Leukemic Blasts Research Articles

Isolated peripheral neuroleukemiosis mimicking Guillain‐Barré syndrome in an adolescent with relapsed B‐lymphoblastic leukemia

AbstractBackgroundNeuroleukemiosis, leukemic infiltration of the peripheral nervous system (PNS), is rare. Very few cases of isolated neuroleukemiosis, PNS leukemic infiltration without leukemia blasts in the blood or bone marrow, have been reported in pediatrics. Most cases have occurred in adults with acute myelogenous leukemia (AML) in remission who presented with peripheral neuropathy. We describe a pediatric patient presenting with isolated neuroleukemiosis mimicking Guillain‐Barré syndrome.Patient descriptionA 15‐year‐old boy presented 1 month after IVIG treatment for Guillain‐Barre syndrome with worsening ataxia and weakness. He had a past medical history of B‐cell acute lymphoblastic leukemia (B‐ALL) in remission for 8 years. Examination revealed distal greater than proximal weakness of the bilateral lower extremities, areflexia at the Achilles tendon, and 1+ patellar and upper extremity reflexes. Initial magnetic resonance imaging (MRI) of the brain and spine were normal, and lumbar puncture revealed increased protein with uninterpretable white count due to excessive red blood cells. Repeat MRI brain and spinal cord showed extensive enlargement of all nerve roots and enhancement of the cauda equina and portions of cranial nerve VII bilaterally. Repeat lumbar puncture with cytology revealed leukemic blast cells. Blasts were not detected in peripheral blood smear or by flow cytometry. Bone marrow biopsy was also free of blast cells, confirming the diagnosis of relapsed B‐ALL restricted to the nervous system.ConclusionsNeuroleukemiosis is a rare entity with typical clinical features of mono‐ or polyneuropathy. It most often occurs in adults in remission from AML. However, neuroleukemiosis should also be on the differential for pediatric patients in remission from ALL presenting with neuropathy.

Single-cell transcriptional mapping reveals genetic and non-genetic determinants of aberrant differentiation in AML.

In acute myeloid leukemia (AML), genetic mutations distort hematopoietic differentiation, resulting in the accumulation of leukemic blasts. Yet, it remains unclear how these mutations intersect with cellular origins and whether they converge upon similar differentiation patterns. Single-cell RNA sequencing (scRNA-seq) has enabled high-resolution mapping of the relationship between leukemia and normal cell states, yet this application is hampered by imprecise reference maps of normal hematopoiesis and small sample sizes among patient cohorts. As a first step we constructed a reference atlas of human bone marrow hematopoiesis from 263,519 single-cell transcriptomes spanning 55 cellular states, that was benchmarked against independent datasets of immunophenotypically pure hematopoietic stem and progenitor cells. Using this reference atlas, we mapped over 1.2 million single-cell transcriptomes spanning 318 AML, mixed phenotype acute leukemia (MPAL), and acute erythroid leukemia (AEL) samples. This large-scale analysis, together with systematic mapping of genotype-to-phenotype associations between driver mutations and differentiation landscapes, revealed convergence of diverse genetic alterations on twelve recurrent patterns of aberrant differentiation in AML. This included unconventional lymphoid and erythroid priming linked to RUNX1 and TP53 mutations, respectively. We also identified non-genetic determinants of AML differentiation such as two subgroups of KMT2A-rearranged AML that differ in the identity of their leukemic stem cells (LSCs), likely reflecting distinct cellular origins. Furthermore, distinct LSC-driven hierarchies can co-exist within individual patients, providing insights into AML evolution. Together, precise mapping of normal and malignant cell states provides a framework for advancing the study and disease classification of hematologic malignancies thereby informing therapy development.

