Introduction Thrombocytopenia is a common complication after allogeneic hematopoietic stem cell transplantation (allo-SCT). Underlying mechanisms are poorly known and usually multifactorial. Its treatment is not well defined, mostly based in platelet transfusion. Thus, is important to identify new strategies to manage this important post-SCT complication. Romiplostim and Eltrombopag are currently available thrombopoietin receptor agonists (TPO-RAs) that stimulate platelet production. Some studies with very small number of cases have reported their potential efficacy in the allo-SCT setting. For this reason, the aim of our study is to analyze the efficacy and safety of TPO-RAs for severe and persistent thrombocytopenia after allo-SCT. Patients and methods We performed a retrospective multicenter study including patients from centers of GETH with prolonged isolated thrombocytopenia (PT) or secondary failure of platelet recovery (SFPR) after allo-SCT. PT was defined as the engraftment of all peripheral blood cell lines but with platelet count ≤20000/µL for 7 consecutive days or requirement of transfusion for more than 60 days after allo-SCT. SFPR was defined as a decline of platelet counts to ≤20000/µL for 7 consecutive days or requirement of transfusion after achievement platelets ≥50000/µL without transfusion for 7 days post-SCT. The primary endpoint was platelet recovery to ≥50000/µL. Results Eighty-six patients with thrombocytopenia after allo-SCT were included. The characteristic of the patients, are summarized in table 1. Sixteen (19%) of the patients had PT and 71 (82%) SFPR. TPO-RA was started at a median time of 127 days (27-1177) after allo-SCT (41% Romiplostim / 59% Eltrombopag). Median initial and maximum administered doses were 50 mg/daily (25-150) and 75 (25-150) for Eltrombopag and 1 µg/kg (1-7) and 5 (1-10) for Romiplostin, respectively. Eighteen patients (21%) were previously treated with cell infusion (67% mesenchymal cells and 33% CD34+ boost). Median platelet count before TPO-RA onset was 14000/µL (1000-57000). Platelet recovery to ≥50000/µL was 60% and the response was achieved at a median time of 56 days (2-247). Responses were similar considering all potential causes of thrombocytopenia evaluated. 81% of the patients had decrease number of megakaryocytes prior to treatment showing a worse response to therapy: median time to ≥20000/µL platelets 43 days versus 28 days (p=0.011), with also a lower rate of platelet recovery to ≥50000/µL (62% versus 85% if normal megakaryocytes). In patients treated with Eltrombopag, 27% had neutropenia <1000/µL and 74% achieved >1000/µL after therapy. The median treatment duration was 62 days (7-700) and 62% discontinued TPO-Ra maintaining response. Grade 3-4 adverse events (hepatic and asthenia) were observed in only 2% of the cases. At last follow up with a median of 10 months (1-59), 72% of the patients maintained the response and 61 (71%) were alive. Death rate was significantly lower in responder-patients to TPO-RAs, 15% versus 53% in non-responders (p<0.001). Causes of death were disease progression (28%), infections (48%), graft versus host disease (GvHD) (16%) and others (8%). Conclusion To our knowledge this is the biggest series analyzing the use of TPO-Ra after allo-SCT. Our results support the efficacy and safety in this new setting with responses around 60% and a low number of side effects. Additional studies to identify predictors of response are needed. Disclosures No relevant conflicts of interest to declare.
