Chronic Neutrophilic Leukemia Research Articles

Coexisting Oncogenic Signaling Pathway Mutations in Cnl/Acml/CMML/MPN-U

Purpose: Chronic neutrophilic leukemia (CNL), chronic myelomonocytic leukemia (CMML), atypical myeloid leukemia (aCML), and unclassified myeloproliferative neoplasms (unMPN) are rare entities of myeloproliferative or myelodysplastic/myeloproliferative (MDS/MPN) syndromes. Due to poorly defined molecular mechanisms, these diseases have been, until now, diagnosed based on morphology and exclusionary criteria and treated empirically, resulting in dismal outcomes. Recent application of next generation sequencing has shed light on the genetic mechanisms of CNL/aCML/CMML/MPN-U. In particular, Maxson et al. and others have shown that CSF3R membrane proximal and transmembrane mutations are present in 83-89% of CNL and 3.3-44% of aCML patients, and expression of CSF3R membrane proximal mutants is sufficient to recapitulate the clinical features (mature granulocyte accumulation) of CNL in a mouse model. This has led to revision of the WHO diagnostic criteria for CNL, enabling a more accurate diagnosis and facilitating the development of targeted treatment for this disease. Aside from the CSF3R driver mutations, few recurrent signaling pathway mutations have been characterized in this group of diseases that could serve as the basis for such targeted therapeutic strategies. The aim of the current study is to characterize the frequency and distribution of signaling pathway driver mutations in a large cohort of CNL/aCML/CMML/MPN-U patients with the hope of informing diagnosis, prognosis and treatment.Methods and results: We performed whole exome sequencing on a large cohort of patients (n=160) with plausible diagnosis of CNL/aCML/MPN-U/CMML. We screened hotspot variants in genes representing kinases, non-kinase growth factor and cytokine receptors. We observed that 66.9% of patients harbor at least one signaling pathway driver mutations (CSF3R 20.6%, NRAS 17.5%, JAK2 9.4%, CBL 6.5%, PTPTN11 5.6%, ETNK1 5.6, KRAS 4.4%, NF1 3.1%, FLT3 3.1%, SH3B2 3.1%, etc.), largely involving JAK/STAT and RAS signaling pathways. Interestingly, MPL mutations and CALR indels were rare in our cohort. The variants of signaling pathway driver mutations were observed with high allele frequencies: CSF3R (52.1%), JAK2 (48.9%), NRAS (46.3%), PTPN11 (40.7%), CBL (34.4%) and KRAS (29.5%), indicating the majority of these driver mutations are present in the dominant leukemic clones.Interestingly, 21.5% and 3.7% patients harbor two and three different active signaling pathway mutations, respectively. Clonality analysis demonstrated a co-occurrence pattern in more than half of the cases where more than two signaling pathway mutations were identified, underscoring a complex genetic pathogenesis. CSF3R was shown to co-occur with NRAS, SH2B3, PTPN11, NTRK2, CBL, ETNK1 and ABL1 mutations; NRAS mutations were present in combination with CSF3R, KRAS, JAK2, CBL, STAT3, NTRK2, FLT3, and GNB1 mutation. Since CSF3R and RAS mutation co-occur at high frequencies (n=5, 22%) in this cohort. We performed drug sensitivity assays, and we observed reduced drug sensitivity to either JAK or MEK inhibitors in cells transformed by co-existing mutations, whereas drug combinations targeting the co-existing mutations demonstrated synergistic cytotoxicity .Conclusions: In sum, CNL/aCML/MPN-U/CMML is a group of heterogeneous diseases associated with high frequencies of signaling pathway mutations in the major clone. More than 25% of patients demonstrate multiple different pathway mutations in a co-existing pattern, which warrants comprehensive screening of molecular targets and high-efficacy drug combination strategies. DisclosuresTyner:AstraZeneca: Research Funding; Incyte Corporation: Research Funding; Leap Oncology: Consultancy; Syros: Research Funding; Seattle Genetics: Research Funding; Agios Pharmaceuticals: Research Funding; Takeda Pharmaceutical Company: Research Funding; Constellation Pharmaceuticals: Research Funding; Aptose Biosciences: Research Funding; Janssen Pharmaceutica: Research Funding; Gilead: Research Funding; Genentech: Research Funding; Array Biopharma: Research Funding.

