Leukemic Blasts Research Articles

P10 Blastic plasmacytoid dendritic cell neoplasm: two representative cases

Abstract Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a malignant proliferation of plasmacytoid dendritic cells, representing < 1% of primary cutaneous lymphomas. It most commonly presents in the skin and has a poor prognosis with median survival of 1 year. The fifth World Health Organization classification of haematolymphoid tumours encompasses two entities in plasmacytoid dendritic cell neoplasms: BPDCN and ‘mature plasmacytoid dendritic cell neoplasm associated with myeloid neoplasm’. We present two cases, one representing each subset. Our first case was a 58-year-old man who presented with an asymptomatic, rapidly progressive, skin coloured-to-ery­thematous and hyperpigmented firm papules, nodules and plaques over the trunk, upper limbs and face of 2.5 months’ duration. This was associated with loss of appetite, loss of weight and leucopenia (2180 cells μL−1). Skin biopsy revealed a grenz zone with pandermal infiltration by large cells with high nuclear : cytoplasmic ratio, vesicular nuclei and prominent nucleoli, and frequent mitotic figures. Immunohistochemistry (IHC) was leucocyte common antigen (LCA)+ but CD3–, CD20–, myeloperoxidase (MPO)– and CD117–. Bone marrow biopsy showed a similar infiltrate of cells, but the peripheral blood smear and flow cytometry was within normal limits. Further IHC was CD4+, CD56+, CD43+ and CD123+, establishing a diagnosis of BPDCN, and the patient was initiated on the Hoelzer protocol with 80% clearance of lesions after two cycles of chemotherapy. The second case was a 60-year-old woman who presented with asymptomatic firm skin-coloured nodules on her scalp, trunk, extremities and oral mucosa, associated with a low-grade fever, fatigability, weight loss, generalized lymphadenopathy and hepatosplenomegaly of 4 months’ duration. Histopathology showed similar features to the first case, with IHC being negative for CD3, CD20, CD138 and MPO. However, cells were LCA+, CD4+, CD56+ and CD43+. Bone marrow showed 77% acute leukaemia blasts with a MPO+ result, establishing diagnosis of acute myeloid leukaemia, suggestive of a mature plasmacytoid dendritic cell neoplasm associated with myeloid neoplasm. To conclude, BPDCN is an aggressive neoplasm that commonly presents in the skin and should be suspected by dermatologists when screening IHC for lymphoid and myeloid cell lines is negative in a suspected case of leukaemia cutis. A panel of CD4/CD56/CD43/CD123 may be used to establish the diagnosis.

DP06 (P10) Blastic plasmacytoid dendritic cell neoplasm: two representative cases

Abstract Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a malignant proliferation of plasmacytoid dendritic cells, representing <1% of primary cutaneous lymphomas. It most commonly presents in the skin and has a poor prognosis with median survival of 1 year. The fifth World Health Organization classification of haematolymphoid tumours encompasses two entities in plasmacytoid dendritic cell neoplasms: BPDCN and ‘mature plasmacytoid dendritic cell neoplasm associated with myeloid neoplasm’. We present two cases, one representing each subset. Our first case was a 58-year-old man who presented with an asymptomatic, rapidly progressive, skin coloured-to-ery­thematous and hyperpigmented firm papules, nodules and plaques over the trunk, upper limbs and face of 2.5 months’ duration. This was associated with loss of appetite, loss of weight and leucopenia (2180 cells μL–1). Skin biopsy revealed a grenz zone with pandermal infiltration by large cells with high nuclear:cytoplasmic ratio, vesicular nuclei and prominent nucleoli and frequent mitotic figures. Immunohistochemistry (IHC) was leucocyte common antigen (LCA)+ but CD3–, CD20–, myeloperoxidase (MPO)– and CD117–. Bone marrow biopsy showed a similar infiltrate of cells, but the peripheral blood smear and flow cytometry was within normal limits. Further IHC was CD4+, CD56+, CD43+ and CD123+, establishing a diagnosis of BPDCN, and the patient was initiated on the Hoelzer protocol with 80% clearance of lesions after two cycles of chemotherapy. The second case was a 60-year-old woman who presented with asymptomatic firm skin-coloured nodules on her scalp, trunk, extremities and oral mucosa, associated with a low-grade fever, fatigability, weight loss, generalized lymphadenopathy and hepatosplenomegaly of 4 months’ duration. Histopathology showed similar features to the first case, with IHC being negative for CD3, CD20, CD138 and MPO. However, cells were LCA+, CD4+, CD56+ and CD43+. Bone marrow showed 77% acute leukaemia blasts with a MPO+ result, establishing diagnosis of acute myeloid leukaemia, suggestive of a mature plasmacytoid dendritic cell neoplasm associated with myeloid neoplasm. To conclude, BPDCN is an aggressive neoplasm that commonly presents in the skin and should be suspected by dermatologists when screening IHC for lymphoid and myeloid cell lines is negative in a suspected case of leukaemia cutis. A panel of CD4/CD56/CD43/CD123 may be used to establish the diagnosis.