Chronic lymphocytic leukemia (CLL) patients harboring 11q22.3 deletion, del(11q), are characterized by a rapid disease progression. One of the suggested genes to be involved in the pathogenesis of this deletion is BIRC3, a negative regulator of NF-κB, which is monoallelically deleted in ~80% of del(11q) CLL cases. In addition, truncating mutations in the remaining allele of this gene can lead to BIRC3 biallelic inactivation, which accounts for marked reduced survival in CLL. Nevertheless, the biological mechanisms by which monoallelic or biallelic BIRC3 lesions could contribute to del(11q) CLL pathogenesis, progression and therapy response are partially unexplored. We used the CRISPR/Cas9 system to model monoallelic and biallelic BIRC3 loss in vitro. First, we generated an isogenic HG3 CLL cell line harboring monoallelic del(11q) - HG3-del(11q) - by the introduction of 2 guide RNAs targeting 11q22.1 and 11q23.3 (~17 Mb). Loss-of-function BIRC3 mutations (MUT) were introduced in the remaining allele, generating 3 HG3-del(11q) BIRC3MUT clones. In addition, single BIRC3MUT were introduced in HG3 and MEC1 CLL-derived cells for experimental validation (n = 3 clones/cell line). We first questioned whether monoallelic and biallelic BIRC3 loss had an impact in the DNA-binding activity of NF-κB transcription factors. Interestingly, HG3-del(11q) had higher p52 and RelB (non-canonical NF-κB signaling) activity than HG3WT cells (P = 0.005; P = 0.007), being this activity further increased in HG3-del(11q) BIRC3MUT cells (P < 0.001; P < 0.001). In depth analysis of the non-canonical signaling components by immunoblot revealed that HG3-del(11q) and, to a greater extent, HG3-del(11q) BIRC3MUT cells presented NF-κB-inducing kinase (NIK) cytoplasmic stabilization, high p-IKKα levels and p52-RelB nuclear translocation. Besides, HG3-del(11q) BIRC3MUT cells showed increased levels of the anti-apoptotic proteins BCL2 and BCL-xL. We next assessed this pathway ex vivo in stroma and CpG-stimulated primary CLL cells with or without BIRC3 deletion (n = 22; 11 each group). Remarkably, stimulated BIRC3-deleted primary cells showed higher p52 and RelB activity than BIRC3WT cases (P = 0.01; P = 0.07), and the percentage of BIRC3-deleted cells correlated with p52 activity in del(11q) cases (P = 0.04). We further performed western blot analyses in a homogenous cohort of del(11q) cases including (n = 4) or not including (n = 3) BIRC3 within the deleted region. Interestingly, del(11q)/BIRC3 deleted cases presented high levels of stabilized NIK, which correlated with higher p52 processing (P = 0.003). These patients also showed higher BCL2 levels than those del(11q)/BIRC3 undeleted, and we could further observe a correlation between p52 and BCL2 levels (P = 0.01). Given this p52-dependent BCL2 upregulation, we treated the CRISPR/Cas9 edited clones with venetoclax, demonstrating that HG3-del(11q) BIRC3MUT cells were more sensitive upon BCL2 inhibition than HG3WT clones (mean IC50 3.5 vs. 5.75 μM; P = 0.005). In vitro proliferation assays were performed to interrogate the impact of BIRC3 loss in CLL cell growth, revealing that HG3 BIRC3MUT cell lines had higher growth rates than BIRC3WT cells (P = 0.001). HG3-del(11q) BIRC3MUT cells also showed enhanced proliferation in comparison to HG3-del(11q) clones (P = 0.009). We further determined the clonal dynamics of del(11q) and/or BIRC3MUT cell lines in clonal competition experiments, showing that HG3 BIRC3MUT and HG3-del(11q) BIRC3MUT cells progressively outgrew HG3WT and HG3-del(11q) cells, respectively, overtime (P = 0.02; P = 0.006). Furthermore, we injected these edited cell lines into NSG mice (n = 20) in vivo, showing that mice xenografted with HG3 BIRC3MUT and HG3-del(11q) BIRC3MUT cells presented, by flow cytometry, an increase of human CD45+ cells in spleen 14 days after injection, compared to HG3WT and HG3-del(11q) cells (P = 0.02; P = 0.015). In summary, this work demonstrates that biallelic BIRC3 deletion through del(11q) and mutation triggers non-canonical NF-κB signaling, driving BCL2 overexpression and conferring clonal advantage, which could account for the negative predictive impact of BIRC3 biallelic inactivation in CLL. Taken together, our results suggest that del(11q) CLL patients harboring BIRC3 mutations should be considered as a CLL subgroup at a high risk of progression that might benefit from venetoclax-based therapies. Funding: PI18/01500 Disclosures No relevant conflicts of interest to declare.
