Second haematopoietic SCT using HLA-haploidentical donors in patients with relapse of acute leukaemia after a first allogeneic transplantation

Continuously improving outcome over time after second allogeneic stem cell transplantation in relapsed acute myeloid leukemia: an EBMT registry analysis of 1540 patients

Second allogeneic stem cell transplantation (alloSCT2) is among the most effective treatments for acute myeloid leukemia (AML) relapse after first alloSCT (alloSCT1). Long-term EBMT registry data were used to provide large scale, up-to-date outcome results and to identify factors for improved outcome. Among 1540 recipients of alloSCT2, increasing age, better disease control and performance status before alloSCT2, more use of alternative donors and higher conditioning intensity represented important trends over time. Between the first (2000-2004) and last (2015-2019) period, two-year overall and leukemia-free survival (OS/LFS) increased considerably (OS: 22.5-35%, LFS: 14.5-24.5%). Cumulative relapse incidence (RI) decreased from 64% to 50.7%, whereas graft-versus-host disease and non-relapse mortality (NRM) remained unchanged. In multivariable analysis, later period of alloSCT2 was associated with improved OS/LFS (HR = 0.47/0.53) and reduced RI (HR = 0.44). Beyond, remission duration, disease stage and patient performance score were factors for OS, LFS, RI, and NRM. Myeloablative conditioning for alloSCT2 decreased RI without increasing NRM, leading to improved OS/LFS. Haploidentical or unrelated donors and older age were associated with higher NRM and inferior OS. In summary, outcome after alloSCT2 has continuously improved over the last two decades despite increasing patient age. The identified factors provide clues for the optimized implementation of alloSCT2.

Relapse of acute myeloid leukemia after allogeneic stem cell transplantation: immune escape mechanisms and current implications for therapy

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the expansion of immature myeloid cells in the bone marrow (BM) and peripheral blood (PB) resulting in failure of normal hematopoiesis and life-threating cytopenia. Allogeneic hematopoietic stem cell transplantation (allo-HCT) is an established therapy with curative potential. Nevertheless, post-transplant relapse is common and associated with poor prognosis, representing the major cause of death after allo-HCT. The occurrence of relapse after initially successful allo-HCT indicates that the donor immune system is first able to control the leukemia, which at a later stage develops evasion strategies to escape from immune surveillance. In this review we first provide a comprehensive overview of current knowledge regarding immune escape in AML after allo-HCT, including dysregulated HLA, alterations in immune checkpoints and changes leading to an immunosuppressive tumor microenvironment. In the second part, we draw the line from bench to bedside and elucidate to what extend immune escape mechanisms of relapsed AML are yet exploited in treatment strategies. Finally, we give an outlook how new emerging technologies could help to improve the therapy for these patients, and elucidate potential new treatment options.

Second haploidentical stem cell transplantation (HAPLO-SCT2) after relapse from a first HAPLO-SCT in acute leukaemia-a study on behalf of the Acute Leukaemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

For patients with acute myeloid and lymphoblastic leukaemia (AML/ALL) lacking a matched sibling or unrelated donor, haploidentical stem cell transplantation (HAPLO-SCT) is increasingly used. However, available data on the treatment of relapse after HAPLO-SCT, including feasibility and efficacy of a second HAPLO-SCT (HAPLO-SCT2), is scarce. Hence, adults with AML/ALL, that had undergone HAPLO-SCT2 without ex-vivo manipulation after haematologic relapse from HAPLO-SCT1 were selected for a retrospective registry analysis. Eighty-two patients (AML, n = 63, ALL, n = 19, median follow-up: 33 months) were identified. Engraftment rate was 87%. At day +180, cumulative incidences of acute GvHD II-IV°/chronic GvHD were 23.9%/22.6%, respectively. Two-year overall survival/leukaemia-free survival (OS/LFS) were 34.3%/25.4%; 2-year non-relapse mortality (NRM) and relapse incidence (RI) were 17.6% and 57%. Leukaemia was the most frequent cause of death. Separated by disease, 2-year OS/LFS/NRM/RI were 28.7%/22.3%/16.2%/61.6% in AML, and 55.3%/38.4%/23.5%/38.2% in ALL patients. In a risk-factor analysis among patients with AML, stage at HAPLO-SCT1 and HAPLO-SCT2, and interval from HAPLO-SCT1 to relapse significantly influenced outcome. Our data demonstrate that HAPLO-SCT2 is a viable option in acute leukaemia relapse after HAPLO-SCT1. Engraftment, toxicity, risk factors and long-term outcome are comparable to data reported after allo-SCT2 in a matched donor setting.