Rituximab plus multiagent chemotherapy for newly diagnosed CD20-positive acute lymphoblastic leukemia: a prospective phase II study.

We performed a prospective study to determine the efficacy and safety of rituximab including chemotherapy in CD20-positive acute lymphoblastic leukemia (ALL). Patients with newly diagnosed ALL, aged ≥ 15 years, were eligible for the study if their leukemic blast cells in bone marrow expressed CD20 ≥ 20% at the time of diagnosis. Patients received multiagent chemotherapy with rituximab. After achieving complete remission (CR), patients received five cycles of consolidation with concomitant rituximab. Rituximab was administered monthly from day 90 of transplantation for patients who received allogeneic hematopoietic cell transplantation. In patients with Philadelphia (Ph)-negative ALL, 39 of 41 achieved CR (95.1%), the 2- and 4-year relapse-free survival (RFS) rates were 50.4% and 35.7%, and the 2- and 4-year overall survival (OS) rates were 51.5% and 43.2%, respectively. In the group with Ph-positive ALL, all 32 patients achieved CR, the 2- and 4-year RFS rates were 60.7% and 52.1%, and the 2- and 4-year OS rates were 73.3% and 52.3%, respectively. In the Ph-negative ALL group, patients with higher CD20 positivity experienced more favorable RFS (p < 0.001) and OS (p = 0.06) than those with lower CD20 positivity. Patients who received ≥ 2 cycles of rituximab after transplantation had significantly improved RFS (hazard ratio [HR], 0.31; p = 0.049) and OS (HR, 0.29; p = 0.021) compared with those who received < 2 cycles. The addition of rituximab to conventional chemotherapy for CD20-positive ALL is effective and tolerable (Clinicaltrials. gov NCT01429610).

FLT4 as a marker for predicting prognostic risk of refractory acute myeloid leukemia.

Treating patients with refractory acute myeloid leukemia (AML) remains challenging. Currently there is no effective treatment for refractory AML. Increasing evidence has demonstrated that refractory/relapsed AML is associated with leukemic blasts which can confer resistance to anticancer drugs. We have previously reported that high expression of Fms-related tyrosine kinase 4 (FLT4) is associated with increased cancer activity in AML. However, the functional role of FLT4 in leukemic blasts remains unknown. Here, we explored the significance of FLT4 expression in leukemic blasts of refractory patients and mechanisms involved in the survival of AML blasts. Inhibition or absence of FLT4 in AML blasts suppressed homing to bone marrow of immunocompromised mice and blocked engraftment of AML blasts. Moreover, FLT4 inhibition by MAZ51, an antagonist, effectively reduced the number of leukemic cell-derived colony-forming units and increased apoptosis of blasts derived from refractory patients when it was co-treated with cytosine arabinoside under vascular endothelial growth factor C, its ligand. AML patients who expressed high cytosolic FLT4 were linked to an AML-refractory status by internalization mechanism. In conclusion, FLT4 has a biological function in leukemogenesis and refractoriness. This novel insight will be useful for targeted therapy and prognostic stratification of AML.

Volatile Phases Derived from Serum, DC, or MLC Culture Supernatants to Deduce a VOC-Based Diagnostic Profiling Strategy for Leukemic Diseases.