Fusion Transcripts without Corresponding Cytogenetic Abnormalities in Acute Myeloid Leukemia: Implications for AML Pathogenesis

Chromosomal translocations and inversions that create fusion genes are important causal events in AML. 7 recurrent fusion genes define AML entities in the 2016 revision of the WHO classification of hematologic malignancies. We have developed a comprehensive diagnostic AML platform based on next-generation mRNA sequencing (RNAseq). The adaptable integrated bioinformatic pipeline HAMLET (Human AML Expedited Transcriptomics) analyses the raw data simultaneously for fusion transcripts and for sequence variants and expression levels of genes with relevance to AML pathogenesis, prognosis, or actionability.Poly(A)+ RNA from 100 cryopreserved AML samples with a blast count of 10-99% (median: 75%) from 96 patients (3 diagnosis-relapse pairs, 1 de novo AML and subsequent tAML) was sequenced at a depth of 59x106 paired-end reads/sample with median read length of 126 bp in an ISO17025-accredited Illumina HiSeq 2500 pipeline. Fusion transcripts were called by STAR-Fusion and FusionCatcher. HAMLET detected the recurrent fusion transcripts RUNX1-RUNX1T1, CBFB-MYH11, PML-RARA, ERG-FUS, DEK-NUP214, and KMT2A-MLLT3 plus the variants KMT2A-MLLT4, KMT2A-MLLT1, and KMT2A-MLLT6 with 100% sensitivity and 100% specificity compared to metaphase cytogenetics, FISH, and RT-PCR (Griffioen, ASH 2016).In addition, HAMLET identified fusion transcripts from 54 combinations of genes in 57 AML samples that lacked corresponding chromosomal aberrations by metaphase cytogenetics. 14 “unusual” fusions involved genes located on different chromosomes; 40 fusions represented intrachromosomal events. 8 fusions were detected recurrently, i.e. in at least 2 cases (Fig. A). 32 AML carried at least 2 unusual fusions, with a maximum of 9 different fusions in an AML with a complex karyotype (Fig. B). Unusual fusions were not correlated with classical recurrent AML fusion genes. The 5 most prevalent fusions and an ETV6-LYN fusion were successfully validated in a total of 18 AML by RT-PCR. The only fusion that could not be validated was a YWHAZ-KLF10 fusion (2 cases).The most prevalent RT-PCR-validated fusion (seen in 30 AML cases) has been described in ALL (Roberts, 2012; Safavi, 2015) and was an intrachromosomal TPM4-KLF2 fusion between the tropomyosin 4 and an alternative reading frame (ARF) of the transcription factor Kruppel-like factor 2 genes. Unexpectedly, we detected this fusion in all 3 tested normal bone marrows (BM) but not in EBV-transformed B cells. The hitherto unvalidated C15orf57-CBX3 fusion may be generated by retrotransposition (Schrider, 2013) and was present in 18 AML as well as in 2/3 normal BM and 2/3 EBV B-cells with CBX3 in ARF. The intrachromosomal NCOR2-UBC fusion (9 AML) is listed in the database ChimerDB without further characterization and involves the genes of Nuclear corepressor 2 and Ubiquitin C in the normal reading frame (NRF). The NUP98-NSD1 fusion (3 AML) with NSD1 in NRF is frequently found in hematological malignancies including AML and originates from a cryptic t(5;11) due to telomeric positions of both genes. The PIM3-SCO2 fusion between the serine/threonine kinase PIM3 and an ARF of Cytochrome C oxidase assembly protein can originate from a 0.6 Mb inv(22) in chronic neutrophilic leukemia (Menezes, 2013) and occurs frequently in pediatric AML (Kuhn, 2013). The well-characterized ETV6-LYN fusion (1 AML) fusing the TEL1 oncogene to the SRC family kinase LYN in NRF originates from a complex translocation with inversion involving chromosomes 8 and 12 (Telford, 2016) and has oncogenic activity by activation of STAT5 (Takeda, 2011).Fusion transcripts without recognizable chromosomal abnormalities on metaphase cytogenetics occur frequently in AML and involve actionable targets. The upstream sequence can be fused to the normal or alternative reading frame of the downstream coding sequences and involve potential or validated proto-oncogenes. Apart from cryptic translocations or inversions, trans-splicing is suggested as an alternative mechanism by the presence of some fusion genes in non-malignant hematopoietic cells. Trans-splicing without DNA rearrangement can occur physiologically and alter cellular development towards potential premalignant differentiation (Yuan, 2013). Increasing use of RNAseq technology in routine AML diagnostics, e.g. by HAMLET, will permit to unravel the prognostic significance of unexpected fusion transcripts and to guide novel targeted therapies. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Current Management of Chronic Neutrophilic Leukemia.

Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm (MPN) characterized by oncogenic driver mutations in colony-stimulating factor 3 receptor (CSF3R). Due in large part to the rarity of the disease and dearth of clinical trials, there is currently no standard of care for CNL. Available therapies range from conventional oral chemotherapy to targeted JAK inhibitors to hematopoietic stem cell transplant (HSCT), the latter representing the only potentially curative modality. For this reason, coupled with CNL's typically aggressive clinical course, allogeneic HSCT remains the primary recommended therapy for eligible patients. For ineligible patients, a number of nontransplant therapies have been evaluated in limited trials. These agents may additionally be considered "bridging" therapies pre-transplant in order to control myeloproliferation and alleviate symptoms. Historically, the most commonly utilized first-line agent has been hydroxyurea, though most patients ultimately require second (or subsequent)-line therapy; still hydroxyurea remains the conventional frontline option. Dasatinib has demonstrated efficacy in vitro in cases of CSF3R terminal membrane truncation mutations and may cautiously be considered upfront in such instances, though no substantive studies have validated its efficacy in vivo. Numerous other chemotherapy agents, practically re-appropriated from the pharmaceutical arsenal of MPN, have been utilized in CNL and are typically reserved for second/subsequent-line settings; these include interferon-alpha (IFN-a), hypomethylating agents, thalidomide, cladribine, and imatinib, among others. Most recently, ruxolitinib, a JAK1/2 inhibitor targeting JAK-STAT signaling downstream from CSF3R, has emerged as a potentially promising new candidate for the treatment of CNL. Increasingly robust data support the clinical efficacy, with associated variable reductions in allele burden, and tolerability of ruxolitinib in patients with CNL, particularly those carrying the CSF3RT618I mutation. Similar to conventional nontransplant strategies, however, no disease-modifying or survival benefits have been demonstrated. While responses to JAK-STAT inhibition in CNL have not been uniform, data are sufficient to recommend consideration of ruxolitinib in the therapeutic repertory of CNL. There remains a major unmet need for prospective trials with investigational therapies in CNL.

Chronic Neutrophilic Leukemia: A Literature Review of the Rare Myeloproliferative Pathology.

Hematological malignancies often develop due to a vast spectrum of environmental and genetic etiologies. Chronic neutrophilic leukemia (CNL) can be described as a BCR-ABL1 (Philadelphia chromosome)-negative myeloproliferative neoplastic disease with various genetic mutations that may directly or indirectly play a role in its pathogenesis. A well-established mutation in CNL is the CSF3R (a cytokine receptor) which has been incorporated into the diagnostic criteria for the disease. However, evidence of other mutations such as SETBP1, ASXL1, and TET2 has also shed more light on the pathogenesis of this condition. Due to the unknown incidence and heterogeneous presentation of the disease, the diagnosis and management are often difficult and lack satisfactory data. The purpose of this review is to yield further insight into a disease that lacks awareness in the medical community. Using PubMed as a database, relevant studies and case reports were reviewed. The data compiled were used to acknowledge the disease in terms of etiology, clinical manifestation, molecular pathogenesis, and available treatment modalities. Though existing treatment modalities have been shown to induce clinical improvement, the outcomes are not reliable, and further research is required to reach a comprehensive “standard of care” for the disease.

Chronic Neutrophilic Leukemia with Monocytosis

The presence of a CSF3R gene mutation is diagnostic for chronic neutrophilic leukaemia (CNL).The monocytosis in this patient might have been a new variant of CNL.

Leukemia Cell Lines: In Vitro Models for the Study of Chronic Neutrophilic Leukemia.

Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm that is genetically characterized by the absence of both the Philadelphia chromosome and BCR-ABL1 fusion gene and the high prevalence of mutations in the colony-stimulating factor 3 receptor (CSF3R). Additional disease-modifying mutations have been recognized in CNL samples, portraying a distinct mutational landscape. Despite the growing knowledge base on genomic aberrations, further progress could be gained from the availability of representative models of CNL. To address this gap, we screened a large panel of available leukemia cell lines, followed by a detailed mutational investigation with focus on the CNL-associated candidate driver genes. The sister cell lines CNLBC-1 and MOLM-20 were derived from a patient with CNL and carry CNL-typical molecular hallmarks, namely mutations in several genes, such as CSF3R, ASXL1, EZH2, NRAS, and SETBP1. The use of these validated and comprehensively characterized models will benefit the understanding of the pathobiology of CNL and help inform therapeutic strategies.