Case Series Using Salvage Haplo-Identical Stem Cells for Secondary Transplantation

In order to expand the donor pool and accessibility of the transplant procedure, it was necessary to introduce haplo-identical stem cell transplants in the Fundeni Clinical Institute from 2015. Even if the Romanian population is an ethnically compact white population, many of the patients referred for bone marrow transplant lack a suitable donor. Hematopoietic stem cell transplant from a haplo-identical donor is an alternative option for those patients without an HLA (Human Leucocyte Antigen)-matched donor (sibling or matched unrelated). This procedure was used also as a salvage option for those who experienced engraftment failure or the rejection of the first stem cell graft. In this case series, we present three such cases, with a haplo-transplant used as a salvage protocol (after an engraftment failure or rejection of the first transplanted cells). The patients we present were diagnosed with AML (acute myeloid leukemia) with MDS (myelodysplastic syndrome), MDS-RAEB 2 (myelodysplastic syndrome-refractory anemia with excess blasts 2), and SAA (severe aplastic anemia). In two of the three cases, the engraftment failure may have been due to the conditioning Fludarabine/Busulfan/Cyclophosphamide (Flu/Bu/CFA) used, combined with marrow grafts. In all three cases, the second transplant was of haplo-identical peripheral blood stem cells using Melphalan/Fludarabine (Mel/Flu) conditioning, the cells engrafted properly and the patients experienced complete chimerism, and two of them are alive with an excellent quality of life.

Haploidentical versus Double-Cord Blood Stem Cells as a Second Transplantation for Relapsed Acute Myeloid Leukemia

There are limited data on second stem cell transplantation (SCT2) outcomes with alternative donors for relapsed AML after the first stem cell transplantation (SCT1). We analyzed the outcomes of 52 adult AML patients who received SCT2 from haploidentical donors (HIT, N = 32) and double-cord blood (dCBT, N = 20) between 2008 and 2021. The HIT group received T-cell-replete peripheral blood stem cells after reduced-toxicity conditioning with anti-thymocyte globulin (ATG), while the dCBT group received myeloablative conditioning. For a median follow-up of 64.9 months, the HIT group, compared to the dCBT group, had earlier engraftment, superior 2-year overall survival (OS), disease-free survival (DFS), and non-relapse mortality (NRM) with similar relapse. Multivariate analysis demonstrated that HIT was significantly associated with better OS, DFS, and lower NRM than dCBT. Both longer remission duration after SCT1 and complete remission at SCT2 were significantly associated with a lower relapse rate. In addition, bone marrow WT1 measurable residual disease (MRD) positivity was significantly associated with inferior OS and higher relapse. This study suggests that T-cell-replete HIT with ATG-based GVHD prophylaxis may be preferred over dCBT as SCT2 for relapsed AML and that WT1-MRD negativity may be warranted for better SCT2 outcomes.

Relapse after allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia: an overview of prevention and treatment

Despite therapeutic progress in acute myeloid leukemia (AML), relapse post-allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains a major challenge. Here, we aim to provide an overview of prevention and treatment of relapse in this population, including cell-based and pharmacologic options. Post-transplant maintenance therapy is used in patients who have undetectable measurable residual disease (MRD), while pre-emptive treatment is administered upon detection of MRD. Prompt transfusion of prophylactic donor lymphocyte infusion (DLI) was found to be effective in preventing relapse and overcoming the negative impact of detectable MRD. In addition, patients with persistent targetable mutations can benefit from targeted post-transplant pharmacological interventions. IDH inhibitors have shown promising results in relapsed/refractory AML. Hypomethylating agents, such as decitabine and azacitidine, have been studied in the post-allo-HSCT setting, both as pre-emptive and prophylactic. Venetoclax has been shown effective in combination with hypomethylating agents or low-dose cytarabine in patients with newly diagnosed AML, especially those unfit for intensive chemotherapy. FLT3 inhibitors, the topic of another section in this review series, have significantly improved survival in FLT-3-ITD mutant AML. The role of other cell-based therapies, including CAR-T cells, in AML is currently being investigated.

Outcomes of Second Allogeneic Hematopoietic Cell Transplantation for Patients With Acute Myeloid Leukemia

Relapse after allogeneic hematopoietic cell transplantation (HCT) leads to poor survival in patients with acute myeloid leukemia (AML). A second HCT (HCT2) may achieve durable remission. To determine the outcomes of patients who received an HCT2 for relapsed AML and to evaluate the predictors of overall survival (OS) and progression-free survival (PFS). We retrospectively reviewed medical records of adult patients who underwent an HCT2 for relapsed AML at our institution during 2000 to 2019. Ninety-one patients were identified with a median age of 44 years (range 18-73) at HCT2. Donor types were HLA-identical sibling (n = 37 [41%]), HLA-matched-unrelated (n = 34 [37%]), haploidentical (n = 19 [21%]), and cord blood (n=1 [1%]). Donors were different at HCT2 in 53% of patients. The majority of patients received reduced intensity conditioning (n = 71 [78%]) and were in remission (n = 56 [61%]) at HCT2. The median remission duration after HCT1 was 8.4 months (range 1-70) and the median time between transplants was 14 months (range 3-73). The median follow-up of surviving patients after HCT2 was 66 months (range 2-171), with 32% alive at time of analysis. The most common cause of death was disease recurrence (n = 45 [73%]). At 2 years, the rates of OS, PFS, progression, and nonrelapse mortality were 36%, 27%, 42%, and 18%, respectively. The development of chronic graft-versus-host disease (GVHD) after first HCT and HCT comorbidity index (HCT-CI) ≥2 at HCT2 were associated with inferior PFS and OS after HCT2. A second HCT is feasible in selected patients with AML who have relapsed after HCT1. Long-term survival benefit is possible in patients without chronic GVHD after HCT1 and HCT-CI <2 at HCT2.

