Allogeneic hematopoietic cell transplantation in patients with AML not achieving remission: potentially curative therapy

Allogeneic stem cell transplantation in de novo core-binding factor acute myeloid leukemia in active disease: a study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Core-binding factor acute myeloid leukemia (CBF-AML) generally has a favorable prognosis, with allogeneic hematopoietic stem cell transplantation (allo-SCT) recommended for relapsed/ refractory (R/R) cases achieving second complete remission (CR). However, clinical outcomes remain suboptimal for patients who relapse or fail to achieve CR following induction chemotherapy. Allo-SCT in non-CR is a potential strategy for such patients, though supporting evidence in CBF-AML is limited. To assess outcomes and prognostic factors of allo-SCT in R/R CBF-AML with active disease, we conducted a retrospective analysis of 610 patients with CBF-AML in non-CR undergoing allo-SCT from 2010 to 2021 across 174 centers within the European Society for Blood and Marrow Transplantation. Graft sources included matched sibling (MSD, n = 151), unrelated (UD, n = 368), and haploidentical donors (Haplo, n = 91). Among patients, 124 had inv(16), and 486 had t(8;21). Two-year overall survival (OS) and leukemia-free survival (LFS) were 53.6% and 42.7%, respectively. Haplo-SCT showed inferior OS compared to MSD (HR 1.79, p = 0.003) and UD (HR 1.64, p = 0.004) and reduced chronic graft-versus-host disease. Patients with t(8;21) exhibited higher relapse incidence (HR 2.04, p = 0.002) and poorer survival outcomes than those with inv(16). These findings confirm the therapeutic role of allo-SCT in R/R CBF-AML in non-CR, supporting its favorable risk profile.

Randomized Phase III SIERRA Trial of 131I-Apamistamab Before Allogeneic Hematopoietic Cell Transplantation Versus Conventional Care for Relapsed/Refractory AML

PURPOSE

Older patients with relapsed or refractory AML (RR AML) have dismal prognoses without allogeneic hematopoietic cell transplantation (alloHCT). SIERRA compared a targeted pretransplant regimen involving the anti-CD45 radioconjugate 131I-apamistamab with conventional care.

METHODS

SIERRA (ClinicalTrials.gov identifier: NCT02665065) was a phase III open-label trial. Patients age ≥55 years with active RR AML were randomly assigned 1:1 to either an 131I-apamistamab-led regimen before alloHCT or conventional care followed by alloHCT if initial complete remission (CR)/CR with incomplete platelet recovery (CRp) occurred. Initial response was assessed 28-56 days after alloHCT in the 131I-apamistamab group and 28-42 days after salvage chemotherapy initiation; patients without CR/CRp or with AML progression could cross over to receive 131I-apamistamab followed by alloHCT. The primary end point was durable complete remission (dCR) lasting 180 days after initial CR/CRp. Secondary end points were overall survival (OS) and event-free survival (EFS), assessed hierarchically in the intention-to-treat (ITT) population.

RESULTS

The ITT population included 153 patients (131I-apamistamab [n = 76]; conventional care [n = 77]). In total, 44/77 conventional care arm patients crossed over and 40/77 (52%) received 131I-apamistamab and alloHCT, with six patients (13.6%) experiencing a dCR. In the ITT population, the dCR rate was significantly higher with 131I-apamistamab (17.1% [95% CI, 9.4 to 27.5]) than conventional care (0% [95% CI, 0 to 4.7]; P < .0001). The OS hazard ratio (HR) was 0.99 (95% CI, 0.70 to 1.41; P = .96), and the EFS HR was 0.23 (95% CI, 0.15 to 0.34), with HR <1 favoring 131I-apamistamab. Grade ≥3 treatment-related adverse events occurred in 59.7% and 59.2% of the 131I-apamistamab and conventional care groups, respectively.

CONCLUSION

The 131I-apamistamab-led regimen was associated with a higher dCR rate than conventional care in older patients with RR AML. 131I-apamistamab was well tolerated and could address an unmet need in this population.

89Zr-immunoPET-guided selection of a CD33xIL15 fusion protein optimized for antitumor immune cell activation and in vivo tumour retention in acute myeloid leukaemia

PURPOSE

Immune cells are capable of eliminating leukemic cells, as evidenced by outcomes in hematopoietic cell transplantation (HCT). However, patients who fail induction therapy will not benefit from HCT due to their minimal residual disease (MRD) status. Thus, we aimed to develop an immunomodulatory agent to reduce MRD by activating immune effector cells in the presence of leukaemia cells via a novel fusion protein that chimerises two clinically tolerated biologics: a CD33 antibody and the IL15Ra/IL15 complex (CD33xIL15).

METHODS

We generated a set of CD33xIL15 fusion protein constructs with varying configurations and identified those with the best in vitro AML-binding, T cell activation, and NK cell potentiation. Using 89Zr-immunoPET imaging we then evaluated the biodistribution and in vivo tumour retention of the most favourable CD33xIL15 constructs in an AML xenograft model. Ex vivo biodistribution studies were used to confirm the pharmacokinetics of the constructs.

RESULTS

Two of the generated fusion proteins, CD33xIL15 (N72D) and CD33xIL15wt, demonstrated optimal in vitro behaviour and were further evaluated in vivo. These studies revealed that the CD33xIL15wt candidate was capable of being retained in the tumour for as long as its parental CD33 antibody, Lintuzumab (13.9 ± 3.1%ID/g vs 18.6 ± 1.1%ID/g at 120 h).

CONCLUSION

This work demonstrates that CD33xIL15 fusion proteins are capable of targeting leukemic cells and stimulating local T cells in vitro and of concentrating in the tumour in AML xenografts. It also highlights the importance of 89Zr-immunoPET to guide the development and selection of tumour-targeted antibody-cytokine fusion proteins.

Haploidentical transplantation in primary refractory/relapsed secondary vs de novo AML: from the ALWP/EBMT

ABSTRACT

We compared the outcomes of haploidentical stem cell transplantation (haplo-HSCT) with posttransplant cyclophosphamide (PTCy) in 719 patients with primary refractory (PR) or first relapse (Rel) secondary acute myeloid leukemia (sAML; n = 129) vs those with de novo AML (n = 590), who received HSCT between 2010 and 2022. A higher percentage of patients with sAML vs de novo AML had PR disease (73.6% vs 58.6%; P = .002). In 81.4% of patients with sAML , the antecedent hematological disorder was myelodysplastic syndrome. Engraftment was 83.5% vs 88.4% in sAML and de novo AML, respectively (P = .13). In multivariate analysis, haplo-HSCT outcomes did not differ significantly between the groups: nonrelapse mortality hazard ratio (HR), 1.38 (95% confidence interval [CI], 0.96-1.98; P = .083), relapse incidence HR, 0.68 (95% CI, 0.4.7.-1.00; P = .051). The HRs for leukemia-free survival, overall survival, and graft-versus-host disease (GVHD)-free, and GVHD and relapse-free survival were 0.99 (95% CI, 0.76-1.28; P = .94), 0.99 (95% CI, 0.77-1.29; P = .97), and 0.99 (95% CI, 0.77-1.27; P = .94), respectively. We conclude that outcomes of haplo-HSCT with PTCy are not different for PR/Rel sAML in comparison with PR/Rel de novo AML, a finding of major clinical importance.