Introduction Inherited thrombocytopenias (ITs) are a heterogeneous group of rare platelet disorders. which lead not only to increased bleeding, but also to syndromic forms. ITs are caused by genetic alterations in megakaryopoiesis-related genes. In the last years, whole-exome sequencing (WES) has allowed the identification of novel genes involved in IT. Aim To perform the molecular, clinical and platelet characterization of two unrelated families with syndromic IT, to unveil the underlaying alteration leading to the disease. To explore the functional role of the identified alterations during megakaryocytic (Mk) differentiation. Methods WES was performed in two unrelated non-consanguineous families with lifelong severe macrothrombocytopenia (MCT), bleeding, and extra-hematological manifestations. Bleeding score (BS) was recorded by ISTH-BAT. Platelet phenotyping included platelet count (P), blood film, aggregometry (LTA) and flow cytometry (FC). UDP-galactose-4-epimerase enzymatic activity was measure by HPLC/MS/MS. In vitro functional studies were performed through overexpression of GALE genetic variants in human K562 cell line to elucidate its role in Mk differentiation, by measuring cell ploidy and expression of CD41, CD61 and CD42b surface markers after 7-days of PMA treatment. Results Family pedigrees are shown in Figure 1. Three patients (A.II.1, A.II.2 and B.II.1) were referred due to lifelong severe MCT and moderate-severe bleeding tendency (Figure 1). Moreover, they presented mental retardation, mitral insufficiency, and increased bilirubin levels. Blood film revealed enlarged, giant, and grey platelets (A.II.1: 36%, 6% and 54%, respectively; A.II.2: 56%, 4%, 34%, respectively; B.II.1: 32%, 46%, 12%). LTA showed moderate/severe impaired aggregation with ADP, TRAP-6, CRP, epinephrine, arachidonic acid, and ristocetin. FC confirmed null secretion of alpha and dense granules in A.II.1, A.II.2 and reduced levels in B.II.1 (7.8%, 8.1%, 28.3% respectively, vs. 51.7% control platelets with ADP 10µM; 10.8%, 7.8%, 36.7% respectively, vs. 95.6% control platelets with TRAP6 25µM). WES revealed that both pedigrees carried compound heterozygous variants in GALE (NM_001127621.2): c.230_231insTGTT; p.Lys78Valfs*32 (exon 3), and c.449C>T; p.Thr150Met (exon 5) in A.II.1 and A.II.2 patients; and, c.668T>C, p.Leu223Pro (exon 7), and c.382G>A, p.Val128Met (exon 5) in B.II.1 (Figure 1). Enzymatic activity of the GALE-encoded protein UDP-galactose-4-epimerase was severely reduced in the affected patients: both A.II.1, A.II.2 patients had 1.3 μmol/h/g hemoglobin (control: 8.8 μmol/h/g hemoglobin), and B.II.1 patient had 0.6 μmol/h/g hemoglobin (control: 8 μmol/h/g hemoglobin). Furthermore, in vitro overexpression assays between wild-type GALE and p.Thr150Met, p.Leu223Pro and p.Val128Met variants, confirmed a delayed maturation of Mks upon PMA treatment (at 3, 5 and 7 days). characterized by a significant reduction in the expression of the megakaryocytic surface markers CD41, CD61 and CD42b. Conclusion WES has allowed us to identify pathogenic variants in GALE, which were associated with syndromic IT characterized by severe macrothrombocytopenia. Patients harboring these pathogenic variants presented moderate to severe bleeding tendency associated with cardiovascular and neurological abnormalities. Regarding the platelet phenotype, the presence of giant and grey platelets and the absence of both platelet granules were the most remarkable features reported. Moreover, these GALE variants led to an alteration in in vitro Mk maturation, supporting the thrombocytopenic phenotype observed in patients. Funding ISCIII (PI17/01966, PI 17/01311, PI20/00926), GRS (GRS2061A/19, GRS2135/A/2020), Fundación Séneca (19873/GERM/15), Fundación Mutua Madrileña (AP172142019), Premio López Borrasca (2019), Grupo Trabajo Patología Hemorrágica-SETH (2020). Figure 1 Figure 1. Disclosures Hernández-Rivas: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees.
