Integrative single-cell expression and functional studies unravels a sensitization to cytarabine-based chemotherapy through HIF pathway inhibition in AML leukemia stem cells.

Relapse remains a major challenge in the clinical management of acute myeloid leukemia (AML) and is driven by rare therapy-resistant leukemia stem cells (LSCs) that reside in specific bone marrow niches. Hypoxia signaling maintains cells in a quiescent and metabolically relaxed state, desensitizing them to chemotherapy. This suggests the hypothesis that hypoxia contributes to the chemoresistance of AML-LSCs and may represent a therapeutic target to sensitize AML-LSCs to chemotherapy. Here, we identify HIFhigh and HIFlow specific AML subgroups (inv(16)/t(8;21) and MLLr, respectively) and provide a comprehensive single-cell expression atlas of 119,000 AML cells and AML-LSCs in paired diagnostic-relapse samples from these molecular subgroups. The HIF/hypoxia pathway signature is attenuated in AML-LSCs compared with more differentiated AML cells but is more expressed than in healthy hematopoietic cells. Importantly, chemical inhibition of HIF cooperates with standard-of-care chemotherapy to impair AML growth and to substantially eliminate AML-LSCs in vitro and in vivo. These findings support the HIF pathway in the stem cell-driven drug resistance of AML and unravel avenues for combinatorial targeted and chemotherapy-based approaches to specifically eliminate AML-LSCs.

The relapsed acute lymphoblastic leukemia network (ReALLNet): a multidisciplinary project from the spanish society of pediatric hematology and oncology (SEHOP).

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, with survival rates exceeding 85%. However, 15% of patients will relapse; consequently, their survival rates decrease to below 50%. Therefore, several research and innovation studies are focusing on pediatric relapsed or refractory ALL (R/R ALL). Driven by this context and following the European strategic plan to implement precision medicine equitably, the Relapsed ALL Network (ReALLNet) was launched under the umbrella of SEHOP in 2021, aiming to connect bedside patient care with expert groups in R/R ALL in an interdisciplinary and multicentric network. To achieve this objective, a board consisting of experts in diagnosis, management, preclinical research, and clinical trials has been established. The requirements of treatment centers have been evaluated, and the available oncogenomic and functional study resources have been assessed and organized. A shipping platform has been developed to process samples requiring study derivation, and an integrated diagnostic committee has been established to report results. These biological data, as well as patient outcomes, are collected in a national registry. Additionally, samples from all patients are stored in a biobank. This comprehensive repository of data and samples is expected to foster an environment where preclinical researchers and data scientists can seek to meet the complex needs of this challenging population. This proof of concept aims to demonstrate that a network-based organization, such as that embodied by ReALLNet, provides the ideal niche for the equitable and efficient implementation of "what's next" in the management of children with R/R ALL.

Clonal heterogeneity and rates of specific chromosome gains are risk predictors in childhood high-hyperdiploid B-cell acute lymphoblastic leukemia.

B-cell acute lymphoblastic leukemia (B-ALL) is the commonest childhood cancer. High hyperdiploidy (HHD) identifies the most frequent cytogenetic subgroup in childhood B-ALL. Although hyperdiploidy represents an important prognostic factor in childhood B-ALL, the specific chromosome gains with prognostic value in HHD-B-ALL remain controversial, and the current knowledge about the hierarchy of chromosome gains, clonal heterogeneity and chromosomal instability in HHD-B-ALL remains very limited. We applied automated sequential-iFISH coupled with single-cell computational modeling to identify the specific chromosomal gains of the eight typically gained chromosomes in a large cohort of 72 primary diagnostic (DX, n = 62) and matched relapse (REL, n = 10) samples from HHD-B-ALL patients with either favorable or unfavorable clinical outcome in order to characterize the clonal heterogeneity, specific chromosome gains and clonal evolution. Our data show a high degree of clonal heterogeneity and a hierarchical order of chromosome gains in DX samples of HHD-B-ALL. The rates of specific chromosome gains and clonal heterogeneity found in DX samples differ between HHD-B-ALL patients with favorable or unfavorable clinical outcome. In fact, our comprehensive analyses at DX using a computationally defined risk predictor revealed low levels of trisomies +18+10 and low levels of clonal heterogeneity as robust relapse risk factors in minimal residual disease (MRD)-negative childhood HHD-B-ALL patients: relapse-free survival beyond 5 years: 22.1% versus 87.9%, P < 0.0001 and 33.3% versus 80%, P < 0.0001, respectively. Moreover, longitudinal analysis of matched DX-REL HHD-B-ALL samples revealed distinct patterns of clonal evolution at relapse. Our study offers a reliable prognostic sub-stratification of pediatric MRD-negative HHD-B-ALL patients.

