Hematopoietic Stem Cell Transplantation for Acute Myeloid Leukemia: To Whom, When, and How

Pre-transplant CRP-albumin ratio as a biomarker in patients receiving haploidentical allogeneic hematopoietic transplantation: Developing a novel DRCI-based nomogram

Background

In allogeneic hematopoietic stem cell transplantation (allo-HSCT), prognostic indicators effectively predict survival. The Disease conditions prior to transplantation dramatically affects the outcome of HSCT. Optimization of the pre-transplant risk assessment is critical for enhancing allo-HSCT decision-making. Inflammation and nutritional status play significant roles in cancer genesis and progression. As a combined inflammatory and nutritional status biomarker, the C-reactive protein/albumin ratio (CAR) can accurately forecast the prognosis in various malignancies. This research sought to examine the predictive value of CAR and develop a novel nomogram by combining biomarkers and evaluating their importance following HSCT.

Methods

Analyses were conducted retroactively on a cohort of 185 consecutive patients who underwent haploidentical hematopoietic stem cell transplantation (haplo-HSCT) at Wuhan Union Medical College Hospital during the period from February 2017 to January 2019. Of these patients, 129 were randomly assigned to the training cohort, and the remaining 56 patients constituted the internal validation cohort. Univariate and multivariate analyses were carried out to examine the predictive significance of clinicopathological factors in the training cohort. Subsequently, the survival nomogram model was developed and compared with the disease risk comorbidity index (DRCI) using the concordance index (C-index), calibration curve, receiver operating characteristics (ROC) curve, and decision curve analysis (DCA).

Results

Patients were separated into low and high CAR groups using a cutoff of 0.087, which independently predicted overall survival (OS). Based on risk factors, CAR, the Disease Risk Index(DRI), and the Hematopoietic Cell Transplantation-specific Comorbidity Index(HCT-CI), the nomogram was developed to predict OS. The C-index and area under the ROC curve confirmed the improved predictive accuracy of the nomogram. The calibration curves revealed that the observed probabilities agreed well with those predicted by the nomogram in training, validation and entire cohort. It was confirmed by DCA that the nomogram offered greater net benefits than DRCI among all cohorts.

Conclusion

CAR is an independent prognostic indicator for haplo-HSCT outcomes. Higher CAR was related to worse clinicopathologic characteristics and poorer prognoses in patients underwent haplo-HSCT. This research provided an accurate nomogram for predicting the OS of patients following haplo-HSCT, illustrating its potential clinical utility.

Applicability of the acute leukemia (AL) - EBMT score as a prognostic model for allogeneic hematopoietic stem cell transplantation: a single-center, prospective, cohort study at a reference transplant center in Brazil

INTRODUCTION

The Acute Leukemia-European Society for Blood and Marrow Transplantation (AL-EBMT) risk score was recently developed and validated by Shouval et al. OBJECTIVE: To assess the ability of this score in predicting the 2-year overall survival (OS-2), leukemia-free survival (LFS-2) and transplant-related mortality (TRM) in acute leukemia (AL) adult patients undergoing a first allogeneic hematopoietic stem cell transplant (HSCT) at a transplant center in Brazil.

METHODS

In this prospective, cohort study, we used the formula published by Shouval et al. to calculate the AL-EBMT score and stratify patients into three risk categories.

RESULTS

A total of 79 patients transplanted between 2008 and 2018 were analyzed. The median age was 38 years. Acute myeloid leukemia was the most common diagnosis (68%). Almost a quarter of the cases were at an advanced stage. All hematopoietic stem cell transplantations (HSCTs) were human leukocyte antigen-matched (HLA-matched) and the majority used familial donors (77%). Myeloablative conditioning was used in 92% of the cases. Stratification according to the AL-EBMT score into low-, intermediate- and high-risk groups yielded the following results: 40%, 12% and 47% of the cases, respectively. The high scoring group was associated with a hazard ratio of 2.1 (p = 0.007), 2.1 (p = 0.009) and 2.47 (p = 0.01) for the 2-year OS, LFS and TRM, respectively.

CONCLUSION

This study supports the ability of the AL-EBMT score to reasonably predict the 2-year post-transplant OS, LFS and TRM and to discriminate between risk categories in adult patients with AL, thus confirming its usefulness in clinical decision-making in this setting. Larger, multicenter studies may further help confirm these findings.

Patient-reported symptom burden and impact on daily activities in chronic graft-versus-host disease

BACKGROUND

Chronic graft-versus-host disease (GVHD) is a potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT) treatment for hematologic malignancies. There are limited patient-reported data concerning symptom burden and effects on activities of daily living (ADL).