Volatile organic compounds (VOCs) reflect the metabolism in healthy and pathological conditions, and can be collected easily in a noninvasive manner. They are directly measured using electronical nose (eNose), and may qualify as a systemic tool to monitor biomarkers related to disease. Myeloid leukemic blasts can be transformed into leukemia-derived dendritic cells (DCleu) able to improve (anti-leukemic) immune responses. To profile immunological changes in healthy and acute myeloid leukemic (AML) patients' ex vivo cell cultures, we correlated the cell biological data with the profiles of cell culture supernatant-derived VOCs. DC/DCleu from leukemic or healthy whole blood (WB) were generated without (Control) or with immunomodulatory Kit M (Granulocyte macrophage-colony-stimulating-factor (GM-CSF) + prostaglandin E1 (PGE1)) in dendritic cell cultures (DC culture). Kit-pretreated/not pretreated WB was used to stimulate T cell-enriched immunoreactive cells in mixed lymphocyte cultures (MLC culture). Leukemia-specific adaptive and innate immune cells were detected with a degranulation assay (Deg) and an intracellular cytokine assay (InCyt). Anti-leukemic cytotoxicity was explored with a cytotoxicity fluorolysis assay (CTX). VOCs collected from serum or DC- and MLC culture supernatants (with vs. without Kit M pretreatment and before vs. after culture) were measured using eNose. Compared to the Control (without treatment), Kit M-pretreated leukemic and healthy WB gave rise to higher frequencies of mature (leukemia-derived) DC subtypes of activated and (memory) T cells after MLC. Moreover, antigen (leukemia)-specific cells of several lines (innate and adaptive immunity cells) were induced, giving rise to blast-lysing cells. The eNose could significantly distinguish between healthy and leukemic patients' serum, DC and MLC culture supernatant-derived volatile phases and could significantly separate several supernatant (with vs. without Kit M treatment, cultured vs. uncultured)-derived VOCs within subgroups (healthy DC or leukemic DC, or healthy MLC or leukemic MLC supernatants). Interestingly, the eNose could indicate a Kit M- and culture-associated effect. The eNose may be a prospective option for the deduction of a VOC-based profiling strategy using serum or cell culture supernatants and could be a useful diagnostic tool to recognize or qualify AML disease.

Development of TCR-T cell therapy targeting mismatched HLA-DPB1 for relapsed leukemia after allogeneic transplantation.

Relapsed leukemia after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains a significant challenge, with the re-emergence of the primary disease being the most frequent cause of death. Human leukocyte antigen (HLA)-DPB1 mismatch occurs in approximately 70% of unrelated allo-HSCT cases, and targeting mismatched HLA-DPB1 is considered reasonable for treating relapsed leukemia following allo-HSCT if performed under proper conditions. In this study, we established several clones restricted to HLA-DPB1*02:01, -DPB1*04:02, and -DPB1*09:01 from three patients who underwent HLA-DPB1 mismatched allo-HSCT using donor-derived alloreactive T cells primed to mismatched HLA-DPB1 in the recipient's body after transplantation. A detailed analysis of the DPB1*09:01-restricted clone 2A9 showed reactivity against various leukemia cell lines and primary myeloid leukemia blasts, even with low HLA-DP expression. T cell receptor (TCR)-T cells derived from clone 2A9 retained the ability to trigger HLA-DPB1*09:01-restricted recognition and lysis of various leukemia cell lines in vitro. Our study demonstrated that the induction of mismatched HLA-DPB1 specific T cell clones from physiologically primed post-allo-HSCT alloreactive CD4+ T cells and the redirection of T cells with cloned TCR cDNA by gene transfer are feasible as techniques for future adoptive immunotherapy.

Bone Marrow Microenvironment-Induced Chemoprotection in KMT2A Rearranged Pediatric AML Is Overcome by Azacitidine–Panobinostat Combination

Advances in therapies of pediatric acute myeloid leukemia (AML) have been minimal in recent decades. Although 82% of patients will have an initial remission after intensive therapy, approximately 40% will relapse. KMT2A is the most common chromosomal translocation in AML and has a poor prognosis resulting in high relapse rates and low chemotherapy efficacy. Novel targeted approaches are needed to increase sensitivity to chemotherapy. Recent studies have shown how interactions within the bone marrow (BM) microenvironment help AML cells evade chemotherapy and contribute to relapse by promoting leukemic blast survival. This study investigates how DNA hypomethylating agent azacitidine and histone deacetylase inhibitor panobinostat synergistically overcome BM niche-induced chemoprotection modulated by stromal, endothelial, and mesenchymal stem cells and the extracellular matrix (ECM). We show that direct contact between AML cells and BM components mediates chemoprotection. We demonstrate that azacitidine and panobinostat synergistically sensitize MV4;11 cells and KMT2A rearranged pediatric patient-derived xenograft lines to cytarabine in multicell coculture. Treatment with the epigenetic drug combination reduced leukemic cell association with multicell monolayer and ECM in vitro and increased mobilization of leukemic cells from the BM in vivo. Finally, we show that pretreatment with the epigenetic drug combination improves the efficacy of chemotherapy in vivo.

