Second allogeneic stem cell transplantation in patients with acute lymphoblastic leukaemia: a study on behalf of the Acute Leukaemia Working Party of the European Society for Blood and Marrow Transplantation

Consolidation with First and Second Allogeneic Transplants in Adults with Relapsed/Refractory B-ALL Following Response to CD19CAR T Cell Therapy

CD19-targeted chimeric antigen receptor T cell (CAR-T) therapy has led to unprecedented rates of complete remission (CR) in children and adults with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL), yet the majority of adults relapse after initial response. One proposed method to extend the durability of remission in adults following response to CAR-T therapy is consolidation with allogeneic hematopoietic cell transplantation (alloHCT). Considering the limited published data for the utility of post CAR-T therapy consolidative alloHCT in r/r B-ALL, especially data related to patients receiving a second alloHCT, we sought to describe outcomes of patients with r/r B-ALL at our institution who received their first or second alloHCT following response to CAR-T therapy. We performed a retrospective analysis of adult patients with r/r B-ALL who responded to either investigational or standard of care (SOC) CD19-targeted CAR-T therapy and underwent consolidation with alloHCT while in CR without interim therapy. We identified 45 patients, of whom 26 (58%) and 19 (42%) received their first and second alloHCT as consolidation post CAR-T therapy, respectively. The median age was 31 years (range: 19-67) and 31 (69%) patients were Hispanic. Ph-like was the most common genetic subtype and comprised over half of cases (53%; n = 24). The median number of prior therapies pre-transplant was 5 (range: 2-7), and disease status at the time of alloHCT was CR1, CR2 or ≥CR3 in 7 (16%), 22 (49%) and 16 (35%) patients, respectively. The median time from CAR-T therapy until alloHCT was 93 (range: 42-262) days. The conditioning regimen was radiation-based myeloablative (MAC) in 22 (49%) patients. With a median follow-up of 2.47 years (range: 0.13-6.93), 2-year overall survival (OS), relapse free survival (RFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were 57.3% (95% CI: 0.432-0.760), 56.2% (95% CI: 0.562-0.745), 23.3% (95% CI: 0.13-0.42), and 20.4% (95% CI: 0.109-0.384), respectively. Two-year OS (52% vs. 68%, P = .641), RFS (54% vs. 59%, P = .820), CIR (33.5% vs. 8.5%, P = .104), and NRM (12.5% vs. 32.2%, P = .120) were not significantly different between patients who underwent their first vs. second transplant, respectively. In univariate analysis, only Ph-like genotype was associated with inferior RFS (P = .03). AlloHCT post CAR-T response is associated with a relatively low early mortality rate and encouraging survival results in high-risk adults with r/r B-ALL, extending to the second alloHCT for fit and eligible patients.

[Second allogeneic (update). Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

Relapse after allogeneic hematopoietic cell transplantation (allo-HCT) remains a major concern because it is associated with poor survival. A second allo-HCT is a valid option in this situation. During the 13th annual harmonization workshops of the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC), a designated working group reviewed the literature in order to update the second allo-HCT recommendations elaborated during the previous workshop (2016). The main indication for a second allo-HCT remains relapse of initial hematologic malignancy. Disease status; complete remission (CR), and relapse time after the first allo-HCT>6 months impact positively the overall survival of patients after the second allo-HCT. Donor change is a valid option, particularly if there is HLA loss on leukemic cells after a first haploidentical or following a mismatched allo-HCT is documented. Reduced intensity conditioning is recommended, while a sequential protocol is a reasonable option in patients with proliferative disease. A post-transplant maintenance strategy after hematological recovery is recommended as soon as day 60, even if the immunosuppressive treatment has not yet been stopped. Hypomethylating agents, and targeted therapies such as anti FLT3, anti BCL2, anti-IDH1/2, TKI, anti-TP53, anti-CD33, anti-CD19, anti-CD22, anti-CD30, check point inhibitors, and CAR-T cells can be used as a bridge to transplant or as an alternative treatment to the second allo-HCT.

Long-term outcome of second allogeneic hematopoietic stem cell transplantation (HSCT2) for primary graft failure in patients with acute leukemia in remission: A study on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Second transplantation (HSCT2) is a potential treatment for primary graft failure (pGF). We assessed the outcome of HSCT2, performed between 2000 and 2021, for pGF in 243 patients with acute leukemia. Median age was 44.8 years. Conditioning at first HSCT (HSCT1) was myeloablative (MAC) in 58.4%. Median time from HSCT1 to HSCT2 was 48 days. Donors for HSCT2 were the same as for HSCT1 in 49%. Engraftment post HSCT2 was achieved by 73.7% of patients. The incidence of acute (a) graft versus host disease (GVHD) grades II-IV and III-IV was 23.2 and 8.1%. 5-year total and extensive chronic (c) GVHD was 22.3 and 10.1%. 5-year nonrelapse mortality (NRM), relapse incidence (RI), leukemia-free survival (LFS), overall survival (OS) and GVHD free, relapse-free survival (GRFS) was 51.6, 18.8, 29.6, 30.7 and 22.4%, respectively. Infections were the main cause of death. In multivariable analysis, being transplanted at second vs. first remission, lower Karnofsky performance status (KPS; <90) and receiving MAC at HSCT1 were adverse prognostic factors for NRM, LFS, OS, and GRFS, as was increased age for NRM, LFS, OS. We conclude that HSCT2 can rescue about a third of the patients who experienced pGF, but NRM is as high as 50%.