Second allogeneic haematopoietic cell transplantation using HLA-matched unrelated versus T-cell replete haploidentical donor and survival in relapsed acute myeloid leukaemia

Optimal donor choice for a second allogeneic haematopoietic cell transplant (allo-HCT) in relapsed acute myeloid leukaemia (AML) remains unknown. We compared overall survival (OS) using registry data from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT) involving 455 adults who received a second allo-HCT from a human leucocyte antigen (HLA)-matched unrelated (MUD) (n = 320) or a haploidentical (n = 135) donor. Eligibility criteria required adults aged ≥18 years who received a second allo-HCT for treating AML relapse between 2005 and 2019. The primary end-point was OS. There was no statistically significant difference in the median (interquartile range) age between the groups, MUD 46 (35-58) versus haploidentical 44 (33-53) years (P = 0·07). The median OS was not different between the MUD and the haploidentical groups (10 vs. 11 months, P = 0·57). Similarly, the 2-year OS was 31% for the MUD and 29% for the haploidentical donor groups. The OS was worse if the procedure was performed with active AML [hazard ratio (HR) 1·42, 95% confidence interval (CI) 1·07-1·89; P = 0·02]. Conversely, a longer time from first allo-HCT to relapse (>13·2 months) was associated with better OS (HR 0·50, 95% CI 0·37-0·69; P < 0·0001). The results of the present analysis limit the ability to recommend one donor type over another when considering a second allo-HCT for relapsed AML. Our findings highlight that best OS is achieved when receiving the second allo-HCT in complete remission.

Haploidentical transplants for patients with relapse after the first allograft

Relapse after allogeneic hematopoietic stem-cell transplantation (AHSCT) is associated with very poor outcomes. A second transplant offers the possibility of long-term disease control. We analyzed outcomes with haploidentical donors for second allograft at our institution. All consecutive patients with hematological malignancies (N = 29) who relapsed after AHSCT and underwent a haploidentical transplant (haploSCT) as second transplant between February 2009 and October 2018 were included. Median age was 36 years (interquartile range (IQR) 24-60); 83% of patients had high/very high disease risk index; 61% of AML/MDS patients had high-risk cytogenetics; and only 24% were in complete remission at transplant. With a median follow-up of 46.9 months, the 3-year relapse, non-relapse mortality (NRM), progression-free survival (PFS) and overall survival (OS) were 30%, 39%, 31% and 40%, respectively. In multivariable analysis (MVA), comorbidity index (HCT-CI) and detectable donor-specific anti-HLA antibodies (DSA) prior to second transplant were significantly associated with worse outcomes. Patients with HCT-CI <3 and without DSA had 3-year PFS and OS of 53% and 60.3%, respectively. Our findings suggest that haploSCT as second AHSCT is feasible and potentially curative. Lower HCT-CI and no DSA were associated with lower NRM and improved survival. Haploidentical grafts might be a preferred donor source for second AHSCT as these are high-risk patients who frequently need to proceed urgently to transplant.

Reduced dose of posttransplant cyclophosphamide in HLA-haploidentical peripheral blood stem cell transplantation

Posttransplant cyclophosphamide (PTCy:100 mg/kg) has been increasingly used in allogeneic hematopoietic stem cell transplantation, however, few studies compared different doses of PTCy. We conducted two consecutive prospective multicenter phase II studies to evaluate the safety and efficacy of 80 mg/kg of PTCy in 137 patients who underwent HLA-haploidentical peripheral blood stem cell transplantation (haploPBSCT) following reduced-intensity conditioning (RIC). GVHD prophylaxis consisted of PTCy at a dose of 40 mg/kg/day on days 3 and 4, tacrolimus, and mycophenolate mofetil. Neutrophil engraftment was achieved in 97% and 96% in the first and second studies, respectively. The incidences of grades II-IV acute GVHD, III-IV acute GVHD, all grade chronic GVHD, and moderate to severe chronic GVHD at 2 years were 26%, 5%, 35%, and 18% in the first study, and 23%, 1%, 28%, and 15% in the second study, respectively. Overall survival (OS), disease-free survival (DFS), and non-relapse mortality (NRM) at 2 years were 51%, 42%, and 18% in the first study, and 58%, 48%, and 16% in the second study, respectively. The rates of off-immunosuppressants in patients who survived without relapse at 2 years were 83 and 76%. Our results suggest that 80 mg/kg of PTCy is a valid option in haploPBSCT following RIC.

