 0.0018) and a 2.58-fold [99% CI: 1.43-4.66; p < 0.001] increase in infection-related mortality (IRM). There was a significant overlap in the onset of acute graft versus host disease (aGVHD) and CDI. IRM increased to >4 fold when CDI + aGVHD was considered. Despite advances in the management of CDI, increased IRM and decreased OS still results from CDI.

Murine allogeneic CAR T cells integrated before or early after posttransplant cyclophosphamide exert antitumor effects.

Relapse limits the therapeutic efficacy both of chimeric antigen receptor (CAR) T cells and allogeneic hematopoietic cell transplantation (allo-HCT). Patients may undergo these therapies sequentially to prevent or treat relapsed malignancy. However, direct integration of the 2 therapies has been avoided over concerns for potential induction of graft-versus-host disease (GVHD) by allogeneic CAR T cells. We have shown in murine T-cell-replete MHC-haploidentical allo-HCT that suppressive mechanisms induced immediately after posttransplant cyclophosphamide (PTCy), given on days +3/+4, prevent GVHD induction by alloreactive T cells infused as early as day +5. Therefore, we hypothesized that allogeneic CAR T cells given in a similarly integrated manner in our murine MHC-haploidentical allo-HCT model may safely exert antitumor effects. Indeed, allogeneic anti-CD19 CAR T cells given early after (day +5) PTCy or even prior to (day 0) PTCy cleared leukemia without exacerbating the cytokine release syndrome occurring from the MHC-haploidentical allo-HCT or interfering with PTCy-mediated GVHD prevention. Meanwhile, CAR T-cell treatment on day +9 or day +14 was safe but less effective, suggesting a limited therapeutic window. CAR T cells infused before PTCy were not eliminated, but surviving CAR T cells continued to proliferate highly and expand despite PTCy. In comparison with infusion on day +5, CAR T-cell infusion on day 0 demonstrated superior clinical efficacy associated with earlier CAR T-cell expansion, higher phenotypic CAR T-cell activation, less CD4+CD25+Foxp3+ CAR T-cell recovery, and transcriptional changes suggesting increased activation of CD4+ CAR T cells and more cytotoxic CD8+ CAR T cells. This study provides mechanistic insight into PTCy's impact on graft-versus-tumor immunity and describes novel approaches to integrate CAR T cells and allo-HCT that may compensate for deficiencies of each individual approach.

Efflux capacity and aldehyde dehydrogenase both contribute to CD8+ T-cell resistance to posttransplant cyclophosphamide.

Mechanisms of T-cell survival after cytotoxic chemotherapy, including posttransplantation cyclophosphamide (PTCy), are not well understood. Here, we explored the impact of PTCy on human CD8+ T-cell survival and reconstitution, including what cellular pathways drive PTCy resistance. In major histocompatibility complex (MHC)-mismatched mixed lymphocyte culture (MLC), treatment with mafosfamide, an in vitro active cyclophosphamide analog, preserved a relatively normal distribution of naïve and memory CD8+ T cells, whereas the percentages of mucosal-associated invariant T (MAIT) cells and phenotypically stem cell memory (Tscm) T-cell subsets were increased. Activated (CD25+) and proliferating CD8+ T cells were derived from both naïve and memory subsets and were reduced but still present after mafosfamide. By contrast, cyclosporine-A (CsA) or rapamycin treatment preferentially maintained nonproliferating CD25- naïve cells. Drug efflux capacity and aldehyde dehydrogenase-1A1 expression were increased in CD8+ T cells in allogeneic reactions in vitro and in patients, were modulated by common γ-chain cytokines and the proliferative state of the cell, and contributed to CD8+ T-cell survival after mafosfamide. The CD8+ T-cell composition early after hematopoietic cell transplantation (HCT) in PTCy-treated patients was dominated by CD25+ and phenotypically memory, including Tscm and MAIT, cells, consistent with MLC. Yet, MHC-mismatched murine HCT studies revealed that peripherally expanded, phenotypically memory T cells 1 to 3 months after transplant originated largely from naïve-derived rather than memory-derived T cells surviving PTCy, suggesting that initial resistance and subsequent immune reconstitution are distinct. These studies provide insight into the complex immune mechanisms active in CD8+ T-cell survival, differentiation, and reconstitution after cyclophosphamide, with relevance for post-HCT immune recovery, chemotherapy use in autologous settings, and adoptive cellular therapies.