Aberrant expression of T cell activation markers and upregulation of Tregs in bone marrow and peripheral blood in acute myeloid leukemia patients

ABSTRACTBackground:T cells’ function and activation and the immunosuppressive effect of regulatory T cells (Tregs) play a pivotal role in the occurrence and progression of acute myeloid leukemia (AML). In this study, we investigate the expression of T cell activation markers and quantity of Tregs in bone marrow (BM) and peripheral blood (PB) from AML patients and further characterized their correlation with BM leukemic blasts.Methods:Expression of CD25, CD38, CD69, and HLA-DR on the surfaces of CD4+ and CD8+ T cells and the quantity of Tregs in BM and PB from new diagnosed (ND), relapsed-refractory (RR), complete remission (CR) AML patients were measured via flow cytometry.Results:Compared to normal controls (NC), we found higher proportion of CD4+ CD69+ T cells, CD8+ CD69+ T cells and Tregs in PB. CD8+ CD38+ T cells and CD8+ HLA-DR+ T cells in RR were significantly higher than ND, CR and NC). Tregs were normalized when AML patients achieved CR. Moreover, there was a minor positive correlation between AML blasts and CD8+ CD25+ T cells or Tregs, while AML blasts had a minor negative correlation with CD4+ CD69+ T cells.Conclusion:Abnormal activation markers of T cells and Tregs may be involved in the pathological mechanism of ND and RR AML. Our results indicated that CD8+ CD38+ T cells and CD8+ HLA-DR+ T cells might be RR markers of AML patients. Furthermore, Tregs could be used as clinical indicators to evaluate prognosis for AML patients.

Advances in molecular characterization of pediatric acute megakaryoblastic leukemia not associated with Down syndrome; impact on therapy development.

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia (AML) in which leukemic blasts have megakaryocytic features. AMKL makes up 4%-15% of newly diagnosed pediatric AML, typically affecting young children (less than 2years old). AMKL associated with Down syndrome (DS) shows GATA1 mutations and has a favorable prognosis. In contrast, AMKL in children without DS is often associated with recurrent and mutually exclusive chimeric fusion genes and has an unfavorable prognosis. This review mainly summarizes the unique features of pediatric non-DS AMKL and highlights the development of novel therapies for high-risk patients. Due to the rarity of pediatric AMKL, large-scale multi-center studies are needed to progress molecular characterization of this disease. Better disease models are also required to test leukemogenic mechanisms and emerging therapies.

A randomized, open-label study of the efficacy and safety of galinpepimut-S (GPS) maintenance monotherapy compared to investigator's choice of best available therapy (BAT) in patients with acute myeloid leukemia (AML) who have achieved complete remission (CR) after second-line salvage therapy.

TPS7074 Background: Patients with relapse/refractory (r/r) AML have poor outcomes. Allogeneic stem cell transplantation (allo-SCT) can potentially cure some patients with r/r AML who achieve second CR (CR2). However, barriers to transplantation such as advanced age, poor functional status/comorbidities or lack of donor exist and not all patients are able to proceed to allo-SCT. Therefore, novel strategies to decrease relapse risk in these patients are urgently needed. A National Cancer Institute consensus study on prioritization of cancer antigens ranked the Wilms tumor 1 (WT1) protein as the top immunotherapy target in cancer. WT1 has emerged as an encouraging vaccine target in AML due to its overexpression in leukemic blasts. Maintenance therapy with Galinpepimut-S (GPS), a multivalent heteroclitic WT1 peptide vaccine, has shown promising activity in patients with AML by inducing a strong innate immune response (CD4+/CD8+) against the WT1 antigen and across a broad range of HLA types. Methods: This is an open-label, multicenter, randomized, phase III study of GPS vs. BAT in patients with AML in CR2/CRp2 (CR2 with incomplete platelet recovery). BAT may include observation, low dose cytarabine and hypomethylating agents +/- venetoclax. The primary endpoint of the study is overall survival (OS). Secondary endpoints include safety and tolerability of GPS and leukemia-free survival. Exploratory endpoints include WT1-specific immune response dynamics in blood and bone marrow. Approximately 125 - 140 patients will enroll, in a 1:1 ratio, to provide at least 90% power under an assumed hazard ratio of 0.52, based on median OS of 8.0 m (BAT) and 15.4m (GPS). Randomization will be stratified by duration of CR1 ( &lt; 12m vs. ≥12m), Cytogenetics (poor-risk vs. all other), CR2 vs. CRp2 and measurable residual disease (MRD) after CR2 (MRD- vs. MRD+). Inclusion criteria consists of willing subjects ≥18y with AML within 6m of achieving CR2/CRp2, ineligible for allo-SCT due to any reason, with ≥300 lymphocytes/ul and with adequate renal and hepatic function. Subjects with central nervous involvement, having received a live vaccine 30d prior to first dose of study drug, having a diagnosis of immunodeficiency, receiving ≥10mg daily of prednisone equivalent (or any other systemic immunosuppressant) for any indication 7d prior to first dose of study drug, hypersensitivity to study agent and with a history of solid organ transplant would be excluded. The clinical trial is actively enrolling, and the registry number is NCT04229979 . Clinical trial information: NCT04229979 .

