High-risk Acute Lymphoblastic Leukemia Research Articles

Higher Efficacy of TBI + Cyclophosphamide Than TBI + Fludarabine As Conditioning Prior to Allogeneic Hematopoietic Cell Transplantation for Acute Lymphoblastic Leukemia: An Analysis By the Acute Leukemia Working Party of the EBMT

BACKGROUNDAllogeneic hematopoietic cell transplantation (allo-HCT) is a standard of care for adults with high-risk acute lymphoblastic leukemia (ALL) in first or subsequent complete remission (CR). Myeloablative total body irradiation (TBI) combined with cyclophosphamide (Cy) is the most frequently used conditioning regimen. In order to reduce toxicity Cy may be replaced by fludarabine (Flu). The goal of this registry-based, retrospective study was to compare outcomes of allo-HCT following TBI/Cy vs. TBI/Flu conditioning. PATIENTS AND METHODSIncluded in the analysis were 2255 patients aged 18-65 years, treated with allo-HCT from either a matched sibling (43%) or unrelated (57%) donor in CR1 (83%) or CR2 (17%), between the years 2010-2020. Patients with Ph(-) B-ALL, Ph(+) B-ALL, and T-ALL were represented in equal proportions. TBI 12Gy + Cy was used in 2105 cases while TBI 12Gy + Flu was administered to 150 patients. Patients treated with TBI/Flu were significantly older (median 35 years vs. 33 years, p=0.006), with poorer Karnofsky performance score (<90, 27% vs. 20%, p=0.03), more frequently transplanted from unrelated donors (71% vs. 57%, p=0.0007) with less frequently use of bone marrow as a source of stem cells (5% vs. 21%, p<0.0001), and in more recent year (median 2018 vs. 2015, p<0.0001). RESULTSEngraftment rate was 99% for both TBI/Cy and TBI/Flu patients. In a univariate analysis the use of TBI/Cy as compared to TBI/Flu was associated with a tendency to reduced incidence of relapse (24% vs. 29% at 2 years, p=0.1), increased incidence of grade 2-4 acute graft versus host disease (GVHD, 35.5% vs. 28%, p=0.08) and improved leukemia-free survival (LFS, 62% vs. 57%, p=0.18). The rates and causes of non-relapse mortality (NRM) did not differ significantly between the two conditioning groups. In a multivariate model adjusted for other prognostic factors, TBI/Cy conditioning was associated with reduced risk of relapse (HR=0.69, p=0.049) and increased risk of grade 2-4 acute GVHD (HR=1.57, p=0.03) without significant effect on other transplantation outcomes.An additional analysis was performed with TBI/Cy treated patients (n=132) matched strictly to those treated with TBI/Flu (n=132) in terms of disease subtype, disease status and donor type with the nearest neighbor for patient age, patient and donor sex, in vivo T-cell depletion, Karnofsky score and source of stem cells; the use of TBI/Cy as compared to TBI/Flu was associated with significantly reduced rate of relapse (18% vs. 30% at 2 years, p=0.015) and a tendency to an improved LFS (65% vs. 59%, p=0.07) and overall survival (OS, 73% vs. 68%, p=0.16) without effect on NRM and GVHD. CONCLUSIONSThe use of myeloablative TBI/CY as conditioning prior to allo-HCT for adult patients with ALL in CR1 or CR2 is associated with stronger anti-leukemic effect leading to significantly lower relapse rate compared to TBI/Flu and therefore should be likely considered a preferable regimen. DisclosuresGiebel: Janssen: Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy, Honoraria, Speakers Bureau. Labopin: Jazz Pharmaceuticals: Honoraria. Socie: Alexion: Research Funding. Yakoub-Agha: Jazz Pharmaceuticals: Honoraria. Kröger: Novartis: Research Funding; Riemser: Honoraria, Research Funding; Sanofi: Honoraria; Neovii: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Gilead/Kite: Honoraria; Celgene: Honoraria, Research Funding; AOP Pharma: Honoraria. Forcade: Novartis: Consultancy, Other: Travel Support, Speakers Bureau; Gilead: Other: Travel Support, Speakers Bureau; Jazz: Other: Travel Support, Speakers Bureau; MSD: Other: Travel Support. Huynh: Jazz Pharmaceuticals: Honoraria. Spyridonidis: Menarini: Current Employment. Perić: therakos: Honoraria; servier: Honoraria; MSD: Honoraria; Astellas: Honoraria; NOVARTIS: Honoraria; Abbvie: Honoraria; Pfizer: Honoraria. Mohty: Pfizer: Honoraria; Celgene: Honoraria, Research Funding; Amgen: Honoraria; Astellas: Honoraria; Gilead: Honoraria; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Novartis: Honoraria; Bristol Myers Squibb: Honoraria; Takeda: Honoraria; Sanofi: Honoraria, Research Funding; Adaptive Biotechnologies: Honoraria.

Predictive Factors and Outcomes after Allogeneic Stem-Cell Transplantation for Adults with Acute Lymphoblastic Leukemia in Brazil

Introduction: Allogeneic stem-cell transplantation (HSCT) remains a potentially curative approach for acute lymphoblastic leukemia (ALL), especially for high-risk patients and those with relapsed/refractory disease, although its efficacy is offset by a not negligible toxicity. Adult patients with ALL fare worse in developing countries with low data about the HSCT in this setting. In this study, we aim to describe outcomes and examine risk factors for overall survival (OS), disease-free survival (DFS), cumulative incidence of relapse (CIR), non-relapse mortality (NRM) and graft-versus-host disease (GVHD) after HSCT for ALL in Brazilian centers.Methods: This is a retrospective registry study. Patients with ALL or ambiguous lineage leukemia above 16 years who underwent a first HSCT in 5 Brazilian centers between January 2007 and December 2017 were included. Kaplan-Meier method and competing risk analysis were used. Multivariable analysis (MVA) was performed using Cox regression and the Akaike's information criteria was used for model selection. Cut-offs for continuous variables were calculated through “findcut” R function. Center effect was evaluated by using frailty model.Results: Overall, 275 patients were included with a median age of 31y (range, 16-65). Philadelphia chromosome was found in 35%. Baseline characteristics are summarized in Table 1. Matched sibling donor (MSD), matched unrelated donor (MUD), mismatched unrelated donor (MMUD), haploidentical donor and umbilical cord were reported in 53%, 19%, 9%, 19%, and 5%, respectively. Total body irradiation (TBI) was used in 67% of myeloablative HSCT. Median time to HSCT in CR1 was 7.8 months. Engraftment failure rate was 1.5%. Median follow-up time was 6.4 y. Cumulative incidence of acute grade II-IV and chronic GVHD were 54.2% and 26.2%, respectively. In MVA, the use of MUD (HR=2.3) and increased donor age (HR=1.02) were associated with GVHD. Five-year CIR was 28.1% (95% CI 22.9-33.6) and 5-y NRM was 34.1% (95% CI 28.4-39.8). At D+100, NRM incidence was 22.6%. Central nervous system involvement at the diagnosis (HR=2.2), and disease status (HR 1.8 for CR2+, and HR 7.9 for refractory) increased relapse incidence, whereas the use of peripheral blood graft (HR=0.51) and haploidentical donor (HR=0.4) significantly decreased relapse incidence. In MVA, NRM was increased by patient's age (HR=1.04), refractory status (HR=4.2), MUD (HR=3.8) and donor age (HR=1.02). Center effect was significantly associated with relapse and NRM. Five-year OS and DFS were 40.7% (95% CI 35.1-47.1) and 37.8% (95% CI-32.3-44.1), respectively (Figure 1). Patient's age, donor age and disease status were independently associated with OS and DFS (Table 2). When GVHD (as a time-dependent variable) was introduced in the MVA for OS and DFS, it was associated with decreased OS (HR 4.2, p<0.001) but not with DFS. Pre-HSCT positivity of minimal residual disease (>0.01%) was associated with worse DFS in univariate analysis (HR=1.47) in available cases.Conclusions: This is the largest series of ALL adults receiving HSCT from Brazil. While OS and DFS were similar to published data, NRM was higher. Patient's age and donor age outweighed donor type or graft source in our analysis. Interestingly, haploidentical HSCT related to lower CIR, whereas the use of MUD was associated with higher NRM and GVHD rates. These results impact on donor selection strategy in our country, aiming to timely offer HSCT for high-risk ALL patients in our setting. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Association between Sociodemographic, Clinical and Immunophenotypic Variables with Disease Relapse and Survival at 12 Months, in Patients with B-Cell Acute Lymphoblastic Leukemia Treated at a Colombian University Hospital