English

Excessive growth of mature granulocytes in the bone marrow induces chronic myeloid leukemia. The excess neoplastic granulocytes travel massively into the peripheral blood and in the end invade the liver and spleen. The protein encoded on the Philadelphia chromosome by the newly created BCR-ABL gene interferes with normal cell cycle activities, including regulating cell proliferation. Philadelphia chromosome is present in 90 - 95 percent of chronic myeloid leukemia (CML) patients. Their involvement is often a vital indicator of persistent disease or posttreatment relapse. However, for the diagnosis of CML, the presence of the Philadelphia chromosome is not specific since it is also present in acute lymphocytic leukemia (ALL) and rarely in acute myeloid leukemia (AML). 1 Chronic myeloid leukemia is a myeloproliferative neoplasm (MPN) characterised by involvement of the fusion gene BCRABL1 located in the Philadelphia chromosome. In reactive neutrophilia or chronic neutrophilic leukemia, the Ph chromosome is pathognomonic to CML and is never registered.2,3

CSF3R T618I, SETBP1 G870S, SRSF2 P95H, and ASXL1 Q780* tetramutation co-contribute to myeloblast transformation in a chronic neutrophilic leukemia

Chronic neutrophilic leukemia (CNL) is a rare but serious myeloid malignancy. In a review of reported cases for WHO-defined CNL, CSF3R mutation is found in about 90% cases and confirmed as the molecular basis of CNL. Concurrent mutations are observed in CSF3R-mutated CNL patients, including ASXL1, SETBP1, SRSF2, JAK2, CALR, TET2, NRAS, U2AF1, and CBL. Both ASXL1 and SETBP1 mutations in CNL have been associated with a poor prognosis, whereas, SRSF2 mutation was undetermined. Our patient was a 77-year-old man and had no significant past medical history and symptoms with leukocytosis. Bone marrow (BM) aspirate and biopsy revealed a markedly hypercellular marrow with prominent left-shifted granulopoiesis. Next-generation sequencing (NGS) of DNA from the BM aspirate of a panel of 28 genes, known to be pathogenic in MDS/MPN, detected mutations in CSF3R, SETBP1, and SRSF2, and a diagnosis of CNL was made. The patient did not use a JAK-STAT pathway inhibitor (ruxolitinib) but started on hydroxyurea and alpha-interferon and developed pruritus after 4 months of diagnosis and nasal hemorrhage 1 month later. Then, the patient was diagnosed with CNL with AML transformation and developed intracranial hemorrhage and died. We repeated NGS and found that three additional mutations were detected: ASXL1, PRKDC, MYOM2; variant allele frequency (VAF) of the prior mutations in CSF3R, SETBP1, and SRSF2 increased. The concurrence of CSF3RT618I, ASXL1, SETBP1, and SRSF2 mutation may be a mutationally detrimental combination and contribute to disease progression and AML transformation, as well as the nonspecific treatment of hydroxyurea and alpha-interferon, but the significance and role of PRKDC and MYOM2 mutations were not undetermined.

A Case of Chronic Neutrophilic Leukemia Incidentally Detected by 18F-FDG PET/CT.

Chronic neutrophilic leukemia (CNL) is a rare, potentially aggressive, myeloproliferative neoplasm. To the best of our knowledge, there are no previous reports dealing with 18F-FDG PET findings in CNL. We describe a case of CNL in a 69-year-old male, imaged with 18F-FDG PET/CT at diagnosis and during treatment.

Multiple myeloma with G-CSF production mimicking chronic neutrophilic leukemia.

Multiple myeloma with G-CSF production mimicking chronic neutrophilic leukemia.