Characterization of Hepatic Dysfunction in Subjects Diagnosed With Chronic GVHD by NIH Consensus Criteria.

Hepatic chronic graft-versus-host disease (cGVHD) causes morbidity and current diagnostic criteria are nonspecific. An accurate diagnosis is imperative because overdiagnosis can lead to unnecessary treatment with immunosuppressive agents and raising the risk of opportunistic infections. We aim to characterize different patterns of liver injury and cytokine profiles associated with hepatic dysfunction in cGVHD, to evaluate the accuracy of the NIH Consensus Criteria (NCC) for hepatic cGVHD and to explore predictors for hepatic cGHVD. Patients were evaluated in this prospective cross-sectional study of patients with cGVHD recruited under a natural history protocol. Laboratory tests and cytokines were measured. The cGVHD were diagnosed and scored based on NCC. Clinically indicated liver biopsy specimens or autopsies were reviewed by an expert hepatopathologist (D.E.K.). Comparisons were made between groups, and univariable and multivariable logistic regression were calculated. Of the 302 patients enrolled, 151 fulfilled hepatic cGVHD based on NCC; however, 69% had at least 1 abnormal liver test result. Abnormal alanine aminotransferase (ALT) and aspartate aminotransferase were associated with lower platelets, higher total bilirubin (TB), total cholesterol, serum amyloid A, and IL 15. Abnormal ALP and gamma-glutamyl transpeptidase were associated with higher cholesterol, and IL7. Lower platelet count was associated with higher ALT, TB, and triglycerides and lower albumin. Of the 27 with liver tissue, 16 had histologic features of GVHD, only eight met clinical criteria for hepatic GVHD. Sensitivity and specificity of NCC in identifying hepatic GVHD were 50% and 27% (Kappa = -0.23). Only 6 had only hepatic GVHD, whereas 10 had hepatic GVHD with either iron overload, nodular regenerative hyperplasia, or steatosis. Multivariable logistic regression showed that ALP and total cholesterol were associated with hepatic GVHD and total cholesterol >220 mg/dL increased the sensitivity for histologic hepatic GVHD. In conclusion, abnormal liver enzymes in cGVHD are nonspecific and have poor correlation with histologic evidence for hepatic GVHD, highlighting the importance of histology. Cytokines provide insight into the pathogenesis of hepatic cGVHD. Decreased platelet count was associated with factors associated with liver disease including portal vein diameter, which may suggest progression of liver disease. This highlights the need of incorporating these factors in natural history study and using liver biopsy to understand the development of liver dysfunction in hematopoietic stem cell transplantation and to develop better instruments to decreased hepatic cGVHD related morbidity and mortality. The study was registered with a ClinicalTrials.gov identifier NCT00092235.

Abnormal liver tests are not sufficient for diagnosis of hepatic graft-versus-host disease in critically ill patients.

Hepatic graft-versus-host disease (HGVHD) contributes significantly to morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Clinical findings and liver biomarkers are neither sensitive nor specific. The relationship between clinical and histologic diagnoses of HGVHD was assessed premortem and at autopsy. Medical records from patients who underwent HSCT at the National Institutes of Health (NIH) Clinical Center between 2000 and 2012 and expired with autopsy were reviewed, and laboratory tests within 45 days of death were divided into 15-day periods. Clinical diagnosis of HGVHD was based on Keystone Criteria or NIH Consensus Criteria, histologic diagnosis based on bile duct injury without significant inflammation, and exclusion of other potential etiologies. We included 37 patients, 17 of whom had a cholestatic pattern of liver injury and two had a mixed pattern. Fifteen were clinically diagnosed with HGVHD, two showed HGVHD on autopsy, and 13 had histologic evidence of other processes but no HGVHD. Biopsy or clinical diagnosis of GVHD of other organs during life did not correlate with HGVHD on autopsy. The diagnostic accuracy of the current criteria was poor (κ = -0.20). A logistic regression model accounting for dynamic changes included peak bilirubin 15 days before death, and an increase from period -30 (days 30 to 16 before death) to period -15 (15 days before death) showed an area under the receiver operating characteristic curve of 0.77. Infection was the immediate cause of death in 68% of patients. In conclusion, liver biomarkers at baseline and GVHD elsewhere are poor predictors of HGVHD on autopsy, and current clinical diagnostic criteria have unsatisfactory performance. Peak bilirubin and cholestatic injury predicted HGVHD on autopsy. A predictive model was developed accounting for changes over time. Further validation is needed.