INTRODUCTIONAcute lymphoblastic leukemia (ALL) is a clonal hematopoietic disorder that originates from B or T lymphoid progenitors. It affects more frequently children, but prognosis is worse in adults. ALL has a high incidence in Hispanics (Swords R et al. Blood Cancer J. 2016) and is important to identify baseline clinical, sociodemographic, and cytogenetic characteristics in these patients that are relevant for relapse free and overall survival. Reports of Hispanic patients with ALL outsides of the U.S.A are scare but are important to further characterize the impact of this disease in minority populations.OBJETIVETo describe the association between sociodemographic, clinical and immunophenotypic variables with 12-month relapse free survival (RFS) and overall survival (OS) in patients diagnosed and treated for ALL in a Colombian university hospital (FOSCAL).MATERIALS AND METHODSThis is a descriptive observational cohort study that included patients older than 18 years with a confirmed diagnosis of ALL treated in a tertiary university hospital between 2013-2020 and that had at least 12 months follow-up after starting treatment. Baseline sociodemographic, clinical, laboratory and immunophenotypic data were collected. Bivariate analyses of both relapse and mortality cumulative incidences at 12 months, with relative risks (RR) and their 95% Confidence intervals were performed, using either chi-square or Fischer exact test when needed. In a second term, bivariate survival analyses through Kaplan-Meier survival function and Hazard ratios were evaluated, using Cox proportional hazards as the main statistical test.RESULTSAmong 128 of include patients, the median age at diagnosis was 34 years (range 0-89 years), 54% were men, 6.2% had type 2 Diabetes Mellitus (T2DM), most had an ECOG PS of 0 (72.7%), 31.8% had splenomegaly, 12% had hepatomegaly and 47% presented without organomegalies. The proportion of patients with overweight and obesity were 26.3% and 22.2% respectively. At diagnosis 80.5% and 8.8% of patients had high risk and standard risk ALL, respectively Forty-eight patients had a FAB classification with 58% being ALL-2 and most of the were unclassified. Most cases (81%) had B-cell immunophenotype, with 55% being pre-B-cell and 32% mature B-cell. Twelve percent of patients were Ph+ B-ALL. At 12 months, the proportion of mortality was 34.4%. Most of the patients (83%) did not have major co-morbidities, however patients with T2DM had a significantly inferior survival at 12 months, HR: 3.68 (95%CI 1.54-8.8 P=0.003), as patients older than 35 years (HR: 2.15, 95%CI: 1.14-4.0, P=0.017) (Table 1).CONCLUSIONSColombian patients with B-cell ALL have similar clinical, immunophenotypic and cytogenetic (Ph+ prevalence) characteristics as seen in other international cohorts. In our cohort patients older than 35 years and subjects with T2DM had inferior survival at 1 year. Further analyses of socioeconomic factors, molecular features and response to specific regimens are needed to have a better understanding of Colombian B-ALL patients. [Display omitted] DisclosuresSalazar: Amgen: Research Funding. Peña: Amgen: Research Funding. Sandoval-Sus: BMS: Other: Advisory Board, Speakers Bureau; SeaGen, Janssen, MassiveBio, TG: Other: Advisory Board. Sossa: Amgen: Research Funding.

How Important Are in-Person Clinic Visits during Maintenance Therapy for Pediatric Acute Lymphoblastic Leukemia?

▪BackgroundAcute Lymphoblastic Leukemia (ALL) is the most common cancer seen in the pediatric age group. The treatment consists of an initial intensive phase of chemotherapy followed by a prolonged period of maintenance chemotherapy intended to reduce the risk of relapse. Children are commonly seen in clinic every 4-6 weeks for bloodwork and physical examination during the maintenance phase. The COVID-19 pandemic has prompted consideration of alternative means of providing medical care. The objective of this study was to determine the proportion of in-person clinic visits during ALL maintenance therapy for which the outcome of the physical examination resulted in a change of patient management.MethodsA retrospective chart review of children diagnosed with precursor-B ALL between January 2017 and December 2018, and who were in maintenance therapy between September 2019 and February 2020, was conducted. All routine maintenance visits were reviewed to identify new physical examination findings and patient outcomes and classified as either “could be managed virtually” or “essential in-person visit”. For the latter, a second classification was conducted to distinguish between visits necessitating a change of management versus not.ResultsEighty-five children were diagnosed with precursor B ALL and continued to maintenance treatment during the study period. 10 children were excluded as not meeting the inclusion criteria or not evaluable. Of the remaining 75 children, 54 were male (72%) and 21 female (28%). The median age at diagnosis was 4.83 years (0.73 - 14.8 years). 39 patients (52%) had standard risk ALL, 35 patients (46.7%) had high risk ALL and one patient had Infant ALL (1.3%) A total of 240 routine maintenance visits were included in the final analysis. An abnormal physical exam finding was noted in 20 visits (8.3%) and of these, new findings were noted in 14 (5.8%). 6 visits were classified as essential in-person visits (2 for new bruising, 1 for new limp, 1 for new lymphadenopathy, 1 for acute otitis media, and 1 for new wheezing). Among the 14 visits with new exam findings, only 5 had an impact on patient management and of these, only 2 (0.8%) were classified as obligate in-person visit for requiring immediate management (acute otitis media and wheezing).ConclusionOur results demonstrate that most in-person visits can be provided as virtual visits without affecting patient outcomes. The results of this study provide the foundation for a prospective study that will evaluate the benefits, risks and families' preferences associated with virtual visits and delineate the optimal frequency and timing of in-person clinic visits during ALL maintenance therapy. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Early Hematopoietic Stem Cell Transplantation in the Treatment of High-Risk Infant Leukemia