CD8+ T lymphocytes are sensitive to NKG2A/HLA-E licensing interaction: role in the survival of cancer patients.

NK and CD8+ T cells are the main cytolytic effectors involved in innate and adaptive tumor immune surveillance, respectively. Although their educational pathways differ, similarities in their development and function suggest that CD8+ T lymphocytes could be sensitive to NK cell licensing signals, which might influence their antitumor response. To demonstrate this hypothesis, we retrospectively evaluated the impact that NK cell licensing interactions have on the expression of CD226 on CD8+ T lymphocytes and on the survival of patients with different hematopoietic and solid cancers (n = 1,023). Prospectively, we analyzed by multiparametric flow cytometry the anti-CD3/CD28-induced proliferation and immune-receptor expression of purified CD8+ T lymphocytes from healthy donors (n = 17) with different combinations of NK cell licensing ligands. Results show that methionine/threonine (M/T) dimorphism at position -21 of the HLA-B leader peptide, but not other HLA class-I dimorphisms involved in the education of NK cells (HLA-C1/C2 or HLA-Bw4), is associated with greater survival and expression of CD226 in cancer patients, which was proportional to the number of methionines present in their genotype. CD8+ T lymphocytes from healthy donors with -21 M showed higher proliferation rates and lower expression of TIGIT after in vitro stimulation. Therefore, CD8+ T lymphocytes, like NK cells, appear to be sensitive to the -21 M/T dimorphism of HLA-B leader peptide, which results in the modulation of CD226 in vivo and the proliferation and expression of TIGIT after in vitro stimulation, all of which could be related to their immune-surveillance capacity and the survival of cancer patients.

Haploidentical transplantation in pediatric non-malignant diseases: A retrospective analysis on behalf of the Spanish Group for Hematopoietic Transplantation (GETH).

OBJECTIVE: Describe the GETH haploidentical stem cell transplantation (haplo-HSCT) activity in non-malignant disease (NMDs). METHODS: We retrospectively analyzed data from children with NMDs who underwent haplo-HSCT. RESULTS: From January 2001 to December 2016, 26 pediatric patients underwent 31 haplo-HSCT through ex vivo T cell-depleted (TCD) graft platforms or post-transplantation cyclophosphamide (PT-Cy) at 7 Spanish centers. Five cases employed unmanipulated PT-Cy haplo-HSCT, 16 employed highly purified CD34+ cells, and 10 employed ex vivo TCD grafts manipulated either with CD3+ CD19+ depletion, TCRαß+ CD19+ selection or naive CD45RA+ T-cell depletion. Peripheral blood stem cells were the sole source for patients following TCD haplo-HSCT, and bone marrow was the source for one PT-Cy haplo-HSCT. The most common indications for transplantation were primary immunodeficiency disorders (PIDs), severe aplastic anemia, osteopetrosis, and thalassemia. The 1-year cumulative incidence of graft failure was 27.4%. The 1-year III-IV acute graft-versus-host disease (GvHD) and 1-year chronic GvHD rates were 34.6% and 16.7%, respectively. The 2-year overall survival was 44.9% for PIDs, and the 2-year graft-versus-host disease-free and relapse-free survival rate was 37.6% for the other NMDs. The transplantation-related mortality at day 100 was 30.8%. CONCLUSION: Although these results are discouraging, improvements will come if procedures are centralized in centers of expertise.

Blinatumomab and inotuzumab for B cell precursor acute lymphoblastic leukaemia in children: a retrospective study from the Leukemia Working Group of the Spanish Society of Pediatric Hematology and Oncology (SEHOP).