Post-Transplantation Cyclophosphamide Uniquely Restrains Alloreactive CD4+ T-Cell Proliferation and Differentiation After Murine MHC-Haploidentical Hematopoietic Cell Transplantation.

Post-transplantation cyclophosphamide (PTCy) reduces the incidence and severity of graft-versus-host disease (GVHD), thereby improving the safety and accessibility of allogeneic hematopoietic cell transplantation (HCT). We have shown that PTCy works by inducing functional impairment and suppression of alloreactive T cells. We also have identified that reduced proliferation of alloreactive CD4+ T cells at day +7 and preferential recovery of CD4+CD25+Foxp3+ regulatory T cells (Tregs) at day +21 are potential biomarkers associated with optimal PTCy dosing and timing in our B6C3F1→B6D2F1 MHC-haploidentical murine HCT model. To understand whether the effects of PTCy are unique and also to understand better the biology of GVHD prevention by PTCy, here we tested the relative impact of cyclophosphamide compared with five other optimally dosed chemotherapeutics (methotrexate, bendamustine, paclitaxel, vincristine, and cytarabine) that vary in mechanisms of action and drug resistance. Only cyclophosphamide, methotrexate, and cytarabine were effective in preventing fatal GVHD, but cyclophosphamide was superior in ameliorating both clinical and histopathological GVHD. Flow cytometric analyses of blood and spleens revealed that these three chemotherapeutics were distinct in constraining conventional T-cell numerical recovery and facilitating preferential Treg recovery at day +21. However, cyclophosphamide was unique in consistently reducing proliferation and expression of the activation marker CD25 by alloreactive CD4+Foxp3- conventional T cells at day +7. Furthermore, cyclophosphamide restrained the differentiation of alloreactive CD4+Foxp3- conventional T cells at both days +7 and +21, whereas methotrexate and cytarabine only restrained differentiation at day +7. No chemotherapeutic selectively eliminated alloreactive T cells. These data suggest that constrained alloreactive CD4+Foxp3- conventional T-cell numerical recovery and associated preferential CD4+CD25+Foxp3+ Treg reconstitution at day +21 may be potential biomarkers of effective GVHD prevention. Additionally, these results reveal that PTCy uniquely restrains alloreactive CD4+Foxp3- conventional T-cell proliferation and differentiation, which may explain the superior effects of PTCy in preventing GVHD. Further study is needed to determine whether these findings also hold true in clinical HCT.

Post-Transplantation Cyclophosphamide Is Associated with an Increase in Non-Cytomegalovirus Herpesvirus Infections in Patients with Acute Leukemia and Myelodysplastic Syndrome.