INTRODUCTIONAcute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) are rare diseases in children less than one and two years old respectively. Infant ALL and AML demonstrates unique biological characteristics associated with aggressive clinical features, i.e. high frequency of KMT2A gene rearrangements, poor response to standard chemotherapy, and thus worse prognosis compared to older children. These patients (pts) are at high risk (HR). Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapy for HR infant leukemia especially in 1 st CR, but proportion of these patients unable to undergo allo-HSCT due to early events, mainly relapse or treatment-related toxicity during initial therapy. We investigated the role of early allo-HSCT from different types of donors. The primary end points were overall survival (OS), transplant-relate mortality (TRM), graft-versus-host disease (GVHD) free, relapse-free survival (GRFS). Secondary end points included neutrophil engraftment and acute and chronic GVHD. MethodsWe included 50 infants with HR ALL (n=10, of with MLLr+ n=6) and AML (n=40, of with MLLr+ n=14) in CR 1. Median age at allo-HSCT 12,5 months old (range from 4 m.o. till 35 m.o.). Median time from diagnosis to allo-HSCT was 9 months (range from 3 till 21). Donor of SCT was: MSD-10% (n=5), MUD-46% (n=23), Haplo-44% (n=22). Majority of patients, 86% received MAC based on busulfan 12-16mg/kg (n=43, including IV busulfan-20pts), 14% (n=7) received RIC based on melphalan 140 mg/m 2. GVHD prophylaxis consisted of PTCy±CNI and m-TOR inhibitor in 62% (n=31), seroprophylaxis±CNI in 38% (n=19). Median follow-up was 64,3 months (range 1-220). Patient data were censored at the time of death or last follow-up. Probabilities of OS and GRFS were estimated using Kaplan-Meier curves. TRM was defined as any death that occurred in the absence of disease relapse; relapse was a competing risk for this event. ResultsEngraftment rate was 82%. Cumulative incidences by day 100 of TRM in Haplo were 2% vs 4% in MSD+MUD (р=0,9). Ten-year rates OS in Haplo and MSD+MUD were 77,3% (±4,7%) vs 78,6% (±9%) respectively (p=0,73). Ten-year GRFS did not differ between two study cohorts being 50% vs 57% for Haplo and MSD+MUD (p=0,76). Clinically significant aGVHD (grades 2-4) after allo-HSCT was observed in 27% (n=6) Haplo and 32% (n=9) MSD+MUD (p=0,77). A total of 12% (n = 6) patients developed severe cGVHD. ConclusionsEarly allogeneic HSCT in 1 st CR from different types of donors, including haploidentical is associated with favorable outcomes in infant acute leukemias. This approach should be evaluated in further controlled clinical studies. DisclosuresKulagin: X4 Pharmaceuticals, Alexion, Apellis, Biocad: Research Funding; Novartis, Generium, Sanofi, Roche, Johnson & Johnson, Pfizer: Speakers Bureau.

Outcomes of Allogeneic Hematopoietic Cell Transplantation in Adults with Ph-like ALL

Outcomes of Allogeneic Hematopoietic Cell Transplantation in Adults with Ph-like ALL

Utilizing Organ-Sparing Marrow Irradiation to Condition Patients Prior to Allogeneic Hematopoietic Cell Transplant with High-Risk Hematologic Malignancies: Results of a Pilot Study

Background: Total body irradiation (TBI) has long been incorporated as part of the conditioning regimen prior to hematopoietic stem cell transplant (HSCT). While the myeloablative TBI conditioning is associated with a lower relapse rate in high risk diseases such as Acute Myeloid Leukemia (AML), Myelodysplastic Syndrome (MDS), and Acute Lymphoblastic Leukemia (ALL), it is also associated with substantial toxicities, and increased NRM so use of this regimen is limited to young patients with excellent performance status. In this study, we used a linac-based volumetric modulated arc therapy (VMAT) technique to deliver standard myeloablative radiation to high risk body sites while sparing radiation sensitive organs (Organ Sparing Marrow Targeted Irradiation, OSMI). We hypothesized that this technique would be feasible and safe in patients who are older or who have higher transplant specific comorbidity index (HCT-CI), typically ineligible for standard TBI conditioning.Methods: This is a single-arm prospective study. Patients from age 18-75 with high risk AML, MDS or ALL were eligible. There are 3 cohorts: (1) age 18-50 with HCT-CI of 3/4; (2) age 51-65 with HCT-CI of ≤ 3; and (3) age 66-75 with HCT-CI of ≤ 2. Patients receive OSMI to a total dose of 1200 cGy delivered twice daily for 6 fractions for a total of 7200 cGy. Clinical tumor volume includes total skeletal bone marrow and any sanctuary or high-risk areas. Graft-versus-host disease (GVHD) prophylaxis originally was tacrolimus and methotrexate. Given high incidence of bacterial infections related to mucositis, prophylaxis was changed to tacrolimus and sirolimus without methotrexate. All patients received Keratinocyte growth factor for prevention of mucositis. The primary objective was to assess feasibility and tolerability of OSMI based HSCT as defined by transplant-related mortality (TRM) at day 30 (D30) as well as rate of grade II/III organ toxicity (defined by Bearman Regimen-Related Toxicities Scale) attributable to conditioning occurring within 30 days.Results: Patient demographics for the 24 patients are shown in Table 1. Median age of recipients was 56.5 years. No graft failures were observed. The most common grade II or III Bearman toxicities include mucositis (grade 2: n=4), and diarrhea (grade 2: n=4). Clinical outcomes are shown in Figure 2. With a median follow-up of 3.3 years, overall survival (OS) and relapse-free survival (RFS) at 2 years was 78% and 74% respectively. Among the 5 patients who were not in complete remission at the time of transplant, 2-year OS and RFS rate was 40%. Incidence of Grades II-IV acute GVHD was 79% and Grades III-IV GVHD was 30%. Relapse incidence was 4% at 2 years. Incidence of Thrombotic microangiopathy by day 100 (TMA) as defined by Jodele's criteria was 17%. Incidence of chronic GVHD was 45% and severe chronic GVHD was 16%. One year non-relapse mortality was 22%, likely due to higher incidence of GVHD.Conclusions: Selected patients who are older or with higher HCT-CI, who are typically not candidates for standard TBI conditioning, were able to receive a radiation-based myeloablative conditioning regimen with 2 year overall survival rates of 78%. We observed a high incidence of TMA, possibly related to use of tacrolimus and sirolimus as GVHD prophylaxis, and a high incidence of Grade II-IV acute GVHD. Low incidence of relapse was observed. OSMI-based conditioning was feasible in this cohort with median age of 56 years and was associated with low rates of relapse and favorable 2 year overall survival. [Display omitted] DisclosuresVasu: Boehringer Ingelheim: Other: Travel support; Seattle Genetics: Other: travel support; Kiadis, Inc.: Research Funding; Omeros, Inc.: Membership on an entity's Board of Directors or advisory committees. Jaglowski: Novartis: Consultancy, Research Funding; Takeda: Consultancy; Juno: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; CRISPR Therapeutics: Consultancy. Brammer: Seattle Genetics: Speakers Bureau; Celgene: Research Funding; Kymera Therapeutics: Consultancy. de Lima: Incyte: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Miltenyi Biotec: Research Funding.

