Significance of Measurable Residual Disease in Adult Philadelphia Chromosome-Positive ALL: A GRAAPH-2014 Study.

PURPOSE: BCR::ABL1 quantification is widely regarded as the standard for monitoring measurable residual disease (MRD) in Philadelphia chromosome-positive (Ph+) ALL. However, recent evidence of BCR::ABL1 multilineage involvement questions the significance of BCR::ABL1 MRD. We aimed to define the prognostic role of MRD as assessed by BCR::ABL1 or lymphoid-specific immunoglobulin/T-cell receptor (IG/TR) gene markers. PATIENTS AND METHODS: We conducted BCR::ABL1 and IG/TR quantification after each treatment cycle in 264 patients treated in the GRAAPH-2014 trial, which used four cycles of reduced-intensity chemotherapy with nilotinib, followed by hematopoietic stem-cell transplantation (HSCT). RESULTS: Comparing BCR::ABL1 and IG/TR MRD revealed residual BCR::ABL1-positive non-ALL cells in 98 (43%) of 228 patients, defining multilineage Ph+ ALL. Despite poorer BCR::ABL1 responses, patients with multilineage Ph+ ALL had similar disease-free survival (DFS; hazard ratio [HR], 0.83 [95% CI, 0.49 to 1.41]; P = .50). Although BCR::ABL1 response failed to predict outcomes, IG/TR positivity (≥0.01%) was strongly associated with lower DFS (after cycle 2, HR, 2.49 [95% CI, 1.40 to 4.40]; P = .002; after cycle 4, HR, 4.13 [95% CI, 1.82 to 9.38]; P = .001). In multivariable analysis, both IG/TR positivity after cycle 2 and initial WBC count ≥30 × 109/L predicted poorer DFS, enabling to define a high-risk group having a 4-year DFS of 56.5% compared with 87.6% (HR, 3.72 [95% CI, 1.93 to 7.15]; P < .001). Moreover, allogeneic HSCT significantly improved DFS in the high-risk group (HR, 0.33 [95% CI, 0.18 to 0.60]; P < .001), whereas the standard-risk group had favorable outcomes regardless of allogeneic HSCT. CONCLUSION: Our findings challenge the significance of BCR::ABL1 monitoring in adult Ph+ ALL and demonstrate the prognostic role of IG/TR MRD. This study provides a framework for using MRD to guide treatment strategies in adults with Ph+ ALL.

Impact of the Type of Tyrosine Kinase Inhibitor (imatinib or dasatinib) Used Before allo-HCT on Outcome of Patients with Philadelphia-Positive Acute Lymphoblastic Leukemia. A Study on Behalf of the Acute Leukemia Working Party of the EBMT.

The use of tyrosine kinase inhibitors (TKIs) during induction and consolidation, followed by allogeneic hematopoietic cell transplantation (allo-HCT), is a standard of care for patients with Philadelphia (Ph)-positive acute lymphoblastic leukemia (ALL). The goal of this study was to compare results of allo-HCT according to the type of TKI used pre-transplant, either imatinib, dasatinib or both. This was a retrospective, registry-based analysis including adult patients with Ph-positive ALL treated with allo-HCT between years 2010-2022. The analysis included 606 patients pre-treated with imatinib, 163 with dasatinib and 94 with both imatinib and dasatinib. Allo-HCTs were performed in first complete remission from either unrelated (56%), matched sibling (36%) or haploidentical donors (8%). Relapse incidence at 2 years was 26% in the imatinib group and 21% in the dasatinib group and 19% in the imatinib + dasatinib group (P = .06) while non-relapse mortality was 19%, 15%, and 23%, respectively (P = .37). No significant differences were found for leukemia-free survival (55% vs. 63% vs. 58%, P = .11) and overall survival (72% vs. 76% vs. 65%, P = .32). The incidence of grade 2-4 acute graft-versus-host disease (GVHD) and chronic GVHD was comparable across study groups, while the incidence of grade 3-4 acute GVHD was significantly increased for patients pre-treated with dasatinib alone (20%) than in the imatinib group (10%) or imatinib + dasatinib group (13%) (P = .002). On multivariate analysis a chance of GVHD and relapse-free survival (GRFS) was significantly decreased while the risk of grade 3-4 acute GVHD was increased for the dasatinib compared to imatinib group (hazard ratio, HR = 1.27, P = .048 and HR = 2.26, P = .0009, respectively). This study provides no evidence for the advantage of one TKI over another in terms of LFS and OS. However, the use of dasatinib is associated with increased risk of severe acute GVHD and decreased GRFS.