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.

Donor-derived CD19 CAR-T Cells versus Chemotherapy Plus Donor Lymphocyte Infusion for Treatment of Recurrent CD19-positive B-ALL After Allogeneic Hematopoietic Stem Cell Transplantation

OBJECTIVE

This study aimed to compare the efficacy of anti-CD19 chimeric antigen receptor T cells (CAR-T cells) versus chemotherapy plus donor lymphocyte infusion (chemo-DLI) for treating relapsed CD19-positive B-cell acute lymphoblastic leukemia (B-ALL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODS

Clinical data of 43 patients with B-ALL who relapsed after allo-HSCT were retrospectively analyzed. Twenty-two patients were treated with CAR-T cells (CAR-T group), and 21 with chemotherapy plus DLI (chemo-DLI group). The complete remission (CR) and minimal residual disease (MRD)-negative CR rates, leukemia-free survival (LFS) rate, overall survival (OS) rate, and incidence of acute graft-versus-host disease (aGVHD), cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were compared between the two groups.

RESULTS

The CR and MRD-negative CR rates in the CAR-T group (77.3% and 61.5%) were significantly higher than those in the chemo-DLI group (38.1% and 23.8%) (P=0.008 and P=0.003). The 1- and 2-year LFS rates in the CAR-T group were superior to those in the chemo-DLI group: 54.5% and 50.0% vs. 9.5% and 4.8% (P=0.0001 and P=0.00004). The 1- and 2-year OS rates in the CAR-T versus chemo-DLI group were 59.1% and 54.5% vs. 19% and 9.5% (P=0.011 and P=0.003). Six patients (28.6%) with grade 2-4 aGVHD were identified in the chemo-DLI group. Two patients (9.1%) in the CAR-T group developed grade 1-2 aGVHD. Nineteen patients (86.4%) developed CRS in the CAR-T group, comprising grade 1-2 CRS in 13 patients (59.1%) and grade 3 CRS in 6 patients (27.3%). Two patients (9.1%) developed grade 1-2 ICANS.

CONCLUSION

Donor-derived anti-CD19 CAR-T-cell therapy may be better, safer, and more effective than chemo-DLI for B-ALL patients who relapse after allo-HSCT.

Total marrow irradiation for second allogeneic hematopoietic stem cell transplantation in patients with advanced acute leukemia

BACKGROUND

Second allogeneic hematopoietic stem cell transplantation (HSCT) is a treatment option for patients with acute leukemia relapsing after a first HSCT. While a myeloablative (MA) conditioning regimen before the first HSCT is considered better than reduced intensity (RIC) in terms of disease control in acute leukemia patients, the optimal conditioning regimen for the second allogeneic HSCT remains controversial. The most important prognostic factors are the remission disease phase at the time of the second HSCT and more than 12 months from the first to the second HSCT. Total Marrow Irradiation (TMI) is an advanced high-precision radiation treatment that delivers therapeutic doses over extensively selected targets while substantially reducing radiation to vital organs compared to conventional Total Body Irradiation (TBI). Herein we report the results of a retrospective analysis on second allogeneic transplantation treated with TMI as a myeloablative conditioning regimen, intending to limit toxicity.

OBJECTIVE

We investigated the efficacy of a high dose per fraction TMI in combination with thiotepa, fludarabine and melphalan in 13 consecutive patients with acute leukemia relapsed after a first allogeneic HSCT treated between March 2018 and November 2021.

STUDY DESIGN

Donor type was haploidentical (HAPLO, n=10), unrelated (UD n=2), and HLA-identical sibling (SIB, n=1). The conditioning regimen consisted of TMI 8 Gy in 5 patients on day -8 -7 or TMI 12 Gy in 8 patients on day -9 -8 -7, plus Thiotepa 5 mg/Kg on day -6, Fludarabine 50 mg/mq on day -5 -4 -3, Melphalan 140 mg/mq on day -2. TMI was delivered in a hypofractionated daily single dose of 4 Gy for three consecutive fractions. The median age was 45 years (range, 19-70 years); 7 patients were in remission, and 6 had active disease at the time of the second allogeneic HSCT.

RESULTS

The median time to neutrophil counts of > 0.5×10e9/L was 16 days (range 13-22), and platelet counts of > 20×10e9/L were 20 days (range 14-34), respectively. All patients showed a complete donor chimerism on day 30 after the transplant. The cumulative incidence of grade I II acute GvHD (aGvHD) was 43%, and chronic GvHD (cGVHD) was 30%. The median follow-up was 1121 days (range 200-1540). Day +30 and +100 transplant-related mortality (TRM) was 0. Overall cumulative incidence of TRM, relapse rate, and disease free-survival (DFS) were respectively 27%,7%, and 67%.

CONCLUSIONS

This retrospective study showed the safety and efficacy of a hypofractionated TMI conditioning regimen in patients with acute leukemia receiving second HSCT with encouraging outcomes regarding engraftment, early toxicity, GvHD, and relapse.