Superior Overall Survival with Blinatumomab Versus Chemotherapy As Pre-Transplant Consolidation Treatment in Children with High-Risk First-Relapse B-Cell Precursor Acute Lymphoblastic Leukemia (B-ALL): Longer Follow-up (FU) of a Phase 3 Randomized Controlled Trial (RCT)

Superior Overall Survival with Blinatumomab Versus Chemotherapy As Pre-Transplant Consolidation Treatment in Children with High-Risk First-Relapse B-Cell Precursor Acute Lymphoblastic Leukemia (B-ALL): Longer Follow-up (FU) of a Phase 3 Randomized Controlled Trial (RCT)

Outcome of Donor-Derived Tumor Associated Antigen-Specific T Cell Therapy in Patients with High-Risk or Relapsed Acute Leukemia Post Allogeneic BMT

Background: Patients with hematologic malignancies relapsing after allogeneic blood or marrow transplantation (BMT) have limited response to conventional salvage therapies with an expected 1-year overall survival (OS) of <20%. Current strategies to treat relapsed hematopoietic cancer after BMT, such as chemotherapy and donor lymphocyte infusions (DLI) to enhance the immunologic graft-versus-leukemia (GVL) effect, have low efficacy and are associated with graft-versus-host disease (GVHD). An alternative strategy to boost the GVL effect is to infuse donor-derived T-cells targeting tumor-associated antigen (TAA) peptides as circulating TAA-specific T-cells are associated with maintenance of remission post-BMT. In this phase-I study, we evaluated the safety and clinical outcomes following administration of a novel T-cell therapeutic targeting three TAAs, WT1, PRAME and survivin in patients with acute leukemia who relapsed or were at high-risk of relapse after allogeneic BMT.Methods: Lymphocytes obtained from the BMT donor were manufactured to target TAAs; WT1, PRAME and survivin, which are over-expressed and immunogenic in most hematologic malignancies. Patients received TAA-T infusions at doses of 0.5-4x10 7/m 2. Patients were evaluated for acute infusion-related toxicity, cytokine release syndrome (CRS), neurotoxicity, GVHD and monitored for clinical response post-infusion. T-cell receptor sequencing was conducted on the TAA-T product and the recipients' peripheral blood prior to and post-infusion to monitor persistence and expansion of the product.Results: Twenty-three BMT recipients with relapsed/refractory (n=11) and/or high-risk (n=12) acute myeloid leukemia (n=20) and acute lymphoblastic leukemia (n=3) were infused post-transplant. No patient developed CRS or neurotoxicity, and only one patient developed grade III GVHD. Of the patients who relapsed post-BMT and received bridging therapy, the majority (n=9/11) achieved complete hematologic remission before receiving TAA-T. Relapsed patients exhibited a 1-year OS of 36% and 1-year leukemia-free survival of 27.3% post-TAA-T (Figure 1A and B). The poorest prognosis patients (relapsed less than 6 months after transplant) exhibited a 1-year OS of 42.8% post-relapse (n=7) (Figure 1C). Median survival was not reached for high-risk patients who received pre-emptive TAA-T post-transplant (n=12) with eight of the nine (88.9%) evaluable patients at 1-year post-infusion remaining alive (Figure 1B). Of those, five (62.5%) were alive and in continued remission at the time of submission. Evaluation of unique T-cell receptor clonotypes (present in the product but not the recipient prior to infusion) demonstrated expansion and persistence in patients up to 1-year post-infusion (Figure 1D).Conclusions: Although as a Phase-I study, concomitant anti-leukemic therapy was allowed, TAA-T cell therapy was shown to be safe and well-tolerated with sustained remissions observed in high-risk and relapsed patients. Moreover, adoptively transferred TAA-T expanded in vivo as detected by T-cell receptor V-beta (TCRVb) sequencing persisted up to at least 1-year post-infusion (Figure 1D). (ClinicalTrials.gov numbers, NCT002203902) [Display omitted] DisclosuresCruz: Mana Therapeutics: Consultancy, Current holder of individual stocks in a privately-held company, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Catamaran Bio: Consultancy, Patents & Royalties, Research Funding. Hanley: Mana Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellevolve: Consultancy; Maxcyte: Membership on an entity's Board of Directors or advisory committees. Bollard: SOBI: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cabaletta Bio: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Catamaran Bio: Membership on an entity's Board of Directors or advisory committees; Cellectis: Honoraria, Membership on an entity's Board of Directors or advisory committees; ROCHE: Consultancy, Honoraria; Repertoire Immune Medicines: Current equity holder in publicly-traded company; Neximmune: Current equity holder in publicly-traded company; Mana Therapeutics: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

Successful Outpatient Administration of Blinatumomab Infusion in Pediatric Patients with Acute Lymphoblastic Leukemia

Introduction:Acute lymphoblastic leukemia (ALL) is the most common type of pediatric cancer. Unfortunately, approximately 15% of children with high-risk B-cell ALL (B-ALL) relapse after frontline chemotherapy. Treatment of relapsed/refractory B-ALL is still challenging, and more effective novel therapies are urgently warranted. Blinatumomab, a first in class bispecific antibody therapeutic, has demonstrated superiority compared to standard chemotherapy in patients with B-ALL and has a manageable toxicity profile. Blinatumomab functions by binding to CD19 expressed on B-cells and CD3 expressed on T-cells, resulting in T-cell-mediated killing of CD19-positive cells common in B-cell malignancies.Despite remarkable efficacy and a manageable toxicity profile compared to standard-of-care chemotherapy, blinatumomab poses unique healthcare system challenges related to preparation, administration, toxicity monitoring, and medication error prevention. The drug's success in helping patients achieve complete remission relies on its continuous and uninterrupted administration. In order to ensure that it is delivered in the safest and most effective manner, education on its unique logistical and administration challenges is imperative.Objectives:The primary objective of this study is to describe and share the 6 years of institutional experience on the outpatient delivery of blinatumomab for the management of pediatric patients with B-ALL as per Children's Oncology Group protocols, as well as to retrospectively analyze the safety of this novel 28-day home-based therapy.Methods:A multidisciplinary team composed of physicians, nurses, and pharmacists was created to address administration challenges associated with blinatumomab infusions. Although blinatumomab requires a 28-day continuous infusion, it is not necessary for patients to remain hospitalized for the entire cycle. To ensure tolerability prior to discharge, patients are monitored closely during the first 3 days of Cycle 1 and 2 days of Cycle 2 for signs of cytokine release syndrome and neurological toxicities. Once discharged, they are seen every 96/72 hours for bag changes in either an outpatient hematology/oncology unit or by home health for those off study.Results:A total of 16 patients were treated with blinatumomab between May 2015 and June 2021; 10 were newly diagnosed and 6 were in first relapse. Of the 26 total infusions, 24 were successfully completed without significant adverse reactions. Two patients treated for relapsed disease had to discontinue therapy; one experienced neurotoxicity within 72 hours of blinatumomab infusion initiation and the other developed refractory disease and was switched to another protocol. No adverse events were observed in the home setting.Discussion:The team was successfully able to transform the original inpatient-only blinatumomab protocol to the outpatient setting. Retrospective analysis over 6 years demonstrates a clinically significant reduced rate of complications of blinatumomab administration in comparison to previous reports (Amicucci et al. 2021), which can be attributed to careful multidisciplinary team planning and delivery. This study confirms the feasibility of a home-based continuous blinatumomab infusion without adverse effects on safety. Additionally, this outpatient protocol leads to cost savings associated with reduced length of stay and an overall improved quality of life for pediatric patients able to receive therapy at home with their caregivers. DisclosuresNo relevant conflicts of interest to declare.