Defining risk of central nervous system relapse in acute myeloid leukemia following allogeneic stem cell transplantation.

e19009 Background: Relapse following allogeneic stem cell transplant (AlloSCT) for acute myeloid leukemia (AML) remains the commonest cause of death post-transplant. Central nervous system (CNS) relapse is a devastating complication. With an estimated incidence of 2-8%, defining those patients at high risk and the management following CNS relapse remains controversial. We sought to identify demographic, clinical, molecular, and laboratory risk factors that would predispose AML patients to CNS relapse. Methods: This was a single institution retrospective study at Loyola University Medical Center. Inclusion criteria were adult patients with AML undergoing first AlloSCT from January 2012 to June 2021. Diagnosis of CNS relapse following AlloSCT was defined as leukemic blasts detected in spinal fluid analysis in accordance with established criteria. Chi-square tests were used to test the association between the experiencing of relapse and the categorical variables recorded. Wilcoxon Rank Sum test were used to assess the relationship between relapse experience and each of the demographic variables. Due to the low count of patients with CNS relapse and in order to avoid a poor estimation of confidence limits of any effect size, we limited our analyses to descriptive statistics and univariable analyses. Results: 198 patients met inclusion criteria with 8 cases (4.0% total) identified with CNS relapse following AlloSCT. Our analysis initially characterized 44 variables including age, race, HCT-CI risk, and day 100 chimerism. Univariate analysis is shown in the table below. Of note, it revealed that 62.50% of patients with CNS relapse had a chimerism value ≤98% at day 100 post-transplant as compared to 22.58% of patients without CNS relapse (p-value 0.02). Additionally, 87.50% of the CNS relapse group versus 51.38% of the group without relapse had favorable to intermediate AML risk scores (p-value 0.07). Conclusions: We observed a 4.0% rate of CNS relapse, which is consistent with what has been repored in the literature. Our results suggest that day 100 chimerism and disease risk index may be predictive of CNS relapse. Since there is a 10.6% incidence (5/47) of eventual CNS relapse amongst those with ≤98% chimerism at day 100, these patients could be considered for a lumbar puncture and bone marrow biopsy to prevent full relapse. Further research in this topic would be valuable to provide additional AML guidance in managing this uncommon complication, such as which patients may benefit from prophylactic strategies. [Table: see text]

Responses in patients with AML and treated with entospletinib monotherapy.

e19010 Background: AML is a disease defined by the acquisition of genetic lesions in normal hematopoietic stem cells and progenitors resulting in poorly differentiated and highly proliferative leukemic blasts. Spleen tyrosine kinase (SYK) is a nonreceptor tyrosine kinase that maintains de-differentiation and leukemogenesis. MLL rearrangements (MLL-r) occur in up to 10% of adult AML and are associated with upregulated expression of the transcription factors HOXA9 and MEIS1 and worse clinical outcomes. Entospletinib (ENTO), an oral, selective inhibitor of SYK, has been studied in clinical trials for unselected AML patients as well as MLL-r patients. ENTO plus standard induction chemotherapy in front line had a 76% (13/17) composite complete response (CR) in AML patients with high HOXA9 and MEIS1. We have 3 patients that achieved CRs with ENTO monotherapy; one patient achieved CR to 14 days of ENTO monotherapy prior to initiation of chemotherapy; 2 patients with relapsed/refractory AML with MLL-r treated with ENTO monotherapy achieved CRs. Methods: This was part of an international multicenter phase Ib/II study (NCT02343939) which evaluated the efficacy, safety, and tolerability of ENTO in subjects with AML. During dose escalation, ENTO was administered in combination with induction chemotherapy (Group A) or with a hypomethylating agent (Group B). ENTO was administered as monotherapy for R/R AML in Group C. This report includes one patient from group A (newly diagnosed AML, MLL-r, 14-day monotherapy lead-in with ENTO) and two patients from group C monotherapy (relapsed/refractory AML, MLL-r). Results: Three patients receiving ENTO monotherapy had CRs. 18-year-old male from group A, that was MLL-r, NPM1-mutant (-). Patient treated at 400 mg PO, BID, achieved a cytogenetic CR with incomplete count recovery after cycle 0 (before chemotherapy); the patient continued study with induction chemotherapy and ultimately received ASCT in CR. Two additional patients in group C (with multiple therapies), both at 400 mg bid: (i) 37-year-old male, MLL-r, NPM1(-), was on study for 28 days, achieved CR; (ii) 28-year-old female, MLL-r, NPM1(-) on study for 60 days, achieved CR, both proceeded to SCT. Conclusions: Based on the results from these three patients, the clinical activity of SYK inhibition should be explored further in AML. We are testing Lanraplenib, a next-generation SYK inhibitor with enhanced selectivity, and more favorable pharmacologic properties in combination in genetically defined subsets of AML (NCT05028751). Clinical trial information: NCT02343939 .