Sequencing antigen-targeting antibodies and cellular therapies in adults with relapsed/refractory B-cell acute lymphoblastic leukemia

The recent approvals of four CD19-or CD22-targeted therapies for B-cell acute lymphoblastic leukemia (B-ALL) have transformed the treatment of relapsed/refractory (r/r) disease. Adults with r/r B-ALL are usually eligible for all options, but there are no studies directly comparing these agents, and the treating physician must decide which to select. Each therapy has notable activity as a single agent but has limitations in particular settings, and the optimal choice varies. These therapies can be complementary and used either sequentially or concomitantly. Here, we review the current landscape of antigen-targeted therapies for r/r B-ALL and discuss considerations for their use.

Late relapse after hematopoietic stem cell transplantation for acute leukemia: a retrospective study by SFGM-TC

Late relapse (LR) after allogeneic hematopoietic stem cell transplantation (AHSCT) for acute leukemia is a rare event (nearly 4.5%) and raises the questions of prognosis and outcome after salvage therapy. We performed a retrospective multicentric study between January 1, 2010, and December 31, 2016, using data from the French national retrospective register ProMISe provided by the SFGM-TC (French Society for Bone Marrow Transplantation and Cellular Therapy). We included patients presenting with LR, defined as a relapse occurring at least 2 years after AHSCT. We used the Cox model to identify prognosis factors associated with LR. During the study period, a total of 7582 AHSCTs were performed in 29 centers, and 33.8% of patients relapsed. Among them, 319 (12.4%) were considered to have LR, representing an incidence of 4.2% for the entire cohort. The full dataset was available for 290 patients, including 250 (86.2%) with acute myeloid leukemia and 40 (13.8%) with acute lymphoid leukemia. The median interval from AHSCT to LR was 38.2 months (interquartile range [IQR], 29.2 to 49.7 months), and 27.2% of the patients had extramedullary involvement at LR (17.2% exclusively and 10% associated with medullary involvement). One-third of the patients had persistent full donor chimerism at LR. Median overall survival (OS) after LR was 19.9 months (IQR, 5.6 to 46.4 months). The most common salvage therapy was induction regimen (55.5%), with complete remission (CR) obtained in 50.7% of cases. Ninety-four patients (38.5%) underwent a second AHSCT, with a median OS of 20.4 months (IQR, 7.1 to 49.1 months). Nonrelapse mortality after second AHSCT was 18.2%. The Cox model identified the following factors as associated with delay of LR: disease status not in first CR at first HSCT (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.04 to 1.64; P = .02) and the use of post-transplantation cyclophosphamide (OR, 2.23; 95% CI, 1.21 to 4.14; P = .01). Chronic GVHD appeared to be a protective factor (OR, .64; 95% CI, .42 to .96; P = .04). The prognosis of LR is better than in early relapse, with a median OS after LR of 19.9 months. Salvage therapy associated with a second AHSCT improves outcome and is feasible, without creating excess toxicity.

Prognosis of patients with acute lymphoblastic leukaemia relapsing after allogeneic stem cell transplantation

The outcomes of patients with acute lymphoblastic leukaemia (ALL) presenting relapse after allogeneic stem cell transplant (allo-SCT) are poor, with few data available in this setting.

OBJECTIVE AND METHODS

To evaluate the outcomes of patients with ALL presenting relapsed after allo-SCT, we performed a retrospective study including 132 from 11 centres in Spain.

RESULTS

Therapeutic strategies consisted of palliative treatment (n = 22), chemotherapy (n = 82), tyrosine kinase inhibitors (n = 26), immunotherapy with inotuzumab and/or blinatumumab (n = 19), donor lymphocyte infusions (n = 29 pts), second allo-SCT (n = 37) and CAR T therapy (n = 14). The probability of overall survival (OS) at 1 and 5 years after relapse was 44% (95% confidence interval [CI]: 36%; 52%) and 19% (95% CI: 11%; 27%). In the 37 patients undergoing a second allo-SCT, the 5-year estimated OS probability was 40% [22%; 58%]. Younger age, recent allo-SCT, late relapse, 1st complete remission at 1st allo-SCT and chronic graft-versus-host disease confirmed their positive impact on survival in the multivariable analysis.

CONCLUSION

Despite the poor prognosis of patients with ALL presenting relapse after a first allo-SCT, some can be satisfactorily rescued and a second allo-SCT still remains a valid option for selected patients. Moreover, emerging therapies really might improve ALL patients outcome when relapsing after an allo-SCT.

[Role of allogeneic hematopoietic cell transplantation after anti-CD19 CAR T-cell treatment: Guidelines from the SFGM-TC]

The role of allogeneic hematopoietic cell transplantation (allo-HCT) after CAR T- treatment cells in hematologic malignancies is currently controversial. Prolonged remissions after several years of follow-up suggest that there is a curative effect of CAR T-cells therapy, whereas allo-HCT was previously considered the only curative treatment in relapse situation. The aim of this harmonization workshop is to detail the existing data in the literature on the feasibility of allo-HCT after CAR T-cells and to propose to consider allograft in selected patients with B-acute lymphoblastic leukemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL). In B-ALL, various intrinsic factors (inherent to the patient, to the disease, to the type of CAR T-cells) and especially various post CAR T-cells criteria (early expansion kinetics, residual disease at D28, early loss of B-cell aplasia) should lead to consider performing allo-HCT before the occurrence of a relapse. In DLBCL, although there are risk factors for relapse at diagnosis and prior to CAR T-cells therapy, response assessed by PET-CT at three months is critical and allo-HCT cannot currently be recommended in cases of complete or partial remission. In any case, if the age is appropriate for allogeneic transplantation, HLA typing should be performed before CAR T-cells treatment in order not to delay the allo-HCT project if needed.