A Single-Arm, Open-Label Phase 2 Pilot Study of Vyxeos (CPX-351) in Adults with Relapsed or Refractory Acute Lymphoblastic Leukemia

Introduction:Vyxeos® is a liposomal formulation employing a 1:5 molar ratio of daunorubicin:cytarabine. Clinical trials in high risk acute myeloid leukemias demonstrated a significant benefit in CR rates and median OS, culminating in FDA approval August 2017. Emerging pediatric data suggest this benefit may extend to acute lymphoblastic leukemia (ALL). The following pilot trial was performed to better understand the activity and toxicity profile in adults with relapsed and refractory ALL.Methods:Adults with ALL or mixed phenotype leukemia were eligible if >5% lymphoblasts and/or extramedullary disease >1x1cm. Induction consisted of Vyxeos 100 units/m2 on days 1, 3 and 5. Those with clinical benefit could receive up to 3 cycles of consolidation delivered at 65 units/m2 on days 1 & 3 after recovery of neutrophils (>500 cells/uL) and platelets (>50,000 cells/uL).Response:11 patients (pts) have been treated to date, with median age of 39y (22-74y), 9 male, and 3 Caucasian. Six pts had B-ALL, including 1 B-myeloid. Four of 5 T-ALL pts had early T-cell precursor (ETP) phenotype. NGS was available in 9 pts, and included TP53 mutation (n=4), and PH-like changes (n=2). Median prior lines of therapy was 3, with 7 pts showing primary refractory disease. Prior blinatumomab, inotuzumab, CAR-T cell therapy, and allogeneic transplant were noted in 5, 2, 1, and 3 pts.Pancytopenia was uniform during induction, with febrile neutropenia noted in 9 pts. One pt passed from pneumonia after moving to comfort measures in lieu of intubation 20 days after Vyxeos, and is non-evaluable for response. A second pt developed grade 3 sepsis. The remainder of infections were grade 1-2. One pt had grade 3 gastrointestinal bleed, and 3 pts had grade 1 spontaneous subdural bleeding. One pt developed recurrent pericarditis in setting of anterior mediastinal mass. One case of veno-occlusive disease was observed in a pt with prior allogeneic transplant and inotuzumab. Median time to ANC recovery was 33.5 days among 10 evaluable pts. Two pts with refractory disease failed to recover platelets; among the remaining pts, median time to platelet recovery was 30.5 days. Adverse events were uncommon during consolidation, and include foot cellulitis and myopericarditis, each in 1 pt.Among 10 evaluable pts, 3 achieved CR/CRi, including 2 ETP T-ALL and one B-ALL. Two pts with TP53 mutation demonstrated >50% blast reduction with hematologic recovery, allowing for prolonged time to subsequent therapy. Four pts received 1-3 cycles consolidation. One pt was bridged to donor leukocyte infusion. Responses were noted in only 2 pts after progression following Vyxeos, highlighting refractory status of those enrolled. Median PFS was 57 days (95%CI: 10, 105), time to next therapy 76 days (95%CI: 47, 105), and OS 223 days (95%CI: 144, 302).ConclusionsVyxeos in high-risk refractory adult ALL was overall well tolerated and active, with median OS of approximately 7.5 months in this pilot trial. Confirmation of benefit in a larger study is warranted, incorporating a second induction course and/or the addition of novel agents to further improve on remission rate and duration of response. DisclosuresShah: Incyte: Research Funding; Jazz Pharmaceuticals: Research Funding; Servier Genetics: Other; BeiGene: Consultancy, Honoraria; Acrotech/Spectrum: Honoraria; Pharmacyclics/Janssen: Honoraria, Other: Expenses; Kite, a Gilead Company: Consultancy, Honoraria, Other: Expenses, Research Funding; Precision Biosciences: Consultancy; Amgen: Consultancy; Novartis: Consultancy, Other: Expenses; Pfizer: Consultancy, Other: Expenses; Bristol-Myers Squibb/Celgene: Consultancy, Other: Expenses; Adaptive Biotechnologies: Consultancy. Chavez: Astra Zeneca: Research Funding; Novartis: Consultancy; Merck: Research Funding; Morphosys: Speakers Bureau; Adaptive Biotech: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Beigene: Speakers Bureau; Kite/Gilead: Consultancy; karyopharm: Consultancy; Epizyme: Speakers Bureau; Abbvie: Consultancy. Sokol: Dren Bio: Membership on an entity's Board of Directors or advisory committees; Kyowa-Kirin: Membership on an entity's Board of Directors or advisory committees. Lancet: Celgene/BMS: Consultancy; Millenium Pharma/Takeda: Consultancy; Daiichi Sankyo: Consultancy; AbbVie: Consultancy; BerGenBio: Consultancy; ElevateBio Management: Consultancy; Agios: Consultancy; Astellas: Consultancy; Jazz: Consultancy. OffLabel Disclosure:Vyxeos is being evaluated in the described trial for the treatment of relapsed or refractory acute lymphoblastic leukemia in adults.

Modeling Relapsed, Refractory Acute Lymphoblastic Leukemia from a Child with Neurofibromatosis

Neurofibromatosis type 1 (NF-1) is an autosomal dominant disorder affecting approximately 1:3000 individuals globally. While approximately 50% are familial, with over 3000 causative germline variants in the neurofibromatosis (NF1) gene identified, the remainder occur sporadically. These mutations lead to haploinsufficiency of NF1 and neurofibromin, a tumor suppressor and important negative regulator of RAS signaling. Children with NF-1 have a higher risk of developing juvenile myelomonocytic leukemia and acute myeloid leukemia, but rarely develop acute lymphoblastic leukemia (ALL).A 9-year-old male presented in 2015 with persistent migratory subcutaneous swellings and multiple bony aches with lytic lesions on bone imaging. He had a high white cell count with eosinophilia (WCC 43.4 x 10 9/L, eosinophils 23.87 x 10 9/L) with no circulating blasts, 10% marrow blasts (CD10+/CD19+/CD34+) and was CNS negative. Although previously undiagnosed, NF-1 was clinically suspected due to typical skin changes.He was diagnosed with iAMP21 ALL and NF-1 was confirmed with the identification of a germline NF1 donor splice site mutation (c.1845G>A:p.L615=). Bone marrow cells were sorted by flow cytometry on CD19 positivity and underwent transcriptomic sequencing. This revealed a P2RY8-CRLF2 gene fusion, with no other clinically relevant variants, while a custom Taqman low density array indicated high-risk B-ALL subtype Ph-like ALL. Multiplex ligation-dependent probe amplification (MLPA) confirmed iAMP21 and also identified IKZF1 exon 2-3 and BTG1 deletions.Treatment followed the high-risk B-ALL arm of the AEIOP-BFM ALL2009 protocol due to persistent end-consolidation MRD in addition to iAMP21 and the Ph-like phenotype. He relapsed three years later off treatment and was refractory to both salvage chemotherapy and blinatumomab. The iAMP21, P2RY8-CRLF2 gene fusion, IKZF1 exon 2-3 and BTG1 deletions remained detectable. Whole exome sequencing of CD19 positive samples from diagnosis, relapse and mesenchymal stem cells (germline control) was performed, identifying a NF1 c.7400dupT:p.L2467 frameshift (fs) mutation only at relapse.To understand the implications of NF1 p.L2467fs, the P2RY8-CRLF2 gene fusion was first transduced into the interleukin 3 (IL3) dependent murine pro-B cell line Ba/F3. P2RY8-CRLF2 alone is not transforming and is thought to be a secondary event in iAMP21 ALL, providing an ideal model to study the cumulative effect of the NF1fs. The NF1fs was then introduced to the P2RY8-CRLF2 cells by CRISPR/Cas9. A proliferation assay was performed without IL3 and demonstrated the P2RY8-CRLF2+NF1fs cell line was IL3 independent, indicative of leukemic transformation, whereas all other lines were not (vs Ba/F3, p = 0.001).Neurofibromin can be constitutively phosphorylated at the c-terminus, negatively regulating NF1-GAP activity, suppressing RAS signaling and inducing cell cycle arrest. Therefore, to demonstrate loss of function due to the c-terminus NF1 p.L2467fs and increased RAS signaling, western blotting for pERK was performed. Significant upregulation of pERK was confirmed in P2RY8-CRLF2+NF1fs in comparison to Ba/F3 control cells (p=0.007) (Figure 1).The MEK inhibitors trametinib and mirdametinib are in clinical trials for NF-1 patients and have shown efficacy in ALL models with RAS mutations. In a 3-day cell death assay, only P2RY8-CRLF2+NF1fs demonstrated sensitivity to trametinib (LD 50 P2RY8-CRLF2 = >6.4 µM, NF1fs = >6.4 µM, P2RY8-CRLF2+NF1fs =1.7µM; p < 0.001) and mirdametinib (LD 50 P2RY8-CRLF2 = >16 µM, NF1fs = >16 µM, P2RY8-CRLF2+NF1fs = 8.3 µM; p < 0.0001) (Figure 2).Here, we have demonstrated a LOF NF1fs mutation using an in-vitro model of ALL. Germline NF1 haploinsufficiency and a second hit NF1 mutation in ALL is limited to one report of monozygotic twins with neurofibromatosis. We propose that NF1 p.L2467fs caused bi-allelic LOF and therefore contributed to relapse in this patient. An understanding of the genomic complexities that lead to relapse may also inform personalized treatment strategies. While this patient subsequently achieved remission with inotuzomab and underwent successful stem cell transplantation, the sensitivity to MEK inhibitors is an exciting development for neurofibromatosis patients with ALL. [Display omitted] DisclosuresYeung: Amgen: Honoraria; BMS: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria, Research Funding. White: BMS: Honoraria, Research Funding; Novartis: Research Funding.