Blinatumomab and inotuzumab ozogamycin represent promising alternatives to conventional chemotherapy in acute lymphoblastic leukaemia (ALL). We analysed data from 29 children with ALL treated under compassionate use with blinatumomab, inotuzumab or both. The complete remission (CR) rate in a heavily pretreated population with overt relapse was 47·6%. At earlier stages (first/second CR), both antibodies represented a useful tool to reduce minimal residual disease, and/or avoid further toxic chemotherapy until stem cell transplantation. Six patients developed grade 3 reversible non-haematological toxicity. The 12-month overall survival and event-free survival rates were 50·8 ± 26·4% and 38·9 ± 25·3% with blinatumomab, 45·8 ± 26% and 27·5 ± 25% with inotuzumab.

Overexpression of KIR inhibitory ligands (HLA-I) determines that immunosurveillance of myeloma depends on diverse and strong NK cell licensing.

Missing self recognition makes cancer sensitive to natural killer cell (NKc) reactivity. However, this model disregards the NKc licensing effect, which highly increases NKc reactivity through interactions of inhibitory killer cell immunoglobulin-like receptors (iKIR) with their cognate HLA-I ligands. The influence of iKIR/HLA-ligand (HLA-C1/C2) licensing interactions on the susceptibility to and progression of plasma cell (PC) dyscrasias was evaluated in 164 Caucasian patients and 286 controls. Compared to controls, myeloma accumulates KIR2DL1-L2+L3- genotypes (2.8% vs. 13.2%, p < 0.01, OR = 5.29) and less diverse peripheral repertoires of NKc clones. Less diverse and weaker-affinity repertoires of iKIR2D/HLA-C licensing interactions increased myeloma susceptibility. Thus, the complete absence of conventional iKIR2D/HLA-C licensing interactions (KIR2DL1-L2+L3-/C2C2, 2.56% vs. 0.35%; p < 0.05; OR = 15.014), single-KIR2DL3+/C1+ (20.51% vs. 10.84%; p < 0.05; OR = 2.795) and single-KIR2DL2+/C1+ (12.82% vs. 4.9%; p < 0.01; OR = 5.18) interactions were over-represented in myeloma, compared to controls. Additionally, KIR2DL1-L2+L3- (20% vs. 83%, p < 0.00001) as well as KIR3DL1- (23% vs. 82%, p < 0.00001) genotypes had a dramatic negative impact on the 3-y progression-free survival (PFS), particularly in patients with low-tumor burden. Remarkably, myeloma-PCs, compared to K562 and other hematological cancers, showed substantial over-expression of HLA-I ("increasing-self" instead of missing-self), including HLA-C, and mild expression of ligands for NKc activating receptors (aRec) CD112, CD155, ULBP-1 and MICA/B, which apparently renders myeloma-PCs susceptible to lysis mainly by licensed NKc. KIR2DL1-L2+L3-/C2C2 patients (with no conventional iKIR2D/HLA-C licensing interactions) lyse K562 but barely lyse myeloma-PCs (4% vs. 15%; p < 0.05, compared to controls). These results support a model where immunosurveillance of no-missing-self cancers, e.g., myeloma, mainly depends on NKc licensing.

Chediak-Higashi syndrome: description of two novel homozygous missense mutations causing divergent clinical phenotype.

Chediak-Higashi syndrome (CHS) is a rare autosomal recessive disease resulting from mutations in the LYST/CHS1 gene, which encodes for a 429 kDa protein, CHS1/LYST, that regulates vesicle trafficking and determines the size of lysosomes and other organelles. To date, 60 different mutations have been characterized, and a reasonably straightforward phenotype-genotype correlation has been suggested. We describe two patients on opposite ends of the CHS clinical spectrum with novel missense mutations. We characterized these patients in terms of their mutations, protein localization and expression, mRNA stability, and electrostatic potential. Patient 1 is the first report of a severe early-onset CHS with a homozygous missense mutation (c.11362 G>A, p.G3725R) in the LYST/CHS1 gene. This molecular change results in a reduction at the CHS1 protein level, not due to an mRNA effect, but maybe a consequence of both, a change in the structure of the protein and most likely attributable to the remarkable serious perturbation in the electrostatic potential. Patient 2, who exhibited the adolescence form of the disease, was found to be homozygous for a novel missense mutation c.961 T>C, p.C258R, which seemed to have minor effect on the structure of the CHS1/LYST protein. Reexamining accepted premises of missense mutant alleles being reported among patients with clinically mild forms of the disorder should be carried out, and attempts to link genotype and clinical phenotype require identifying the actual molecular effect of the mutation. Early and accurate diagnosis of the severity of the disease is extremely important to early differentiate patients who would benefit from premature enrollment into a transplantation protocol.