Outgrowth of a CSF3R-mutant clone drives a second myeloproliferative neoplasm in a chronic myeloid leukemia patient: a case report

BackgroundChronic myeloid leukemia (CML) and chronic neutrophilic leukemia (CNL) are two myeloproliferative neoplasms with mutually exclusive diagnostic criteria. A hallmark of CML is the Philadelphia chromosome (Ph), which results in a BCR-ABL1 fusion gene and constitutive tyrosine kinase activity. CNL is a Ph-negative neoplasm and is defined in part by the presence of CSF3R mutations, which drive constative JAK/STAT signaling.Case presentationHere, we report the exceedingly rare co-occurrence of two granulocytic myeloproliferative neoplasms in a 69-year old male patient. After an initial diagnosis of chronic myeloid leukemia, the patient’s clinical course was shaped by hematologic toxicity, the emergence of treatment-resistant BCR-ABL1 clones, and the expansion of a CSF3R-mutant clone without ABL1 mutations under selective pressure from tyrosine kinase inhibitors. The emergence of the CSF3R-mutant, neutrophilic clone led to the diagnosis of CNL as a second myeloproliferative neoplasm in the same patient.ConclusionsThis is the first reported case of CNL arising subsequent to CML, which occurred under selective pressure from targeted therapy in a patient with complex clonal architecture. Patients with such molecularly complex disease may ultimately benefit from combination therapy that targets multiple oncogenic pathways.

Secondary CNL after SAA reveals insights in leukemic transformation of bone marrow failure syndromes

AbstractAcquired aplastic anemia and severe congenital neutropenia (SCN) are bone marrow (BM) failure syndromes of different origin, however, they share a common risk for secondary leukemic transformation. Here, we present a patient with severe aplastic anemia (SAA) evolving to secondary chronic neutrophilic leukemia (CNL; SAA-CNL). We show that SAA-CNL shares multiple somatic driver mutations in CSF3R, RUNX1, and EZH2/SUZ12 with cases of SCN that transformed to myelodysplastic syndrome or acute myeloid leukemia (AML). This molecular connection between SAA-CNL and SCN progressing to AML (SCN-AML) prompted us to perform a comparative transcriptome analysis on nonleukemic CD34high hematopoietic stem and progenitor cells, which showed transcriptional profiles that resemble indicative of interferon-driven proinflammatory responses. These findings provide further insights in the mechanisms underlying leukemic transformation in BM failure syndromes.

A Unique Case of CSF3R-Mutated Chronic Neutrophilic Leukemia with Thrombocytosis

Chronic neutrophilic leukemia (CNL) is a well-recognized, extremely rare myeloproliferative neoplasm (MPN) with only ~200 reported cases until 2017. The current WHO diagnostic criteria include leukocytosis of ≥ 25 x 109/L with ≥ 80% neutrophils/bands, < 10% circulating neutrophil precursors and <1% blasts (<5% bone marrow blasts). Exclusion criteria includes dysplasia, or clinical/molecular diagnosis of other MPN. The WHO classification was updated in 2016 to include CSF3R T618I and other activating mutations in CSF3R as diagnostic. SETBP1 and ASXL1 mutations are frequent but unspecific in CNL and appear to be of prognostic significance. Hepatosplenomegaly and a hypercellular bone marrow with marked granulocytic hyperplasia are common in CNL, but thrombocytosis has not been reported previously. We report a 72-year-old man with past medical history of hypertension and hepatitis C status post-treatment, who presented with WBC 38.4k/cmm, Hgb 6.3g/dl, MCV 102 fl and platelet count of 2601k/cmm. Reactive etiology of thrombocytosis was ruled out. Peripheral blood smear revealed rare blasts. Bone marrow biopsy was hypercellular (60-80%) with M:E ratio of 10:1, granulocytic and megakaryocytic hyperplasia, clustering of dyspoietic megakaryocytes, no erythroid or myeloid dysplasia and minimal patchy reticulin fibrosis suggestive of primary MPN. Chromosome analysis showed normal karyotype of 46 XY. Molecular studies were negative for BCR-ABL, JAK-2 V617F, CALR and MPL, Next Generation Sequencing revealed mutations in the CSF3R gene (Q781* and T618I) and concurrent inactivating ASXL1-G646fs*12 and activating U2AF1-Q157P mutations. These findings were compatible with a diagnosis of CNL. We describe an unusual case of CNL confirmed by CSF3R gene mutations (T618I and Q781*) with significant thrombocytosis and without splenomegaly. Although the T618I mutation has commonly been reported in CNL, to the best of our knowledge, the Q781* mutation is novel in CNL, and has only been reported before in severe congenital neutropenia (SCN). Association of Q781* mutation in CSF3R gene with significant thrombocytosis in our patient needs further investigation. Disclosures No relevant conflicts of interest to declare.