Frontline Consolidation with Blinatumomab for High-Risk Philadelphia-Negative Acute Lymphoblastic Adult Patients. Early Results from the Graall-2014-QUEST Phase 2

Introduction: Philadelphia chromosome (Ph)-negative acute lymphoblastic leukemia (ALL) with high-risk genetics and/or measurable residual disease (MRD) are at high-risk of disease recurrence. In the previous GRAALL-2005 study, we identified KMT2A rearrangements (KMT2A-r), IKZF1 intragenic deletion (IKZF1del) and post-induction (TP1, week 6) MRD ≥ 0.01% as independent factors to predict relapse in Ph-negative B-cell precursor (BCP) ALL (Beldjord K, Blood 2014). In the GRAALL-2014 trial, high-risk (HR) patients were thus defined by the presence of at least one of these three factors. Among them, only those with higher MRD levels defined as TP1-MRD ≥ 0.1% and/or week 12 (TP2) MRD ≥ 0.01% were considered at very high risk (VHR) and proposed allogeneic hematopoietic stem cell transplant (alloSCT) in first remission (Dhedin et al., Blood 2015). Since October 2018, all these patients were eligible to be included in the GRAALL-2014-QUEST phase 2 study to receive blinatumomab as part of consolidation and maintenance phases or as a bridge to transplant.Methods: From October 2018 to December 2020, 95 patients with high-risk Ph-negative BCP-ALL without central nervous system involvement at diagnosis and in continuous complete remission after induction and consolidation 1, were prospectively included to start blinatumomab at week 12. One patient was excluded because of T-ALL phenotype (with CD19 aberrant expression). Patients with alloSCT indication and a stem cell source received blinatumomab 28 microg/d administered by continuous intravenous infusion (cIV) until transplant. A minimum of 4 weeks blinatumomab was recommended before proceeding to transplantation. All other patients received 5 cycles of blinatumomab 28 microg/day cIV (for 28 days), during consolidation 2 and 3 and at months 1/3/5 of the maintenance phase respectively. The primary objective was disease-free survival (DFS). Secondary objectives included post-blinatumomab MRD response at TP3 (after consolidation 2 or before alloSCT), overall survival (OS), and safety. Early results are reported here.Results: Median age was 35 years old (range, 18-60). Median white blood cell count (WBC) at diagnosis was 12 G/L (range, 1-449). Oncogenetic analyses allowed classifying ALL as Ph-like (18%), KMT2A-r (17%), DUX4/ERGdel (13%), ZNF384-r (11%), low hypodiploidy/near triploidy (7%), B-other (26%) or unknown (9%). An IKZF1del was found in 37/93 (40%). A TP1-MRD ≥ 0.01% was found in 46/94 patients (49%). Final risk group was HR for 45 patients and VHR for 49 patients. Last pre-blinatumomab MRD was <0.01% in 49/88 (56%) of evaluable patients. A total of 40 patients (42%) received an alloSCT. The median number of blinatumomab cycles received in patients not proceeding to alloSCT was 4 cycles (range, 1-5). Thirty-nine severe adverse events (SAEs) were reported: 1 CRS (grade 2), 8 neurotoxicities (1 grade 2, 3 grade 3, 3 grade 4, 1 grade 5), 19 infections, and 11 others. The only grade 5 SAE occurred after alloSCT (seizures). After blinatumomab, a complete MRD response (with at least 0.01% sensitivity) was achieved in 61/82 (74%) evaluable patients and in evaluable patients with pre-blinatumomab detectable MRD. MRD response to blinatumomab was lower in patients with high pre-blinatumomab MRD level, while not impacted by age, WBC, or oncogenic subgroup. With a median follow-up of 20 months, 18-month DFS and OS was 78.8% (95% CI [66.9-86.8]) and 92.1% (95% CI [83.2-96.4]) respectively (Figure 1). Patients with VHR diseases had a worse DFS (68.8%, 95% CI [51.1-81.2]) as compared to other patients (90.6%, 95% CI [72.1-97.1]); p=0.018). This difference of DFS was abrogated by censoring patients at transplant (VHR 88.1%, 95% CI [65.5-96.3] versus others 90.6%, 95% CI [72.1-97.1%], p=0.10). Other factors significantly associated with better DFS were DUX4/ERGdel subgroup, low pre-blinatumomab MRD, and complete MRD response after blinatumomab.Conclusion. In patients wih high-risk BCP-ALL, blinatumomab added to consolidation is safe and gives promising results. A comparison to similar patients treated in the same GRAALL-2014 study before October 2018 is planned with a longer follow-up. [Display omitted] DisclosuresBoissel: Novartis: Consultancy, Honoraria, Research Funding; Incyte: Honoraria; Amgen: Consultancy, Honoraria, Research Funding; SANOFI: Honoraria; Servier: Consultancy, Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; CELGENE: Honoraria; JAZZ Pharma: Honoraria, Research Funding; PFIZER: Consultancy, Honoraria. Huguet: Novartis: Other: Advisor; Jazz Pharmaceuticals: Other: Advisor; Celgene: Other: Advisor; BMS: Other: Advisor; Amgen: Other: Advisor; Pfizer: Other: Advisor. Rousselot: Incyte, Pfizer: Consultancy, Research Funding. Chalandon: Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Amgen: Other: Advisory Board; Incyte: Speakers Bureau; Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Gilead, Amgen, Jazz, Astra Zenec: Other: Travel EXpenses, Accomodation. Delabesse: Astellas: Consultancy; Novartis: Consultancy. Dombret: Abbvie: Honoraria; Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; NOVARTIS: Research Funding; pfizer: Honoraria, Research Funding; servier: Research Funding; BMS-Celgene: Honoraria; Daiichi Sankyo: Honoraria. OffLabel Disclosure:Blinatumomab in frontline high-risk acute lymphoblastic leukemia

HDACi Targets IKZF1 Deletion High-Risk Acute Lymphoblastic Leukemia By Inducing IKZF1 Expression and Rescuing IKZF1 Function in Vitro and In Vivo