The use of post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis in recipients of haploidentical and fully matched transplantations is on the increase. Published studies have reported an increased incidence of cytomegalovirus (CMV) infection with the use of PTCy. Limited data exist on the incidence and outcomes of infection with non-CMV herpesviruses (NCHV) in this setting. The aim of this study was to evaluate the cumulative incidence of NCHV infections and the association of NCHV infections with transplantation-specific outcomes in recipients of haploidentical transplantation with PTCy (HaploCy), matched sibling donor transplantation with PTCy (SibCy), and matched sibling donor transplantation with calcineurin inhibitor-based prophylaxis (SibCNI). We hypothesized that, like CMV infection, HaploCy recipients of also will have a higher risk of NCHV infections. Using the Center for International Blood and Marrow Transplantation Research database, we analyzed 2765 patients (HaploCy, n = 757; SibCNI, n = 1605; SibCy, n = 403) who had undergone their first hematopoietic stem cell transplantation (HCT) between 2012 and 2017 for acute myelogenous leukemia, acute lymphoblastic leukemia, or myelodysplastic syndrome. The cumulative incidence of NCHV at 6 months post-NCT was 13.9% (99% confidence interval], 10.8% to 17.3%) in the HaploCy group, 10.7% (99% CI, 7.1% to 15%) in the SibCy group, and 5.7% (99% CI, 4.3% to 7.3%) in the Sib CNI group (P < .001). This was due primarily to a higher frequency of human herpesvirus 6 viremia reported in patients receiving PTCy. The incidence of Epstein-Barr viremia was low in all groups, and no cases of post-transplantation lymphoproliferative disorder were seen in either PTCy group. The incidence of NCHV organ disease was low in all 3 cohorts. The development of NCHV infection was associated with increased treatment-related mortality, particularly in the HaploCy group. There was no association with the development of GVHD, relapse, or disease-free survival. Patients in PTCy cohorts who did not develop NCHV infection had lower rates of cGVHD. This study demonstrates that the use of PTCy is associated with an increased risk of NCHV infection. The development of NCHV infection was associated with increased nonrelapse mortality, especially in the HaploCy group. Prospective trials should consider viral surveillance strategies in conjunction with assessment of immune reconstitution for a better understanding of the clinical relevance of viral reactivation in different HCT settings.

Signatures of GVHD and relapse after posttransplant cyclophosphamide revealed by immune profiling and machine learning.

The key immunologic signatures associated with clinical outcomes after posttransplant cyclophosphamide (PTCy)-based HLA-haploidentical (haplo) and HLA-matched bone marrow transplantation (BMT) are largely unknown. To address this gap in knowledge, we used machine learning to decipher clinically relevant signatures from immunophenotypic, proteomic, and clinical data and then examined transcriptome changes in the lymphocyte subsets that predicted major posttransplant outcomes. Kinetics of immune subset reconstitution after day 28 were similar for 70 patients undergoing haplo and 75 patients undergoing HLA-matched BMT. Machine learning based on 35 candidate factors (10 clinical, 18 cellular, and 7 proteomic) revealed that combined elevations in effector CD4+ conventional T cells (Tconv) and CXCL9 at day 28 predicted acute graft-versus-host disease (aGVHD). Furthermore, higher NK cell counts predicted improved overall survival (OS) due to a reduction in both nonrelapse mortality and relapse. Transcriptional and flow-cytometric analyses of recovering lymphocytes in patients with aGVHD identified preserved hallmarks of functional CD4+ regulatory T cells (Tregs) while highlighting a Tconv-driven inflammatory and metabolic axis distinct from that seen with conventional GVHD prophylaxis. Patients developing early relapse displayed a loss of inflammatory gene signatures in NK cells and a transcriptional exhaustion phenotype in CD8+ T cells. Using a multimodality approach, we highlight the utility of systems biology in BMT biomarker discovery and offer a novel understanding of how PTCy influences alloimmune responses. Our work charts future directions for novel therapeutic interventions after these increasingly used GVHD prophylaxis platforms. Specimens collected on NCT0079656226 and NCT0080927627 https://clinicaltrials.gov/.

Risk classification at diagnosis predicts post-HCT outcomes in intermediate-, adverse-risk, and KMT2A-rearranged AML.

Little is known about whether risk classification at diagnosis predicts post-hematopoietic cell transplantation (HCT) outcomes in patients with acute myeloid leukemia (AML). We evaluated 8709 patients with AML from the CIBMTR database, and after selection and manual curation of the cytogenetics data, 3779 patients in first complete remission were included in the final analysis: 2384 with intermediate-risk, 969 with adverse-risk, and 426 with KMT2A-rearranged disease. An adjusted multivariable analysis detected an increased risk of relapse for patients with KMT2A-rearranged or adverse-risk AML as compared to those with intermediate-risk disease (hazards ratio [HR], 1.27; P = .01; HR, 1.71; P < .001, respectively). Leukemia-free survival was similar for patients with KMT2A rearrangement or adverse risk (HR, 1.26; P = .002, and HR, 1.47; P < .001), as was overall survival (HR, 1.32; P < .001, and HR, 1.45; P < .001). No differences in outcome were detected when patients were stratified by KMT2A fusion partner. This study is the largest conducted to date on post-HCT outcomes in AML, with manually curated cytogenetics used for risk stratification. Our work demonstrates that risk classification at diagnosis remains predictive of post-HCT outcomes in AML. It also highlights the critical need to develop novel treatment strategies for patients with KMT2A-rearranged and adverse-risk disease.