Time-dependent effects of hypoxia on cell metabolism, signaling, and iron homeostasis in the hematopoietic progenitor model KG1a.

Lowered availability of oxygen in the micro-environment of cells perturbs metabolic and signaling pathways. It affects proliferation, tissue morphology, and differentiation. Leukemia impairs maturation of hematopoietic progenitors: the immune system, healing, and erythropoiesis are weakened, thereby perturbing iron homeostasis and further lowering oxygen provision to tissues. Here, the time-dependent molecular consequences of sudden hypoxia were studied in the KG1a model of immature hematopoietic progenitors. The oxygen tension of KG1a cells was abruptly lowered from the experimentally usual ca. 20 to 1%. Growth and key hubs of signaling, metabolism, and iron homeostasis were monitored by a combination of immunological methods and functional assays. The collapse of oxygen availability stopped proliferation after one generation. The number of cells then remained approximately constant over several days, including after anaerobic changes in the culture medium. Lowered oxygen resulted in transient increase of the hypoxia-inducible factor 1α and of its REDD1 target, inhibition of mechanistic (or mammalian) target of rapamycin, decreased autophagy, altered cap-dependent translation, and minimal repression of the already weak oxidative phosphorylation. These adjustments did not trigger important cellular iron fluxes since the cells relied on their internal iron stores to survive. In conclusion, the response of the KG1a cells to stringent hypoxia is varied, with some established hypoxia-sensitive pathways exhibiting activation whereas others were unaffected. The results draw attention to the flexibility of the environmental adaptation of cancer cells. They suggest that thorough characterization of early leukemic blasts is warranted to propose informed treatments to patients.

Sabatolimab (MBG453) model-informed drug development for dose selection in patients with myelodysplastic syndrome/acute myeloid leukemia and solid tumors.

Sabatolimab is a novel immunotherapy with immuno-myeloid activity that targets T-cell immunoglobulin domain and mucin domain-3 (TIM-3) on immune cells and leukemic blasts. It is being evaluated for the treatment of myeloid malignancies in the STIMULUS clinical trial program. The objective of this analysis was to support the sabatolimab dose-regimen selection in hematologic malignancies. A population pharmacokinetic (PopPK) model was fit to patients with solid tumors and hematologic malignancies, which included acute myeloid leukemia, myelodysplastic syndrome (including intermediate-, high-, and very high-risk per Revised International Prognostic Scoring System), and chronic myelomonocytic leukemia. The PopPK model, together with a predictive model of sabatolimab distribution to the bone marrow and binding to TIM-3 was used to predict membrane-bound TIM-3 bone marrow occupancy. In addition, the total soluble TIM-3 (sTIM-3) kinetics and the pharmacokinetic (PK) exposure-response relationship in patients with hematologic malignancies were examined. At intravenous doses above 240 mg Q2w and 800 mg Q4w, we observed linear PK, a plateau in the accumulation of total sTIM-3, and a flat exposure-response relationship for both safety and efficacy. In addition, the model predicted membrane-bound TIM-3 occupancy in the bone marrow was above 95% in over 95% of patients. Therefore, these results support the selection of the 400 mg Q2w and 800 mg Q4w dosing regimens for the STIMULUS clinical trial program.

The palmitoyltransferase ZDHHC21 regulates oxidative phosphorylation to induce differentiation block and stemness in AML

AbstractAcute myeloid leukemia (AML) is an aggressive hematological malignancy. Nearly 50% of patients who receive the most intensive treatment inevitably experience disease relapse, likely resulting from the persistence of drug-resistant leukemia stem cells (LSCs). AML cells, especially LSCs, are highly dependent on mitochondrial oxidative phosphorylation (OXPHOS) for survival, but the mechanism involved in OXPHOS hyperactivity is unclear, and a noncytotoxic strategy to inhibit OXPHOS is lacking. To our knowledge, this study is the first to demonstrate that ZDHHC21 palmitoyltransferase serves as a key regulator of OXPHOS hyperactivity in AML cells. The depletion/inhibition of ZDHHC21 effectively induced myeloid differentiation and weakened stemness potential by inhibiting OXPHOS in AML cells. Interestingly, FMS-like tyrosine kinase-3 internal tandem duplication (FLT3-ITD)–mutated AML cells expressed significantly higher levels of ZDHHC21 and exhibited better sensitivity to ZDHHC21 inhibition. Mechanistically, ZDHHC21 specifically catalyzed the palmitoylation of mitochondrial adenylate kinase 2 (AK2) and further activated OXPHOS in leukemic blasts. Inhibition of ZDHHC21 arrested the in vivo growth of AML cells and extended the survival of mice inoculated with AML cell lines and patient derived xenograft AML blasts. Moreover, targeting ZDHHC21 to suppress OXPHOS markedly eradicated AML blasts and enhanced chemotherapy efficacy in relapsed/refractory leukemia. Together, these findings not only uncover a new biological function of palmitoyltransferase ZDHHC21 in regulating AML OXPHOS but also indicate that ZDHHC21 inhibition is a promising therapeutic regimen for patients with AML, especially relapsed/refractory leukemia.