Geriatric nutritional risk index as a useful prognostic factor in second allogeneic hematopoietic stem cell transplantation

Second allogeneic hematopoietic stem cell transplantation (allo-HSCT) has a low survival outcome and a high non-relapse mortality (NRM) rate which is a major obstacle to this treatment. We hypothesized that the status of malnourishment after first allo-HSCT as represented by the geriatric nutritional risk index (GNRI) could be used as a prognostic factor to determine the outcomes of second allo-HSCT. A total of 108 patients with a median age of 42 (range, 17-69) years, who received second allo-HSCT for disease recurrence after first allo-HSCT from our institution, were included in this study. Low GNRI had a significant impact on NRM at 2 years after second allo-HSCT: 56.9% in patients with GNRI ≤ 92 compared with 27.5% in patients with GNRI > 92 (P = 0.002). In multivariate analysis, GNRI of ≤ 92 was the only significant factor for NRM (hazard ratio [HR] 2.29, 95% confidence interval [CI] 1.15-4.56, P = 0.018). High-risk disease status at second allo-HSCT (HR 2.74, 95% CI 1.46-5.14, P = 0.002) and GNRI of ≤ 92 (HR 1.70, 95% CI 1.02-2.82, P = 0.042) were identified as significant factors for overall survival (OS). A score of 1 was assigned to each factor, and the OS rate at 2 years after second allo-HSCT decreased according to the score: 53.0% in patients with score 0, 32.3% with score 1, and 2.5% with score 2 (P < 0.001). In conclusion, GNRI could be a useful predictor for the outcomes of second allo-HSCT. A prospective study in other cohorts is warranted to validate the findings of our study.

Donor selection for a second allogeneic stem cell transplantation in AML patients relapsing after a first transplant: a study of the Acute Leukemia Working Party of EBMT

Second allogeneic stem-cell transplantation (SCT2) is a therapeutic option for patients with AML relapsing after a first transplant. Prior studies have shown similar results after SCT2 from the same or different donor; however, there are limited data on second non-T-depleted haplo-identical transplant in this setting. We retrospectively analyzed SCT2 outcomes in 556 patients, median age 46 years, relapsing after first transplant given in CR1. Patients were divided into three groups based on SCT2 donor (donor2): same donor (n = 163, sib/sib-112, UD/UD-51), different matched donor (n = 305, sib/different sib-44, sib/UD-93, UD/different UD-168), or haplo-donor (n = 88, sib/haplo-45, UD/haplo-43). Two-year leukemia-free survival (LFS) rate after SCT2 was 23.5%, 23.7%, and 21.8%, respectively (P = 0.30). Multivariate analysis showed no effect of donor2 type on relapse: hazard ratio (HR) 0.89 (P = 0.57) and 1.11 (P = 0.68) for different donor and haplo-donor compared to same donor, respectively. However, donor2 did predict for non-relapse mortality (NRM) after SCT2: HR 1.21 (P = 0.50) and 2.08 (P = 0.03), respectively, and for LFS: HR 1.00 (P = 0.97) and 1.43 (P = 0.07), respectively. In conclusion, SCT2 with the same or different matched donor is associated with similar outcomes in patients with relapsed AML. Non-T-depleted haplo-identical transplant may be associated with higher NRM, similar relapse rate and with no better results in this setting.

Second allogeneic hematopoietic cell transplantation for relapse after first allografts

We analyzed outcomes of 126 patients with hematologic malignancies, who relapsed after first allogeneic hematopoietic cell transplantation (HCT) and received subsequent allografts. In 17 cases, the original donors were utilized, while in 109 cases different donors were identified. The 2-year overall survival (OS), relapse, and non-relapse mortality (NRM) rates were 33%, 42%, and 33%, respectively. Patients with early relapse after first allogeneic HCT (within 100 days vs. 100 days to 12 months vs. >12 months) had higher relapse rates (50% vs. 47% vs. 34%, respectively; p = .01) and worse OS (15% vs. 25% vs. 45%, respectively, p = .005) at 2 years after second allogeneic HCT. In conclusion, second allogeneic HCT should be considered in patients who relapse after first allografts, especially in those who relapse after more than a year. Utilizing a different donor for the second allotransplant including umbilical cord blood or HLA-haploidentical, related donors did not adversely impact outcomes.

Rescue haploidentical peripheral blood stem cell transplantation for engraftment failure: a single-centre case series

Graft failure affects approximately 5% of allogeneic stem cell transplants, with a poor prognosis. Salvage second allogeneic stem cell transplantation (alloSCT2) is limited by high rates of transplant-related mortality from infection and graft-versus-host disease. We report on five adult patients receiving rescue alloSCT2 using haploidentical peripheral blood stem cells. All patients achieved neutrophil engraftment, two subsequently died from sepsis and disease relapse, respectively. Three patients remain alive up to 2 years post-transplant. We suggest consideration of haploidentical alloSCT2 for patients with graft failure.

Relapse of Acute Myeloid Leukemia after Allogeneic Stem Cell Transplantation: Prevention, Detection, and Treatment

Acute myeloid leukemia (AML) is a phenotypically and prognostically heterogeneous hematopoietic stem cell disease that may be cured in eligible patients with intensive chemotherapy and/or allogeneic stem cell transplantation (allo-SCT). Tremendous advances in sequencing technologies have revealed a large amount of molecular information which has markedly improved our understanding of the underlying pathophysiology and enables a better classification and risk estimation. Furthermore, with the approval of the FMS-like tyrosine kinase 3 (FLT3) inhibitor Midostaurin a first targeted therapy has been introduced into the first-line therapy of younger patients with FLT3-mutated AML and several other small molecules targeting molecular alterations such as isocitrate dehydrogenase (IDH) mutations or the anti-apoptotic b-cell lymphoma 2 (BCL-2) protein are currently under investigation. Despite these advances, many patients will have to undergo allo-SCT during the course of disease and depending on disease and risk status up to half of them will finally relapse after transplant. Here we review the current knowledge about the molecular landscape of AML and how this can be employed to prevent, detect and treat relapse of AML after allo-SCT.