Introduction: Thromboxane A2 [TxA2] is generated from arachidonic acid by cyclooxigenase-1 (COX-1) (prostaglandin H synthase-1) and thromboxane synthase. Aspirin, which irreversibly inhibits COX-1, is a widely used antiplatelet therapy with proven clinical efficacy. Inherited platelet disorders (IPD) are rare diseases caused by alterations of relevant genes in platelet formation and/or function. Despite the relevance of the TxA2 pathway in platelet physiology, few patients with mutations in PTGS1, the gene encoding COX-1, have been identified (<5 cases worldwide). Objective: Characterization of a patient with aspirin-like platelet defect and moderate bleeding, enrolled in the Spanish multicentric project "Functional and molecular characterization of patients with IPD". Methods: The index case is a 13-year-old adopted girl of Asian origin, referred because of moderate chronic bleeding (BAT-ISTH=6) and an aspirin-like platelet dysfunction. No coagulation defect or other relevant clinical symptoms were present. Platelet phenotyping included: blood count, PFA-100; platelet aggregation [LTA], glycoproteins (GP), activation and secretion of granules by flow cytometry (FC), TxA2 synthesis by enzyme-immunoassay, synthesis of eicosanoids by tandem gas chromatography with mass spectrometry (LC-MS), western-blot (WB) of platelet lysates, and immunofluorescence (IF) assays. The patient's DNA was analyzed with a HTS-gene panel (Bastida et al, Haematologica 2018). A HEK 293T cell transfection model was established to further assess the pathogenicity of the candidate variant found in the patient. Results: The index case has normal platelet size and count (206x109/L; 11.4 fL). PFA-100 times were normal for COL-ADP and prolonged for COL-EPI (>300s). The FC analysis showed normal expression of GPs (Ib/IX, IIb/IIIa, Ia, GPVI) and reduced fibrinogen*488 binding (20-30%) in response to ADP, TRAP and low dose CRP (2ug/mL). P-selectin and CD63 secretion with agonists was comparable to those of controls. LTA was normal with ristocetin (1.25mg/mL) and TRAP (25uM), reduced by 40-50% with ADP (10uM) and collagen (3ug/mL) and absent with epinephrine (10uM), low dose collagen (1ug/mL) and arachidonic acid (1.6mM). LTA with U46619 (5uM), a direct agonist of the TxA2 receptor, was normal, suggesting a defect in TxA2 synthesis. Indeed, TxA2 levels in LTA supernatants in the patient were very low (5ng/mL; <10% vs. two controls). A significant reduction (50-90%) in TxA2 production was confirmed in the patient whole blood stimulated with collagen or TRAP, as measured by LC-MS. HTS analysis revealed that the patient is a heterozygous carrier of the variant c.428A>G, [p.Asn143Ser] in PTGS1. This variant, not previously described, affects a conserved residue in the catalytic domain of COX-1, which is one of the three N-glycosylation sites in the enzyme. The variant was not associated with reduced COX-1 expression as evaluated by WB in platelet lysates, and by IF in spread washed platelets and leukocytes. HEK 293T cells transfected with wild-type COX-1 construct (validated by RT-PCR and WB), displayed substantial TxA2 synthesis (500ng/mL; 2.5x105 transfected cells) in response to arachidonic acid. In contrast, similar transfection of p.143Ser COX-1 mutant almost abrogated this TxA2 production (≈50-75ng/mL in 2.5x105 transfected cells). Conclusion: We have identified a novel autosomal dominant COX-1 variant, p.Asn143Ser, associated with functional haploinsufficiency of the enzyme and platelet aggregation defects. To our knowledge, this case represents the third description of variants in PTGS1 (Nance, JTH 2016; Sivapalaratnam, Blood 2018), which cause platelet dysfunction and bleeding. Disclosures Almarza: Rocket Pharmaceuticals: Equity Ownership, Patents & Royalties, Research Funding. Bueren:Rocket Pharmaceuticals, Inc.: Consultancy, Equity Ownership, Patents & Royalties: Inventor on patents on lentiviral vectors filled by CIEMAT, CIBERER and F.J.D and may be entitled to receive financial benefits from the licensing of such patents, Research Funding.