Proteogenomic characterization of highly enriched viable leukemic blasts in acute myeloid leukemia: A SWOG report

AbstractIntroductionAcute myeloid leukemia (AML) remains one of the deadliest hematopoietic malignancies. A better understanding of the molecular biology governing AML may lead to improved risk stratification and facilitate the development of novel therapies. Proteins are responsible for much of the biology of cells. Several studies have examined the global proteome in bulk mononuclear cells (MNCs) from AML specimens, which are comprised a heterogenous population of cells at various stages of differentiation.MethodsGiven the potential impact of the nonleukemic cells on protein expression profiles, we applied an integrative proteogenomic approach utilizing next‐generation sequencing and mass spectrometry‐based proteomics to identify novel protein biomarkers in unsorted MNCs and viable leukemic blasts (VLBs) isolated from blood and bone marrow specimens obtained at the time of AML diagnosis.ResultsWe identified significant differences in protein expression between VLBs and MNCs. Subsequent studies (N = 27) focused on proteomic profiling of VLBs that identified novel candidate biomarkers associated with mutational genotypes and clinical outcome, some of which were recapitulated in an independent cohort of patients. Using mass spectrometry, we also detected mutated protein products, some of which were predicted via in silico analyses to be potential neoantigens amenable to adoptive immunotherapy. As previously described, analyses comparing transcript and protein expression showed an overall modest correlation between mRNA and protein dataset, but enriching for genes associated with mutations significantly improved the protein–RNA correlation.ConclusionTogether, the results provide insight into the biology of VLBs and demonstrate the gains derived from examining the proteome in addition to genome and transcriptome.

Characteristics and Prognosis of "Acute Promyelocytic Leukemia-like" Nucleophosmin-1-Mutated Acute Myeloid Leukemia in a Retrospective Patient Cohort.

Background: AML with NPM1 mutation is the largest subcategory of AML, representing about 35% of AML cases. It is characterized by CD34 negativity, which suggests a relatively differentiated state of the bulk of leukemic blasts. Notably, a significant subset of NPM1-mutated AML cases also exhibit HLA-DR negativity, classifying them as "double-negative", and mimicking, therefore, the CD34- HLA-DR- immunophenotype of acute promyelocytic leukemia (APL). Objectives: This study focuses on the "acute promyelocytic leukemia-like" ("APL-like") subset of NPM1-mutated AML, which can be challenging to distinguish from APL at presentation, prior to confirming RARa translocations. We aim to investigate the hematologic and immunophenotypic parameters that may aid to its distinction from APL. Additionally, we explore differences in genetic profile and prognosis between "APL-like" and "non-APL-like" NPM1-mutated AML cases. Methods: We conducted a retrospective evaluation of 77 NPM1-mutated AML cases and 28 APL cases. Results: Morphological characteristics, hematologic parameters (such as DD/WBC and PT/WBC), and specific immunophenotypic markers (including SSC, CD64, and CD4) can assist in the early distinction of "APL-like" NPM1-mutated AML from APL. Regarding differences in genetic profiles and outcomes between "APL-like" and non-"APL-like" NPM1-mutated AML cases, we observed a significantly higher incidence of IDH1/2 /TET2 mutations, along with a significantly lower incidence of DNMT3A mutations in the "APL-like" subset compared to the non-"APL-like" subset. The frequency of Ras-pathway and FLT3 mutations did not differ between these last two groups, nor did their prognoses. Conclusions: Our findings contribute to a comprehensive characterization of NPM1-mutated AML, enhancing diagnostic accuracy and aiding in the detailed classification of the disease. This information may potentially guide targeted therapies or differentiation-based treatment strategies.

Thioredoxin-interacting protein (TXNIP) is a substrate of the NEDD4-like E3 ubiquitin-protein ligase WWP1 in cellular redox state regulation of acute myeloid leukemia cells.