Post-Hematopoietic Cell Transplantation Relapsed Acute Lymphoblastic Leukemia: Current Challenges and Future Directions

Allogeneic hematopoietic cell transplantation (allo-HCT) represents an important and potentially curative treatment option for adult patients with acute lymphoblastic leukemia. Relapse continues to remain the most important factor influencing overall survival post allo-HCT. We discuss early identification, clinical manifestations, and management of relapsed disease. Routine evaluation of measurable residual disease (MRD) and change in donor chimerism play a crucial role in early detection. Pivotal clinical trials have led to FDA approval of multiple novel agents like blinatumomab and inotuzumab. Combining targeted therapy with cellular immunotherapy serves as the backbone for prolonging overall survival in these patients. Donor lymphocyte infusions have traditionally been used in relapsed disease with suboptimal outcomes. This review provides insight into use of cellular therapy in MRD positivity and decreasing donor chimerism. It also discusses various modalities of combining cellular therapy with novel agents and discussing the impact of chimeric antigen receptor T-cell therapy in the setting of post allo-HCT relapse both as consolidative therapy and as a bridge to second transplant.

Prognostic factors of second hematopoietic allogeneic stem cell transplantation among hematological malignancy patients relapsed after first hematopoietic stem cell transplantation: A single center study

Introduction

We aimed to evaluate prognostic factors of a second allogeneic stem cell transplantation (allo-HSCT2) among hematological malignancy patients who have relapsed after the first allo-HSCT(allo-HSCT1).

Methods

We retrospectively analyzed 199 hematological malignancy patients who received allo-HSCT2 as a salvage treatment post allo-HSCT1 relapse between November 2012 and October 2021.

Results

The median age at allo-HSCT2 was 23 (range: 3-60) years. The median time to relapse after HSCT1 was 9 (range: 1-72) months. Prior to allo-HSCT2, patients had the following hematopoietic cell transplantation-comorbidity indexes (HCT-CI): 127 with a score of 0, 52 with a score of 1, and 20 with a score of 2 or greater. Fifty percent of patients received chimeric antigen receptor (CAR) T-cell therapy following HSCT1 relapse. Disease status was minimal residual disease (MRD)-negative complete remission (CR) among 119 patients, MRD-positive CR among 37 patients and non-remission (NR) for 43 patients prior to allo-HSCT2. Allo-HSCT2 was performed from a new donor in 194 patients (97.4%) and 134 patients (67.3%) received a graft with a new mismatched haplotype. The median follow-up time was 24 months (range: 6-98 months), and the 2-year OS and LFS were 43.8% ± 4.0% and 42.1% ± 4.1%, respectively. The 2-year cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) was 30.0%±4.8% and 38.5%±3.8%, respectively. Cox regression multivariate analysis showed that disease statusof MRD-negative CR, HCT-CI score of 0 prior to allo-HSCT2, and new mismatched haplotype donor were predictive factors of improved OS and LFS compared to patients without these characteristics. Based on these three favorable factors, we developed a predictive scoring system for patients who received allo-HSCT2. Patients with a prognostic score of 3 who had the three factors showed a superior 2-year OS of 63.3% ± 6.7% and LFS of 63.3% ± 6.7% and a lower CIR of 5.5% ± 3.1% than patients with a prognostic score of 0. Allo-HSCT2 is feasible and patients with good prognostic features prior to allo-HSCT2 -disease status of CR/MRD- and HCT-CI score of 0 as well as a second donor with a new mismatched haplotype could have the maximal benefit from the second allo-HSCT.

Conclusions

Allo-HSCT2 is feasible and patients with good prognostic features prior to allo-HSCT2 -disease status of CR/MRD- and HCT-CI score of 0 as well as a second donor with a new mismatched haplotype could have the maximal benefit from the second allo-HSCT.

RCMNet: A deep learning model assists CAR-T therapy for leukemia

Acute leukemia is a type of blood cancer with a high mortality rate. Current therapeutic methods include bone marrow transplantation, supportive therapy, and chemotherapy. Although a satisfactory remission of the disease can be achieved, the risk of recurrence is still high. Therefore, novel treatments are demanding. Chimeric antigen receptor-T (CAR-T) therapy has emerged as a promising approach to treating and curing acute leukemia. To harness the therapeutic potential of CAR-T cell therapy for blood diseases, reliable cell morphological identification is crucial. Nevertheless, the identification of CAR-T cells is a big challenge posed by their phenotypic similarity with other blood cells. To address this substantial clinical challenge, herein we first construct a CAR-T dataset with 500 original microscopy images after staining. Following that, we create a novel integrated model called RCMNet (ResNet18 with Convolutional Block Attention Module and Multi-Head Self-Attention) that combines the convolutional neural network (CNN) and Transformer. The model shows 99.63% top-1 accuracy on the public dataset. Compared with previous reports, our model obtains satisfactory results for image classification. Although testing on the CAR-T cell dataset, a decent performance is observed, which is attributed to the limited size of the dataset. Transfer learning is adapted for RCMNet and a maximum of 83.36% accuracy is achieved, which is higher than that of other state-of-the-art models. This study evaluates the effectiveness of RCMNet on a big public dataset and translates it to a clinical dataset for diagnostic applications.