Survival outcomes in patients with acute myeloid leukaemia who received subsequent therapy for relapse in QUAZAR AML-001

In the phase 3 QUAZAR AML-001 trial (NCT01757535) of patients with acute myeloid leukaemia (AML) in remission following intensive chemotherapy (IC) and ineligible for haematopoietic stem cell transplant (HSCT), oral azacitidine (Oral-AZA) maintenance significantly prolonged overall survival (OS) versus placebo. The impact of subsequent treatment following maintenance has not been evaluated. In this post hoc analysis, OS was estimated for patients who received subsequent AML therapy, and by regimen received (IC or lower-intensity therapy). First subsequent therapy (FST) was administered after treatment discontinuation in 134/238 Oral-AZA and 173/234 placebo patients. OS from randomization in patients who received FST after Oral-AZA versus placebo was 17.8 versus 12.9 months (HR: 0.82 [95% CI: 0.64-1.04], median follow-up: 56.7 months); OS from FST was similar between arms. Among patients who received injectable hypomethylating agents as FST, median OS was 8.2 versus 4.9 months in the Oral-AZA versus placebo groups (HR: 0.66 [95% CI: 0.41-1.06]). Forty-eight patients (16/238 Oral-AZA, 32/234 placebo) received HSCT following treatment discontinuation, including six Oral-AZA patients still in first remission; Oral-AZA OS benefit persisted when censoring these patients. Oral-AZA maintenance can prolong AML remission duration without negatively impacting survival outcomes after salvage therapies.

Lack of RBC transfusion independence by Day 30 following allogeneic hematopoietic stem cell transplant strongly predicts inferior survival and high non-relapse mortality in acute myeloid leukemia patients

BACKGROUND

Studies have suggested that acute myeloid leukemia (AML) patients with incomplete hematologic recovery undergoing allogeneic stem cell transplantation (allo-HSCT) had inferior overall survival (OS).

STUDY DESIGN AND METHODS

This single-center, retrospective study of AML patients evaluated the relationship between red blood cell (RBC) and platelet (PLT) transfusion requirements during the first 30 days and long-term outcomes after allo-HSCT through multivariate analyses.

RESULTS

A total of 692 AML patients received peripheral blood stem cells (89.2%), marrow (5.6%), or umbilical cord (5.2%) from matched related (37.4%), unrelated (49.1%), or haploidentical (8.2%) donors in 2011-2017. Transfusion requirements during the first 30 days for RBC (89.5% transfused, median 3, range 1-18 units) or PLT (98.2% transfused, median 6, range 1-144 units) were variable. By Day 30, 56.7% (95% confidence interval [CI]: 52.8-60.3%) and 86.1% (95% CI: 83.2-88.5%) had achieved RBC and PLT transfusion independence, respectively. Median follow-up among survivors (n = 307) was 7.1 years (range: 2.7-11.8). Lack of RBC transfusion independence by Day 30 was strongly and independently associated with worse 5-year OS (39.2% vs. 59.6%, adjusted hazard ratio [HR] 1.83, 95% CI: 1.49-2.25), leukemia-free survival (35.8% vs. 55.5%, HR = 1.75, 95% CI: 1.43-2.14), and NRM (29.7% vs. 13.7%, HR = 2.05, 95% CI: 1.45-2.89) (p < .001). There was no difference in relapse rates among patients who achieved or did not achieve RBC (p = .34) or PLT (p = .64) transfusion independence.

CONCLUSION

Prolonged RBC dependence predicted worse survival and NRM rates, but not increased relapse. Posttransplant surveillance of such patients should be adjusted with more attention to non-relapse complications.

Outcomes of adult patients with type 1 primary refractory acute myeloid leukemia: a single center experience

Adult patients with newly diagnosed de novo acute myeloid leukemia (AML), who had less than a 50% reduction in blast numbers and with > 15% residual blasts after first cycle of induction chemotherapy, defined as type 1 primary refractory (REF1), have grave prognosis. We retrospectively analyzed the data of 58 patients with REF1 who received salvage treatments with curative intension to evaluate the impact of salvage regimens with regard to response and overall survival (OS). Seventeen patients received intermediate- or high-dose cytarabine (ID/HD Ara-C) based intensive salvage chemotherapy, 36 patients received G-CSF primed less intensive chemotherapy and 5 patients received novel targeted drugs based low intensive therapy. The CR/CRi and MLFS rate was 6/17 and 2/17, 14/36 and 3/36, 3/5 and 0/5, respectively. The median OS for the whole cohort was 20.3 months. Median OS was comparable between the 3 arms. Overall, 42 patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), 14 patients in the intensive arm, 24 patients in the less intensive arm and 4 patients in the low intensive arm. Median survival for allo-HSCT patients was significantly longer than for non-allo-HSCT patients (38.8 months vs. 2.1 months, p < 0.001). In multivariate analysis, achievement of CR/CRi after the salvage regimen were predictive of OS. We conclude that no significant difference in outcome among traditional salvage regimens in patients with REF1. G-CSF primed less intensive chemotherapy could serve as an alternative of ID/HD Ara-C based intensive chemotherapy and allo-HSCT is indispensable for long-term survival.

Impact of extramedullary disease in AML patients undergoing sequential RIC for HLA-matched transplantation: occurrence, risk factors, relapse patterns, and outcome

We sought to evaluate the role of extramedullary disease (EMD) in sequential RIC retrospectively analyzing data of 144 high-risk AML patients undergoing HLA-matched transplantation. Median long-term follow-up was 11.6 years. Eighteen percent of patients (n = 26/144) presented with extramedullary AML (EM AML) or a history of EMD at time of transplantation. Overall relapse rate was 25% (n = 36/144) with 15% (n = 21/144) of all patients developing isolated BM relapse and 10% (n = 15/144) developing EM AML relapse with or without concomitant BM relapse (EM ± BM). Manifestation of EM relapse after transplantation occurred frequently at multiple sites and presented mostly as solid tumor mass. Only 3/15 patients with EM ± BM relapse showed a prior EMD manifestation. EMD prior to allogeneic transplantation had no impact on post-transplant OS when compared to non-EMD (median post-transplant OS 3.8 years versus 4.8 years; ns). Risk factors (p =  < 0.1) for EM ± BM relapse included younger age and a higher number of prior intensive chemotherapies, whereas the presence of chronic GVHD was a protective factor. Median post-transplant OS (15.5 months vs. 15.5 months), RFS (9.6 months vs 7.3 months), and post-relapse OS (6.7 months vs. 6.3 months) were not significantly different between patients with isolated BM vs. EM ± BM relapse. Taken together, occurrence of EMD prior to as well as of EM ± BM AML relapse after transplantation was moderate, presenting mostly as solid tumor mass after transplantation. However, diagnosis of those does not seem to influence outcomes after sequential RIC. A higher number of chemotherapy cycles prior to transplantation was identified as recent risk factor for EM ± BM relapse.