Oncogenic SETBP1 Mutations Combine with Activating Mutations in CSF3R to Produce a Highly Proliferative, Lethal Leukemia through Aberrant Myc Signaling

SETBP1 (SET Binding Protein 1) mutations are associated with exceptionally poor prognosis in myeloid neoplasms. Despite this, SETBP1's role in oncogenesis remains incompletely understood. In this study, we find that SETBP1 leads to a marked upregulation of the Myc oncogene and associated pro-stem and progenitor programs through epigenetic dysregulation. We further identify an epigenetic modulatory drug that normalizes SETBP1-driven Myc overexpression and synergizes with disease-relevant therapy. SETBP1 has documented roles in both the regulation of tumor suppressor pathways and modulation of transcription. To understand how SETBP1 modulates leukemia biology and leverage this mechanistic insight to develop novel therapeutic strategies, we turned to a genetically well-defined model system, chronic neutrophilic leukemia (CNL). SETBP1 is mutated in approximately half of all cases of CNL, a myeloproliferative neoplasm characterized by the presence of signaling-activating mutations in Colony Stimulating Factor 3 Receptor (CSF3R). By expressing SETBP1 and CSF3R mutations in mouse hematopoietic progenitors, we have generated models of CNL that can be leveraged for mechanistic studies and drug development. In a hematopoietic colony forming unit (CFU) assay, murine hematopoietic progenitors co-expressing mutant SETBP1 and mutant CSF3R have a high proliferation phenotype compared to those with mutant CSF3R alone. When cells co-expressing mutant SETBP1 and CSF3R are transplanted into lethally irradiated mice, they develop a rapidly lethal disease relative to the control mice. This is associated with an expansion of the granulocyte lineage, quantified by complete blood count, flow cytometry and histology. We find that SETBP1 is essential for the induction of a pro-proliferative transcriptional program. One of the most prominent SETBP1-associated signatures is that of Myc target genes. Myc itself is one of the top differentially expressed genes driven by SETBP1. Congruent with its increased expression, we also find higher Myc transcriptional activity in cells overexpressing SETBP1. To better understand the epigenetic regulation of Myc and progenitor pathways by SETBP1, we employed a low input profiling methods called CUT&Tag to assess the activation of regulatory elements. We began by profiling two epigenetic marks associated with active enhancers-H3K4me1 and H3K27Ac. We also assessed activation of the Myc promoter by measuring H3K27Ac and H3K4me3. Together this data helps us to understand the epigenetic underpinnings for dysregulation of Myc-driven programs by SETBP1. Therapeutic strategies that normalize aberrant Myc activity may be effective against SETBP1-driven disease. We found that SETBP1 and CSF3R transformed hematopoietic progenitors are highly sensitive to inhibitors of the epigenetic regulator lysine specific demethylase 1 (LSD1). LSD1 inhibition restores Myc expression to physiological levels and represses Myc promotor activity in vitro. Furthermore, LSD1 inhibitors are highly synergistic with JAK inhibitors, which block signaling downstream of CSF3R. Together these data establish the importance of Myc activation in SETBP1-driven malignancies and identify a therapeutic approach to normalize aberrant Myc activity. In future, we will use the insight gained in this genetically well defined disease to inform studies on the mechanistic basis and therapeutic vulnerabilities of other SETBP1-mutant myeloid malignancies. Disclosures Maxson: Gilead Sciences: Research Funding; Ionis Pharmaceuticals: Other: Joint oversight committee for a collaboration between OHSU and Ionis Pharmaceuticals.

Chronic Neutrophilic Leukemia - Stem Cell Transplantation in a Very Young Patient