New Insights Into Infections' Risk of Adolescents and Young Adults Treated for Acute Lymphoblastic Leukemia.

BACKGROUND: This study aims to compare the infections' risk between adolescents and young adults (AYAs), treated for acute lymphoblastic leukemia, and pediatric population. We also focused on their bacterial and fungal infection specificities. METHODS: This case-control study investigated the occurrence of bacterial bloodstream infection (BSI) and proven and probable invasive fungal infection (IFI) in AYAs (15-25 years old) and children (1-14 years old) treated for acute lymphoblastic leukemia between January 2013 and December 2020 in 2 French tertiary pediatric and 2 referral adult hematological centers, independent of their treatment protocol. We also evaluated the impact of these infections on morbidity (necessity of intensive care) and mortality. RESULTS: We analyzed 83 AYAs and 230 children and found that AYAs developed significantly more IFI than the pediatric population (22% vs. 10%, P = 0.007), regardless of their care center (adult or pediatric). Furthermore, the occurrence of BSI was similar between the 2 populations (48% vs. 51%, P = 0.66). Moreover, the occurrence of infection increased with the AYAs' risk group of treatment: standard, medium or high risk (P = 0.021 for BSI and P = 0.029 for IFI). Finally, the mortality rate is only 1.3% after a BSI whereas it increases to 4.9% after IFI. CONCLUSION: AYAs have their own specificity with an increased risk of fungal infection compared to children, independent of the care center. Antifungal prophylaxis should be contemplated, especially for patients classified in high-risk groups.

Prognostic factors impacting post-transplant outcomes in adult T-cell acute lymphoblastic leukemia: a registry-based study by the EBMT acute leukemia working party.

T-cell acute lymphoblastic leukemia (T-ALL) predominantly affects individuals in late childhood and young adulthood. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative modality particularly in the setting of poor risk genetics and/or persistent minimal residual disease. Limited studies have directly explored the impact of patient- and transplant-related factors on post-transplant outcomes in T-ALL. Using a large dataset from the European Society for Blood and Marrow Transplantation registry, we identified 1907 adult T-ALL patients (70% male) who underwent their first allo-HSCT in first complete remission (CR1) from matched sibling donors (MSD; 45%), unrelated donors (UD; 43%) or haploidentical donors (12%) between 2010 and 2021. The median age at transplant was 33.4 years (18.1-75). The median follow up was 2.9 years. Most patients underwent total body irradiation (TBI)-based myeloablative conditioning (69%). The 2-year overall survival (OS) was 69.4%, and leukemia -free survival (LFS) was 62.1%. In multivariate analysis, advanced age at transplant negatively affected LFS (for each 10-year increment, HR = 1.11, p = 0.004), GVHD-free, relapse-free survival (GRFS) (HR = 1.06, p = 0.04), OS (HR = 1.12, p = 0.002), and non-relapse mortality (NRM) (HR = 1.23, p < 0.001). More recent years of allo-HSCT were associated with improved GFRS (For each 3-year increment, HR = 0.89, p < 0.001), OS (HR = 0.9, p = 0.02), and decreased NRM (HR = 0.82, p = 0.008). TBI improved LFS. (HR = 0.79, p = 0.02), GRFS (HR = 0.83, p = 0.04), and relapse incidence (RI) (HR = 0.65, p < 0.001). Female-to-male transplant negatively affected GRFS (HR = 1.21, p = 0.02) and OS (HR = 1.23, p = 0.048). In vivo T-cell depletion significantly improved GFRS (HR = 0.74, p < 0.001). This large study identified prognostic factors, such as age at transplant conditioning regimen, in influencing post-transplant in adult T-ALL patients undergoing allo-HSCT. Importantly, a significant improvement over time was noted. These findings hold great promise for new adapted treatment strategies and can serve as a benchmark for future studies in that setting.

NGS-based stratification refines the risk stratification in T-ALL and identifies a very-high-risk subgroup of patients.

