The KMT2A recombinome of acute leukemias in 2023

Chromosomal rearrangements of the human KMT2A/MLL gene are associated with de novo as well as therapy-induced infant, pediatric, and adult acute leukemias. Here, we present the data obtained from 3401 acute leukemia patients that have been analyzed between 2003 and 2022. Genomic breakpoints within the KMT2A gene and the involved translocation partner genes (TPGs) and KMT2A-partial tandem duplications (PTDs) were determined. Including the published data from the literature, a total of 107 in-frame KMT2A gene fusions have been identified so far. Further 16 rearrangements were out-of-frame fusions, 18 patients had no partner gene fused to 5’-KMT2A, two patients had a 5’-KMT2A deletion, and one ETV6::RUNX1 patient had an KMT2A insertion at the breakpoint. The seven most frequent TPGs and PTDs account for more than 90% of all recombinations of the KMT2A, 37 occur recurrently and 63 were identified so far only once. This study provides a comprehensive analysis of the KMT2A recombinome in acute leukemia patients. Besides the scientific gain of information, genomic breakpoint sequences of these patients were used to monitor minimal residual disease (MRD). Thus, this work may be directly translated from the bench to the bedside of patients and meet the clinical needs to improve patient survival.publishedVersionPeer reviewe

Chronic Delivery of Antibody Fragments Using Immunoisolated Cell Implants as a Passive Vaccination Tool

BACKGROUND: Monoclonal antibodies and antibody fragments are powerful biotherapeutics for various debilitating diseases. However, high production costs, functional limitations such as inadequate pharmacokinetics and tissue accessibility are the current principal disadvantages for broadening their use in clinic. METHODOLOGY AND PRINCIPAL FINDINGS: We report a novel method for the long-term delivery of antibody fragments. We designed an allogenous immunoisolated implant consisting of polymer encapsulated myoblasts engineered to chronically release scFv antibodies targeted against the N-terminus of the Aβ peptide. Following a 6-month intracerebral therapy we observed a significant reduction of the production and aggregation of the Aβ peptide in the APP23 transgenic mouse model of Alzheimer's disease. In addition, functional assessment showed prevention of behavioral deficits related to anxiety and memory traits. CONCLUSIONS AND SIGNIFICANCE: The chronic local release of antibodies using immunoisolated polymer cell implants represents an alternative passive vaccination strategy in Alzheimer's disease. This novel technique could potentially benefit other diseases presently treated by local and systemic antibody administration

The Chemokine Receptor CXCR4 Strongly Promotes Neuroblastoma Primary Tumour and Metastatic Growth, but not Invasion

Neuroblastoma (NB) is a heterogeneous, and particularly malignant childhood neoplasm in its higher stages, with a propensity to form metastasis in selected organs, in particular liver and bone marrow, and for which there is still no efficient treatment available beyond surgery. Recent evidence indicates that the CXCR4/CXCL12 chemokine/receptor axis may be involved in promoting NB invasion and metastasis. In this study, we explored the potential role of CXCR4 in the malignant behaviour of NB, using a combination of in vitro functional analyses and in vivo growth and metastasis assessment in an orthotopic NB mouse model. We show here that CXCR4 overexpression in non-metastatic CXCR4-negative NB cells IGR-NB8 and in moderately metastatic, CXCR4 expressing NB cells IGR-N91, strongly increased tumour growth of primary tumours and liver metastases, without altering the frequency or the pattern of metastasis. Moreover shRNA-mediated knock-down experiments confirmed our observations by showing that silencing CXCR4 in NB cells impairs in vitro and almost abrogates in vivo growth. High levels of CXCL12 were detected in the mouse adrenal gland (the primary tumour site), and in the liver suggesting a paracrine effect of host-derived CXCL12 on NB growth. In conclusion, this study reveals a yet unreported NB-specific predominant growth and survival-promoting role of CXCR4, which warrants a critical reconsideration of the role of CXCR4 in the malignant behaviour of NB and other cancers

The MLL recombinome of acute leukemias in 2017

Chromosomal rearrangements of the human MLL/KMT2A gene are associated with infant, pediatric, adult and therapy-induced acute leukemias. Here we present the data obtained from 2345 acute leukemia patients. Genomic breakpoints within the MLL gene and the involved translocation partner genes (TPGs) were determined and 11 novel TPGs were identified. Thus, a total of 135 different MLL rearrangements have been identified so far, of which 94 TPGs are now characterized at the molecular level. In all, 35 out of these 94 TPGs occur recurrently, but only 9 specific gene fusions account for more than 90% of all illegitimate recombinations of the MLL gene. We observed an age-dependent breakpoint shift with breakpoints localizing within MLL intron 11 associated with acute lymphoblastic leukemia and younger patients, while breakpoints in MLL intron 9 predominate in AML or older patients. The molecular characterization of MLL breakpoints suggests different etiologies in the different age groups and allows the correlation of functional domains of the MLL gene with clinical outcome. This study provides a comprehensive analysis of the MLL recombinome in acute leukemia and demonstrates that the establishment of patient-specific chromosomal fusion sites allows the design of specific PCR primers for minimal residual disease analyses for all patients