Sequential HLA-haploidentical transplantation utilizing post-transplantation cyclophosphamide for GvHD prophylaxis in high-risk and relapsed/refractory AML/MDS

This study evaluates the role of sequential therapy in HLA-haploidentical transplantation (haplo-HSCT) of high-risk, relapsed/refractory AML/MDS. We analyzed the course of 33 adults with active disease at time of transplantation (AML n = 30; MDS n = 3; median age 58 years, range: 32-71). Sequential therapy consisted of cytoreductive chemotherapy (FLAMSA n = 21; clofarabine n = 12) applied shortly prior to reduced intensity conditioning for T-cell-replete haplo-HSCT using post-transplantation cyclophosphamide as GvHD prophylaxis. No graft rejection was observed. Complete remission at day +30 was achieved in 97% of patients. CI of acute GvHD grade II-IV and chronic GvHD was 24% (no grade IV) and 23%, respectively. NRM at 1 and 3 years was 15%, each. Severe regimen-related toxicities (grade III-IV) were observed in 58%, predominantly involving the gastrointestinal tract (diarrhea 48%, mucositis 15%, transient elevation of transaminases 18%). Probability of relapse at 1 and 3 years was 28% and 35%. At a median follow-up of 36 months, the estimated 1- and 3-year overall survival was 56% and 48%. Disease-free survival was 49% and 40%, respectively. At 3 years, GvHD and relapse-free survival (GRFS) was 24% while chronic GvHD and relapse-free survival (CRFS) was 29%. Thus, our results indicate that sequential haplo-HSCT is an effective salvage treatment providing high anti-leukemic activity, favorable tolerance, and acceptable toxicity in patients suffering from advanced AML/MDS.

[Second allogeneic hematopoietic stem cell transplant: Guidelines from the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC)]

Disease recurrence and graft dysfunction after allogeneic hematopoietic stem cell transplantation (allo-HSCT) currently remain among the major causes of treatment failure in malignant and non-malignant hematological diseases. A second allo-HSCT is a valuable therapeutic option to salvage those situations. During the 8th annual harmonization workshops of the french Society of bone marrow transplantation and cellular therapy (SFGM-TC), a designated working group reviewed the literature in order to elaborate unified guidelines on feasibility, indications, donor choice and conditioning in the case of a second allo-HSCT. In case of relapse, a second allo-HSCT with reduced intensity or non-myeloablative conditioning is a reasonable option, particularly in patients with a good performance status (Karnofsky/Lansky>80%), low co-morbidity score (EBMT score≤3), a longer remission duration after the first allo-HSCT (>6 months), and who present low disease burden at the time of second allo-HSCT. Matched related donors tend to be associated with better outcomes. In the presence of graft dysfunction (primary and secondary graft rejection), an immunoablative conditioning regimen is recommended. A donor change remains a valid option, especially in the absence of graft-versus-host disease after the first allo-HSCT.

Myeloablative and reduced-intensity conditioning in HLA-haploidentical peripheral blood stem cell transplantation using post-transplant cyclophosphamide

We conducted two parallel prospective, multicenter, phase II studies to evaluate the safety and efficacy of HLA-haploidentical peripheral blood stem cell transplantation using post-transplant cyclophosphamide (PTCy-haploPBSCT) following myeloablative conditioning (MAC, n = 50) and reduced-intensity conditioning (RIC, n = 77). Event-free survival (EFS) at 1-year as for primary endpoint was 64% and 43% in the MAC and RIC groups, respectively. Neutrophil engraftment was achieved in 98% and 94% in the MAC and RIC groups, respectively. The incidences of grades II-IV and III-IV acute graft-versus-host disease (GVHD) were 18% and 8% in the MAC group, and 14% and 5% in the RIC group, respectively. Those of all grade and moderate to severe chronic GVHD at 2-year were 36% and 20% in the MAC group, and 27% and 20% in the RIC group, respectively. Overall survival (OS), EFS, nonrelapse mortality, and relapse rate at 2-year were 68%, 54%, 10%, and 36% in the MAC group, and 44%, 35%, 20%, and 45% in the RIC group, respectively. Notably, 83% and 86% of patients who survived without relapse stopped immunosuppressant at 2-year in the MAC and RIC groups, respectively. Our results indicate that both MAC and RIC are valid options for PTCy-haploPBSCT for adults with hematological malignancies.