Clofarabine and Busulfan Myeloablative Conditioning in Allogeneic Hematopoietic Cell Transplantation for Patients With Active Myeloid Malignancies

Patients with refractory or relapsed and refractory myeloid malignancies have a poor prognosis. Allogeneic hematopoietic cell transplantation (HCT) with myeloablative conditioning (MAC) in patients with active, chemotherapy-refractory myeloid disease is historically associated with high rates of relapse and nonrelapse mortality (NRM). A MAC regimen combining clofarabine with busulfan (Clo/Bu4) has been reported to exhibit antileukemic activity with acceptable toxicity in patients age ≤70 years. Here we describe the clinical outcomes of a real-world population of patients with active myeloid malignancies undergoing allogeneic HCT with Clo/Bu4 MAC. In a single-center retrospective descriptive analysis, we identified patients who underwent HCT for myeloid malignancies not in remission using Clo/Bu4 MAC between 2012 and 2020. We report event-free survival (EFS) and overall survival (OS), cumulative incidences of relapse and NRM, and the incidence and severity of acute and chronic graft-versus-host disease (GVHD). We identified 69 patients with a median age of 60 years (range, 22 to 70 years). Most patients had relapsed/refractory or primary refractory acute myelogenous leukemia (AML; n = 55) or refractory myelodysplastic syndrome (MDS; n = 12); 1 patient had chronic myelogenous leukemia, and 1 patient had a blastic plasmacytoid dendritic cell neoplasm. Fifty patients (72.5%) had complete remission at day 100 post-transplantation. Two-year EFS and OS were 30% (95% confidence interval [CI], 20% to 44%) and 40% (95% CI, 29% to 54%), respectively. Patients with AML had a 2-year EFS and OS of 28% (95% CI, 18% to 44%) and 38% (95% CI, 27% to 54%), respectively; those with MDS had a 2-year EFS and OS of 47% (95% CI, 25% to 88%) and 56% (95% CI, 33% to 94%), respectively. The cumulative incidence of relapse at 2 years was 39% (95% CI, 27% to 51%) for all patients, including 45% (95% CI, 31% to 58%) in the patients with AML and 18% (95% CI, 2% to 45%) in those with MDS. NRM at 2 years was 31% (95% CI, 20% to 42%), including 27% (95% CI, 15% to 39%) in patients with AML and 35% (95% CI, 10% to 63%) in those with MDS. The total incidence of acute GVHD (aGVHD) of any severity was 80%, and the incidence of grade III-IV aGVHD was 22%. In patients who achieved remission, those who required systemic immunosuppression for aGVHD (58%) had poorer 2-year EFS (29% versus 54%; P = .05) and 2-year OS (39% versus 70%; P = .04) compared to those who did not. The 2-year cumulative incidence of chronic GVHD was 44% (95% CI, 28% to 58%). Clo/Bu4 MAC followed by allogeneic HCT for patients with active myeloid malignancies is an effective transplantation strategy for patients up to age 70, particularly those with advanced MDS. The high incidence of and poor outcomes associated with aGVHD highlight the importance of optimizing preventative strategies.

Re-induction therapy in patients with acute myeloid leukemia not in complete remission after the first course of treatment

A standard salvage regimen for patients with acute myeloid leukemia (AML) who are not in complete remission (CR) after initial induction therapy does not exist. We retrospectively investigated re-induction therapy for 151 patients with AML who did not achieve CR after the initial course between January 2014 and March 2021. The re-induction regimen did not correlate with the CR rate after the second course, whereas patients had similar 5-year overall survival (OS) and event-free survival (EFS) based on different re-induction regimens. Multivariable analysis revealed that International European Leukaemia Net (ELN) risk stratification independently predicted both OS and EFS among patients not in CR after the first course, although the re-induction regimen did not predict prognosis. Urgent salvage alloHSCT may improve the prognosis of patients with refractory AML. In summary, our study showed that the re-induction regimen did not significantly predict the prognosis of patients with AML not in CR after the first course of treatment. The development and selection of an efficient treatment algorithm for the treatment of AML remains a pressing research challenge.

Allogeneic Hematopoietic Stem Cell Transplantation for Relapsed/Refractory Acute Myeloid Leukemia: A Single-Centre Experience

INTRODUCTION

Patients with relapsed/refractory acute myeloid leukemia (r/r AML) are characterized as having a poor prognosis. The only viable option of treatment for these patients is allogenic stem cell transplantation (allo-HSCT). Therefore, we have attempted to analyse factors related to both the disease itself and the transplantation procedure that could have an influence on the improvement of outcomes in this group of patients.

PATIENTS AND METHODS

Sixty-four patients with r/r AML underwent allo-HSCT at our center in 2012 to 2021. Fifty-two had active disease at the beginning of theallo-HSCT procedure, with amedian number of blasts in bone marrow (BM) of 18, and 12 had therapeutic aplasia after the last reinduction (blasts < 5% in BM).

RESULTS

The probability of overall survival (OS) at 2 years was 25%. The median follow-up for survivors was 21.5 months. Progression-free survival (PFS) estimates were above 46%. The main cause of death was disease progression (49%). A statistically significant effect on premature death was reported for the diagnosis of secondary AML (sAML) and cytomelovirus (CMV) reactivation post allo-HSCT. On the other hand, chronic graft versus host disease (cGVHD) decreased the risk of disease progression. sAML and CMV reactivation were found to have opposite effects.

Enhancing Administrative Claims Data: Feasibility, Validation and Application of Linking Medicare Claims Data and National Marrow Donor Program Search Data

PURPOSE

Administrative claims data provide real-world service utilization of acute myeloid leukemia (AML) treatment, but lacks insight into treatment delays or barriers. The National Marrow Donor Program (NMDP)/Be The Match Search (Search) data contains information on donor search, but lacks information on treatment received if allogeneic hematopoietic cell transplant (HCT) is not performed. We hypothesized that linking these two data sets would create a rich resource to define factors associated with receiving HCT that could not be evaluated with either data set alone.

METHODS

A subset of 2010-2016 Medicare administrative claims data was linked with Search data. A total of 5,351 patients with AML age 65-74 years (HCT = 607, no HCT = 4,744) were identified using Medicare. These patients were then linked to 93,800 records with a donor search between 2009 and 2016. Patient date of birth, sex, disease, ZIP code, transplant center/hospital, and diagnosis date were used for matching. Exploratory analysis was conducted to identify predictors associated with receiving HCT for patients with AML who received a search.

RESULTS

The data sets were successfully linked, showing high sensitivity and specificity. The final cohort included 5,085 patients with AML (HCT = 533, no HCT = 4,552). Of 97 patients who received HCT without a matched search, more than 85% received a related donor HCT. Of those not receiving HCT, 609 had a matched NMDP search and 3,943 did not have a matched NMDP search. Multivariate analysis showed time to search, age, diagnosis year, race/ethnicity, and neighborhood education status associated with receiving HCT.