Acute Myeloid Leukemia Stem Cells in Minimal/Measurable Residual Disease Detection.

Acute myeloid leukemia (AML) is a hematological malignancy characterized by an abundance of incompletely matured or immature clonally derived hematopoietic precursors called leukemic blasts. Rare leukemia stem cells (LSCs) that can self-renew as well as give rise to leukemic progenitors comprising the bulk of leukemic blasts are considered the cellular reservoir of disease initiation and maintenance. LSCs are widely thought to be relatively resistant as well as adaptive to chemotherapy and can cause disease relapse. Therefore, it is imperative to understand the molecular bases of LSC forms and functions during different stages of disease progression, so we can more accurately identify these cells and design therapies to target them. Irrespective of the morphological, cytogenetic, and cellular heterogeneity of AML, the uniform, singularly important and independently significant prognosticator of disease response to therapy and patient outcome is measurable or minimal residual disease (MRD) detection, defined by residual disease detection below the morphology-based 5% blast threshold. The importance of LSC identification and frequency estimation during MRD detection, in order to make MRD more effective in predicting disease relapse and modifying therapeutic regimen is becoming increasingly apparent. This review focuses on summarizing functional and cellular composition-based LSC identification and linking those studies to current techniques of MRD detection to suggest LSC-inclusive MRD detection as well as outline outstanding questions that need to be addressed to improve the future of AML clinical management and treatment outcomes.

Epidermal growth factor-like 7 is a novel therapeutic target in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive, noncurative, mature B-cell lymphoma, with a median overall survival of 6-7 years. This underlines a need for effective therapeutic strategies to treat MCL better. Epidermal growth factor-like 7 (EGFL7) is a protein secreted by endothelial cells shown to play a critical role in angiogenesis. Our laboratory has previously demonstrated that EGFL7 supports the growth of leukemic blasts in patients with acute myeloid leukemia (AML); however, its role in MCL has not been investigated yet. In this study, we report that EGFL7 messenger RNA (mRNA) is increased in the cells of patients with MCL compared with cells from healthy controls, and patients with high EGFL7 are associated with lower overall survival rates. Furthermore, EGFL7 is increased in the plasma of patients with MCL compared with the plasma from healthy controls. We further show that EGFL7 binds to epidermal growth factor receptor (EGFR) and activates AKT signaling pathway in MCL cells and that blocking EGFL7 in MCL in patient and cell lines decreases cell growth and increases apoptosis in vitro. Finally, anti-EGFL7 treatment inhibits tumor size and prolongs survival in a mouse model of MCL. In conclusion, our study reveals a role for EGFL7 in MCL cell proliferation and highlights EGFL7 inhibition as a promising new treatment for patients with MCL.

Preclinical Validation of an Advanced Therapy Medicinal Product Based on Cytotoxic T Lymphocytes Specific for Mutated Nucleophosmin (NPM1mut) for the Treatment of NPM1mut-Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) with nucleophosmin (NPM1) genetic mutations is the most common subtype in adult patients. Refractory or relapsed disease in unfit patients or after allogeneic hematopoietic stem cell transplantation (allo-HSCT) has a poor prognosis. NPM1-mutated protein, stably expressed on tumor cells but not on normal tissues, may serve as an ideal target for NPM1-mutated AML immunotherapy. The study aim was to investigate the feasibility of producing mutated-NPM1-specific cytotoxic T cells (CTLs) suitable for somatic cell therapy to prevent or treat hematologic relapse in patients with NPM1-mutated AML. T cells were expanded or primed from patient or donor peripheral blood mononuclear cells by NPM1-mutated protein-derived peptides, and tested for leukemia antigen-targeted cytotoxic activity, cytokine production and hematopoietic precursor inhibitory effect. We found that mutated-NPM1-specific CTLs, displaying specific cytokine production and high-level cytotoxicity against patients' leukemia blasts, and limited inhibitory activity in clonogenic assays, could be obtained from both patients and donors. The polyfunctional mutated-NPM1-specific CTLs included both CD8+ and CD4+ T cells endowed with strong lytic capacity. Our results suggest that mutated-NPM1-targeted CTLs may be a useful therapeutic option to control low-tumor burden relapse following conventional chemotherapy in older NPM1-mutated AML patients or eradicate persistent MRD after HSCT.

