To fight the COVID-19 pandemic caused by the RNA virus SARS-CoV-2, a global vaccination campaign is in progress to achieve the immunization of billions of people mainly with adenoviral vector- or ...mRNA-based vaccines, all of which encode the SARS-CoV-2 Spike protein. In some rare cases, cerebral venous sinus thromboses (CVST) have been reported as a severe side effect occurring 4-14 days after the first vaccination and were often accompanied by thrombocytopenia. Besides CVST, splanchnic vein thromboses (SVT) and other thromboembolic events have been observed. These events only occurred following vaccination with adenoviral vector-based vaccines but not following vaccination with mRNA-based vaccines. Meanwhile, scientists have proposed an immune-based pathomechanism and the condition has been coined vaccine-induced immune thrombotic thrombocytopenia (VITT). Here, we describe an unexpected mechanism that could explain thromboembolic events occurring with DNA-based but not with RNA-based vaccines. We show that DNA-encoded mRNA coding for Spike protein can be spliced in a way that the transmembrane anchor of Spike is lost, so that nearly full-length Spike is secreted from cells. Secreted Spike variants could potentially initiate severe side effects when binding to cells via the ACE2 receptor. Avoiding such splicing events should become part of a rational vaccine design to increase safety of prospective vaccines.
Pediatric acute myeloid leukemia (AML) is a highly heterogeneous disease making standardized measurable residual disease (MRD) assessment challenging. Currently, patient-specific DNA-based assays are ...only rarely applied for MRD assessment in pediatric AML. We tested whether quantification of genomic breakpoint-specific sequences via quantitative polymerase chain reaction (gDNA-PCR) provides a reliable means of MRD quantification in children with non-standardrisk AML and compared its results to those obtained with state-of-the-art ten-color flow cytometry (FCM). Breakpointspecific gDNA-PCR assays were established according to Euro-MRD consortium guidelines. FCM-MRD assessment was performed according to the European Leukemia Network guidelines with adaptations for pediatric AML. Of 77 consecutively recruited non-standard-risk pediatric AML cases, 49 (64%) carried a chromosomal translocation potentially suitable for MRD quantification. Genomic breakpoint analysis returned a specific DNA sequence in 100% (41/41) of the cases submitted for investigation. MRD levels were evaluated using gDNA-PCR in 243 follow-up samples from 36 patients, achieving a quantitative range of at least 10-4 in 231/243 (95%) of samples. Comparing gDNA-PCR with FCM-MRD data for 183 bone marrow follow-up samples at various therapy timepoints showed a high concordance of 90.2%, considering a cut-off of ≥0.1%. Both methodologies outperformed morphological assessment. We conclude that MRD monitoring by gDNA-PCR is feasible in pediatric AML with traceable genetic rearrangements and correlates well with FCM-MRD in the currently applied clinically relevant range, while being more sensitive below that. The methodology should be evaluated in larger cohorts to pave the way for clinical application.
Background
The detection of
KMT2A
gene rearrangements have an important impact on the prognosis and management of acute leukemias. These alterations most commonly involve reciprocal translocations at ...specific breakpoint regions within
KMT2A
. To date, more than 100 translocation partner genes of
KMT2A
have been identified, with different effects on risk stratification.
Methods and results
We report the case of a mature plasmacytoid dendritic cells proliferation associated with B lymphoblasts harboring a
KMT2A
-
ARHGEF12
fusion. This rare rearrangement, resulting from a cryptic deletion on the long arm of chromosome 11, is located outside the known major and minor breakpoint regions of
KMT2A,
not reported to date. The review of the few cases of
KMT2A
-
ARHGEF12
reveals the tendency of this deletion to occur in therapy related hematologic neoplasm and confer unfavorable prognosis.
Conclusion
This review sheds light into the rare
KMT2A
-
ARHGEF12
fusion in leukemia. Reporting rare chimeras is essential to improve knowledge about the biological mechanism and associated clinical consequences
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Several studies demonstrated a relevant role of polymorphisms located within the HLA-B and -C loci and the Killer Immunoglobulin Receptors (KIRs) 3DL1 and 3DS1 in controlling HIV-1 replication. KIRs ...are regulatory receptors expressed at the surface of NK and CD8+ T-cells that specifically bind HLA-A and -B alleles belonging to the Bw4 supratype and all the -C alleles expressing the C1 or C2 supratype. We here disclose a novel signature associated with the Elite Controller but not with the long-term nonprogressor status concerning 2DS activating KIRs and HLA-C2 alleles insensitive to miRNA148a regulation. Overall, our findings support a crucial role of NK cells in the control of HIV-1 viremia.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The most frequent genetic aberration leading to infant ALL (iALL) is the chromosomal translocation t(4;11), generating the fusion oncogenes KMT2A:AFF1 and AFF1:KMT2A, respectively. KMT2A-r iALL ...displays a dismal prognosis through high relapse rates and relapse-associated mortality. Relapse occurs frequently despite ongoing chemotherapy and without the accumulation of secondary mutations. A rational explanation for the observed chemo-resistance and satisfactory treatment options remain to be elucidated. We found that elevated ICOSLG expression level at diagnosis was associated with inferior event free survival (EFS) in a cohort of 43 patients with t(4;-11) iALL and that a cohort of 18 patients with iALL at relapse displayed strongly increased ICOSLG expression. Furthermore, co-culturing t(4;11) ALL cells (ICOSLGhi) with primary T-cells resulted in the development of Tregs. This was impaired through treatment with a neutralizing ICOSLG antibody. These findings imply ICOSLG (1) as a relapse-predicting biomarker, and (2) as a therapeutic target involved in a potential immune evasion relapse-mechanism of infant t(4;11) ALL.