ABSTRACT: We previously reported a better outcome in adult and pediatric T-cell acute lymphoblastic leukemia (T-ALL) harboring NOTCH1 and/or FBXW7 mutations without alterations of K-N-RAS and PTEN genes. Availability of high-throughput next-generation sequencing (NGS) strategies led us to refine the outcome prediction in T-ALL. Targeted whole-exome sequencing of 72 T-ALL-related oncogenes was performed in 198 adults with T-ALLs in first remission from the GRAALL-2003/2005 protocols and 242 pediatric patients with T-ALLs from the FRALLE2000T. This approach enabled the identification of, to our knowledge, the first NGS-based classifier in T-ALL, categorizing low-risk patients as those with N/F, PHF6, or EP300 mutations, excluding N-K-RAS, PI3K pathway (PTEN, PIK3CA, and PIK3R1), TP53, DNMT3A, IDH1/2, and IKZF1 alterations, with a 5-year cumulative incidence of relapse (CIR) estimated at 21%. Conversely, the remaining patients were classified as high risk, exhibiting a 5-year CIR estimated at 47%. We externally validated this stratification in the pediatric cohort. NGS-based classifier was highly prognostic independently of minimal residual disease (MRD) and white blood cell (WBC) counts, in both adult and pediatric cohorts. Integration of the NGS-based classifier into a comprehensive risk-stratification model, including WBC count at diagnosis and MRD at the end of induction, enabled the identification of an adverse-risk subgroup (25%) with a 5-year CIR estimated at 51%, and a favorable-risk group (32%) with a 5-year CIR estimated at 12%. NGS-based stratification combined with WBC and MRD sharpens the prognostic classification in T-ALL and identifies a new subgroup of patients who may benefit from innovative therapeutic approaches. The GRAALL-2003/2005 studies were registered at www.ClinicalTrials.gov as #NCT00222027 and #NCT00327678.

Genomic imbalance analysis provides new insight into prognostic factors in adult and pediatric T-ALL.

ABSTRACT: Given the poor outcome of refractory and relapsing T-cell acute lymphoblastic leukemia (T-ALL), identifying prognostic markers is still challenging. Using single nucleotide polymorphism (SNP) array analysis, we provide a comprehensive analysis of genomic imbalances in a cohort of 317 newly diagnosed patients with T-ALL including 135 children and 182 adults with respect to clinical and biological features and outcomes. SNP array results identified at least 1 somatic genomic imbalance in virtually all patients with T-ALL (∼96%). Del(9)(p21) (∼70%) and UPD(9)p21)/CDKN2A/B (∼28%) were the most frequent genomic imbalances. Unexpectedly del(13)(q14)/RB1/DLEU1 (∼14%) was the second most frequent copy number variant followed by del(6)(q15)/CASP8AP2 (∼11%), del(1)(p33)/SIL-TAL1 (∼11%), del(12)(p13)ETV6/CDKN1B (∼9%), del(18)(p11)/PTPN2 (∼9%), del(1)(p36)/RPL22 (∼9%), and del(17)(q11)/NF1/SUZ12 (∼8%). SNP array also revealed distinct profiles of genomic imbalances according to age, immunophenotype, and oncogenetic subgroups. In particular, adult patients with T-ALL demonstrated a significantly higher incidence of del(1)(p36)/RPL22, and del(13)(q14)/RB1/DLEU1, and lower incidence of del(9)(p21) and UPD(9p21)/CDKN2A/B. We determined a threshold of 15 genomic imbalances to stratify patients into high- and low-risk groups of relapse. Survival analysis also revealed the poor outcome, despite the low number of affected cases, conferred by the presence of chromothripsis (n = 6, ∼2%), del(16)(p13)/CREBBP (n = 15, ∼5%) as well as the newly-identified recurrent gain at 6q27 involving MLLT4 (n = 10, ∼3%). Genomic complexity, del(16)(p13)/CREBBP and gain at 6q27 involving MLLT4, maintained their significance in multivariate analysis for survival outcome. Our study thus demonstrated that whole genome analysis of imbalances provides new insights to refine risk stratification in T-ALL. This trial was registered at www.ClinicalTrials.gov as #NCT00222027 and #NCT00327678, and as #FRALLE 2000T trial.

PHF6-altered T-ALL Harbor Epigenetic Repressive Switch at Bivalent Promoters and Respond to 5-Azacitidine and Venetoclax.