Background: Chronic neutrophilic leukemia (CNL) is a rare BCR/ABL negative myeloproliferative neoplasm (MPN) characterized by sustained, predominantly mature neutrophil proliferation, bone marrow granulocytic hyperplasia, and hepatosplenomegaly. CSF3R mutation is a central diagnostic criterion. Most patients are over the age of 60 and the median survival is estimated at 2 years. No effective standard therapy has been established yet. Case-report: In March 2019 a 29 y/o male presented with cough, arthralgias, and hepatosplenomegaly. His initial WBC was 47.000/µl with 80% neutrophils, few neutrophil progenitors, no monocytosis. Bone marrow was consistent with a myeloproliferative syndrome, particularly CML, however BCR/ABL was negative. Flow cytometry suggested a myelodysplastic syndrome (MDS Score ↑) und with the preliminary diagnosis of mixed MPN/MDS he received one course of azacytidine without response. After this course we received the results of molecular genetic analysis which showed CSF3R c.1853C>T (also pos. for DNMT3A, IDH2, neg. for JAK2, CALR, PDGFRα/β, FGFR1). WBC increased further to 77.000/µl and we initiated hydroxyurea and - after insurance granted coverage - switched to ruxolitinib (initially 10 mg BID, then 15 mg BID). His hepatosplenomegaly responded and WBC came down slowly. In August he started to lose response, WBC rose again, and he needed blood transfusions. Because of his young age we had planned stem cell transplantation from the very beginning. The main purpose of ruxolitinib had been to reduce pre-transplant leukemic burden. Bone marrow from March 2019 showed 2% CD34+ cells, in Sept. 4%, Jan 2020 20-25%, consistent with transformation to AML. There was no family donor. In March 2020 he underwent allogeneic stem cell transplantation from a matched female unrelated donor (MUD allo-SCT 10/10 match) which he tolerated well. Conditioning was busulfan based. His further clinical course was complicated starting d+40 after SZT with °IV gastrointestinal GvHD (no CMV or other infectious agent identified). Immunosuppression had to be escalated using steroids (1 mg/kg BW BID) + ruxolitinib + photopheresis. Eventually AML recurred and the patient deceased on d +81 due to multi organ failure induced by refractory GvHD and AML recurrence. Conclusion: As most described cases of CNL occur in elderly patients reports on stem cell transplantation are rare. Here we present the course of a 29 y/o male who had only a short response to ruxolitinib and hydroxyurea. Both agents did not alter the bone marrow leukemic burden, therefore he proceeded to alloSCT. He did not achieve a sustained remission. We decided to present this case despite the unfortunate outcome because - to our knowledge - there has been no prior report on alloSCT in such a young patient with CNL. Disclosures Matzdorff: Novartis Oncology: Consultancy, Other: Honoraria paid to institution; Amgen GmbH: Consultancy, Other: Honoraria paid to institution; Grifols Deutschland GmbH: Consultancy, Other: Honoraria paid to institution; Swedish Orphan Biovitrium GmbH: Consultancy, Other: Honoraria paid to institution; UCB Biopharma SRL: Consultancy, Other: Honoraria paid to institution; Roche Pharma AG: Other: Family stockownership.

The Colony-Stimulating Factor 3 Receptor M696T Mutated in a Patient with Ph+ Acute Lymphoblastic Leukemia

Purpose: Colony-stimulating factor 3 receptor (CSF3R) mutations have been identified in a variety of myeloid disorders, such as severe congenital neutropenia (SCN), chronic neutrophilic leukemia (CNL), myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and atypical chronic myelogenous leukemia (aCML). Although CSF3R point mutations (e.g., T618I) are emerging as key players in CNL/aCML, the significance of rarer CSF3R mutations is unknown. We report a case of philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ ALL) with the M696T mutation in CSF3R gene and assess the pathogenicity of the CSF3R M696T mutation in Ph+ ALL. Experimental Design: Here we report on a 32-year-old female who presented with asthenia. The initial hematological workup revealed white blood cell (WBC) count of 97 x 109/L (normal range 4-10 x 109/L). There was 84% prolymphocyte in the bone marrow. The immunophenotype of the blasts as judged from flow cytometry was in accordance with a B-ALL. The fusion gene for BCR-ABL P210 was positive. Hot mutation closely related to diseases was: CSF3R (nucleotide change c.2087 T>C, amino acid change p.M696T, mutation frequency 50.4%). Cytogenetic analysis showed 46, XX, t (9;22) (q34;q11). The patient was diagnosed as Ph+ ALL with the CSF3R M696T mutation and achieved Long-term survival after unrelated donor hematopoietic stem cell transplantation. Meanwhile we performed a series of experiments using murine interleukin 3 (IL-3)-dependent Ba/F3 cell line to evaluate the transforming capacity of the CSF3R M696T mutation. The phosphorylation of STAT3 was analyzed by G-CSF dependence assays and immunoblot analysis to evaluate the CSF3R M696T mutation contribution to the tumor transformation ability of Ba/F3 cells. Results: This patient achieved complete remission with chemotherapy in combination with tyrosine kinase inhibitor (TKI) and long-term survival by unrelated donor transplantation. We confirmed the presence of a CSF3R M696T germline mutation in this patient, and the mutation was inherited from her mother. The experiments in vitro result showed the CSF3R M696T mutation harbors marginal contribution to the tumor transformation ability of Ba/F3 cells. CSF3R M696T mutation was neutral in tumor transformation ability. Conclusions: We believe that TKI is still effective in patients with the CSF3R M696T mutation in Ph+ ALL. Donor with CSF3R M696T mutation might still be selected. Disclosures No relevant conflicts of interest to declare.