METHODS

The cross-sectional Living With Chronic GVHD Patient Survey was administered online in the United States (May-August 2020) to participants aged ≥18 years who underwent allogeneic HSCT, were diagnosed with chronic GVHD by a healthcare provider, and self-reported active chronic GVHD (within past 5 years). Information on patient demographics, disease characteristics, symptom burden, and ability to perform ADL was collected. Symptom burden was assessed using the validated Lee Symptom Scale (range from 0-100 with higher scores indicating greater burden). All data were summarized using descriptive statistics; no formal statistical comparisons were conducted.

RESULTS

Out of 580 participants who entered the survey screener, 165 participants (28.4%) across 33 states fulfilled all study eligibility criteria, completed the entire survey, and were included (age: mean [SD], 53.7 (13.8) years; median [range], 57.0 [18-78] years; female, n = 105 [63.6%]; White, n = 137 [83.0%]). Respondents described their chronic GVHD severity primarily as moderate (n = 54 [32.7%]) or severe (n = 102 [61.8%]) at the time when symptoms were at their worst. One-third of respondents (33.9%) indicated that their chronic GVHD symptoms were at their worst for ≥1 year in duration. Mean (SD; range) Lee Symptom Scale score was 44.8 (19.4; 2-100); 44% of respondents considered "dry eye" the most burdensome symptom. Almost half of respondents (n = 73 [44.2%]) rated their overall quality of life (QoL) as poor. Participants reported a detrimental impact of symptoms on ADL, including basic activities (eg, eating, personal hygiene, dressing).

CONCLUSIONS

Survey respondents self-reported high chronic GVHD symptom burden and felt that their symptoms severely interfered with physical function and ADL. Effective strategies to mitigate chronic GVHD symptoms are needed to improve QoL among HSCT survivors.

Comparison of the Prognostic Ability of the HCT-CI, the Modified EBMT, and the EBMT-ADT Pre-transplant Risk Scores for Acute Leukemia

BACKGROUND

Allogeneic hematopoietic cell transplantation (HCT) outcomes may be predicted by published risk scores; however, the ideal system has not been identified for acute leukemias.

PATIENTS AND METHODS

We retrospectively examined the Hematopoietic Cell Transplantation-Comorbidity Index (HCT-CI), modified European Group for Blood and Marrow Transplantation (mEBMT), EBMT-Alternating Decision Tree (ADT), and others on 231 patients with acute leukemia.

RESULTS

Acute myeloid leukemia was diagnosed in 200 patients, and acute lymphocytic leukemia was diagnosed in 31 patients. For HCT-CI, patients were grouped as 0 to 1, 2 to 3, and > 3. For mEBMT, patients were grouped as 0 to 2, 3, and > 3. For EBMT-ADT, the 100-day mortality was calculated and grouped as ≤ 4.1%, 4.1% to 11.5%, and > 11.5%. Higher HCI-CI demonstrated inferior overall survival (P = .04; c-statistic, 0.57), whereas mEBMT and EBMT-ADT did not stratify well. A new weighted score was developed that assigned 1 point for age ≥ 60 years, acute lymphocytic leukemia diagnosis, mismatch unrelated or haploidentical donor, cardiovascular comorbidity, and pre-transplant diabetes, whereas arrhythmia received 2 points. The new weighted score assigned 0 points to 88 (38%), 1 to 2 points to 121 (52%) and ≥ 3 points to 22 (10%) patients, and demonstrated improved prognostic capability compared with the other scores (P = .0001; c-statistic, 0.61).

CONCLUSIONS

The HCT-CI stratifies patients with leukemia for overall survival but is inferior to our single-center score, which is influenced by cardiac comorbidity and arrhythmia. Differences in pre-transplant risk scores may be related to different transplant practices.

Immunotherapy in Myeloproliferative Diseases

Myeloproliferative diseases, including myeloproliferative neoplasms (MPN) and myelodysplastic syndromes (MDS), are driven by genetic abnormalities and increased inflammatory signaling and are at high risk to transform into acute myeloid leukemia (AML). Myeloid-derived suppressor cells were reported to enhance leukemia immune escape by suppressing an effective anti-tumor immune response. MPNs are a potentially immunogenic disease as shown by their response to interferon-α treatment and allogeneic hematopoietic stem-cell transplantation (allo-HSCT). Novel immunotherapeutic approaches such as immune checkpoint inhibition, tumor vaccination, or cellular therapies using target-specific lymphocytes have so far not shown strong therapeutic efficacy. Potential reasons could be the pro-inflammatory and immunosuppressive microenvironment in the bone marrow of patients with MPN, driving tumor immune escape. In this review, we discuss the biology of MPNs with respect to the pro-inflammatory milieu in the bone marrow (BM) and potential immunotherapeutic approaches.