CONCLUSION

Methods herein demonstrate the feasibility of linking Search and Medicare data. Similar methods may be applied to answer critical questions regarding barriers to HCT, thereby identifying areas to improve access to care.

Serologic response and safety of COVID-19 vaccination in HSCT or CAR T-cell recipients: a systematic review and meta-analysis

Background

Patients receiving hematopoietic stem cell transplantation (HSCT) or chimeric antigen receptor T cell (CAR T-cell) therapy are immunocompromised and at high risk of viral infection, including SAR2-CoV-2 infection. However, the effectiveness and safety of COVID-19 vaccines in these recipients is not well characterized. The present meta-analysis evaluated the serologic response and safety of COVID-19 vaccines in these population.

Methods

Literature databases (MEDLINE, EMBASE, Web of Science, MedRvix and BioRvix) were searched for original studies with serologic response post COVID-19 vaccination in HSCT or CAR T-cell recipients published until July 14, 2022. The analysis included 27 observational studies with a total of 2899 patients receiving allogeneic HSCT (2506), autologous HSCT (286) or CAR T-cell therapy (107), and 683 healthy participants with serologic response data. Random effects models were used to pool the rate of serologic response to COVID-19 vaccination in HSCT or CAR T-cell recipients and odds ratio comparing with healthy controls.

Results

The pooled seropositivity rates in HSCT and CAR T-cell recipients were 0.624 [0.506–0.729] for one dose, 0.745 [0.712–0.776] for two doses. The rates were significantly lower than those in healthy controls (nearly 100%). In subgroup analysis, CAR T-cell recipients exhibited an even lower seroconversion rate (one dose: 0.204 [0.094–0.386]; two doses: 0.277 [0.190–0.386]) than HSCT counterparts (one dose: 0.779 [0.666–0.862]; two doses: 0.793 [0.762–0.821]). The rates were comparable between autologous and allogeneic HSCT recipients. Other possible impact factors related to seropositivity were time interval between therapy and vaccination, use of immunosuppressive drugs and immune cell counts. Most vaccine-related adverse effects were mild and resolvable, comparable to general population.

Conclusions

This analysis revealed a diminished response to COVID-19 vaccines in HSCT or CAR T-cell recipients. Our findings may inform regular COVID-19 vaccination at appropriate intervals after HSCT or CAR T-cell therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40164-022-00299-6.

Adding melphalan to fludarabine and a myeloablative dose of busulfan improved survival after allogeneic hematopoietic stem cell transplantation in a propensity score-matched cohort of hematological malignancies

Fludarabine and a myeloablative dose of busulfan (Flu/Bu4) can improve prognosis after allogeneic hematopoietic stem cell transplantation (HSCT) with melphalan (Mel). We investigated the prognostic impact of adding Mel to Flu/Bu4 by comparing between Flu/Bu4/Mel and Flu/Bu4 groups. This study included 846 propensity score (PS)-matched patients who received either Flu/Bu4/Mel (n = 423) or Flu/Bu4 (n = 423) from 2394 patients enrolled in a multicenter prospective registry, from January 2010 to December 2016. The primary endpoint (5-year overall survival [OS]), and the prognostic impact of adding Mel was evaluated using Cox regression analysis. The study population median age was 58 (interquartile 50-64) years and 61.0% were male. Patient characteristics were well-balanced between groups. Five-year OS was 34.2% (95% confidence interval [CI]: 27.3-41.1%) and 30.1% (24.8-35.6%) in the Flu/Bu4/Mel and Flu/Bu4 groups, respectively (log-rank P = 0.019). The adjusted hazard ratio of adding Mel was 0.77 (95% CI: 0.62-0.96) (P = 0.022) for the 5-year OS, and this attributed to a lower incidence of 5-year relapse (0.71, 0.56-0.90, P = 0.005) and relapse associated mortality (0.73, 0.57-0.95, P = 0.018). There was no statistical difference in 5-year non-relapse mortality between groups (log-rank P = 0.855). Flu/Bu4/Mel was associated with better 5-year OS compared to Flu/Bu4 in a PS-matched cohort after allogeneic HSCT.

The impact of cytogenetic risk on the outcomes of allogeneic hematopoietic cell transplantation in patients with relapsed/refractory acute myeloid leukemia: On behalf of the acute leukemia working party (ALWP) of the European group for blood and marrow transplantation (EBMT)

Karyotypic analysis at time of diagnosis has an important value in determining initial response to treatment, remission duration and overall survival (OS) in acute myeloid leukemia (AML). Less is known about its value before allogeneic hematopoietic cell transplantation (allo-HCT) in patients transplanted with active disease, either relapsed or primary refractory (Rel-Ref) AML. We explored the impact of cytogenetic risk (stratification according to MRC-UK) in 2089 patients with either Ref (n = 972) or Rel AML (n = 1117) transplanted during the period 2000-2017. Overall, 154 patients had a favorable risk, 1283 had an intermediate risk and 652 had an adverse cytogenetic risk. Median follow-up was 49 months. Compared to the favorable risk group, intermediate and adverse risk patients were associated with worse leukemia-free survival and OS and also with a higher incidence of relapse. In a subgroup analysis of patients in the intermediate risk group harboring Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), this remained an important prognostic factor, being associated with worse outcomes. When analyzing patients according to the intensity of the conditioning regimen, no differences were observed for the main transplant outcomes. In conclusion, in patients diagnosed with AML and transplanted with active disease, karyotype remains an important prognostic factor, allowing splitting patients into different risk groups according to their cytogenetics. Similarly, FLT3-ITD mutation also remains a negative prognostic factor in this population.

Evaluation of six different types of sequential conditioning regimens for allogeneic stem cell transplantation in relapsed/refractory acute myelogenous leukemia - a study of the Acute Leukemia Working Party of the EBMT

The Acute Leukemia Working Party (ALWP) of the EBMT assessed the outcome of allogeneic stem cell transplantation (alloSCT) in patients with relapsed/refractory AML (r/rAML) evaluating six sequential conditioning regimens (SR) groups. A total of 2132 patients were included. LFS at 2 years was 28.9%, 33.6%, 35.3%, 20.6%, 24.4%, and 27% for the FLAMSA-TBI4, FLAMSA-Chemo, Mel-Flu-TBI8, Mel-Treo-Flu, Thio-ETO-Cy-Bu2-Flu, and Clo-ARAC-(Bu2/TBI4)-Cy groups, respectively. In patients <55 years of age Mel-Flu-TBI8 had the best LFS, which was statistically significant only in comparison to the Mel-Treo-Flu group, while in patients ≥55 years LFS was best with FLAMSA-Chemo without significant differences compared to FLAMSA-TBI4 and Mel-Flu-TBI8. Furthermore, best NRM rates were obtained with the two FLAMSA regimens groups. Our study suggests that in younger (<55 years) patients a more intense regimen might be used whereas in older (≥55 years) patients the focus might be more on tolerability.