Haploidentical Versus Matched Sibling Donor Hematopoietic Stem Cell Transplantation for Adult Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia: A Study From the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

The results of haploidentical stem cell transplantation (haploHCT) for patients with acute lymphoblastic leukemia (ALL) transplanted in active disease remain largely unknown. We retrospectively analyzed adult patients with R/R ALL who underwent haploHCT or matched sibling donor (MSD-HCT) as a first transplantation between 2012 and 2020. The analysis comprised 274 patients, 94 had a haploHCT, and 180 had an MSD-HCT. The median follow-up was 32 months. The median age was 33 (range 18-76) and 37 (18-76) years in the haplo- and MSD-HCT groups, respectively. Post-transplant cyclophosphamide (PTCy) was used in 88% of haploHCT and in 4% of the MSD-HCT group. Graft-versus-host disease grade III-IV was higher in haploHCT than in the MSD-HCT group (18% versus 9%; P = 0.042). The 2-year chronic (c) graft-versus-host disease rates were 17% versus 33% (hazard ratio [HR] = 0.56; P = 0.14), respectively. By multivariate analysis, relapse incidence, and leukemia-free survival were not significatively different between the transplant groups, while nonrelapse mortality (NRM) was significantly higher (25% versus 18% at 2 years; HR = 2.03; P = 0.042) and overall survival (OS) lower (22% versus 38% at 2 years; HR = 1.72; P = 0.009) in the haploHCT group compared with the MSD-HCT group. We conclude that the 2-year OS of R/R ALL patients undergoing MSD transplants is significantly better than in haploHCT with a higher NRM in the latter.

Infectious complications after second allogeneic hematopoietic cell transplant in adult patients with hematological malignancies

We conducted a retrospective review of the infectious complications and outcomes over a 2-year follow-up period of adult patients who received a second allogeneic hematopoietic cell transplant (2nd allo-HCT) during a five-year period at two cancer centers in Michigan. Sixty patients, of whom 44 (73%) had acute leukemia or myelodysplastic syndrome, were studied. The majority (n = 37,62%) received a 2nd allo-HCT because of relapsed leukemia. Infection episodes after the 2nd allo-HCT totaled 112. Bacteria were identified in 76 episodes, the majority of which occurred pre-engraftment. The most common infecting organisms were Enterococcus species and Clostridioides difficile. Viral infections, predominantly cytomegalovirus, accounted for 59 infection episodes and occurred mostly in pre-engraftment and early post-engraftment periods. There were 16 proven/probable fungal infections, of which 9 were invasive aspergillosis or candidiasis. Mortality was 45% (n = 27) at one year and 65% (n = 39) at 2 years after transplant, and 16 deaths (41%) were due to infection. Of those 16 infection deaths, 8 were bacterial, 4 fungal, 2 both bacterial and fungal, and 2 viral. Failure to engraft neutrophils or platelets was significantly associated with decreased survival, p < 0.0001 and p < 0.001, respectively. Infections are common after a 2nd allo-HCT and are associated with a high mortality rate.

Outcomes in patients with acute lymphoblastic leukemia who underwent second allogeneic hematopoietic cell transplantation for relapse after first transplantation

Outcomes in patients with acute lymphoblastic leukemia (ALL) who experience relapse after allogeneic hematopoietic cell transplantation (HCT) are unsatisfactory. This study aimed to evaluate the outcomes of patients with ALL who underwent second HCT (HCT2) for relapse after first HCT. It was a single-center retrospective study including adult patients with ALL who underwent HCT2 between 1991 and 2020. The cohort was stratified according to the transplant year, and included 39 patients with a median age of 29 years. A more recent transplant year was associated with achievement of complete remission (CR) and use of reduced-intensity conditioning (RIC), compared with an earlier transplant year. The overall survival (OS) rate and 2-year cumulative incidence of non-relapse mortality (recent vs. earlier) were 55% vs. 8% (P < 0.001) and 26% vs. 75% (P < 0.001), respectively. In multivariate analysis, non-CR (vs. CR; HR 3.6, 95% CI 1.2-11.3, P = 0.025) and myeloablative conditioning (vs. RIC; HR 3.5, 95% CI 1.3-9.4, P = 0.011) were negative prognostic factors for OS. Outcomes of the recent cohort from real-world data are promising, and achieving CR and using the RIC regimen at HCT2 may be an important therapeutic strategy.