The HECT-type E3 ubiquitin WWP1 (also known as NEDD4-like E3 ubiquitin-protein ligase WWP1) acts as an oncogenic factor in acute myeloid leukemia (AML) cells. WWP1 overexpression in AML confers a proliferative advantage to leukemic blasts (abnormal immature white bloodcells) and counteracts apoptotic cell death and differentiation. In aneffort to elucidate the molecular basis of WWP1 oncogenic activities, we identified WWP1 as a previously unknown negative regulator of thioredoxin-interacting protein (TXNIP)-mediated reactive oxygen species (ROS) production in AML cells. TXNIP inhibits the disulfide reductase enzymatic activity of thioredoxin (Trx), impairing its antioxidant function and, ultimately, leading to the disruption of cellular redox homeostasis. In addition, TXNIP restricts cell growth and survival by blocking glucose uptake and metabolism. Here, we found that WWP1 directly interacts with TXNIP, thus promoting its ubiquitin-dependent proteasomal proteolysis. As a result, accumulation of TXNIP in response to WWP1 inactivation inAML blasts reduces Trx activity and increases ROS production, henceinducing cellular oxidative stress. Increased ROS generation in WWP1-depleted cells culminates in DNA strand breaks and subsequent apoptosis. Coherently with TXNIP stabilization following WWP1 inactivation, we also observed an impairment of both glucose up-take and consumption. Hence, a contribution to the increased cell death observed in WWP1-depleted cells also possibly arises from the attenuation of glucose up-take and glycolytic flux resulting from TXNIP accumulation. Future studies are needed to establish whether TXNIP-dependent deregulation of redox homeostasis in WWP1-overexpressing blasts may affect the response of leukemic cells to chemotherapeutic drugs.

Development of a Competitive Nutrient-Based T-Cell Immunotherapy Designed to Block the Adaptive Warburg Effect in Acute Myeloid Leukemia.

Background: T-cell-based adoptive cell therapies have emerged at the forefront of cancer immunotherapies; however, failed long-term survival and inevitable exhaustion of transplanted T lymphocytes in vivo limits clinical efficacy. Leukemia blasts possess enhanced glycolysis (Warburg effect), exploiting their microenvironment to deprive nutrients (e.g., glucose) from T cells, leading to T-cell dysfunction and leukemia progression. Methods: Thus, we explored whether genetic reprogramming of T-cell metabolism could improve their survival and empower T cells with a competitive glucose-uptake advantage against blasts and inhibit their uncontrolled proliferation. Results: Here, we discovered that high-glucose concentration reduced the T-cell expression of glucose transporter GLUT1 (SLC2A1) and TFAM (mitochondrion transcription factor A), an essential transcriptional regulator of mitochondrial biogenesis, leading to their impaired expansion ex vivo. To overcome the glucose-induced genetic deficiency in metabolism, we engineered T cells with lentiviral overexpression of SLC2A1 and/or TFAM transgene. Multi-omics analyses revealed that metabolic reprogramming promoted T-cell proliferation by increasing IL-2 release and reducing exhaustion. Moreover, the engineered T cells competitively deprived glucose from allogenic blasts and lessened leukemia burden in vitro. Conclusions: Our findings propose a novel T-cell immunotherapy that utilizes a dual strategy of starving blasts and cytotoxicity for preventing uncontrolled leukemia proliferation.

Reactive oxygen species and aldehyde dehydrogenase 1A as prognosis and theragnostic biomarker in acute myeloid leukaemia patients.

Acute myeloid leukaemia (AML) remains a major unmet medical, despite recent progress in targeted molecular therapies. One aspect of leukaemic cell resistance to chemotherapy is the development of clones with increased capacity to respond to cellular stress and the production of reactive oxygen species (ROS), thanks in particular to a high aldehyde dehydrogenases (ALDH) 1A1/2 activity. At diagnosis, ROS level and ALDH1A1/2 activity in AML patients BM are correlated with the different ELN 2022 prognostic groups and overall survival (OS). A significant lower ALDH1A1/2 activity in BM was observed in the favourable ELN2022 subgroup compared to the intermediate and adverse group (p < 0.01). In the same way, the ROS levels were significantly lower in the favourable ELN 2022 subgroup compared to the intermediate group (p < 0.0001) and adverse group (p < 0.0002). ROShigh AML patients had a significantly lower median overall survival (OS) (8.2 months) than ROSlow patients (24.6 months) (p = 0.0368). After first-line therapy, a significant increase of ROS level (p = 0.015) and ALDH1A1/2 activity (0 = 0.0273) in leukaemic blasts was observed, especially in the refractory ones. ABD-3001, a competitive and irreversible inhibitor of ALDHs 1 and 3, can invitro inhibit the proliferation of patient-derived leukaemic cells in accordance with redox balance. In multivariate analysis, ROS level was the most significant (p < 0.05) and the strongest predictive factor for the sensitivity of cells to ABD-3001. The safety profile of ABD-3001 is currently being assessed through the first inhuman multicenter phase 1 clinical trial "ODYSSEY" (NCT05601726) for patients with relapsed AML.