Outcome after relapse of myelodysplastic syndrome and secondary acute myeloid leukemia following allogeneic stem cell transplantation: a retrospective registry analysis on 698 patients by the Chronic Malignancies Working Party of the European Society of Blood and Marrow Transplantation

No standard exists for the treatment of myelodysplastic syndrome relapsing after allogeneic stem cell transplantation. We performed a retrospective registry analysis of outcomes and risk factors in 698 patients, treated with different strategies. The median overall survival from relapse was 4.7 months (95% confidence interval: 4.1-5.3) and the 2-year survival rate was 17.7% (95% confidence interval: 14.8-21.2%). Shorter remission after transplantation (P<0.001), advanced disease (P=0.001), older age (P=0.007), unrelated donor (P=0.008) and acute graft-versus-host disease before relapse (P<0.001) adversely influenced survival. At 6 months from relapse, patients had received no cellular treatment, (i.e. palliative chemotherapy or best supportive care, n=375), donor lymphocyte infusion (n=213), or a second transplant (n=110). Treatment groups were analyzed separately because of imbalanced characteristics and difficulties in retrospectively evaluating the reason for individual treatments. Of the patients who did not receive any cellular therapy, 109 were alive at 6 months after relapse, achieving a median overall survival from this landmark of 8.9 months (95% confidence interval: 5.1-12.6). Their 2-year survival rate was 29.7%. Recipients of donor lymphocytes achieved a median survival from first infusion of 6.0 months (95% confidence interval: 3.7-8.3) with a 2-year survival rate of 27.6%. Longer remission after first transplantation (P<0.001) and younger age (P=0.009) predicted better outcome. Among recipients of a second transplant, the median survival from second transplantation was 4.2 months (95% confidence interval: 2.5-5.9), and their 2-year survival rate was 17.0%. Longer remission after first transplantation (P<0.001), complete remission at second transplant (P=0.008), no prior chronic graft-versus-host disease (P<0.001) and change to a new donor (P=0.04) predicted better outcome. The data enabled identification of patients benefiting from donor lymphocyte infusion and second transplantation, and may serve as a baseline for prospective trials.

Haploidentical hematopoietic cell transplantation for adult acute myeloid leukemia: a position statement from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Allogeneic blood or marrow hematopoietic cell transplantation continues to be the most potent anti-leukemic treatment for adult patients with standard, high-risk, or chemo-refractory acute myeloid leukemia. Until recently, this procedure was generally limited to those recipients who had an available matched-sibling donor or matched-unrelated donor. Technical advances in graft cell processing and manipulation, control of bidirectional T cell alloreactivity, graft-versus-host disease prophylaxis, and other supportive measures in haploidentical transplantation now enable nearly all patients with acute myeloid leukemia to benefit from the graft-versus-leukemia effect with substantial reduction in procedure-related mortality. Over recent years, haploidentical donors have been increasingly adopted as a valid donor source in allogeneic hematopoietic cell transplantation for acute myeloid leukemia in the absence of an HLA-matched donor. Among centers of the European Society for Blood and Marrow Transplantation, the use of haploidentical related donor transplantation has increased by 250% since 2010, and 291% since 2005. On behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize recent utilization trends in haploidentical transplantation for acute myeloid leukemia and describe the transformative changes in haploidentical hematopoietic cell transplantation techniques over the past decade, which have led to the current widespread use of this procedure. Furthermore, we review the efficacy of haploidentical hematopoietic cell transplantation for acute myeloid leukemia from available studies, including preliminary comparative studies, and bring attention to remaining unanswered questions and directions for future research. We conclude this report with our recommendations for the role of haploidentical hematopoietic cell transplantation in acute myeloid leukemia.

Haploidentical hematopoietic cell transplantation using in vitro T cell depleted grafts as salvage therapy in patients with disease relapse after prior allogeneic transplantation

Disease relapse after one or more allogeneic hematopoietic cell transplantations (HCT) represents a therapeutic challenge with all options bearing a significant morbidity and mortality. Haploidentical HCT may induce more pronounced anti-leukemic effects and was evaluated at our center in 25 consecutive patients with disease relapse after preceding HCT receiving haploidentical grafts after in vitro T cell depletion. Overall survival at 1 and 2 years was 32 and 14%, respectively. Of note, patients with complete remission (CR) before haploidentical HCT had a very favorable overall survival of 41.7% at 2 years. Cumulative incidence of non-relapse mortality was 36 and 40% at 1 and 2 years, respectively. With a cumulative incidence for relapse of 36 and 45.6% at 1 and 2 years, disease-free survival (DFS) was 28 and 14.4%, respectively. Here also, patients with CR before haploidentical HCT had a favorable DFS of 42% at 2 years. Only very limited acute (11 patients (44%) with a median grade 1) and chronic graft versus host disease (GvHD) (5 patients (11%), limited grade only) was observed. The main complications and causes of death comprised-besides relapse-infections and bleeding complications. Hence, haploidentical HCT can achieve long-term survival comparable to second transplantation with matched or mismatched donors for patients with otherwise deleterious prognosis and should be considered as a treatment option for patients experiencing disease relapse after previous allogeneic HCT.

Treatment of relapse after allogeneic stem cell transplantation in children and adolescents with ALL: the Frankfurt experience

Therapy for post-transplant relapse of paediatric ALL is limited. Standardised curative approaches are not available. We hereby describe our local procedure in this life-threatening situation. A total of 101 ALL patients received their first allogeneic stem cell transplantation (SCT) in our institution. After relapse, our primary therapeutic goal was to cure the patient with high-dose chemotherapy or specific immunotherapy (HDCHT/SIT) followed by a second SCT from a haploidentical donor (transplant approach). If this was not feasible, low-dose chemotherapy and donor lymphocyte infusions (LDCHT+DLI) were offered (non-transplant approach). A total of 23 patients suffered a post-transplant relapse. Eight patients received HDCHT/SIT, followed by haploidentical SCT in 7/8. Ten received LDCHT+DLI. The eight patients treated with a second transplant and the ten treated with the non-transplant approach had a 4-year overall survival of 56% and 40%, respectively (P=0.232). Prerequisites for successful treatment of post-transplant relapse by either a second transplant or experimental non-transplant approaches are good clinical condition and the capacity to achieve haematological remission by the induction treatment element.