The IKZF1 gene codes the transcription factor IKAROS with key regulatory functions in lymphopoiesis. Recurrent focal IKZF1 deletions (IKZF1 del), which affects the coding regions of IKZF1, have been identified as poor outcome in 30-40% adult B-ALL. Loss of IKAROS confer stem cell-like phenotype, upregulation of self-renewal capacity and cell-adhesion molecules, and TKI resistance. However, there are not specifically therapeutic options for IKZF1 del ALL and current protocols could not abrogate the adverse effect of IKZF1 del.Considering that IKAROS acts as a key component of the nucleosome remodeling and deacetylation (NuRD) complex engaging in development and metabolism, we speculate that epigenetic drugs, such as HDACi, might play a potent role in IKZF1 del high-risk B-ALL.Firstly, B-ALL cell lines (IKZF1 del: MUTZ-5, MHH-CALL-4; IKZF1 wt: NALM6) and primary patient samples (n=10, 5 with IKZF1 del and 5 with IKZF1 wt) were treated with different HDACi, including valproic acid, vorinostat, romidepsin, RGFP966 and a novel HDAC-selective inhibitor tucidinostat. But noteworthily, only tucidinostat yielded specific and selective proliferation inhibition in IKZF1 del cell line(IC 50=1.377±0.05) and IKZF1 del patients samples (IC 50=2.318±0.07), compared with the effect on IKZF1 wt cells. Interestingly, tucidinostat induced remarked increase of mRNA and protein of IKZF1 expression in leukemia bulk and IKZF1 del single cell. Seahorse metabolic flux assay, lactate and ATP measurements was performed and revealed that tucidinostat treatment reduced glycolysis (P=0.0067), lactic acid (P＜0.0001) and ATP level (P＜0.0001) in IKZF1 del B-ALL cell lines. To verify metabolic change is depend on IKZF1 induction or not,dominant-negative Ikaros isoform 6 (DN-IK6), deletion of exons 4-7, was transfected into IKZF1 wt Nalm-6 cell line to negative regulate of IKZF1 wide-type expression. Overexpression of DN-IK6 in Nalm-6, increases sensitivity to tucidinostat, glycolytic capacity(p=0.05) and glycolytic reserve (p=0.012) also increases. While tucidinostat treating with the IK6-Nalm-6, tucidinostat would restore the transcriptional repressor function of the remaining wild-type IKZF1 allele and decrease glycolytic capacity(p=0.011) and glycolytic reserve(p=0.014). Notably, the metabolic rate-limiting enzymes HK2 and PKM2 were strongly repressed. These data indicate that tucidinostat reverses the metabolic reprogramming of glycolysis or Warburg effect in IKZF1 del B-ALL in an IKZF1-inducing dependent manner. For in vivo study, PDX model with immunodeficient NOD/SCID/IL2Rgnull mice were injected with heavily-treated refractory/relapsed IKZF1 del B-ALL patient samples (n=2) and treated with tucidinostat with different dosage of 5-12.5mg/kg/day. Administration of tucidinostat observed IKAROS expression trajectory and resulted in prolonged animal survival in IKZF1 del B-ALL PDX model（P＜0.0001). Secondary transplantation of ALL cells from tucidinostat or vehicle-treated (1 x10 6) recipients revealed significantly improved survival in tucidinostat -treated group (p= 0.0235). These results indicate that tucidinostat treatment might elimination leukemia-initiating cells.Additionally, to profile the IKZF1 del B-ALL chromatin accessibility changes after tucidinostat-treatment. We performed ATAC-seq and observed a clear increase in accessibility at TCA cycle related gene and decrease in accessibility at glycolysis related gene.Furthermore, tucidinostat, formerly known as chidamide, was added to an open-label, one-arm PDT-Ph-like-ALL trial targeting adult Ph-like ALL, which is characterized with high frequency in IKZF1 deletions (Clinicaltrials.gov. NCT03564470). Preliminary data of PDT-Ph-like-ALL indicate that tucidinostat was effective and well-tolerated, yielded promising response in IKZF1 del Ph-like ALL (ASH2018, poster 4011; EHA 2019, PF181).Collectively, our study demonstrates that the novel HDAC-selective inhibitor, tucidinostat, could specifically target IKZF1 del high-risk B-ALL, by restoring the IKZF1 expression, resulting in attenuation of proliferation, reverse the Warburg effect and improvement of the survival in PDX model and preliminary data in clinical trial. These findings provide mechanistic insights and a promising therapeutic strategy for IKZF1 haploinsufficiency alterations B-ALL patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

EVALUATION OF VACCINATION RESPONSE IN CHILDREN AFTER TREATMENT FOR ACUTE LEUKEMIA

Our study aims to evaluate the patients’ immunity regarding childhood vaccination after leukemia treatment and determine the vaccines that require additional doses. Sixty-six patients who were followed up with the diagnosis of ALL and AML between 2013 and 2016 were included in our study. The patient's gender, age at diagnosis, leukemia type, leukemia risk groups, vaccination status before chemotherapy (CT) and serologies of hepatitis A, hepatitis B, varicella, measles, rubella, mumps at the end of CT were recorded. At the end of the treatment, loss of protective antibody response against hepatitis A (47.4%), hepatitis B (68.2%), varicella (64.2%), measles (45.5%), rubella (43.9%), and mumps (50%) vaccines were shown. Loss of protective antibodies against hepatitis A (66.7%), hepatitis B (100%), varicella (100%), measles (100%), rubella (91.7%), and mumps (91.7%) in high-risk ALL patients was higher than patients in standard-intermediate risk ALL. Loss of humoral immunity against hepatitis A, hepatitis B, varicella, MMR was shown in patients with leukemia at the end of the treatment. Due to the significant decrease in hepatitis B and MMR protective antibodies in the high-risk group, we recommend patients with leukemia who have completed chemotherapy to be vaccinated with hepatitis B vaccine three months and MMR vaccine six months after the treatment.

Two novel high-risk adult B-cell acute lymphoblastic leukemia subtypes with high expression of CDX2 and IDH1/2 mutations

The genetic basis of leukemogenesis in adults with B-cell acute lymphoblastic leukemia (B-ALL) is largely unclear, and its clinical outcome remains unsatisfactory. This study aimed to advance the understanding of biological characteristics, improve disease stratification, and identify molecular targets of adult B-ALL. Adolescents and young adults (AYA) (15 to 39 years old, n = 193) and adults (40 to 64 years old, n = 161) with Philadelphia chromosome-negative (Ph−) B-ALL were included in this study. Integrated transcriptomic and genetic analyses were used to classify the cohort into defined subtypes. Of the 323 cases included in the RNA sequencing analysis, 278 (86.1%) were classified into 18 subtypes. The ZNF384 subtype (22.6%) was the most prevalent, with 2 novel subtypes (CDX2-high and IDH1/2-mut) identified among cases not assigned to the established subtypes. The CDX2-high subtype (3.4%) was characterized by high expression of CDX2 and recurrent gain of chromosome 1q. The IDH1/2-mut subtype (1.9%) was defined by IDH1 R132C or IDH2 R140Q mutations with specific transcriptional and high-methylation profiles. Both subtypes showed poor prognosis and were considered inferior prognostic factors independent of clinical parameters. Comparison with a previously reported pediatric B-ALL cohort (n = 1003) showed that the frequencies of these subtypes were significantly higher in AYA/adults than in children. We delineated the genetic and transcriptomic landscape of adult B-ALL and identified 2 novel subtypes that predict poor disease outcomes. Our findings highlight the age-dependent distribution of subtypes, which partially accounts for the prognostic differences between adult and pediatric B-ALL.