Anti-CLL1 liposome loaded with miR-497-5p and venetoclax as a novel therapeutic strategy in acute myeloid leukemia

Acute myeloid leukemia (AML) is a lethal hematologic malignancy. Chemotherapy resistance results in a dismal survival of 1-2 years in older adults with AML. Therefore, novel therapies are urgently required. In this context, microRNA (miRNA)-based treatments remain an untapped strategy in AML. Using patient-derived specimens, we found increased inflammatory cytokines including IL-6 in serum of older adults with AML, and decreased miR-497-5p in CD34+ leukemic blasts. Target prediction revealed that miR-497-5p could directly target mitogen-activated protein kinase-1 (MAP2K1) mRNA, to indirectly target cytokines and JAK/STAT signaling pathway through p38-MAPK signaling pathway, potentially inhibiting leukemic growth, and overcoming chemoresistance from venetoclax. To improve miRNA delivery and minimize off-target effects, which represent key barriers to clinical translation, we developed liposomes for co-delivery of miR-497-5p and venetoclax. We decorated our liposomes with a peptide targeting CLL1, which is present on 92% leukemia blasts while being absent in normal hematopoietic cells. This targeted approach demonstrated high efficacy in inhibiting AML growth in mice with minimal toxicity, as well as reduced exposure to chemoresistance. Our findings suggested that anti-CLL1-decorated, miR-497-5p and venetoclax-loaded liposomes represent a promising novel miRNA-based therapeutic, which should be further investigated as a strategy to reduce venetoclax resistance in AML.

Peripheral Hemophagocytosis and Leukemic Blasts from Urine in de novo Pure Erythroid Leukemia.

Peripheral Hemophagocytosis and Leukemic Blasts from Urine in de novo Pure Erythroid Leukemia.

Targeting cellular plasticity: esculetin-driven reversion of stem cell-like characteristics and EMT phenotype in transforming cells with sequential p53/p73 knockdowns

The intricate interplay of cancer stem cell plasticity, along with the bidirectional transformation between epithelial-mesenchymal states, introduces further intricacy to offer insights into newer therapeutic approaches. Differentiation therapy, while successful in targeting leukemic stem cells, has shown limited overall success, with only a few promising instances. Using colon carcinoma cell strains with sequential p53/p73 knockdowns, our study underscores the association between p53/p73 and the maintenance of cellular plasticity. Morphological alterations corresponding with cell surface marker expressions, transcriptome analysis and functional assays were performed to access stemness and EMT (Epithelial-Mesenchymal Transition) characteristics in the spectrum of cells exhibiting sequential p53 and p73 knockdowns. Notably, our investigation explores the effectiveness of esculetin in reversing the shift from an epithelial to a mesenchymal phenotype, characterized by stem cell-like traits. Esculetin significantly induces enterocyte differentiation and promotes epithelial cell polarity by altering Wnt axes in Cancer Stem Cell-like cells characterized by high mesenchymal features. These results align with our previous findings in leukemic blast cells, establishing esculetin as an effective differentiating agent in both Acute Myeloid Leukemia (AML) and solid tumor cells.

The significance of CD49f expression in pediatric B-cell acute lymphoblastic leukemia.