Second Allogeneic Stem Cell Transplantation for Acute Leukemia Using a Chemotherapy-Only Cytoreduction with Clofarabine, Melphalan, and Thiotepa

Relapse after allogeneic hematopoietic stem cell transplantation (alloHSCT) remains one of the leading causes of mortality in patients with leukemia. Treatment options in this population remain limited, with concern for both increased toxicity and further relapse. We treated 18 patients with acute leukemia for marrow ± extramedullary relapse after a previous alloHSCT with a myeloablative cytoreductive regimen including clofarabine, melphalan, and thiotepa followed by a second or third transplantation from the same or a different donor. All patients were in remission at the time of the second or third transplantation. All evaluable patients engrafted. The most common toxicity was reversible transaminitis associated with clofarabine. Two patients died from transplantation-related causes. Seven patients relapsed after their second or third transplanation and died of disease. Nine of 18 patients are alive and disease free, with a 3-year 49% probability of overall survival (OS). Patients whose remission duration after initial alloHSCT was >6 months achieved superior outcomes (3-year OS, 74%, 95% confidence interval, 53% to 100%), compared with those relapsing within 6 months (0%) (P < .001). This new cytoreductive regimen has yielded promising results with acceptable toxicity for second or third transplantations in patients with high-risk acute leukemia who relapsed after a prior transplantation, using various graft and donor options. This approach merits further evaluation in collaborative group studies.

Post-relapse survival after haploidentical transplantation vs matched-related or matched-unrelated hematopoietic cell transplantation

Relapse remains a major cause of mortality among patients receiving allogeneic hematopoietic cell transplantation (HCT). The impact of donor type on post-relapse survival (PRS) has not been widely examined. We compared the survival outcomes for patients relapsing after haploidentical donor transplantation (HIDT) using post-transplant cyclophosphamide with those relapsing after matched-related donor transplantation (MRDT) or matched-unrelated donor transplantation (MUDT) at our institution. Two hundred and thirty-seven consecutive HCT recipients with relapse occurring after HIDT (N=48), MUDT (N=87) and MRDT (N=102) were included in this analysis. Median age was 49 years (19-77 years) and the median time to relapse was 156 days (12-2465) after HCT. HIDT recipients had similar median time to relapse (5.8 vs 4.8 vs 5.5 months, P=0.638) compared with MUDT and MRDT, respectively. One-year PRS was worse among HIDT recipients compared with MRDT and MUDT (17% vs 46% vs 40%, P<0.05). In a multivariate analysis, time to relapse (<3 vs >3 months post transplant), no use of donor lymphocyte infusion (DLI) following relapse, higher Dana Farber disease risk index and HCT comorbidity index scores at the time of transplant and delayed platelet engraftment post transplant were all predictive of worse PRS. This analysis shows that 1-year PRS is inferior among HIDT when compared with MRDT or MUDT. Lower use of DLI after HIDT may have contributed to this inferior survival.

Epidemiology and risk factors for invasive fungal diseases in hematopoietic stem cell transplantation

PURPOSE OF REVIEW

Knowledge of the epidemiology and the risk factors of invasive fungal diseases (IFDs) in hematopoietic stem cell transplant (HSCT) recipients is a critical determinant of the prevention, diagnosis and therapeutic antifungal strategy. Transplant procedures are characterized by a continuous evolution; therefore, an update of the epidemiological findings of IFDs in HSCT populations is needed.

RECENT FINDINGS

In the last few years, the incidence and the clinical risk factors of IFD, mainly in allogeneic HSCT populations, have been investigated in prospective, multicenter studies. New findings in the different types and phases of transplant may be considered for a redefinition of the level of risk of IFD after HSCT. Furthermore, recent studies have uncovered associations between host's and/or donor's genetic variants and immunological risk for IFDs, in particular invasive aspergillosis.

SUMMARY

Evolution of the transplant procedures was followed by an important change in the epidemiology and clinical risk of IFD after allogeneic HSCT. A new stratification of subpopulations according to different clinical infectious risk and genetic susceptibility may be considered to predict those patients most vulnerable to IFD and update tailored antifungal strategies.

Impact of a New Fusion Receptor on PD-1-Mediated Immunosuppression in Adoptive T Cell Therapy

BACKGROUND

Adoptive T cell transfer (ACT) is currently under investigation for the treatment of metastatic cancer. Recent evidence suggests that the coinhibitory PD-1-PD-L1 axis plays a major role in ACT failure. We hypothesized that a new fusion receptor reverting PD-1-mediated inhibition into CD28 costimulation may break peripheral tolerance.