PURPOSE: To assess the impact of PHF6 alterations on clinical outcome and therapeutical actionability in T-cell acute lymphoblastic leukemia (T-ALL). EXPERIMENTAL DESIGN: We described PHF6 alterations in an adult cohort of T-ALL from the French trial Group for Research on Adult Acute Lymphoblastic Leukemia (GRAALL)-2003/2005 and retrospectively analyzed clinical outcomes between PHF6-altered (PHF6ALT) and wild-type patients. We also used EPIC and chromatin immunoprecipitation sequencing data of patient samples to analyze the epigenetic landscape of PHF6ALT T-ALLs. We consecutively evaluated 5-azacitidine efficacy, alone or combined with venetoclax, in PHF6ALT T-ALL. RESULTS: We show that PHF6 alterations account for 47% of cases in our cohort and demonstrate that PHF6ALT T-ALL presented significantly better clinical outcomes. Integrative analysis of DNA methylation and histone marks shows that PHF6ALT are characterized by DNA hypermethylation and H3K27me3 loss at promoters physiologically bivalent in thymocytes. Using patient-derived xenografts, we show that PHF6ALT T-ALL respond to the 5-azacytidine alone. Finally, synergism with the BCL2-inhibitor venetoclax was demonstrated in refractory/relapsing (R/R) PHF6ALT T-ALL using fresh samples. Importantly, we report three cases of R/R PHF6ALT patients who were successfully treated with this combination. CONCLUSIONS: Overall, our study supports the use of PHF6 alterations as a biomarker of sensitivity to 5-azacytidine and venetoclax combination in R/R T-ALL.

Genetic alterations and MRD refine risk assessment for KMT2A-rearranged B-cell precursor ALL in adults: a GRAALL study.

KMT2A-rearranged (KMT2A-r) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is widely recognized as a high-risk leukemia in both children and adults. However, there is a paucity of data on adults treated in recent protocols, and the optimal treatment strategy for these patients is still a matter of debate. In this study, we set out to refine the prognosis of adult KMT2A-r BCP-ALL treated with modern chemotherapy regimen and investigate the prognostic impact of comutations and minimal residual disease (MRD). Of 1091 adult patients with Philadelphia-negative BCP-ALL enrolled in 3 consecutive trials from the Group for Research on Adult Acute Lymphoblastic Leukemia (GRAALL), 141 (12.9%) had KMT2A-r, with 5-year cumulative incidence of relapse (CIR) and overall survival (OS) rates of 40.7% and 53.3%, respectively. Molecular profiling highlighted a low mutational burden in this subtype, reminiscent of infant BCP-ALL. However, the presence of TP53 and/or IKZF1 alterations defined a subset of patients with significantly poorer CIR (69.3% vs 36.2%; P = .001) and OS (28.1% vs 60.7%; P = .006) rates. Next, we analyzed the prognostic implication of MRD measured after induction and first consolidation, using both immunoglobulin (IG) or T-cell receptor (TR) gene rearrangements and KMT2A genomic fusion as markers. In approximately one-third of patients, IG/TR rearrangements were absent or displayed clonal evolution during the disease course, compromising MRD monitoring. In contrast, KMT2A-based MRD was highly reliable and strongly associated with outcome, with early good responders having an excellent outcome (3-year CIR, 7.1%; OS, 92.9%). Altogether, our study reveals striking heterogeneity in outcomes within adults with KMT2A-r BCP-ALL and provides new biomarkers to guide risk-based therapeutic stratification.

Have we made progress in taking care of adolescents and young adults with cancer? Results of a European multi-professional survey.

BACKGROUND: It is well documented that traditional health care models do not meet the specific needs of Adolescents and Young Adults (AYA) cancer patients. METHODS: We explore a map of the development of age-specific AYA cancer care across Europe, from the perspective of healthcare professionals with an interest in AYA care, in order to understand the specific challenges and map progress over time. An on-line survey was developed by international professional cancer organisations. RESULTS: We had 377 respondents from 60 countries. The majority of respondents were physicians 298 (79%), a minority of survey respondents (39, 10.4%) work exclusively with AYA patients, most respondents declared substantial and routine clinical service collaborations to provide care and treatment to AYA with cancer. Policy for the multidisciplinary management of AYA cancer patients commonly appears in Europe now, and was reported by 234 (78.52%) respondents. Specific professional training for AYA cancer care is not uniformly available. CONCLUSION: There is considerable opportunity for many organisations to work together in raising the profile of AYA cancer related issues, in providing education and in encouraging research and collaboration.