Prognostic impact of TP53 mutation, monosomal karyotype, and prior myeloid disorder in nonremission acute myeloid leukemia at allo-HSCT

Outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in nonremission acute myeloid leukemia (AML) are dismal [2-year overall survival (OS): 20-30%]. Though several risk classifications have been used, some factors are unavailable until the start of conditioning or transplantation. We analyzed prognostic gene mutations by targeted next-generation sequencing to identify predisposing factors for predicting OS at 1 month before transplantation. We enrolled 120 patients with nonremission AML who underwent first allo-HSCT between 2005 and 2018. Mutations were found in 98 patients; frequently mutated genes were FLT3-ITD, TP53, RUNX1, and WT1. TP53 mutation was detected in 21 patients and was the only predictor of poor OS. Multivariate analysis using Cox regression hazard model revealed primary AML, monosomal karyotype (MK), and TP53 mutation as independent factors for predicting poor OS. Based on these, patients were stratified into three groups. The low-risk group included patients with prior myeloid disorder without MK (n = 26). Among the rest, patients with TP53 mutation were assigned to the high-risk group (n = 19) and the rest into the intermediate-risk group (n = 75). Two-year OS in low-, intermediate-, and high-risk groups differed significantly (50.0%, 24.9%, and 0%, respectively). This suggests that the indication of allo-HSCT should be carefully judged for high-risk patients.

Novel Approach for Bone Marrow Transplantation Conditioning in Acute Myelogenous Leukemia not Responding to the Induction Therapy Using Etoposide Carried in Lipid Core Nanoparticles: A Pilot Clinical Study

Allogeneic hematopoietic cell transplantation (HCT) is the treatment of choice for acute myelogenous leukemia (AML) not responding to induction therapy. It is a therapeutic choice for the blast phase of chronic myelogenous leukemia (CML-BP) in patients failing to respond to tyrosine kinase inhibitors (TKIs). Lipid core nanoparticles (LDEs) concentrate severalfold more in blast cells than in corresponding normal cells. Incorporation of anticancer drugs to LDE formulations increases the pharmacologic action and decreases the toxicity. We tested a drug-targeting system, LDE-etoposide plus total body irradiation (TBI; 1200 cGy dose), in 13 patients with AML not responding to the induction therapy and in 2 patients with CML-BP refractory to second-generation TKIs. The mean patient age was 46.7 years (range, 22 to 66 years). The LDE-etoposide dose was escalated at 20, 30, 40, 50, and 60 mg/kg. No patients developed grade 4 or 5 toxicity; however, mucositis grade 3 occurred in 6 patients, 3 patients experienced diarrhea, and 1 patient had an elevated total bilirubin level. No deaths were related to conditioning. All patients were successfully engrafted. The median times to neutrophil and platelet engraftment were 20 ± 5 days and 16 ± 4 days, respectively. Five patients (33.4%) had acute graft-versus-host-disease (GVHD), including 4 grade I, and 1 with grade II, and 8 patients (57.1%) had moderate-to-severe chronic GVHD. This pilot study shows the potential of LDE-etoposide plus TBI as an HCT conditioning regimen in AML patients not responding to the induction and refractory therapies for CML-BP patient. These findings pave the way for subsequent larger clinical trials.

Sequential allogeneic hematopoietic stem cell transplantation for active refractory/relapsed myeloid malignancies: results of a reduced-intensity conditioning preceded by clofarabine and cytosine arabinoside, a retrospective study on behalf of the SFGM-TC

Allogeneic stem cell transplantation (allo-SCT) represents the most beneficial treatment for patients with active relapsed/refractory (R/R) hematologic malignancies. Recently, sequential regimens combining debulking chemotherapy followed by reduced-intensity conditioning (RIC) have shown encouraging results for these patients. In this retrospective study, we report the extended results of a sequential regimen of clofarabine, cytosine arabinoside, and RIC in 131 adults with active R/R myeloid disease at transplant. Conditioning consisted of clofarabine (30 mg/m²/day) and cytosine arabinoside (1 g/m²/day) for 5 days, followed, after a rest of 3 days, by an RIC combining cyclophosphamide (60 mg/kg) for 1 day, iv busulfan (3.2 mg/kg/day) for 2 days, and anti-thymocyte globulin (2.5 mg/kg/day) for 2 days. Between 2007 and 2016, 131 patients (males n = 75, median age: 52.6 years) were identified from the SFGM-TC registry. There were 111 acute myeloid leukemia (AML) patients and 20 cases with myelodysplastic or myeloproliferative syndrome. Status at transplant was known for all but 4 patients and was primary refractory (n = 81) and 1st or 2nd relapse (n = 46). All patients received allo-SCT from a matched donor (sibling n = 64, unrelated n = 67). Engraftment was observed in 105/122 (86%) evaluable cases and 63% of the patients achieved complete remission (CR) after transplant. The 1-year overall survival, disease-free survival, relapse incidence, non-relapse mortality, and graft-versus-host disease-free/relapse-free survival were 39.2%, 28.1%, 41.0%, 30.8%, and 22.2%, respectively. This study confirms that this sequential clofarabine-based regimen provides a high CR rate in this critical population, although relapse remains a matter of concern.

Haploidentical versus HLA-matched sibling transplantation for refractory acute leukemia undergoing sequential intensified conditioning followed by DLI: an analysis from two prospective data

BACKGROUND

Compared with HLA-matched sibling donor (MSD) transplant, the outcomes of haploidentical donor (HID) transplant for refractory acute leukemia need to be further explored. In this study, we compared the outcomes of HID with MSD for refractory acute leukemia.

PATIENTS AND METHODS

This study population came from two prospective multicenter trials (NCT01883180, NCT02673008). Two hundred and seventy-eight patients with refractory acute leukemia were enrolled in this study, including 119 in HID group and 132 in MSD group. Sequential intensified conditioning was employed in all patients, and donor lymphocyte infusion (DLI) was administered in patients in the absence of active GVHD and according to minimal residual disease (MRD) from day + 60 post-transplantation for preventing relapse.

RESULTS

The complete remission of leukemia by day + 30 post-transplant were 94% and 93%, respectively, in HID and MSD groups (p = .802). The 1-year incidence of grades II-IV acute GVHD was 62% and 54% (p = .025), and 3-year incidence of chronic GVHD was 55% and 55% (p = .789), respectively, in two groups. HID transplant had lower incidence of first episode of MRD positivity and relapse than MSD transplant (28% vs 45%, p = .006; 26% vs 38%, p = .034). There was higher infection-related mortality in HID than MSD (8% vs 2%, p = .049) within the first 100 days' post-transplant. The 5-year overall survival was 46% and 42% (p = .832), respectively; the 5-year disease-free survival was 43% and 39% (p = .665), in HID and MSD groups, respectively.

CONCLUSIONS

HID transplant has lower relapse, but higher infection-related mortality and similar survival rates in refractory acute leukemia by the strategy of sequential intensified conditioning followed by DLI compared with MSD transplant.