Acute leukemias with complex karyotype show a similarly poor outcome independent of mixed, myeloid or lymphoblastic immunophenotype: A study from the Bone Marrow Pathology Group

Mixed phenotype acute leukemia (MPAL) is a heterogenous group of acute leukemias characterized by leukemic blasts that express markers of multiple lineages. The revised 4th edition WHO classification of MPAL excludes AML with myelodysplasia related changes (AML-MRC), including those with complex karyotype (CK), from a diagnosis of MPAL. Abnormal karyotype is frequent in MPAL with the reported rate of CK in MPAL ranging from 19% to 32%. Due its rarity, the clinical and genetic features of MPAL with CK remain poorly characterized. This study aims to further characterize the genetic features of MPAL with CK in comparison to cases of AML and ALL with CK. Cases of de novo MPAL, AML, and B- and T-ALL patients with CK were collected from 8 member institutions of the Bone Marrow Pathology Group. We found no significant difference in overall survival between MPAL with CK compared to AML and ALL with CK. AML with CK was more strongly associated with TP53 mutations, however the presence of TP53 mutations conferred a worse prognosis regardless of lineage. ALL with CK seems to show increased IKZF1 mutation rates which is known to confer a worse prognosis in ALL. Additionally, MPAL with CK showed similarly poor outcomes regardless of whether a lymphoid or myeloid chemotherapy regimen is chosen. Our results suggest that acute leukemias with complex karyotype show a similarly poor outcome regardless of lineage differentiation and that mutation in TP53 confers a poor prognosis in all lineages. Our results support the exclusion of immunophenotypic MPAL with CK from MPAL and appear to confirm the approach proposed in the revised 4th edition WHO to include them as AML with myelodysplasia-related changes and similar myelodysplasia-related AML categories of newer classifications.

Leukaemic blasts in a urine specimen in acute myeloid leukaemia with CEBPA mutation.

British Journal of HaematologyEarly View IMAGES IN HAEMATOLOGY Leukaemic blasts in a urine specimen in acute myeloid leukaemia with CEBPA mutation Ting Li, Ting Li orcid.org/0000-0002-2027-9462 Department of Laboratory Medicine, Beijing Ludaopei Hospital, Beijing, ChinaSearch for more papers by this authorYun Zhang, Yun Zhang orcid.org/0000-0001-5958-5494 Department of Clinical Laboratory, The District People’s Hospital of Zhangqiu, Shandong Province, Jinan, ChinaSearch for more papers by this authorKaifeng Wang, Kaifeng Wang Department of Hematology, The District People's Hospital of Zhangqiu, Shandong Province, Jinan, ChinaSearch for more papers by this authorHui Zhou, Hui Zhou Department of Gastroenterology, Xiangshan Red Cross Taiwan Compatriot Hospital, Zhejiang Province, Xiangshan, ChinaSearch for more papers by this authorJunge Zhang, Corresponding Author Junge Zhang [email protected] orcid.org/0000-0001-7524-7903 Department of Clinical Laboratory, Xiangshan Red Cross Taiwan Compatriot Hospital, Zhejiang Province, Xiangshan, ChinaSearch for more papers by this author Ting Li, Ting Li orcid.org/0000-0002-2027-9462 Department of Laboratory Medicine, Beijing Ludaopei Hospital, Beijing, ChinaSearch for more papers by this authorYun Zhang, Yun Zhang orcid.org/0000-0001-5958-5494 Department of Clinical Laboratory, The District People’s Hospital of Zhangqiu, Shandong Province, Jinan, ChinaSearch for more papers by this authorKaifeng Wang, Kaifeng Wang Department of Hematology, The District People's Hospital of Zhangqiu, Shandong Province, Jinan, ChinaSearch for more papers by this authorHui Zhou, Hui Zhou Department of Gastroenterology, Xiangshan Red Cross Taiwan Compatriot Hospital, Zhejiang Province, Xiangshan, ChinaSearch for more papers by this authorJunge Zhang, Corresponding Author Junge Zhang [email protected] orcid.org/0000-0001-7524-7903 Department of Clinical Laboratory, Xiangshan Red Cross Taiwan Compatriot Hospital, Zhejiang Province, Xiangshan, ChinaSearch for more papers by this author First published: 08 May 2023 https://doi.org/10.1111/bjh.18838Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Early ViewOnline Version of Record before inclusion in an issue RelatedInformation