First-line second generation tyrosine kinase inhibitors in patients with newly diagnosed accelerated phase chronic myeloid leukemia.

Accelerated phase (AP) CML at onset and have poorer prognosis than CP-CML. We hypothesize that off-license use of second generation TKI (TKI2) as front-line therapy might counterbalance this poor prognosis, with limited toxicity. In "real-life" conditions, newly diagnosed patients meeting the ELN cytological criteria for AP-CML or harboring ACA and treated with first-line TKI2 were included in this retrospective multicenter observational study. We enrolled 69 patients [69.5 % male, median age 49.5 years, median follow-up 43.5 months], segregated into hematologic AP [HEM-AP (n = 32)] and cytogenetically defined AP [ACA-AP (n = 37)]. Hematologic parameters were worse in HEM-AP [spleen size (p = 0.014), PB basophils (p < .001), PB blasts (p < .001), PB blasts+promyelocytes (p < .001), low hemoglobin levels (p < .001)]. Dasatinib was initiated in 56 % patients in HEM-AP and in 27 % in ACA-AP, nilotinib in 44 % and 73 % respectively. Response and survival do not differ, regardless of the TKI2: 81 % vs 84.3 % patients achieved CHR, 88 % vs 84 % CCyR, 73 % vs 75 % MMR respectively. The estimated 5-year PFS 91.5 % (95%CI: 84.51-99.06 %) and 5-year OS 96.84 % (95%CI: 92.61-100 %). Only BM blasts (p < 0.001) and BM blasts+promyelocytes (p < 0.001) at diagnosis negatively influenced OS. TKI2 as front-line therapy in newly diagnosed AP-CML induce excellent responses and survival, and counterbalance the negative impact of advanced disease phase.

Impact on Outcome of Minimal Residual Disease after Hematopoietic Stem Cell Transplantation with Fludarabine, Amsacrine, and Cytosine Arabinoside-Busulfan Conditioning: A Retrospective Monocentric Study.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) after conditioning with a sequential association of fludarabine, amsacrine, and cytosine arabinoside (FLAMSA) followed by a reduced-intensity conditioning regimen has emerged for patients with high-risk acute myeloid leukemia (AML), especially in refractory or relapsing patients. Here we aimed to address retrospectively the impact of pretransplantation minimal residual disease (MRD) by flow cytometry on the outcomes of high-risk AML patients who underwent allo-HSCT after sequential FLAMSA-busulfan (FLAMSA-Bu)-based conditioning regimens. We included 165 high-risk AML patients who underwent transplantation after FLAMSA-BU in this retrospective single-center "real life" study. All patients received in vivo T cell depletion with antithymocyte globulin (5 mg/kg). MRD detection was based on a leukemia-associated immunophenotype using the European LeukemiaNet recommendations, with a threshold of .1%. Univariate and multivariate analyses were performed using R version 4.1.1 (R Foundation for Statistical Computing, Vienna, Austria). With a median follow-up of 4.0 years post-transplantation, the median overall survival (OS) was 54.9 months. Overall, 41 patients (24.8%) relapsed post-transplantation, with a resulting cumulative incidence of relapse (CIR) of 26.7% at 2 years and 34.0% at 5 years. Detectable MRD preceding allo-HSCT and refractory status were associated with worse median OS and CIR rates compared with patients without detectable MRD; however, OS was not significantly different between pre-HSCT MRD-positive and refractory patients (median, .7 year versus 2.0 years; P = .3). Conversely, pre-HSCT MRD negativity was associated with a reduced 2-year CIR. Neither European LeukemiaNet risk stratification nor age had a significant influence on OS. In the multivariate analysis, only pre-HSCT MRD positivity and lower conditioning regimen intensity were significantly associated with a poorer OS. The cumulative incidence of extensive chronic graft-versus-host disease at 2 years was 26.15%. The estimated nonrelapse mortality (NRM) of the entire cohort at 2 years was 23.1%, with age and unrelated donor identified as risk factors for higher NRM. Our data ahow that FLAMSA-Bu conditioning did not reverse the pejorative effect of detectable pre-HSCT MRD, suggesting that such patients should be offered alternative strategies before HSCT to reach deeper remission.

Distinct Immune Reconstitution Profiles Captured by Immune Functional Assays at 6 Months Post Allogeneic Hematopoietic Stem Cell Transplantation.