CD49f is an adhesion molecule present on malignant lymphoblasts in B-cell acute lymphoblastic leukemia; it is associated with a poor prognosis. CD49f expression has been proposed as a marker for measurable residual disease (MRD) marker, but this marker has yet to be implemented in clinical practice. In this study, we used flow cytometry to detect CD49f expression by leukemic blasts in paired bone marrow and cerebrospinal fluid samples at diagnosis and bone marrow at day 15 of treatment. At diagnosis, 93% of bone marrow and 100% of cerebrospinal fluid lymphoblasts expressed CD49f. The intensity of CD49f expression statisticallysignificantly increased during treatment (P < .001). In MRD-negative end-of-treatment samples, only a small population of hematogones expressed CD49f. Interestingly, the intensity of CD49f expression varied among the different groups of recurrent genetic abnormalities. The ETV6::RUNX1 fusion and ETV6::RUNX1 combined with the high hyperdiploid group were associated with increased expression, whereas the Philadelphia-like group showed low CD49f expression. The lower CD49f expression at diagnosis predicted a lower MRD rate at day 15 of treatment. We concluded that CD49f can be used as an MRD marker and possible prognostic factor in B-cell acute lymphoblastic leukemia.

Acute lymphoblastic leukemia with nephrogenic diabetes insipidus as the first symptom: a case report

BackgroundAcute lymphoblastic leukemia is the most common pediatric malignancy, characterized by fever, anemia, hemorrhage, and symptoms brought on by blasts infiltrating organs.Case presentationThis is a case report of a 9-year-old Asian patient with acute lymphoblastic leukemia who presented with polyuria alone as a presenting feature without any other clinical manifestation; primary renal disease or inherited metabolic disease was highly suspected. However, the water deprivation test and water deprivation pressurization test suggested nephrogenic diabetes insipidus, and the renal biopsy displayed diffuse lymphocytic infiltration in the renal interstitium. Bone marrow aspiration was performed immediately, and a comprehensive diagnosis of B-lymphoblastic leukemia was finally made.ConclusionsRenal infiltration with leukemic blasts mostly remains asymptomatic, but our case suggests that it can present with nephrogenic diabetes insipidus. This case fully demonstrates that the presentation of extramedullary infiltration in acute lymphoblastic leukemia is varied. When the patient has renal diabetes insipidus as the first symptom, the possibility of hematological tumor infiltration should be considered when finding the cause, and timely bone marrow cytology should be performed.

TOPORS E3 ligase mediates resistance to hypomethylating agent cytotoxicity in acute myeloid leukemia cells

Hypomethylating agents (HMAs) are frontline therapies for Myelodysplastic Neoplasms (MDS) and Acute Myeloid Leukemia (AML). However, acquired resistance and treatment failure are commonplace. To address this, we perform a genome-wide CRISPR-Cas9 screen in a human MDS-derived cell line, MDS-L, and identify TOPORS as a loss-of-function target that synergizes with HMAs, reducing leukemic burden and improving survival in xenograft models. We demonstrate that depletion of TOPORS mediates sensitivity to HMAs by predisposing leukemic blasts to an impaired DNA damage response (DDR) accompanied by an accumulation of SUMOylated DNMT1 in HMA-treated TOPORS-depleted cells. The combination of HMAs with targeting of TOPORS does not impair healthy hematopoiesis. While inhibitors of TOPORS are unavailable, we show that inhibition of protein SUMOylation with TAK-981 partially phenocopies HMA-sensitivity and DDR impairment. Overall, our data suggest that the combination of HMAs with inhibition of SUMOylation or TOPORS is a rational treatment option for High-Risk MDS (HR-MDS) or AML.

The role of the primitive marker CD133 in CD34-negative acute myeloid leukemia for the detection of leukemia stem cells.