Long term survival outcome of childhood acute lymphoblastic leukemia treated with modified TXIIIB protocol at South Egypt Cancer Institute

Background: The survival of children with acute lymphoblastic leukemia (ALL) has greatly improved in recent decades. Aim: We aimed at evaluating the outcome of children with ALL and their prognostic factors. Materials & Methods: A prospective study included 200 newly diagnosed pediatric ALL patients from 2009 to 2017. All patients were treated according to the modified total therapy study XIIIB for higher risk ALL adopted from St. Jude Children's Research hospital (SJCRH), USA. Results: Favorable age (< 10 y) and total leucocytic count (TLC) (≥ 50x109/L) occurred in 75% and 69%, respectively. B-precursor ALL represented 82.5%. Central nervous system (CNS) involvement occurred in 4.5%. High-risk patients represented 47%. Complete remission was achieved in 92.5% and was significantly affected by the early morphologic response of BM d15, while it wasn’t related to the phenotype. Eight- year overall survival, disease-free survival, and event-free survival were 77 ± 3%, 70 ± 4%, and 66 ± 3%, respectively. Adverse events included induction deaths (4.5 %(, refractory leukemia (3%), relapse (23.2%), secondary AML (0.5%), and deaths in remission (3.5%). By multivariate analysis, unfavorable age group ≥ 10 years, hyperleukocytosis, and patients with slow early response were the only ones associated with unfavorable impact on the outcome. There was statistical significant difference between standard and high risk for B-precursor ALL but not for T- precursor ALL. Conclusion: We concluded that treating children with ALL through modified TXIIIB protocol improved the survival at our institute than previous and the early response to treatment has a strong implication on the outcome.

Barriers to Care and Outcomes of Pediatric Acute Lymphoblastic Leukemia Treatment in the Gaza Strip.

Childhood acute lymphoblastic leukemia (ALL) is the most common pediatric cancer worldwide. Although children in high-income countries enjoy survival rates of ~90%, children in countries with limited resources suffer from survival rates of <35%. No published data on pediatric cancer incidence, management, or outcomes in the Gaza Strip are available. A retrospective cohort study was undertaken for pediatric (below 12 y of age) ALL diagnoses admitted to the only pediatric cancer ward in the Gaza Strip between 2010 and 2015. Outcomes included event-free survival (EFS) and overall survival (OS) calculated by Kaplan-Meier estimates. Events were defined as induction failure, relapse, and death. The 3-year EFS estimate was 80% (95% confidence interval [CI], 66%-89%). The EFS at 1 and 3 years for high-risk ALL was 55% (95% CI, 27%-76%) and 23% (95% CI, 4%-51%), respectively. The 3-year OS was 93% (95% CI, 82%-97%). The 3-year OS for high-risk ALL was 69% (95% CI, 30%-90%). All 84 (100%) patients required referral to an outside hospital for definitive ALL diagnoses and induction therapy. Forty-four (52%) patients required at least one additional referral. The overall outcomes demonstrated relatively high survival rates at 3 years which may be artificially elevated due to exclusion of adolescents, limited follow up, and deceased patient charts unavailable. Structural determinants of health in Gaza lead to limited diagnostic and treatment capabilities, limited access to advanced medical training, and reliance on out-of-territory transfers for care. These barriers impact the access to comprehensive pediatric care within the Gaza Strip.

Bortezomib and rituximab in de novo adolescent/adult CD20-positive, Ph-negative pre-B-cell acute lymphoblastic leukemia

AbstractThe expression of CD20 in precursor B-cell acute lymphoblastic leukemia (B-ALL) is associated with poor outcomes. The addition of rituximab to intensive chemotherapy in CD20+ ALL has led to improved outcomes in several studies. However, there is no clear evidence regarding the optimal number of doses and its benefit without an allogeneic stem cell transplant. Achieving measurable residual disease (MRD)-negative status postinduction would reduce the requirement for a transplant. Novel approaches are needed to induce a higher proportion of MRD-negative complete remission in patients with high-risk ALL. Given bortezomib's activity in relapsed ALL and its synergism with rituximab in B-cell lymphomas, the addition of bortezomib to rituximab and chemotherapy may provide an incremental benefit in CD20+ precursor B-ALL. We conducted a phase 2 study to test the activity of bortezomib and rituximab in combination with a pediatric-inspired regimen during induction therapy in newly diagnosed adolescents and adults (aged >14 years) with CD20+, Philadelphia-negative precursor B-ALL; bone marrow MRD negativity at the end of induction was the primary end point. From December 2017 through August 2019, a total of 35 patients were enrolled. End-of-induction MRD-negative status was achieved in 70.9% of patients, as opposed to 51.7% in the historical cohort treated with chemotherapy alone. MRD-negative rates improved to 87.5% post-consolidation. At a median follow-up of 21 months, event-free survival and overall survival rates were 78.8% (95% confidence interval, 66-94) and 78.7% (95% confidence interval, 65.8-94), respectively. There was no significant increase in toxicity with bortezomib and rituximab compared with the historical cohort. The incidence of neuropathy was 26% (all less than grade 3). The combination of bortezomib, rituximab, and a pediatric-inspired ALL regimen was active and well tolerated in de novo CD20+ Philadelphia-negative precursor B-ALL. This trial was registered with the Clinical Trials Registry-India as CTRI/2017/04/008393(http://ctri.nic.in/Clinicaltrials).

CT-255: Progressive Substitution of Post-Transplant Cyclophosphamide with Bendamustine as GVHD Prophylaxis Reduces GVHD while Preserving GVL

Context Post-transplant cyclophosphamide (PTCy) is approved in haploidentical stem cell transplant setting. However, disease relapse and CMV or BK/JC viral reactivation veno-occlusive disease of the liver (VOD) remains a major challenge with the use of PTCy. Progressive substitution of PTCy with bendamustine (PT-BEN) may be a suitable option as evidenced by murine models. Objective To compare the outcomes for patients receiving PTCy with PT-BEN compared to historical cohorts receiving PTCy alone. Design This is a single arm, retrospective and prospective, single centre study in which all the patients undergoing allogeneic stem cell transplantation with a T-cell replete graft were recruited. Patients or Other Participants All patients received T-cell replete stem cells followed by PTCy 50mg/kg on day +3 and bendamustine 90mg/m2 on day +4. Calcineurin inhibitors with mycophenolate mofetil was given. Main Outcomes Measures The main outcome measures included myeloid and platelet engraftment, viral reactivations, disease status, incidence and severity of acute GVHD, incidence of veno-occlusive disease until D+28 post-transplant. Results Five patients have been recruited, all males, median age being 17 years. Two patients had relapsed/refractory (R/R) ALL after 2 lines of therapy, 1 had R/R AML, 1 had very severe aplastic anemia, 1 was high risk ALL in CR1. 3 fully matched a sibling, whereas 2 had haplomatched donors from mother. All the donors and recipients had seropositivity for CMV. Two patients received FluCyTBI, 2 received FluCyATG, and 1 received FluTreoTBI as conditioning. One patient expired due to neutropenic septic shock on D+8 and has been excluded from analysis. The median day for myeloid engraftment was 12 and platelet engraftment was 14. No patient had VOD, thrombotic microangiopathy, or culture positive bacterial infections. All the patients were in CR, 100% donor chimerism at D+28. Three patients had CMV reactivation, controlled with antivirals. One patient had Gr1 skin GVH and 1 patient had Gr1 gut GVH managed with topical and oral steroids respectively. Conclusions Progressive substitution of PT-BEN may ameliorate the toxicities associated with PT-Cy in post-transplant setting.