The Effect of Renal Impairment on the Pharmacokinetics and Safety of Itacitinib

Itacitinib is a novel, selective, Janus kinase 1 inhibitor in development for treatment of graft‐versus‐host disease. The objective of this study was to assess pharmacokinetics and safety of 300‐mg itacitinib dosed in participants with normal renal function (n = 10), severe renal impairment (n = 8), and end‐stage renal disease (ESRD) on hemodialysis (n = 8). Serial plasma and urine samples (urine from normal and severe groups only) were collected before dosing until 72 hours after dosing. In the ESRD group, itacitinib was evaluated in 2 periods, when dosed before (period 1) and after (period 2) a hemodialysis session. Geometric mean ratios (90% confidence interval) in participants with severe renal impairment, ESRD period 1 and ESRD period 2 relative to participants with normal renal function were 1.65 (1.13‐2.39), 0.71 (0.49‐1.03), and 0.83 (0.57‐1.20) for maximum plasma drug concentration and 2.23 (1.56‐3.18), 0.81 (0.57‐1.16), and 0.95 (0.66‐1.35) for area under the plasma concentration–time curve from time zero to infinity. Itacitinib was well tolerated, and 3 grade 1 treatment‐emergent adverse events were reported over the course of the study. Given the magnitude of exposure changes in participants with severe renal impairment or ESRD and the historic risk‐benefit profile, no dose adjustment is recommended for itacitinib in patients with impaired renal function, although the final dosage recommendation will be based on cumulative pharmacokinetics and safety from this study and from the pivotal graft‐versus‐host disease trial. Additionally, itacitinib may be administered to patients undergoing dialysis regardless of the time of dialysis.

Raised CD40L expression attenuates drug resistance in Adriamycin-resistant THP-1 cells

Acute myeloid leukemia is a common hematological malignancy that often exhibits strong drug resistance when treated using conventional chemotherapy. Although numerous studies have been carried out to develop methods of overcoming drug resistance, the results have generally been unsatisfactory. CD40 ligand (CD40L) has been shown to improve the sensitivity of cancer cells to drug treatment. In the present study, Adriamycin (ADM)-resistant human monocytic THP-1 cells (THP-1/A cells) were developed by incubating THP-1 cells with increasing concentrations of ADM. Cells were transfected with CD40L vectors to explore the potential involvement of CD40L in regulating multidrug resistance (MDR) in cancer. Cell proliferation and viability were measured using the Cell Counting Kit-8 assay; cell apoptosis was evaluated by flow cytometry, trypan blue staining and caspase-3 activity; and the expression of MDR-associated protein 1 (MRP1) and permeability glycoprotein (P-gp) was analyzed using western blotting. The results revealed that the protein expression levels of MRP1 and P-gp were downregulated by raised CD40L expression and that the combination of raised CD40L expression with daunorubicin (DNR), a drug from which ADM is derived, significantly increased the extent of cell apoptosis, indicating that drug resistance was effectively attenuated by CD40L. Collectively, these results suggested that CD40L may contribute towards reducing DNR resistance in THP-1/A cells.

Therapy-related acute myeloid leukemia following treatment for cancer in childhood: A population-based registry study

BACKGROUND

Therapy-related acute myeloid leukemia (t-AML) is defined as AML that develops after exposure to cytotoxic chemotherapy and/or radiation therapy. There is a paucity of available literature, particularly in regard to t-AML following childhood cancer. Our aim was to describe the risk of t-AML among children treated for other cancers and their subsequent survival.

PROCEDURE

We utilized data from the population-based Australian Childhood Cancer Registry to examine all childhood patients (<15 years at diagnosis) treated with chemotherapy and/or radiotherapy for cancers other than AML who received a subsequent diagnosis of AML between 1983 and 2014. Standardized incidence ratios (SIRs) were calculated to approximate the relative risk of being diagnosed with AML compared to the general population. Estimates of 5-year observed survival were obtained using the Kaplan-Meier method, with differences determined by the log-rank test.