Is Hematopoietic Stem Cell Transplantation Required to Unleash the Full Potential of Immunotherapy in Acute Myeloid Leukemia?

From monoclonal antibodies (mAbs) to Chimeric Antigen Receptor (CAR) T cells, immunotherapies have enhanced the efficacy of treatments against B cell malignancies. The same has not been true for Acute Myeloid Leukemia (AML). Hematologic toxicity has limited the potential of modern immunotherapies for AML at preclinical and clinical levels. Gemtuzumab Ozogamicin has demonstrated hematologic toxicity, but the challenge of preserving normal hematopoiesis has become more apparent with the development of increasingly potent immunotherapies. To date, no single surface molecule has been identified that is able to differentiate AML from Hematopoietic Stem and Progenitor Cells (HSPC). Attempts have been made to spare hematopoiesis by targeting molecules expressed only on later myeloid progenitors as well as AML or using toxins that selectively kill AML over HSPC. Other strategies include targeting aberrantly expressed lymphoid molecules or only targeting monocyte-associated proteins in AML with monocytic differentiation. Recently, some groups have accepted that stem cell transplantation is required to access potent AML immunotherapy and envision it as a rescue to avoid severe hematologic toxicity. Whether it will ever be possible to differentiate AML from HSPC using surface molecules is unclear. Unless true specific AML surface targets are discovered, stem cell transplantation could be required to harness the true potential of immunotherapy in AML.

Unmanipulated haploidentical hematopoietic stem cell transplantation using very low-dose antithymocyte globulin and methylprednisolone in adults with relapsed/refractory acute leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) could be the only curative therapy for patients with relapsed/refractory acute leukemia (RRAL). Many reports have described unmanipulated haploidentical HSCT (HID-HSCT) using high-dose antithymocyte globulin (ATG). However, the transplant outcomes of HID-HSCT using very low-dose ATG (thymoglobulin, 2-2.5 mg/kg) and methylprednisolone (mPSL, 1 mg/kg) for patients with RRAL have not been reported. We compared the outcomes of 46 patients with RRAL who underwent HID-HSCT using very low-dose ATG (thymoglobulin) and mPSL with the outcomes of 72 patients who underwent non-HID-HSCT. Patient characteristics differed regarding conditioning intensity (myeloablative; 19.6% in HID-HSCT vs. 61.1% in non-HID-HSCT, P < 0.001) and having undergone multiple HSCT (26.1% vs. 11.1%, P = 0.045). However, we found no significant differences in the 1-year overall survival (OS, 31.7% vs. 29.1%; P = 0.25), disease-free survival (DFS, 20.5% vs. 23.7%; P = 0.23), cumulative incidence of relapse (CIR, 40.0% vs. 42.8%; P = 0.92), non-relapse mortality (NRM, 39.5% vs. 33.5%; P = 0.22), or 100-day grade II-IV acute graft-versus-host disease (32.6% vs. 34.7%; P = 0.64) following HID-HSCT vs. non-HID-HSCT, respectively. Subgroup analysis stratified by disease and intensity of conditioning regimen demonstrated the same results between HID-HSCT and non-HID-HSCT. Furthermore, multivariate analysis showed that HID-HSCT was not an independent prognostic factor for OS (hazard ratio (HR) = 0.95 [95% confidence interval (CI), 0.58-1.58]), DFS (HR = 1.05 [95%CI, 0.67-1.68]), CIR (HR = 0.84 [95%CI, 0.48-1.47]), or NRM (HR = 1.28 [95%CI, 0.66-2.46]). In summary, transplant outcomes for RRAL were comparable in the HID-HSCT and non-HID-HSCT groups. HID-HSCT using very low-dose ATG and mPSL for RRAL may be a viable alternative to non-HID-HSCT.

Association of Second Allogeneic Hematopoietic Cell Transplant vs Donor Lymphocyte Infusion With Overall Survival in Patients With Acute Myeloid Leukemia Relapse

Importance

The optimal treatment approach to patients with acute myeloid leukemia (AML) who relapse after an allogeneic hematopoietic cell transplant (allo-HCT) remains elusive. No randomized clinical trial comparing survival outcomes of a second allo-HCT (allo-HCT2) vs donor lymphocyte infusion (DLI) has been conducted to date.

Objective

To compare overall survival (OS) after an allo-HCT2 or DLI in relapsed AML after a first allo-HCT.

Design, Setting, and Participants

A retrospective registry study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation involving 418 adults who received an allo-HCT2 (n = 137) or DLI (n = 281) for postallograft-relapsed AML. Analysis was assessed on the principle of intent-to-first received intervention. The data were collected from November 21, 2015, to May 15, 2017, and analysis was performed June 1, 2017.

Main Outcomes and Measures

Number of patients with relapsed AML who are alive after 2 years and 5 years from receiving an allo-HCT2 or DLI.

Results

Of the 418 patients, 228 (54.5%) were men; mean age was 46.2 years (interquartile range, 36.5-56.9 years). There was no apparent difference in OS whether an allo-HCT2 or DLI was prescribed (2-year OS with allo-HCT2, 26%; 5-year OS with allo-HCT2, 19%; 2-year OS with DLI, 25%; 5-year OS with DLI, 15%; P = .86). Overall survival was better if either of these procedures was offered when the patient was in complete remission (hazard ratio, 0.55; 95% CI, 0.41-0.74; P < .001). Conversely, OS was low for patients relapsing within less than 6 months after an allo-HCT1, regardless of the treatment prescribed (5-year OS: allo-HCT2, 9%; 95% CI, 1%-17% vs DLI, 4%; 95% CI, 1%-8%; P = .86).

Conclusion and Relevance

Heterogeneity of the patient-, disease-, and treatment-related characteristics limit the ability to recommend one approach over another. Findings of this study highlight that best outcomes seem to be achieved in patients relapsing 6 or more months from an allo-HCT1 or those in complete remission at the time of either allo-HCT2 or DLI.

Conditioning Intensity for Allogeneic Hematopoietic Cell Transplantation in Acute Myeloid Leukemia Patients with Poor-Prognosis Cytogenetics in First Complete Remission

The optimal intensity of conditioning regimen may be dependent on not only age and comorbidities but also disease characteristics and risk of relapse after allogeneic hematopoietic cell transplantation (HCT). We, therefore, analyzed the transplant outcomes of 840 adult patients with cytogenetically poor-risk acute myeloid leukemia (AML) in first complete remission (CR1) who received first allogeneic HCT with either myeloablative conditioning (MAC; n = 652) or reduced-intensity conditioning (RIC; n = 188) between 2006 and 2017. The median age at HCT was 50.5 years (range: 16 to 77 years). The multivariate analysis showed that patients receiving MAC had a significantly higher overall survival and lower leukemia-related mortality than those receiving RIC (P = .011 and P = .025, respectively). In the subgroup analysis, these results applied to patients aged 16 to 59 years, with HCT-comorbidity index scores ≥3, and with cytogenetic remission. Among MAC regimens, there was a trend for worse survival and nonrelapse mortality with the busulfan/fludarabine-based regimen compared with the total body irradiation (TBI) ≥8 Gy-based regimen (P = .082 and P = .062, respectively), whereas the busulfan/cyclophosphamide-based regimen and the fludarabine/melphalan-based regimen had similar outcomes with the TBI-based regimen. These data suggest that MAC is preferable to RIC for patients with cytogenetically poor-risk AML undergoing allogeneic HCT in CR1.