An adapted European LeukemiaNet genetic risk stratification for acute myeloid leukemia patients undergoing allogeneic hematopoietic cell transplant. A CIBMTR analysis.

Cytogenetic and molecular abnormalities are known to influence post-transplant outcomes in acute myeloid leukemia (AML) but data assessing the prognostic value of combined genetic models in the HCT setting are limited. We developed an adapted European LeukemiaNet (aELN) risk classification based on available genetic data reported to the Center for International Blood and Marrow Transplant Research, to predict post-transplant outcomes in 2289 adult AML patients transplanted in first remission, between 2013 and 2017. Patients were stratified according to aELN into three groups: favorable (Fav, N = 181), intermediate (IM, N = 1185), and adverse (Adv, N = 923). Univariate analysis demonstrated significant differences in 2-year overall survival (OS) (Fav: 67.7%, IM: 64.9% and Adv: 53.9%; p < 0.001); disease-free survival (DFS) (Fav: 57.8%, IM: 55.5% and Adv: 45.3; p < 0.001) and relapse (Fav: 28%, IM: 27.5% and Adv: 37.5%; p < 0.001). Multivariate analysis (MVA) revealed no differences in outcomes between the Fav and IM groups, thus they were combined. On MVA, patients in the Adv risk group had the highest risk of relapse (HR 1.47 p ≤ 0.001) and inferior DFS (HR 1.35 p < 0.001) and OS (HR 1.39 p < 0.001), even using myeloablative conditioning or in those without the pre-HCT measurable-residual disease. Novel approaches to mitigate relapse in this high-risk group are urgently needed.

Allogeneic Transplantation to Treat Therapy-Related Myelodysplastic Syndrome and Acute Myelogenous Leukemia in Adults.

Patients who develop therapy-related myeloid neoplasm, either myelodysplastic syndrome (t-MDS) or acute myelogenous leukemia (t-AML), have a poor prognosis. An earlier Center for International Blood and Marrow Transplant Research (CIBMTR) analysis of 868 allogeneic hematopoietic cell transplantations (allo-HCTs) performed between 1990 and 2004 showed a 5-year overall survival (OS) and disease-free survival (DFS) of 22% and 21%, respectively. Modern supportive care, graft-versus-host disease prophylaxis, and reduced-intensity conditioning (RIC) regimens have led to improved outcomes. Therefore, the CIBMTR analyzed 1531 allo-HCTs performed in adults with t-MDS (n = 759) or t-AML (n = 772) between and 2000 and 2014. The median age was 59 years (range, 18 to 74 years) for the patients with t-MDS and 52 years (range, 18 to 77 years) for those with t-AML. Twenty-four percent of patients with t-MDS and 11% of those with t-AML had undergone a previous autologous (auto-) HCT. A myeloablative conditioning (MAC) regimen was used in 49% of patients with t-MDS and 61% of patients with t-AML. Nonrelapse mortality at 5 years was 34% (95% confidence interval [CI], 30% to 37%) for patients with t-MDS and 34% (95% CI, 30% to 37%) for those with t-AML. Relapse rates at 5 years in the 2 groups were 46% (95% CI, 43% to 50%) and 43% (95% CI, 40% to 47%). Five-year OS and DFS were 27% (95% CI, 23% to 31%) and 19% (95% CI, 16% to 23%), respectively, for patients with t-MDS and 25% (95% CI, 22% to 28%) and 23% (95% CI, 20% to 26%), respectively, for those with t-AML. In multivariate analysis, OS and DFS were significantly better in young patients with low-risk t-MDS and those with t-AML undergoing HCT with MAC while in first complete remission, but worse for those with previous auto-HCT, higher-risk cytogenetics or Revised International Prognostic Scoring System score, and a partially matched unrelated donor. Relapse remains the major cause of treatment failure, with little improvement seen over the past 2 decades. These data mandate caution when recommending allo-HCT in these conditions and indicate the need for more effective antineoplastic approaches before and after allo-HCT.