RESULTS

Fifty-eight of 11,753 patients in the study cohort (0.5%) were diagnosed with t-AML, an almost 50-fold higher risk than expected (SIR = 45.6, 95% confidence interval [CI] = 35.3-59.0). Five-year observed survival from the date of t-AML diagnosis was 31.2% (95% CI = 19.6-43.5%). A significant survival advantage was found for patients who underwent hematopoietic stem cell transplantation (HSCT) following diagnosis of t-AML, with a 5-year survival of 52.4% (29.7-70.9%) compared to 5.7% (0.4-22.6%) for those who did not have HSCT (P < 0.001).

CONCLUSIONS

Although rare, t-AML is an important potential late effect of childhood cancer therapy. Prognosis is generally poor, with HSCT offering some survival benefit.

Protein dysregulation in graft versus host disease

Allogeneic hematopoietic stem cell transplantation is a well-established treatment for many malignant and non-malignant hematological disorders. As a frequent complication in up to 50% of all patients, graft-versus-host disease is still the main cause for morbidity and non-relapse mortality. Diagnosis is usually done clinically, even though confirmation by pathology is often used to support the clinical findings. Effective treatment requires intensified immunosuppression as early as possible. Although several promising biomarkers have been proposed for an early diagnosis, no internationally-recognized consensus has yet been established. Protein-based biomarkers represent an interesting tool since they have been recently reported to be an important regulator of various cells, including immune cells such as T cells. Therefore, we assume that protein dysregulation is important in the pathogenesis of acute graft versus host disease and their detection might be an possibility in the early diagnosis and monitoring. In this review, we aim to summarize the previous reports of protein biomarkers, focusing on the pathogenesis of the disease and possible implications in diagnostic approaches.

Validation of the acute leukemia-EBMT score for prediction of mortality following allogeneic stem cell transplantation in a multi-center GITMO cohort

Predictive models may help in determining the risk/benefit ratio of allogeneic hematopoietic stem cell transplantation (HSCT) in acute leukemia (AL). Using a machine-learning algorithm we have previously developed the AL- European Society for Blood and Marrow Transplantation (EBMT) score for prediction of mortality following transplantation. We report here the first external validation of the AL-EBMT score in a cohort of AL patients from the Italian national transplantation network. A total of 1848 patients transplanted between the years 2000-2014 were analyzed. The median age was 45.9. Indications for HSCT were Acute Myeloid Leukemia (68.1%) and Acute Lymphoblastic Leukemia (31.9%). The majority of patients were in first complete remission (60.4%), and received myeloablative conditioning (81.3%). Median follow-up was 2 years. The score was well-calibrated for prediction of day 100 mortality and 2-year overall survival (OS), leukemia free survival (LFS), and nonrelapse related mortality, with corresponding area under the receiver-operator curves of 0.698, 0.651, 0.653, and 0.651, respectively. Increasing score intervals were associated with a decreasing probability of 2-year OS and LFS. The highest scoring group was associated with a hazard ratio of 3.16, 2.8, and 2.27 for 2-year OS, LFS, and NRM, respectively. In conclusion, the AL-EBMT score identified three distinct risk groups and was predictive of OS. It is a valid tool for stratifying the risk of acute leukemia patients undergoing allogeneic HSCT.

Prognostic Significance of Residual Acute Myeloid Leukemia in Bone Marrow Samples Taken Prior to Allogeneic Hematopoietic Cell Transplantation

OBJECTIVES

We sought to identify features in routine evaluation of pre-hematopoietic cell transplantation (HCT) bone marrow samples from patients with acute myeloid leukemia (AML) that influenced patient outcome.

METHODS

Of 140 patients, evidence of residual leukemia (RL) was identified in 38 (27%) of pre-HCT samples, as defined by 5% or more aspirate blasts, increased blood blasts, clustered or necrotic blasts on biopsy specimens, and/or leukemia-associated karyotypic abnormalities.

RESULTS

Morphologic or karyotypic evidence of RL was significantly associated with shorter leukemia-free survival (LFS) compared with cases without identifiable RL (median, 7.1 vs 28.3 months; P  < .0001). Upon multivariable analysis, RL, prior relapse, age, high-risk karyotype, and alternate donor source were each independently associated with shorter LFS. RL in pre-HCT samples was more strongly associated with shorter LFS in patients with intermediate or favorable-risk AML karyotype ( P  = .001) than secondary or adverse karyotype-risk AML ( P  = .04).

CONCLUSIONS

Rigorous morphologic and karyotypic evaluation of pretransplant marrows is practical and important for posttransplant prognosis.