Umbilical cord blood versus unrelated donor transplantation in adults with primary refractory or relapsed acute myeloid leukemia: a report from Eurocord, the Acute Leukemia Working Party and the Cord Blood Committee of the Cellular Therapy and Immunobiology Working Party of the EBMT

The role of umbilical cord blood transplantation (CBT) in acute myeloid leukemia (AML) patients with active disease at allogeneic hematopoietic cell transplantation (allo-HCT) remains poorly investigated. In this study, we compared transplantation outcomes of 2963 patients with primary refractory or relapsed AML given CBT, 10/10 HLA-matched UD, or 9/10 HLA-matched UD allo-HCT from 2004 to 2015 at EBMT-affiliated centers. Neutrophil engraftment and complete remission rates in CBT, UD 10/10, and UD 9/10 recipients were 75 and 48%, 93 and 69%, and 93 and 70%, respectively. In multivariate Cox analyses, in comparison with CBT (n = 285), UD 10/10 recipients (n = 2001) had a lower incidence of relapse (HR = 0.7, P = 0.001), a lower incidence of non relapse mortality (HR = 0.6, P < 0.001), better GVHD-free and leukemia-free survival (GRFS, HR = 0.8, P < 0.001) and better survival (HR = 0.6, P < 0.001). Further, in comparison with CBT, 9/10 UD recipients (n = 677) also had a lower incidence of relapse (HR = 0.8, P = 0.02), a lower incidence of nonrelapse mortality (HR = 0.7, P = 0.008), better GRFS (HR = 0.8, P = 0.01) and better survival (HR = 0.7, P < 0.001). In summary, these data suggest that in AML patients with active disease at transplantation, allo-HCT with UD results in better transplantation outcomes than CBT.

Targeting the niche: depleting haemopoietic stem cells with targeted therapy

Haemopoietic stem cell transplantation is an expanding procedure worldwide but is associated with significant morbidity and mortality. Depletion of resident haemopoietic stem and progenitor cells (HSPC) is required for both autologous and allogeneic haemopoietic stem cell transplantation. Current conditioning protocols utilise chemotherapy or radiation to effectively reduce HSPC but are toxic in both the short and long term. The initial trials to use monoclonal antibodies to target HSPC were limited with marginal efficacy but platforms including antibody drug conjugates and chimeric antigen receptor T cells have made targeted conditioning strategies achievable. In this review we summarise the work developing targeted conditioning that may replace or reduce alkylating agents and total body irradiation. The prospect of conditioning with significantly reduced toxicity will improve outcomes and open transplantation to patients unable to tolerate current conditioning protocols.

Haploidentical versus unrelated allogeneic stem cell transplantation for relapsed/refractory acute myeloid leukemia: a report on 1578 patients from the Acute Leukemia Working Party of the EBMT

Primary refractory or relapsed acute myeloid leukemia is associated with a dismal prognosis. Allogeneic stem cell transplantation is the only therapeutic option that offers prolonged survival and cure in this setting. In the absence of a matched sibling donor, transplantation from unrelated 10/10 HLA allele-matched or 9/10 HLA allele-mismatched donors and haploidentical donors are potential alternatives. The current study aimed to compare the outcomes of acute myeloid leukemia patients with active disease who received allogeneic stem cell transplantation from a haploidentical donor with post-transplant cyclophosphamide (n=199) versus an unrelated 10/10-matched donor (n=1111) and versus an unrelated 9/10-mismatched donor (n=383) between 2007 and 2014 and who were reported to the European Society for Blood and Marrow Transplantation registry. Propensity score weighted analysis was conducted in order to control for disease risk imbalances between the groups. The leukemia-free survival rates at 2 years of recipients of grafts from a haploidentical donor, an unrelated 10/10-matched donor and an unrelated 9/10-mismatched donor were 22.8%, 28% and 22.2%, respectively (P=NS). In multivariate analysis, there were no significant differences in leukemia-free survival, overall survival, relapse incidence, non-relapse mortality, or graft-versus-host-disease-free relapse-free survival between the three groups. Two predictive factors were associated with a higher relapse incidence: transplantation during first or second relapse compared to primary refractory acute myeloid leukemia and poor cytogenetics. Allogeneic stem cell transplantation may rescue about 25% of acute myeloid leukemia patients with active disease. Importantly, the outcomes of transplants from haploidentical donors were comparable to those from 10/10-matched and 9/10-mismatched unrelated donors. Therefore, a haploidentical donor is a valid option for acute myeloid leukemia patients with active disease.

Hematopoietic Cell Transplantation for Acute Panmyelosis with Myelofibrosis: A Retrospective Study in Japan

Acute panmyelosis with myelofibrosis (APMF) is a rare subtype of acute myeloid leukemia characterized by acute onset of cytopenias and bone marrow fibrosis in the absence of splenomegaly. Because the prognosis of APMF is extremely poor even after chemotherapy, hematopoietic cell transplantation (HCT) has been used to treat APMF. However, the outcome after HCT for APMF remains unclear. To evaluate the outcomes and prognostic factors after HCT as a therapeutic modality for APMF, we retrospectively analyzed the Japanese registration data of 40 APMF patients who received allogeneic and syngeneic HCT between 2005 and 2015. The median age at HCT was 53.5 years (range, 16 to 70). The disease status at HCT was first complete remission (CR1) in 13 patients (33%). The probability of overall survival and the cumulative incidence of relapse at 3 years were 24% and 59%, respectively. Univariate analysis identified that female sex and disease status CR1 at the time of HCT were significantly associated with higher overall survival. Although APMF patients have a poor long-term prognosis even after syngeneic and allogeneic HCT, these data suggested that allogeneic HCT offered a curative option for APMF.

Efficacy of haploidentical hematopoietic stem cell transplantation compared to HLA-matched transplantation for primary refractory acute myeloid leukemia

Newly diagnosed acute myeloid leukemia (AML) failed to achieve complete remission after two courses of intensive chemotherapy. This was considered as primary refractory AML (PRR-AML), and still has a dismal prognosis. Allogeneic hematopoietic stem cell transplantation could be the only cure for these patients. However, the role of haploidentical hematopoietic stem cell transplantation (HID-HCT) for PRR-AML is still undetermined. We retrospectively analyzed the outcomes of 45 adult patients with PRR-AML who underwent HID-HCT, and compared it with the result of 53 patients who received HLA-matched related or unrelated donor transplantation (MD-HCT) during the same treatment period. The 3-year overall survival (OS), leukemia-free survival (LFS), cumulative incidence of relapse (CIR), and non-relapse mortality (NRM) rates in the HID-HCT group were 19.0, 16.5, 70.0, and 35.2%, respectively, but showed no significant differences from the results of MD-HCT. Multivariate analysis showed that complex karyotype with del(7) and time > 6 months from diagnosis to transplantation were associated with lower OS and LFS, and chronic GVHD demonstrated better OS and LFS in the entire cohort. Complex karyotype with del(7) was related with higher CIR and chronic GVHD with lower CIR. In conclusion, HID-HCT could be an alternative treatment strategy to improve the long-term survival in PRR-AML adult patients who have no HLA-matched donors.