Impact of conditioning regimen intensity on outcomes of second allogeneic hematopoietic cell transplantation for secondary acute myelogenous leukemia

Limited data is available on factors impacting the outcomes of second hematopoietic cell transplantation (HCT2) in patients with secondary acute myeloid leukemia (sAML). This study aimed to assess HCT2 outcome for sAML comparing reduced-intensity (RIC) to myeloablative (MAC) conditioning. Two hundred and fifteen patients were included: RIC (n = 134), MAC (n = 81). The median follow-up was 41.1 (95% CI: 26.7-69.3) and 28.5 (95% CI: 23.9-75.4) months, respectively. At two years, the relapse incidence (RI) was 58.3% versus 51.1% in RIC and MAC, respectively. The 2-year leukemia free survival (LFS) was 26.6% versus 26%, and the graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) was 16.4% versus 12.1%, while OS was 31.4% and 39.7%, for RIC and MAC respectively. MVA showed a significantly lower RI [hazard ratio (HR) = 0.46 (95% CI, 0.26-0.8, p = 0.006)] and improved LFS [HR = 0.62 (95% CI, 0.39-0.98, p = 0.042)] with MAC versus RIC. The choice of conditioning regimen did not impact non-relapse mortality [HR = 1.14 (95% CI, 0.52-2.5, p = 0.74)], overall survival (OS) [HR = 0.72 (95% CI, 0.44-1.17, p = 0.18)] or GRFS [HR = 0.89 (95% CI, 0.59-1.36, p = 0.6)]. In conclusion, MAC was associated with a lower RI and superior LFS. These results support the use of MAC for eligible patients with sAML who are being considered for HCT2.

Outcomes of third allogeneic hematopoietic stem cell transplantation in relapsed/refractory acute leukemia after a second transplantation

Relapsed acute leukemia after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with poor prognosis. In a subset of patients, durable remissions can be achieved with a second allo-HSCT (allo-HSCT2). However, many patients experience relapse after allo-HSCT2 and they may be considered for a third allo-HSCT (allo-HSCT3). Nevertheless, the benefit of allo-HSCT3 remains unconfirmed. Thus, herein a retrospective analysis of 253 allo-HSCT3s in patients with relapsed/refractory acute leukemia was carried out. In total, 29 (11.5%) survived at a median follow-up of 794 days (range: 87-4 619). The 3-year leukemia-free survival and overall survival (OS) rates were 9.7% and 10.9%, respectively. Patients who maintained remission for ≥2 years after allo-HSCT2 had a significantly better 3-year OS (35.8%) than those who experienced early relapse (<1 year, 7.8%; 1-2 years, 14.0%; P = 0.004). Complete remission at allo-HSCT3, performance status score of 0-1 at allo-HSCT3, grade I acute graft-versus-host disease after allo-HSCT2, and relapse ≥2 years after allo-HSCT2 were associated with better survival in patients who received allo-HSCT3. The prognosis after allo-HSCT3 in patients with relapsed/refractory acute leukemia is generally unfavorable. However, given the lack of alternative treatment options, allo-HSCT3 may be considered in a group of patients.

Comparison of non-first-degree related donors and first-degree related donors in haploidentical HSCT: a multi-centre retrospective analysis

The transplant outcomes of non-first-degree (NFD) related donors in haploidentical haematopoietic stem cell transplantation (haplo-HSCT) remain unclear. This multi-centre analysis compared NFD and first-degree (FD) related donors in haplo-HSCT using a low-dose anti-T-lymphocyte globulin/G-CSF-mobilised peripheral blood stem cell graft-based regimen. Ninety-nine patients (33 NFD; 66 FD) were included. All patients achieved myeloid and platelet engraftment. The 100-day cumulative incidence (CI) of aGVHD, 2-year CIs of relapse, cGVHD, and NRM, and 2-year probabilities of OS and GRFS were comparable between the two cohorts. In multivariate analysis, donor type (NFD vs. FD) had no impact on OS, PFS, GRFS, incidences of relapse, grade II-IV aGVHD or moderate-severe cGVHD. Older donor age was associated with a higher incidence of grade II-IV aGVHD (HR, 1.64, p = 0.03), moderate-severe cGVHD (HR, 1.92, p = 0.01) and worse GRFS (HR, 1.40, p = 0.02). A lower level of donor-recipient HLA matching was associated with a higher incidence of moderate-severe cGVHD (HR, 4.07, p = 0.02), and disease at complete remission was associated with better OS (HR, 0.21, p = 0.01) and PFS (HR, 0.3, p = 0.03). In conclusion, NFD donors may serve as feasible alternatives when FD donors are not available for haplo-HSCT.

Comparing outcomes of a second allogeneic hematopoietic cell transplant using HLA-matched unrelated versus T-cell replete haploidentical donors in relapsed acute lymphoblastic leukemia: a study of the Acute Leukemia Working Party of EBMT

Optimal donor choice for a second allogeneic hematopoietic cell transplant (allo-HCT) in relapsed acute lymphoblastic leukemia (ALL) remains undefined. We compared outcomes using HLA-matched unrelated donors (MUD) versus haploidentical donors in this population. Primary endpoint was overall survival (OS). The MUD allo-HCT group comprised 104 patients (male = 56, 54%), median age 36 years, mostly (76%) with B-cell phenotype in complete remission (CR) (CR2/CR3 + = 76, 73%). The 61 patients (male = 38, 62%) in the haploidentical group were younger, median age 30 years (p = 0.002), had mostly (79%) a B-cell phenotype and the majority were also in CR at time of the second allo-HCT (CR2/CR3 + = 40, 66%). Peripheral blood stem cells was the most common cell source in both, but a significantly higher number in the haploidentical group received bone marrow cells (26% vs. 4%, p < 0.0001). A haploidentical donor second allo-HCT had a 1.5-fold higher 2-year OS (49% vs. 31%), albeit not statistically significant (p = 0.13). A longer time from first allo-HCT to relapse was associated with improved OS, leukemia-free survival, graft-versus-host disease-free-relapse-free survival, and lower cumulative incidences of relapse and non-relapse mortality. Results suggest no major OS difference when choosing either a MUD or haploidentical donor for ALL patients needing a second allo-HCT.