Peripheral blood blast clearance is an independent prognostic factor for survival and response to acute myeloid leukemia induction chemotherapy

In patients with acute myeloid leukemia (AML), rapid reduction of circulating blasts with induction chemotherapy may serve as an in vivo marker of chemosensitivity. We performed a retrospective analysis of 363 patients with untreated AML who received induction chemotherapy in order to determine the relationship between day of blast disappearance (DOBD) and complete remission (CR) rates, event-free survival (EFS), and overall survival (OS). DOBD ≤ 5 vs. >5 was identified as the most discriminating cutoff for OS. DOBD > 5 was observed in 35 patients (9.6%). The CR rate for patients with DOBD ≤ 5 vs. >5 was 74.0 and 28.6%, median EFS was 9.4 and 1.8 months, and median OS was 17.1 and 5.8 months, respectively (P < 0.001 for all). DOBD > 5 was independently associated with a lower CR rate and shorter EFS and OS (P < 0.001 for all). DOBD > 5 retained prognostic significance for EFS and OS when patients were stratified by cytogenetic risk group, de novo vs. secondary or therapy-related AML, European LeukemiaNet-based risk groups, and whether CR was achieved. We propose DOBD > 5 as a simple and early marker of disease resistance that identifies patients with poor prognosis who otherwise may not be identified with existing risk stratification systems. Am. J. Hematol. 91:1221-1226, 2016. © 2016 Wiley Periodicals, Inc.

Post-Transplantation Natural Killer Cell Count: A Predictor of Acute Graft-Versus-Host Disease and Survival Outcomes After Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND

Reconstitution of the immune system after allogeneic hematopoietic stem cell transplantation (allo-HSCT) plays an important role in post-transplant outcomes. However, the clinical relevance of the lymphocyte subset (LST) counts to transplant-related complications and survival outcomes after allo-HSCT has not been fully elucidated.

PATIENTS AND METHODS

A total of 70 patients who had undergone allo-HSCT from 2007 to 2013, with LST results both 7 days before conditioning and 30 or 90 days after allo-HSCT were included. The LST counts in the peripheral blood were determined using 6-color flow cytometry. Clinical information, including transplant-related events during the first 100 days after allo-HSCT, was reviewed, and any association between these events and LST was analyzed.

RESULTS

At 30 days after allo-HSCT, the CD4⁺ T-cell (P = .009) and B-cell (P = .035) counts were lower and the natural killer (NK) cell count was greater (P < .001) than before conditioning. The CD8⁺ T-cell (P = .001) and NK cell (P < .001) counts were high 90 days after transplantation. The hazard ratios for a low NK cell count on days 30 and 90 for acute graft-versus-host disease were 6.22 and 14.67, respectively. Patients with low NK cell counts at 30 and 90 days after allo-HSCT had poorer overall survival (P = .043 and P = .028, respectively) and greater nonrelapse mortality (P = .036 and P = .033, respectively). A low NK cell count on day 30 was still prognostic for overall survival (P = .039) on multivariable analysis.

CONCLUSION

NK cell counts after allo-HSCT, especially on day 30, were predictive of acute graft-versus-host disease, nonrelapse mortality, and survival. Serial lymphocyte subset analysis can be used to identify and treat patients at risk during the early period after allo-HSCT.

Clinical significance of high-dose cytarabine added to cyclophosphamide/total-body irradiation in bone marrow or peripheral blood stem cell transplantation for myeloid malignancy

Background

Addition of high-dose cytarabine (HDCA) to the conventional cyclophosphamide/total-body irradiation (CY/TBI) regimen significantly improved prognosis after cord blood transplantation (CBT) for adult acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS). The efficacy of HDCA in bone marrow or peripheral blood stem cell transplantation (BMT/PBSCT), however, has not yet been elucidated.

Findings

We conducted a cohort study to compare the prognosis of HDCA/CY/TBI (N = 435) and CY/TBI (N = 1667) in BMT/PBSCT for AML/MDS using a Japanese transplant registry database. The median age was 38 years, and 86.0 % of the patients had AML. Unrelated donors comprised 54.6 %, and 63.9 % of donors were human leukocyte antigen (HLA)-matched. Overall survival (OS) was not improved in the HDCA/CY/TBI group (adjusted hazard ratio (HR), 1.14; p = 0.13). Neutrophil engraftment was inferior (HR, 0.80; p < 0.01), and the incidence of hemorrhagic cystitis and thrombotic microangiopathy increased in HDCA/CY/TBI (HR, 1.47 and 1.60; p = 0.06 and 0.04, respectively), leading to significantly higher non-relapse mortality (NRM; HR, 1.48; p < 0.01). Post-transplant relapse and tumor-related mortality were not suppressed by the addition of HDCA.