Introduction The inherited platelet disorders (IPD) are a heterogeneous group of rare diseases including quantitative and/or qualitative platelet defects. Classically, patients with IPD are first functionally tested to know the possible defect before sequencing a single or a few genes. Phenotipyc diagnostic of IPD often requires light transmission aggregometry, quantitative analysis of receptors by flow cytometry and fluorescence and electron microscopy. This diagnostic strategy is complex, poorly standardised and time consuming. In addition, the phenotype can seldom guide the singles candidates genes for conventional Sanger squencing. Therefore, many patients remain without a accurate diagnosis of their IPD. Next generation sequencing (NGS) enables the simultaneous analysis of large groups of candidate genes in IPD and may be useful for rapid genetic diagnosis. The aim of this study was to design and validate a NGS panel for IPD. Patients & Methods We describe a strategy for rapid genetic diagnosis of IPD with Illumina sequencing of 60 candidates genes previously associated with IPD (table1). The baits were designed to tile 400 kb of gDNA sequence corresponding to the exons and splice sites in all known transcripts of the candidate genes identified. The bait library was tested by enriching the candidate IPD genes from 50 ng DNA obtained and sequencing by Nextera Rapid Custom Enrichment system. Results were analysed by Variant Studio system and Sequencing Analysis Viewer. A total of 21 patients were studied. For the validation process, DNA samples of 9 unrelated patients with IPD and their mutation known were used: two patients with Glanzmann Thrombasthenia (ITGA2B, p.Ala989Thr, p.Val982Met and p.Glu538Stop; ITGB3, p.Leu222Pro and p.Tyr216Cys), one Hermansky-Pudlak Sd. (HPS1, p.Glu204 Stop), another with Bernard-Soulier Sd. (GPIX, p.Phe71Stop), a case of Congenital Amegakaryocytic Thrombocytopenia (MPL, p.Arg102Cys), and 2 patients with Chediak Higashi Sd. (LYST, p.Gly3725Arg and p.Cys258Arg). Once validated, the NGS panel was used for genetic diagnostic of 8 patients with suspected IPD. Results Eleven mutations, previously identified in another center by conventional sequencing, were detected by our panel NGS (100% success in the validation process). We then tested this strategy for patients with suspected of IPD without diagnosis: I. a 13 years old girl with agenesis of the corpus callosum, facial dysmorphia, renal agenesis and thrombocytopenia was diagnosed of Thrombocytopenia FLNA-related and Periventricular Nodular Heterotopia (PNHV)[mutation in the FLNA was detected (p.Thr1232Ile)]. II. A two years old patient with severe thrombocytopenia and recurrent infections was diagnosed of Wiskott-Aldrich Sd (WAS, p.Arg268Gly fs Stop40). III. A patient with deafness, macrothrombocytopenia, and Döhle bodies was diagnosed by MYH9 deletion (MYH9; p.Asp1925Thr fs Stop23). IV. Six members of a family (2 of them with symptoms of mucocutaneous bleeding, and macrothrombocytopenia), in which an insertion in NBAL2 (p.Gly1142Arg fs Stop49) gene was found. Therefore, Gray Platelet Sd was diagnosed. Moreover, one patient with aspirin-like syndrome showed a P2RY12 mutation (p.Val279Met). Finally, mother and son with mild Hemophilia A (F8; p.Gln2208Arg) were detected. Conclusions This NGS panel enables a rapid genetic diagnostic of IPD. The use of NGS-based strategy is a feasible tool for the diagnosis of IPD that could be added to the screening of these disorders. Five mutations have not previously been described in the literature. Table 1: Sixty candidates' genes previously associated with IPD: Inherited Platelet Disorders Genes = 60 Cytoskeletal Assembly and Structural Proteins GP1BA, GP1BB, GP5, A2M, GP9, VWF, ITGA2, ITGA2B, ITGB3, ABCA1, ANO6,FERMT3, ACTN1, MASTL Disorders of agonist platelet receptors P2RX1, P2RY1, P2RY12, TBXA2R, TBXAS1, ADRA2A, GP6, CD36 o GP4, DTNBP1 Disorders signal transduction GNAI3, GNAQ, GNAS, PLA2G7, PLCB2PTS, GGCX, DPAGT1, DHCR24 Disorders of platelet granules NBEAL2, GFI1B, PLAU, HPS1, HPS3, HPS4, HPS5, HPS6, LYST, MLPH, BLOC1S3, BLOC1S6, AP3B1, VIPAS39, VPS33B, RAB27A, MYO5A, USF1 Thrombocytopenias and syndromes WAS, MYH9, FLNA, FLI1, STIM1, HOXA11, ANKRD26, MPL, RBM8A RUNX1, GATA1 Disclosures No relevant conflicts of interest to declare.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.