[CART therapy followed by allo-HSCT for patients with B-cell acute lymphoblastic leukemia relapsing after the first hematopoietic stem cell transplantation]

目的

观察嵌合抗原受体T细胞（CART）序贯二次异基因造血干细胞移植（allo-HSCT）治疗移植后复发急性B淋巴细胞白血病（B-ALL）的疗效。

方法

回顾性分析2015年10月至2020年6月在河北燕达陆道培医院接受二次allo-HSCT的41例B-ALL患者的临床资料，入选患者均为移植后骨髓形态学或髓外复发且二次移植前接受CART治疗。

结果

全部41例患者中男21例、女20例，二次移植时中位年龄为16（3～46）岁。移植后骨髓复发31例（75.6％）、髓外复发5例（12.2％）、骨髓和髓外复发5例（12.2％）。复发后接受CD19-CART治疗35例（85.4％）、CD22-CART治疗2例（4.9％）、CD19-CART联合CD22-CART治疗4例（9.8％）。二次移植后预期3年总生存（OS）率为48.9％（95％ CI 23.0％～70.6％）、无白血病生存（LFS）率为41.8％（95％ CI 17.3％～64.9％），累积复发率（RI）为8.8％（95％ CI 2.9％～26.4％），非复发相关死亡率（NRM）为51.1％（95％ CI 31.2％～83.6％）。首次移植后复发时间≤6个月组（10例）二次移植后1年OS率低于复发时间>6个月组（31例）［45.0％（95％ CI 12.7％～73.5％）对75.0％（95％ CI 51.4％～88.8％），P＝0.017］。

结论

CART序贯二次allo-HSCT可使部分造血干细胞移植后复发B-ALL患者获得长生存，但NRM较高，移植方案有待进一步改进。

The evolving role of allogeneic haematopoietic cell transplantation in the era of chimaeric antigen receptor T-cell therapy

Chimaeric antigen receptor T-cell (CAR T) therapy has revolutionized the management of many haematological malignancies. It is associated with impressive disease responses in relapsed or refractory high-grade B-cell non-Hodgkin lymphoma (B-NHL) and acute lymphoblastic leukaemia (B-ALL) with durable remissions in a subset of patients. Historically, haematopoietic cell transplantation (HCT) has been the standard consolidation strategy for many of these patients who are now being treated with CAR T. Relapses are frequent after CD19 CAR T therapy in B-ALL and consolidation with allogeneic HCT (allo-HCT) may improve survival of patients with high-risk disease. There appears to be a clear difference in B-ALL outcomes between paediatric and adult patients, with the latter having a much higher risk of relapse after CAR T therapy. Late relapses are infrequent in patients with B-NHL and consolidation with allo-HCT may not be needed in patients who achieve a complete remission after CAR T therapy. Future registry-based and prospective studies will hopefully provide the needed data in the future to risk-stratify the recipients of CAR T therapy. Meanwhile, we provide guidance on patient selection and practical issues with performing allo-HCT after CAR T therapy.

Outcomes following second allogeneic haematopoietic cell transplantation in patients with myelofibrosis: a retrospective study of the Chronic Malignancies Working Party of EBMT

Therapeutic management of patients with primary or secondary myelofibrosis (MF) who experience relapse or graft failure following allogeneic haematopoietic cell transplantation (allo-HCT) remains heterogeneous. We retrospectively analyzed 216 patients undergoing a second allo-HCT for either relapse (56%) or graft failure (31%) between 2010 and 2017. Median age was 57.3 years (range 51-63). The same donor as for the first allo-HCT was chosen in 66 patients (31%) of whom 19 received an HLA-identical sibling donor, whereas a different donor was chosen for 116 patients (54%). Median follow-up was 40 months. Three-year overall survival (OS) and relapse-free survival (RFS) were 42% and 39%, respectively. Three-year non-relapse mortality (NRM) and relapse rates were 36% and 25%, respectively. Grade II-IV and III-IV acute GVHD occurred in 25% and 11% of patients, respectively, and the 3-year incidence of chronic GVHD was 33% including 14% for extensive grade. Graft-failure incidence at 1 year was 14%. In conclusion, our data suggest that a second allo-HCT is a potential option for patients failing first allo-HCT for MF albeit careful patient assessment is fundamental to identify individual patients who could benefit from this approach.