Conclusions

This study indicated the inefficacy of HDCA/CY/TBI in BMT/PBSCT for AML/MDS. Our results should be validated in large-scale prospective studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-015-0201-x) contains supplementary material, which is available to authorized users.

Conditioning intensity in middle-aged patients with AML in first CR: no advantage for myeloablative regimens irrespective of the risk group-an observational analysis by the Acute Leukemia Working Party of the EBMT

In recipients of allogeneic hematopoietic stem cell transplantation with AML in CR1, reduced intensity (RIC) conditioning regimens are usually given to older patients and myeloablative regimens (MAC) to younger patients. We analyzed whether in middle-aged patients aged 40-60 years, MAC was superior to RIC in cytogenetically higher risk AML. Among 2974 patients, 1638 had MAC and 1336 RIC transplants. Cytogenetics were high risk in 508, intermediate risk in 2297 and low risk in 169. Overall survival (OS) was higher in patients with RIC with low-risk cytogenetics but not in the intermediate- or poor-risk AML. Relapse incidence was lower with MAC in poor- and intermediate-risk AML. Nonrelapse mortality (NRM) was higher in MAC in all cytogenetic risk groups. Multivariate analysis confirmed a significant leukemia-free survival and OS advantage for RIC in low risk but no advantage of MAC in intermediate- and poor-risk leukemia. In patients aged 40-60 years, MAC has no advantage over RIC. We confirm lower relapse but higher NRM risks with MAC. MAC is not superior in patients with higher risk cytogenetics, but is inferior to RIC in the small cohort of AML patients with low-risk cytogenetics.

Phase I/II trial of the combination of midostaurin (PKC412) and 5-azacytidine for patients with acute myeloid leukemia and myelodysplastic syndrome

We investigated the combination of midostaurin and azacitidine (AZA) in patients with acute myeloid leukemia (AML) and high risk myelodysplastic syndrome (MDS). Patients received AZA 75 mg m(-2) on days 1-7 and midostaurin 25 mg bid (in cohort 1 of phase I) or 50 mg bid (in cohort 2 of Phase I and in Phase II) orally on day 8-21 during the first cycle and continuously thereafter. Fourteen patients were enrolled in the phase I and 40 in the phase II. Overall response rate was 26%. The median remission duration (RD) was 20 weeks and was significantly longer in patients with FLT3 mutations not previously exposed to other FLT3 inhibitors (P = 0.05) and in patients not previously transplanted (P = 0.01). Thirty-two (59%) patients have died, all of complications related to disease progression. G3-4 nonhematological toxicity was reported in 38 (70%) patients, most frequently infections (56%), ejection fraction reduction (11%), and diarrhea or nausea/vomiting (9% each). The combination of midostaurin and AZA is an effective and safe regimen in patients with AML and high-risk MDS. Patients with FLT3 mutations but not previously exposed to other FLT3 inhibitors and patients not previously transplanted derived the greatest benefit. Further studies with this combination are warranted.

An autologous leukemia cell vaccine prevents murine acute leukemia relapse after cytarabine treatment

Acute leukemias with adverse prognostic features carry a high relapse rate without allogeneic stem cell transplantation (allo-SCT). Allo-SCT has a high morbidity and is precluded for many patients because of advanced age or comorbidities. Postremission therapies with reduced toxicities are urgently needed. The murine acute leukemia model C1498 was used to study the efficacy of an intravenously administered vaccine consisting of irradiated leukemia cells loaded with the natural killer T (NKT)-cell agonist α-galactosylceramide (α-GalCer). Prophylactically, the vaccine was highly effective at preventing leukemia development through the downstream activities of activated NKT cells, which were dependent on splenic langerin(+)CD8α(+) dendritic cells and which led to stimulation of antileukemia CD4(+) and CD8(+) T cells. However, hosts with established leukemia received no protective benefit from the vaccine, despite inducing NKT-cell activation. Established leukemia was associated with increases in regulatory T cells and myeloid-derived suppressor cells, and the leukemic cells themselves were highly suppressive in vitro. Although this suppressive environment impaired both effector arms of the immune response, CD4(+) T-cell responses were more severely affected. When cytarabine chemotherapy was administered prior to vaccination, all animals in remission posttherapy were protected against rechallenge with viable leukemia cells.