The most important reason for dismal outcomes in acute myeloid leukemia (AML) is the development of relapse. Leukemia stem cells (LSCs) are hypothesized to initiate relapse, and high CD34+CD38- LSC load is associated with poor prognosis. In 10% of AML patients, CD34 is not or is low expressed on the leukemic cells (<1%), and CD34+CD38- LSCs are absent. These patients are classified as CD34-negative. We aimed to determine whether the primitive marker CD133 can detect LSCs in CD34-negative AML. We retrospectively quantified 148 CD34-negative patients for proportions of CD34-CD133+ and CD133+CD38- cell fractions in the diagnostic samples of CD34-negative patients in the HOVON102 and HOVON132 trials. No prognostic difference was found between patients with high or low proportions of CD34-CD133+, which is found to be aberrantly expressed in AML. A high level of CD133+CD38- cells was not associated with poor overall survival, and expression in AML was similar to normal bone marrow. To conclude, CD133 is useful as an additional primitive marker for the detection of leukemic blast cells in CD34-negative AML. However, CD133+CD38 alone is not suitable for the detection of LSCs at diagnosis.

Transformation into acute myeloid leukemia with t(8;21)(q22;q22.1); RUNX1::RUNX1T1 from JAK2-mutated essential thrombocythemia: a case report

BackgroundBlast transformation is a rare but well-recognized event in Philadelphia-negative myeloproliferative neoplasms associated with a poor prognosis. Secondary acute myeloid leukemias evolving from myeloproliferative neoplasms are characterized by a unique set of cytogenetic and molecular features distinct from de novo disease. t(8;21) (q22;q22.1); RUNX1::RUNX1T1, one of the most frequent cytogenetic abnormalities in de novo acute myeloid leukemia, is rarely observed in post-myeloproliferative neoplasm acute myeloid leukemia. Here we report a case of secondary acute myeloid leukemia with t(8;21) evolving from JAK2-mutated essential thrombocythemia.Case presentationThe patient was a 74-year-old Japanese woman who was referred because of thrombocytosis (platelets 1046 × 109/L). Bone marrow was hypercellular with increase of megakaryocytes. Chromosomal analysis presented normal karyotype and genetic test revealed JAK2 V617F mutation. She was diagnosed with essential thrombocythemia. Thrombocytosis had been well controlled by oral administration of hydroxyurea; 2 years after the initial diagnosis with ET, she presented with leukocytosis (white blood cells 14.0 × 109/L with 82% of blasts), anemia (hemoglobin 91 g/L), and thrombocytopenia (platelets 24 × 109/L). Bone marrow was hypercellular and filled with 80% of myeloperoxidase-positive blasts bearing Auer rods. Chromosomal analysis revealed t(8;21) (q22;q22.1) and flow cytometry presented positivity of CD 13, 19, 34, and 56. Molecular analysis showed the coexistence of RUNX1::RUNX1T1 chimeric transcript and heterozygous JAK2 V617F mutation in leukemic blasts. She was diagnosed with secondary acute myeloid leukemia with t(8;21)(q22;q22.1); RUNX1::RUNX1T1 evolving from essential thrombocythemia. She was treated with combination chemotherapy with venetoclax and azacytidine. After the first cycle of the therapy, blasts disappeared from peripheral blood and decreased to 1.4% in bone marrow. After the chemotherapy, RUNX1::RUNX1T1 chimeric transcript disappeared, whereas mutation of JAK2 V617F was still present in peripheral leukocytes.ConclusionsTo our best knowledge, the present case is the first one with JAK2 mutation preceding the acquisition of t(8;21). Our result suggests that t(8;21); RUNX1::RUNX1T1 can be generated as a late event in the progression of JAK2-mutated myeloproliferative neoplasms. The case presented typical morphological and immunophenotypic features associated with t(8;21) acute myeloid leukemia.