Immune reconstitution after allogeneic-hematopoietic-stem-cell transplantation (allo-HSCT) is a complex and individual process. In this cross-sectional study, whole-blood (WB) immune functional assay (IFA) was used to characterize immune function by assessing immune-related gene/pathway alterations. The usefulness of this tool in the context of infection, 6 months after transplantation, was evaluated. Sixty allo-HSCT recipients at 6 months after transplantation and 10 healthy volunteers (HV) were included. WB was stimulated in standardized TruCulture tubes using lipopolysaccharides and Staphylococcal enterotoxin B. Gene expression was quantified using a custom 144-gene panel using NanoString nCounter technology and analyzed using Ingenuity Pathway Analysis. The relationships between immune function and clinical characteristics, immune cell counts, and post-transplantation infections were assessed. Allo-HSCT recipients were able to activate similar networks of the innate and adaptive immune response compared to HV, with, nevertheless, a lower intensity. A reduced number and a lower expression of genes associated with immunoregulatory and inflammatory processes were observed in allo-HSCT recipients. The use of immunosuppressive treatments was associated with a protracted immune reconstitution revealed by transcriptomic immunoprofiling. No difference in immune cell counts was observed among patients receiving or not receiving immunosuppressive treatments using a large immunophenotyping panel. Moreover, the expression of a set of genes, including CCL3/CCL4, was significantly lower in patients with Herpesviridae reactivation (32%, 19/60), which once again was not identified using classical immune cell counts. Transcriptional IFA revealed the heterogeneity among allo-HSCT recipients with a reduced immune function, a result that could not be captured by circulating immune cell counts. This highlights the potential added value of this tool for the personalized care of immunocompromised patients.

CNS Involvement at Initial Diagnosis and Risk of Relapse After Allogeneic HCT for Acute Lymphoblastic Leukemia in First Complete Remission.

Outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) for adult acute lymphoblastic leukemia (ALL) have improved over time. Studies have shown that total body irradiation (TBI) is the preferable type of myeloablative conditioning (MAC). However, outcomes based on central nervous system (CNS) involvement, namely CNS-positive versus CNS-negative, have not been compared. Here, we evaluated outcomes of 547 patients (CNS-positive = 96, CNS-negative = 451) who were allografted in the first complete remission (CR1) between 2009 and 2019. Primary endpoint was leukemia-free survival (LFS). Median follow-up was not different between the CNS-positive and CNS-negative groups (79 versus 67.2 months, P = 0.58). The CNS-positive group were younger (median age 31.3 versus 39.7 years, P = 0.004) and were allografted more recently (median year 2012 versus 2010, P = 0.003). In both groups, MAC was the preferred approach (82.3% versus 85.6%, P = 0.41). On multivariate analysis, the CNS-positive group had higher incidence of relapse (RI) (hazard ratio [HR] = 1.58 [95% confidence interval (CI) = 1.06-2.35], P = 0.025), but no adverse effect on LFS (HR = 1.38 [95% CI = 0.99-1.92], P = 0.057) or overall survival (OS) (HR = 1.28 [95% CI = 0.89-1.85], P = 0.18). A subgroup multivariate analysis limited to CNS-positive patients showed that a TBI-based MAC regimen resulted in better LFS (HR = 0.43 [95% CI = 0.22-0.83], P = 0.01) and OS (HR = 0.44 [95% CI = 0.21-0.92], P = 0.03) and lower RI (HR = 0.35 [95% CI = 0.15-0.79], P = 0.01). Another subgroup analysis in CNS-negative patients showed that MAC-TBI preparative regimens also showed a lower RI without a benefit in LFS or OS. While a MAC-TBI allo-HCT regimen may not be suitable to all, particularly for older patients with comorbidities, this approach should be considered for patients who are deemed fit and able to tolerate.

High tumor burden before blinatumomab has a negative impact on the outcome of adult patients with B-cell precursor acute lymphoblastic leukemia. A real-world study by the GRAALL.