Vaccine therapy in hematologic malignancies

Immune-based therapy has emerged as a paradigm shift in cancer therapy with dramatic responses observed in previously incurable disease. Cancer vaccines are being developed to disrupt tumor-associated tolerance and activate and selectively expand tumor-specific lymphocytes within the native effector cell repertoire while maintaining immune-regulatory protection against autoimmunity. Although individual antigen approaches result in immune response with a suggestion of clinical effect in some settings, broader efficacy may be dependent on presentation of multiple antigens that capture clonal diversity presented in the context of functionally potent antigen-presenting cells. The use of whole cell–based strategies such as dendritic cell/tumor fusions have yielded provocative results in single-arm studies and are currently being explored in multicenter randomized trials. The posttransplant setting is a potentially promising platform for vaccination due to cytoreduction and relative depletion of inhibitory accessory cells fostering greater immune responsiveness. Integration of these efforts with other immunotherapeutic strategies and agents that target the tumor microenvironment is being studied in an effort to generate durable immunologic responses with clinically meaningful impact on disease.

Midostaurin: A New Oral Agent Targeting FMS-Like Tyrosine Kinase 3-Mutant Acute Myeloid Leukemia

Acute myeloid leukemia (AML), a clonal hematologic malignancy that results in bone marrow failure, is the most common acute leukemia in adults (median age of diagnosis 67 yrs), and treatment options, especially in the elderly population, are limited. Induction chemotherapy with 7 + 3, the combination of continuous-infusion cytarabine and intermittent dosing of an anthracycline administered over 7 and 3 days, respectively, has remained the standard of care since its introduction in 1973 in the United States. Midostaurin is a first-generation FMS-like tyrosine kinase 3 (FLT3) inhibitor (TKI) that was approved by the U.S. Food and Drug Administration in April 2017 for the treatment of FLT3-mutant AML. We performed a search of the PubMed database (January 1990-January 2017) to review pertinent clinical trials of midostaurin. Phase I, II, and III trials reported in English evaluating the safety and efficacy of midostaurin in patients with AML or myelodysplastic syndrome were included. The ClinicalTrials.gov database was also searched for ongoing trials. In the only phase III trial that has been conducted to date, midostaurin demonstrated significant improvement compared with placebo in overall and event-free survival in patients aged 18-59 years with newly diagnosed FLT3-mutant AML treated with standard induction chemotherapy. The median overall survival for patients randomized to the midostaurin group was 74.7 months versus 25.6 months in the placebo group (hazard ratio [HR] 0.78, 95% confidence interval [CI] 0.63-0.96, p=0.009). Median event-free survival was 8.2 months with midostaurin compared with 3.0 months with placebo (HR 0.78, 95% CI 0.66-0.93, p=0.002). In addition to being evaluated in combination with conventional chemotherapy, midostaurin has been studied as monotherapy, in combination with the hypomethylating agents azacitidine and decitabine, and as single-agent maintenance. Studies evaluating midostaurin in the maintenance setting after allogeneic stem cell transplantation are underway. Midostaurin is the first oral multitargeted TKI to improve overall survival in patients with FLT3-mutant AML and represents an important addition to the limited armamentarium against AML.

Comparison of matched sibling donors versus unrelated donors in allogeneic stem cell transplantation for primary refractory acute myeloid leukemia: a study on behalf of the Acute Leukemia Working Party of the EBMT

BACKGROUND

Primary refractory acute myeloid leukemia (PRF-AML) is associated with a dismal prognosis. Allogeneic stem cell transplantation (HSCT) in active disease is an alternative therapeutic strategy. The increased availability of unrelated donors together with the significant reduction in transplant-related mortality in recent years have opened the possibility for transplantation to a larger number of patients with PRF-AML. Moreover, transplant from unrelated donors may be associated with stronger graft-mediated anti-leukemic effect in comparison to transplantations from HLA-matched sibling donor, which may be of importance in the setting of PRF-AML.

METHODS

The current study aimed to address the issue of HSCT for PRF-AML and to compare the outcomes of HSCT from matched sibling donors (n = 660) versus unrelated donors (n = 381), for patients with PRF-AML between 2000 and 2013. The Kaplan-Meier estimator, the cumulative incidence function, and Cox proportional hazards regression models were used where appropriate.

RESULTS

HSCT provide patients with PRF-AML a 2-year leukemia-free survival and overall survival of about 25 and 30%, respectively. In multivariate analysis, two predictive factors, cytogenetics and time from diagnosis to transplant, were associated with lower leukemia-free survival, whereas Karnofsky performance status at transplant ≥90% was associated with better leukemia-free survival (LFS). Concerning relapse incidence, cytogenetics and time from diagnosis to transplant were associated with increased relapse. Reduced intensity conditioning regimen was the only factor associated with lower non-relapse mortality.

CONCLUSIONS

HSCT was able to rescue about one quarter of the patients with PRF-AML. The donor type did not have any impact on PRF patients' outcomes. In contrast, time to transplant was a major prognostic factor for LFS. For patients with PRF-AML who do not have a matched sibling donor, HSCT from an unrelated donor is a suitable option, and therefore, initiation of an early search for allocating a suitable donor is indicated.

Older Patients With Acute Myeloid Leukemia: Treatment Challenges and Future Directions

BACKGROUND

Even though acute myeloid leukemia (AML) occurs most commonly in adults ≥60 years, the treatment of AML in older patients remains a significant challenge.

METHODS

We reviewed the current literature regarding patient assessment tools, treatment options, and current therapies in clinical trial for patients with AML who are ≥60 years.

RESULTS

Our approach to the older patient with AML is evolving with better understanding of the unique disease epidemiology in this population and the development of tools to assess individual patient functional status, including grading systems for comorbidities, geriatric assessment tools, and measurements of frailty. Almost all older patients will benefit from therapy, whether intensive curative therapy, such as allogeneic stem cell transplant that should be considered whenever possible, or low-intensity therapy that should be offered with concurrent palliative care at diagnosis to improve patient survival and quality of life. To achieve the improved survival demonstrated in younger adults, older patients should also be considered for clinical trial enrollment as more studies are being designed to specifically target this unique patient population.

CONCLUSION

Older patients with AML are candidates for and benefit from the entire spectrum of AML therapy, including intense chemotherapy, allogeneic stem cell transplant, and clinical trial participation after thorough patient assessment. Older patients with AML would benefit from increased clinical trial enrollment and early inclusion of palliative medicine.