Detection of occult cerebrospinal fluid involvement during maintenance therapy identifies a group of children with acute lymphoblastic leukemia at high risk for relapse.

We aimed at assessing the clinical significance of the levels of acute lymphoblastic leukemia (ALL) cells in samples of cerebrospinal fluid (CSF) during therapy. We studied 990 CSF samples from 108 patients, at the time of diagnosis (108) and at each time of intrathecal therapy (882). The proportions of leukemic cells in CSF samples were assessed by flow cytometry (FCM). Patients with central nervous system (CNS) involvement at diagnosis (FCM+) showed predominantly a T-ALL, and higher percentages of known negative prognostic factors: high risk group, higher white blood cell counts, normal karyotype, and the BCR-ABL fusion gene. No differences in relapse free survival (RFS) and overall survival (OS) were observed between FCM+ versus FCM- at diagnosis. Patients with CNS involvement during therapy showed significantly older age, and higher frequencies of T-cell leukemia. We found a significantly higher RFS in patients with FCM+ during therapy. The detection of subclinical CNS disease by FCM during maintenance was associated with significantly lower 3-years RFS and 3-years OS. A sensitive methodology like FCM can be applied for a close follow-up of the levels of ALL in CFS samples, and may identify a group of patients at high risk for relapse.

Association of monoclonal expansion of Epstein-Barr virus-negative CD158a+ NK cells secreting large amounts of gamma interferon with hemophagocytic lymphohistiocytosis.

We report the first case of hemophagocytic lymphohistiocytosis (HLH) induced by the monoclonal expansion of Epstein-Barr virus (EBV)-negative NK cells. Consanguinity of the patient's parents made it necessary to discard familial HLH in the patient and her sister with identical HLA markers and demonstrate that no cause other than the expansion of NK cells, which secrete high levels of gamma interferon, was inducing HLH in this patient.

L-asparaginase-induced antithrombin type I deficiency: implications for conformational diseases.

Serpinopathies, a group of diseases caused by mutations that disrupt the structurally sensitive serpins, have no known acquired cause. Interestingly, l-asparaginase treatment of acute lymphoblastic leukemia patients causes severe deficiency in the serpin antithrombin. We studied the consequences of this drug on antithrombin levels, activity, conformation, and immunohistological and ultrastructural features in plasma from acute lymphoblastic leukemia patients, HepG2 cells, and plasma and livers from mice treated with this drug. Additionally, we evaluated intracellular deposition of alpha1-antitrypsin. l-Asparaginase did not affect functional or conformational parameters of mature antithrombin; however, patients and mice displayed severe type I deficiency with no abnormal conformations of circulating antithrombin. Moreover, l-asparaginase impaired secretion of antithrombin by HepG2 cells. These effects were explained by the intracellular retention of antithrombin, forming aggregates within dilated endoplasmic reticulum cisterns. Similar effects were observed for alpha1-antitrypsin in plasma, cells, and livers, and intracellular aggregates of additional proteins were observed in frontal cortex and pancreas. This is the first report of a conformational drug-associated effect on serpins without genetic factors involved. l-Asparaginase treatment induces severe, acquired, and transient type I deficiency of antithrombin (and alpha1-antitrypsin) with intracellular accumulation of the nascent molecule, increasing the risk of thrombosis.

Epidural hematoma from a cranial eosinophilic granuloma.

The formation of an epidural hematoma from an eosinophilic granuloma of the skull is an exceptional occurrence. A 9-year-old boy presented with severe headache, somnolence and vomiting following a minor head injury. Cranial computerized tomography scan showed a seemingly depressed skull fracture together with an epidural hematoma in evolution. A neoplasm and an epidural hematoma were removed at operation. Histopathological study of the excised mass confirmed the diagnosis of eosinophilic granuloma.