METHODS

Different PD-1-CD28 fusion receptor constructs were created and retrovirally transduced into primary T cell receptor transgenic murine CD8(+) T cells specific for ovalbumin (OT-1). Cytokine release, proliferation, cytotoxicity, and tumor recognition were analyzed in vitro. Antitumor efficacy and mode of action were investigated in mice bearing subcutaneous tumors induced with the pancreatic carcinoma cell line Panc02 expressing the model antigen ovalbumin (Panc-OVA). For antitumoral efficacy, six to eight mice per group were used. All statistical tests are two-sided.

RESULTS

Transduction of the PD-1-CD28 receptor constructs mediated enhanced cytokine release, T cell proliferation, and T cell-induced lysis of target tumor cells. The PD-1-CD28 receptor function was dependent on two of the CD28-signaling motifs and IFN-γ release. Treatment of mice with established Panc-OVA tumors with fusion receptor-transduced OT-1 T cells mediated complete tumor regression. Mice rejecting the tumor were protected upon subsequent rechallenge with either ovalbumin-positive or -negative tumors, indicative of a memory response and epitope spreading in nine of 11 mice vs none of the six naïve mice (P < .001). Treatment efficacy was associated with accumulation of IFN-γ-producing T cells and an increased ratio of CD8(+) T cells to immunosuppressive myeloid-derived suppressor cells in the tumors.

CONCLUSIONS

Transduction of T cells with this new PD-1-CD28 receptor has the potential of breaking the PD-1-PD-L1-immunosuppressive axis in ACT.

Second allogeneic transplantation using unrelated cord blood for relapsed hematological malignancies after allogeneic transplantation

The efficacy of second allogeneic stem cell transplantation (SCT2) using cord blood (CB) for patients with relapsed hematological malignancies after initial allogeneic stem cell transplantation (SCT1) is unknown. We analyzed the results of SCT2 using single-unit unrelated CB in 34 adult patients with relapsed hematological malignancies after SCT1 in our institution. The patients had acute myeloid leukemia (n = 23), acute lymphoblastic leukemia (n = 7), chronic myelogenous leukemia (n = 2), and myelodysplastic syndrome (n = 2). The cumulative incidence of neutrophil and platelet engraftment was 81.6% at 30 days and 68.5% at 100 days, respectively. With a median follow-up of 40 months, the probability of overall survival at 3 years was 29.0%. The cumulative incidence of relapse and transplant-related mortality at 3 years were 60.7% and 27.2%, respectively. The use of CB could offer the opportunity to receive SCT2 for patients who experienced disease relapse after SCT1 without HLA-identical related or unrelated donors.

Post-transplantation Cyclophosphamide and Sirolimus after Haploidentical Hematopoietic Stem Cell Transplantation Using a Treosulfan-based Myeloablative Conditioning and Peripheral Blood Stem Cells

Haploidentical hematopoietic stem cell transplantation (HSCT) performed using bone marrow (BM) grafts and post-transplantation cyclophosphamide (PTCy) has gained much interest for the excellent toxicity profile after both reduced-intensity and myeloablative conditioning. We investigated, in a cohort of 40 high-risk hematological patients, the feasibility of peripheral blood stem cells grafts after a treosulfan-melphalan myeloablative conditioning, followed by a PTCy and sirolimus-based graft-versus-host disease (GVHD) prophylaxis (Sir-PTCy). Donor engraftment occurred in all patients, with full donor chimerism achieved by day 30. Post-HSCT recovery of lymphocyte subsets was broad and fast, with a median time to CD4 > 200/μL of 41 days. Cumulative incidences of grade II to IV and III-IV acute GVHD were 15% and 7.5%, respectively, and were associated with a significant early increase in circulating regulatory T cells at day 15 after HSCT, with values < 5% being predictive of subsequent GVHD occurrence. The 1-year cumulative incidence of chronic GVHD was 20%. Nonrelapse mortality (NRM) at 100 days and 1 year were 12% and 17%, respectively. With a median follow-up for living patients of 15 months, the estimated 1-year overall and disease-free survival (DFS) was 56% and 48%, respectively. Outcomes were more favorable in patients who underwent transplantation in complete remission (1-year DFS 71%) versus patients who underwent transplantation with active disease (DFS, 34%; P = .01). Overall, myeloablative haploidentical HSCT with peripheral blood stem cells (PBSC) and Sir-PTCy is a feasible treatment option: the low rates of GVHD and NRM as well as the favorable immune reconstitution profile pave the way for a prospective comparative trial comparing BM and PBSC in this specific transplantation setting.

Prophylaxis and treatment of acute lymphoblastic leukemia relapse after allogeneic hematopoietic stem cell transplantation

Relapse of acute lymphoblastic leukemia remains a major cause of death in patients following allogeneic hematopoietic stem cell transplantation. Several factors may affect the concurrence and outcome of relapse, which include graft-versus-host disease, minimal residual disease or intrinsic factors of the disease, and transplantation characteristics. The mainstay of relapse prevention and treatment is donor leukocyte infusions, targeted therapies, second transplantation, and other novel therapies. In this review, we mainly focus on addressing the impact of graft-versus-host disease on relapse and the prophylaxis and treatment of acute lymphoblastic leukemia relapse following allogeneic hematopoietic stem cell transplantation. We also make recommendations for critical strategies to prevent relapse after transplantation and challenges that must be addressed to ensure success.