Differential effect of asparagine and glutamine removal on three adenocarcinoma cell lines

Asparagine and glutamine depletion operated by the drug Asparaginase (ASNase) has revolutionized therapy in pediatric patients affected by Acute Lymphoblastic Leukemia (ALL), bringing remissions to a remarkable 90 % of cases. However, the knowledge of the proproliferative role of asparagine in adult and solid tumors is still limited. We have here analyzed the effect of ASNase on three adenocarcinoma cell lines (A549, lung adenocarcinoma, MCF-7, breast cancer, and 786-O, kidney cancer). In contrast to MCF-7 cells, 786-O and A549 cells proved to be a relevant target for cell cycle perturbation by asparagine and glutamine shortage. Indeed, when the cell-cycle was analyzed by flow cytometry, A549 showed a canonical response to asparaginase, 786-O cells, instead, showed a reduction of the percentage of cells in the G1 phase and an increase of those in the S-phase. Despite an increased number of PCNA and RPA70 positive nuclear foci, BrdU and EdU incorporation was absent or strongly delayed in treated 786-O cells, thus indicating a readiness of replication forks unmatched by DNA synthesis. In 786-O asparagine synthetase was reduced following treatment and glutamine synthetase was totally absent. Interestingly, DNA synthesis could be recovered by adding Gln to the medium. MCF-7 cells showed no significant changes in the cell cycle phases, in DNA-bound PCNA and in total PCNA, but a significant increase in ASNS and GS mRNA and protein expression. The collected data suggest that the effect observed on 786-O cells following ASNase treatment could rely on mechanisms which differ from those well-known and described for leukemic blasts, consisting of a complete block in the G1/S transition in proliferating cells and on an increase on non-proliferative (G0) blasts.

CD19-chimeric antigen receptor-invariant natural killer T cells transactivate NK cells and reduce alloreactivity

Invariant natural killer T (iNKT) cells are a small fraction of T lymphocytes with strong cytotoxic and immunoregulatory properties. We previously showed that human culture-expanded iNKT cells prevent alloreactivity and lyse primary leukemia blasts. Here, iNKT cells have several advantages over T cells based on their immunoregulatory capabilities. Since chimeric antigen receptors (CARs) increase the benefit of immune effector cells, they play a crucial role in improvement of cytotoxic abilities of novel cellular therapeutics such as iNKT cells. In the present study, we investigated transactivation of NK cells and prevention of alloreactivity through iNKT cells transduced with a CD19-directed CAR. iNKT cells were isolated by magnetic cell separation from peripheral blood mononuclear cells and transduced with a CD19-CAR retrovirus. Transduction efficiency, purity and cell subsets were measured by flow cytometry. Transactivation and cytotoxicity assays have been established to investigate the ability of CD19-CAR-iNKT cells to transactivate primary NK cells. A mixed lymphocyte reaction (MLR) was performed to explore the inhibition of alloreactive CD3+ T cells by CD19-CAR-iNKT cells. CD19-CAR-iNKT cells are able to transactivate NK cells independent of cell contact: The expression of activation marker CD69 was significantly increased and also production of the proinflammatory cytokine interferon-gamma was higher in NK cells pretreated with CD19-CAR-iNKT cells. Consequently, the cytotoxic activity of such NK cells was significantly increased being able to lyse leukemia cells more effectively than without prior transactivation. Adding CD19-CAR-iNKT cells to an MLR resulted in a decreased expression of the T cell activation marker CD25 on alloreactive CD3+ T lymphocytes stimulated with HLA mismatched dendritic cells. Also, the proliferation of alloreactive CD3+ T lymphocytes was significantly reduced in this setting. We demonstrate that CD19-CAR-iNKT cells keep their immunoregulatory properties despite transduction with a CAR making them an attractive effector cell population for application after allogeneic hematopoietic cell transplantation. By transactivating NK cells, increasing their cytotoxic activity and suppressing alloreactive T cells, they might further improve outcomes through prevention of both relapse and graft-versus-host disease.