The MLL recombinome of acute leukemias in 2017

Chromosomal rearrangements of the human MLL/KMT2A gene are associated with infant, pediatric, adult and therapy-induced acute leukemias. Here we present the data obtained from 2345 acute leukemia patients. Genomic breakpoints within the MLL gene and the involved translocation partner genes (TPGs) were determined and 11 novel TPGs were identified. Thus, a total of 135 different MLL rearrangements have been identified so far, of which 94 TPGs are now characterized at the molecular level. In all, 35 out of these 94 TPGs occur recurrently, but only 9 specific gene fusions account for more than 90% of all illegitimate recombinations of the MLL gene. We observed an age-dependent breakpoint shift with breakpoints localizing within MLL intron 11 associated with acute lymphoblastic leukemia and younger patients, while breakpoints in MLL intron 9 predominate in AML or older patients. The molecular characterization of MLL breakpoints suggests different etiologies in the different age groups and allows the correlation of functional domains of the MLL gene with clinical outcome. This study provides a comprehensive analysis of the MLL recombinome in acute leukemia and demonstrates that the establishment of patient-specific chromosomal fusion sites allows the design of specific PCR primers for minimal residual disease analyses for all patients.</p

The MLL recombinome of acute leukemias in 2017

Chromosomal rearrangements of the human MLL/KMT2A gene are associated with infant, pediatric, adult and therapy-induced acute leukemias. Here we present the data obtained from 2345 acute leukemia patients. Genomic breakpoints within the MLL gene and the involved translocation partner genes (TPGs) were determined and 11 novel TPGs were identified. Thus, a total of 135 different MLL rearrangements have been identified so far, of which 94 TPGs are now characterized at the molecular level. In all, 35 out of these 94 TPGs occur recurrently, but only 9 specific gene fusions account for more than 90% of all illegitimate recombinations of the MLL gene. We observed an age-dependent breakpoint shift with breakpoints localizing within MLL intron 11 associated with acute lymphoblastic leukemia and younger patients, while breakpoints in MLL intron 9 predominate in AML or older patients. The molecular characterization of MLL breakpoints suggests different etiologies in the different age groups and allows the correlation of functional domains of the MLL gene with clinical outcome. This study provides a comprehensive analysis of the MLL recombinome in acute leukemia and demonstrates that the establishment of patient-specific chromosomal fusion sites allows the design of specific PCR primers for minimal residual disease analyses for all patients

Mol. Microbiol

MspA is an extremely stable, oligomeric porin from Mycobacterium smegmatis that forms water-filled channels in vitro. Immunogold electron microscopy and an enzyme-linked immunosorbent assay demonstrated that MspA is localized in the cell wall. An mspA deletion mutant did not synthesize detectable amounts of mspA mRNA, as revealed by amplification using mspA-specific primers and reverse-transcribed RNA. Detergent extracts of the Delta mspA mutant exhibited a significantly lower porin activity in lipid bilayer experiments and contained about fourfold less porin than extracts of wild-type M. smegmatis. The chromosome of M. smegmatis encodes three proteins very similar to MspA, Sequence analysis of the purified porin revealed that mspB or mspC or both genes are expressed in the Delta mspA mutant. The properties of this porin, such as single channel conductance, extreme stability against denaturation, molecular mass and composition of 20 kDa subunits, are identical to those of MspA, Deletion of mspA reduced the cell wall permeability towards cephaloridine and glucose nine- and fourfold respectively. These results show that MspA is the main general diffusion pathway for hydrophilic molecules in M. smegmatis and was only partially replaced by fewer porins in the cell wall of the Delta mspA mutant. The minimal permeability coefficient of the Delta mspA mutant for glucose was 7.2 x 10(-8) cm s(-1), which is the lowest value reported so far for bacteria. This is the first experimental evidence that porins are the major determinants of the exceptionally low permeability of mycobacteria to hydrophilic molecules. [References: 44

A Nanotechnology-Based Platform for Extending the Pharmacokinetic and Binding Properties of Anti-methamphetamine Antibody Fragments

To address the need for effective medications to aid in the treatment of methamphetamine (METH) abuse, we used a nanotechnology approach to customize the in vivo behavior of an anti-METH single chain antibody (scFv7F9Cys). Anti-METH scFv7F9Cys was conjugated to dendrimer nanoparticles via a polyethylene glycol (PEG) linker to generate high-order conjugates termed dendribodies. We found that the high affinity (K(D) = 6.2 nM) and specificity for METH was unchanged after nanoparticle conjugation. The dendribodies were administered in an i.v. bolus to male Sprague Dawley rats after starting a s.c. infusion of METH. The PCKN values for clearance and volume of distribution of scFv7F9Cys after conjugation to dendrimers decreased 45 and 1.6-fold respectively, and the terminal elimination half-life increased 20-fold. Organ distribution of scFv7F9Cys and dendribody in blood and urine agreed well with the PCKN data. Renal clearance appeared to be the major route of elimination for both experimental medications. We have thus successfully developed a novel multivalent METH-binding nanomedicine by conjugating multiple anti-METH scFvs to dendrimer nanoparticles, extending the scFv half-life from 1.3 (±0.3) to 26 (±2.6) hr. These data suggest that the dendribody design could be a feasible platform for generating multivalent antibodies with customizable PCKN profiles