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•Early growth response 3 (EGR3) is a direct transactivator of the immune checkpoint gene ICOSLG•high ICOSLG expression at diagnosis is predictive for ALL relapse•EGR3 and ICOSLG expressions are relapse-associated•expression of ICOSLG on t(4;11) ALL cells leads to the rapid expansion of Tregs
Health sciences; Immunology; Cancer
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Chromosomal rearrangements of the KMT2A gene are associated with acute leukemias and myelodysplastic syndromes. The large number of known KMT2A fusions (>100) renders a precise diagnosis a demanding ...task. More than 50% of all KMT2A partner genes have been analyzed at the DCAL, including the novel partner genes BCAS4, FAM13A, RANBP3, and STK4. Even though all KMT2A rearrangements are associated with high-risk acute leukemia, the outcome (poor or very poor) is influenced by the partner gene. So far, we have analyzed more than 3,200 patients positive for a KMT2A rearrangement. The breakpoints of these cases are located mainly in the major breakpoint cluster region (bcr1) and to a small extent in the recently described minor bcr (bcr2). A small number of breakpoints were also found outside of these two bcrs.
Most of these patients were analyzed by long distance inverse (LDI)- or multiplex-PCR which only cover bcr1. More recently, we used targeted KMT2A-NGS with whole gene coverage in over 450 patients, which was initially applied selectively in patients negative by LDI- and multiplex-PCR and then used more widely.
Within the KMT2A-NGS group, 410 patients had bcr1 breakpoints mainly between the KMT2A exons 7 and 13, while 46 patients bcr2 breakpoints mainly between exons 20 and 24. Of note, five patients had their breakpoint outside of these two bcrs: three of them within intron 2 and no functional KMT2A rearrangement; the other two within intron 35 and intron 36, fusing almost the whole KMT2A gene in frame to the respective partner genes ARHGEF12 and MLLT4. These two breakpoints may define a third and rare bcr (bcr3), although further cases are needed to support this hypothesis. Interestingly, 70 patients displayed a 3‘-KMT2A deletion, indicating that the number of terminal deletions is higher than described previously. Two patients had a 5‘-KMT2A deletion. All deletions started or ended in bcr1 and bcr2.
We also observed a striking difference in the distribution of partner genes between bcr1 and bcr2. The most frequent translocation partners fused to bcr1 sites are transcription factors, while the partner genes linked to bcr2 sites generally code for cytosolic proteins. In bcr1, the 4 most frequent partner genes AFF1, MLLT3, MLLT1, and MLLT10, found in 80% of cases, all code for transcription factors that are part of the super elongation complex (SEC). These fusions therefore all lead to disruption of the hematopoietic lineage commitment.
In contrast in bcr2, 3 partner genes USP2, MLLT4, and USP8 account for 85% of the cases. USP2 and USP8 are ubiquitin specific peptidases involved in cell signaling and exclusively fused to bcr2 in KMT2A. While MLLT4 is found as a partner in bcr1, bcr2 and bcr3 fusions; unlike other recurrent KMT2A partners linked to bcr1, it is not a transcription factor and it exerts oncogenic potential via dimerization like other cytosolic partners. We hypothesize that the oncogenic properties of USP2 and USP8 are dependent on dimerization like MLLT4 and that the most frequent fusions involving at different bcrs favor different oncogenic mechanisms: bcr1 transactivation and bcr2 dimerization. Further studies are needed to explain why USP2 and USP8 are exclusively associated with bcr2, and why the most frequent partner genes AFF1 and MLLT3 of the bcr1 are less frequent in bcr2.
In conclusion, targeted NGS combined with bioinformatic analysis has expanded our knowledge of the KMT2A recombinome to include more fusion partners and has generated new hypotheses for future research on oncogenic mechanisms.
No relevant conflicts of interest to declare.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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