Blinatumomab is a bispecific T-cell engager approved for B-cell precursor acute lymphoblastic leukemia (B-ALL) with persistent minimal residual disease (MRD) or in relapse. The prognostic impact of tumor load has been suggested before other immunotherapies but remains poorly explored before blinatumomab. We retrospectively analyzed the outcome of 73 patients who received blinatumomab either in first complete remission (CR) with MRD (n=35) or at relapse (n=38). Among MRD patients, 91% had MRD >0.01% before blinatumomab, and 89% achieved complete MRD response after blinatumomab. High pre-blinatumomab MRD levels were associated with shorter relapse-free survival (P=0.049) and overall survival (OS) (P=0.011). At 3 years, OS was 33%, 58% and 86% for pre-blinatumomab MRD >1%, between MRD 0.1- 1% and <0.1% respectively. Among relapsed patients, 23 received blinatumomab with overt relapse and 15 were in complete response (CR) after bridging chemotherapy. At 3 years, overall CR rate was 68% and complete MRD response rate was 84%. Patients who directly received blinatumomab had shorter relapse-free survival (P=0.033) and OS (P=0.003) than patients bridged to blinatumomab. Three-year OS was 66% in the latter group compared to 16% in the former group. Our observations suggest that pre-blinatumomab tumor burden should help to design more tailored strategies including tumor load reduction in relapsed patients.

Class I/Class II HLA Evolutionary Divergence Ratio Is an Independent Marker Associated With Disease-Free and Overall Survival After Allogeneic Hematopoietic Stem Cell Transplantation for Acute Myeloid Leukemia.

Class I Human Leukocyte Antigen (HLA) evolutionary divergence (HED) is a metric which reflects immunopeptidome diversity and has been associated with immune checkpoint inhibitor responses in solid tumors. Its impact and interest in allogeneic hematopoietic stem cell transplantation (HCT) have not yet been thoroughly studied. This study analyzed the clinical and immune impact of class I and II HED in 492 acute myeloid leukemia (AML) recipients undergoing HCT. The overall cohort was divided into a training (n=338) and a testing (n=132) set. Univariate cox screening found a positive impact of a high class I HED and a negative impact of a high class II HED on both disease-free (DFS) and overall survival (OS). These results were combined in a unique marker, class I/class II HED ratio, and assessed in the testing cohort. The final multivariate cox model confirmed the positive impact of a high versus low class I/class II HED ratio on both DFS (Hazard Ratio (HR) 0.41 [95% CI 0.2-0.83]; p=0.01) and OS (HR 0.34 [0.19-0.59]; p<0.001), independently of HLA matching and other HCT parameters. No significant association was found between the ratio and graft-versus-host disease (GvHD) nor with neutrophil and platelet recovery. A high class I HED was associated with a tendency for an increase in NK, CD8 T-cell, and B cell recovery at 12 months. These results introduce HED as an original and independent prognosis marker reflecting immunopeptidome diversity and alloreactivity after HCT.

20-Year Steady Increase in Survival of Adult Patients with Relapsed Philadelphia-Positive Acute Lymphoblastic Leukemia Post Allogeneic Hematopoietic Cell Transplantation.

PURPOSE: Relapse after allogeneic hematopoietic cell transplantation (allo-HCT) remains the first cause of transplant failure in patients with Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL). In other hematologic malignancies, therapeutic advances resulted in significant improvement over time in survival of patients relapsing after transplant. EXPERIMENTAL DESIGN: We compared outcomes at European Society for Blood and Marrow Transplantation (EBMT) participating centers of 899 adult patients with Ph+ ALL who relapsed between 2000 and 2019 after allo-HCT performed in first complete remission. Median follow-up for alive patients was 56 months. RESULTS: Overall, 116 patients relapsed between 2000 and 2004, 225 between 2005 and 2009, 294 between 2010 and 2014, and 264 between 2015 and 2019. Patient and transplant characteristics were similar over the four time periods except for a progressive increase in unrelated donors, peripheral blood stem cells, reduced intensity conditioning, and in vivo T-cell depletion and a progressive decrease in total body irradiation. The 2-year overall survival (OS) after relapse increased from 27.8% for patients relapsing between 2000 and 2004 to 54.8% for 2015 and 2019 (P = 0.001). A second allo-HCT within 2 years after relapse was performed in 13.9% of patients resulting in a 2-year OS of 35.9%. In multivariate analysis, OS from relapse was positively affected by a longer time from transplant to relapse and the year of relapse. CONCLUSIONS: We observed a major progressive improvement in OS from posttransplant relapse for patients with Ph+ ALL over the years, likely multifactorial including transplant-related factors, posttransplant salvage, and improvement in supportive care. These large-scale real-world data can serve as a benchmark for future studies in this setting. See related commentary by Gale, p. 813.