A Follow-Up Case of Breast Carcinoma with the Unusual Visitor in Peripheral Blood: Unlock Feathered Edge Secret

Background: Breast cancer is the most common cancer in women worldwide and in India. There are very few cases of breast cancer with peripheral blood dissemination having acute leukaemia-like blast cells. Case presentation: Here we present a 44-year-old breast cancer follow-up patient with the presence of leukaemia-like blast cells in peripheral blood. The specific cytochemical staining and immunophenotyping assays on bone marrow biopsy revealed that atypical cells in her peripheral blood were from breast cancer metastasis. A comprehensive workup confirmed carcinocythemia in the present case and systemic chemotherapy and hormonal therapy were planned. However, she died 15 days after the carcinocythemia presentation. Carcinocythemia patients have a poor survival. Conclusion: Because carcinocythemia cells can mimic leukemic blasts and share morphological features, the patient's medical history and a careful analysis of the feathery border of the smear are needed to make a definitive diagnosis.

Targeting ferritinophagy impairs quiescent cancer stem cells in acute myeloid leukemia in vitro and in vivo models.

Acute myeloid leukemia (AML) remains a challenging hematological malignancy with poor prognosis and limited treatment options. Leukemic stem cells (LSCs) contribute to therapeutic failure, relapse, and adverse outcome. This study investigates the role of quiescence and related molecular mechanisms in AML pathogenesis and LSC functions to identify potential therapeutic targets. Transcriptomic analysis revealed that the LSC-enriched quiescent cell population has a distinct gene signature with prognostic relevance in patients with AML. Mechanistically, quiescent blasts exhibit increased autophagic activity, which contributes to their sustained viability. Proteomic profiling uncovered differential requirements for iron metabolism between quiescent and cycling cells, revealing a unique dependence of quiescent cells on ferritinophagy, a selective form of autophagy mediated by nuclear receptor coactivator 4 (NCOA4), which regulates iron bioavailability. We evaluated the therapeutic potential of inhibiting NCOA4-mediated ferritinophagy using genetic knockdown and chemical inhibition approaches. In vitro assays showed that suppression of NCOA4 was toxic to leukemic blasts, particularly the CD34+CD38- LSC-enriched population, without affecting normal CD34+ hematopoietic progenitors. In vivo studies using murine patient-derived xenograft (PDX) models of AML confirmed that NCOA4 inhibition reduced tumor burden and impaired LSC viability and self-renewal, indicating a specific vulnerability of these cells to ferritinophagy disruption. Our findings underscore the role of NCOA4-mediated ferritinophagy in maintaining LSC quiescence and function and suggest that targeting this pathway may be an effective therapeutic strategy for AML. This study highlights the potential of NCOA4 inhibition to improve AML outcomes and paves the way for future research and clinical development.

Hu8F4-CAR T cells with mutated Fc spacer segment improve target specificity and mediate anti-leukemia activity in vivo

Background aimsHu8F4 is a T-cell receptor–like antibody with high affinity for the leukemia-associated antigen PR1/HLA-A2 epitope. Adapted into a chimeric antigen receptor (CAR) format, Hu8F4-CAR is composed of the Hu8F4 single-chain variable fragment, the human IgG1 CH2CH3 extracellular spacer domain, a human CD28 costimulatory domain and the human CD3ζ signaling domain. We have demonstrated high efficacy of Hu8F4-CAR-T cells against PR1/HLA-A2-expressing cell lines and leukemic blasts from patients with acute myeloid leukemia in vitro. Previous studies have shown that modification of the Fc domains of IgG4 CH2CH3 spacer regions can eliminate activation-induced cell death and off-target killing mediated by mouse Fc gamma receptor–expressing cells. MethodsWe generated Hu8F4-CAR(PQ) with mutated Fc receptor binding sites on the CH2 domain of Hu8F4-CAR to prevent unwanted interactions with Fc gamma receptor–expressing cells in vivo. ResultsThe primary human T cells transduced with Hu8F4-CAR(PQ) can specifically lyse HLA-A2+ PR1-expressing leukemia cell lines in vitro. Furthermore, both adult donor-derived and cord blood-derived Hu8F4-CAR(PQ)-T cells are active and can eliminate U937 leukemia cells in NSG mice. ConclusionsHerein, we demonstrate that modification of the IgG1-based spacer can eliminate Fc receptor binding–induced adverse effects and Hu8F4-CAR(PQ)-T cells can kill leukemia in vivo.