Outcome predictors after retransplantation in relapsed acute lymphoblastic leukemia: a multicenter, retrospective study

Retransplantation is the only curative treatment option for patients with acute lymphoblastic leukemia (ALL) that has relapsed after allogeneic hematopoietic cell transplantation (allo-HCT); however, data in this setting remain scant. Hence, this multicenter, retrospective study aims to determine outcome predictors after retransplantation in relapsed ALL. We examined 55 recipients who underwent multiple allo-HCTs during 2006-2018. The 2-year overall survival (OS), progression-free survival (PFS), and non-relapse mortality rates were 35.9%, 29.1%, and 23.6%, respectively. We observed a trend of better outcome in Ph + ALL (n = 22) patients compared with non-Ph ALL (n = 33) patients; the 2-year PFS was 40.9% versus 21.2%, indicating a beneficial effect of more potent second- or third-generation tyrosine kinase inhibitors. Univariate analysis revealed that late relapse after the previous transplant was the only significant predictor of better transplant outcome among Ph + ALL patients, whereas factors related to prolonged OS/PFS in non-Ph ALL patients were late relapse after the previous transplant, longer duration from disease relapse/progression to second or more allo-HCT, disease status at the transplantation, and good performance status. Nevertheless, further investigations are warranted to determine whether novel molecular-targeted agents with higher efficacy and fewer toxicities could exceed conventional chemotherapies as a bridging strategy to next allo-HCT and improve the outcomes of non-Ph ALL patients.

Donor-derived CD19 CAR-T cell therapy of relapse of CD19-positive B-ALL post allotransplant

Safety and efficacy of allogeneic anti-CD19 chimeric antigen receptor T cells (CAR-T cells) in persons with CD19-positive B-cell acute lymphoblastic leukemia (B-ALL) relapsing after an allotransplant remain unclear. Forty-three subjects with B-ALL relapsing post allotransplant received CAR-T cells were analyzed. 34 (79%; 95% confidence interval [CI]: 66, 92%) achieved complete histological remission (CR). Cytokine release syndrome (CRS) occurred in 38 (88%; 78, 98%) and was ≥grade-3 in 7. Two subjects died from multiorgan failure and CRS. Nine subjects (21%; 8, 34%) developed ≤grade-2 immune effector cell-associated neurotoxicity syndrome (ICANS). Two subjects developed ≤grade-2 acute graft-versus-host disease (GvHD). 1-year event-free survival (EFS) and survival was 43% (25, 62%). In 32 subjects with a complete histological remission without a second transplant, 1-year cumulative incidence of relapse was 41% (25, 62%) and 1-year EFS and survival, 59% (37, 81%). Therapy of B-ALL subjects relapsing post transplant with donor-derived CAR-T cells is safe and effective but associated with a high rate of CRS. Outcomes seem comparable to those achieved with alternative therapies but data from a randomized trial are lacking.

Allogeneic stem-cell transplantation with sequential conditioning in adult patients with refractory or relapsed acute lymphoblastic leukemia: a report from the EBMT Acute Leukemia Working Party

Treatment of relapsed/refractory acute lymphoblastic leukemia (RR-ALL) remains a clinical challenge with generally dismal prognosis. Allogeneic stem-cell transplantation using sequential conditioning ("FLAMSA"-like) has shown promising results in relapsed/refractory acute myeloid leukemia, but little is known about its efficacy in RR-ALL. We identified 115 patients (19-66 years) with relapsed (74%) or primary-refractory (26%) ALL allografted from matched related (31%), matched unrelated (58%), or haploidentical donor (11%). Median follow-up was 37 (13-111) months. At day 100, cumulative incidences of grade II-IV/III-IV acute graft-versus-host-disease (GVHD) were 30% and 17%, respectively. Two-year cumulative incidence of chronic GVHD was 25% with 11% extensive cases. Two-year relapse incidence (RI) was 45%, non-relapse mortality was 41%. Two-year leukemia free survival (LFS) was 14%, overall survival (OS) 17%, and GVHD relapse-free survival (GRFS) was 14%. In multivariable analysis, Karnofsky score <90 negatively affected RI, LFS, OS, and GRFS. Conditioning with chemotherapy alone, compared with total body irradiation (TBI) negatively affected RI (HR = 3.3; p = 0.008), LFS (HR = 1.94; p = 0.03), and OS (HR = 2.0; p = 0.03). These patients still face extremely poor outcomes, highlighting the importance of incorporating novel therapies (e.g., BITE antibodies, inotuzumab, CAR-T cells). Nevertheless, patients with RR-T-cell ALL remain with an unmet treatment need, for which TBI-based sequential conditioning could be one of few available options.

Hematopoietic Cell Transplantation in the Treatment of Adult Acute Lymphoblastic Leukemia: Updated 2019 Evidence-Based Review from the American Society for Transplantation and Cellular Therapy

The role of hematopoietic cell transplantation (HCT) in adults with acute lymphoblastic leukemia (ALL) is reviewed and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the recommendations. A panel of ALL experts developed consensus on the treatment recommendations based on the evidence. Allogeneic HCT offers a survival benefit in selected patients with ALL, and this review summarizes the standard indications as well as the areas of controversy. There is now greater experience with pediatric-inspired chemotherapy regimens that has transformed upfront therapy for adult ALL, resulting in higher remission rates and overall survival. This in turn has increased the equipoise around decision making for ALL in first complete remission (CR1) when there is no measurable residual disease (MRD) at the end of induction and/or consolidation. Randomized studies are needed for adults with ALL to compare allogeneic HCT in CR1 with pediatric-inspired chemotherapy alone. Indications for transplantation in the evolving landscape of MRD assessments and novel targeted and immune therapeutics remain important areas of investigation.