Implementation of Flow Cytometric Monocyte Repartition Assay for Assessment of Chronic Myelomonocytic Leukaemia (CMML) in Bone Marrow

Background: CMML is a myelodysplastic/myeloproliferative overlap syndrome associated with persistent monocytosis. Previous studies have shown a characteristic phenotype of peripheral blood (PB) monocytes in CMML that may have diagnostic utility. There is expansion of the classical monocyte (Mo1) population (CD14+CD16-) with concomitant reduction in the intermediate (Mo2; CD14+16+) and non-classical (Mo3; CD14-16+) populations. It is unclear whether an increased Mo1 population or a reduced Mo2/Mo3 population is a better discriminator in detecting CMML by flow cytometry. Diagnostic thresholds for these populations have most often been established by comparison with normal donors using PB samples. The objective of this study was to determine the optimal cut-off limits for flow cytometric monocyte repartition (FMR) in bone marrow (BM) samples and to assess the diagnostic accuracy of this method in patients undergoing BM evaluation for other causes of monocytosis using a novel gating strategy. Patients/Methods: 71 BM aspirates were analysed comprising 35 confirmed CMML (21 proliferative CMML , 14 dysplastic CMML), 13 other myeloid neoplasm (MN) disease controls and 23 normal bone marrow aspirates. The MN cohort was identified through local samples with a known peripheral blood monocytosis of ≥1.0x109 and peripheral blast count of <20% not fulfilling criteria for CMML. The MN cohort comprised of 4 cases of chronic myeloid leukaemia (CML), 2 cases of myelodysplasia/myeloproliferative neoplasm unspecified (MDS/MPN-U), two cases of atypical CML (aCML), 2 cases of primary myelofibrosis, 1 case of juvenile myelomonocytic leukaemia (JMML), 1 case of chronic neutrophilic leukaemia (CNL) and 1 case of therapy-related acute myeloid leukaemia (T-AML). The median age of CMML patients within our cohort was 74 years (range 44- 89 years) and 77% were male. Stored flow cytometric data were reanalysed to assess monocyte subsets. After initial removal of doublets and non-cellular events, sequential gating selected a CD45+CD33bright population with low side scatter to select monocytes and exclude granulocytes. The lymphocyte gate as determined on the CD45 vs CD33 plot was used to establish a threshold for CD16 positivity. Immature double negative monocytes (CD14-CD16-) were excluded as in published gating strategies. Results: Linear regression analysis of the percentage of both the Mo1 and Mo2 populations demonstrated a significant difference between the CMML, MN, and normal cohorts (global P<0.0001). Post hoc analysis demonstrated a significant increase in the Mo1% fraction (mean 92.5%; 95% Confidence Interval [CI]: 88.1%, 96.9%) in CMML cases when compared to the normal BM cohort (mean 63.5%; 95% CI: 58.1%, 69.0%; comparison P <0.0001) and the MN cohort (mean 79.9%; 95% CI: 72.7%,87.2%; comparison P = 0.004). Conversely, the Mo2% was significantly decreased (mean 6.8% 95% CI: 2.7%, 10.9%) in CMML cases when compared to the normal cohort (mean 33.0%; 95% CI: 27.9%; 38.1%; comparison P value <0.0001) and the MN cohort (mean 17.6%; 95% CI 10.8%; 24.3%; comparison P value 0.008). Receiver Operator Curve (ROC) curve analysis of the Mo1 population demonstrated an area under the curve (AUC) of 0.8738 (95% CI: 0.7897, 0.9579; P<0.0001) with a marginally lower AUC for Mo2% (Figure 1A). Priority was given to selecting a cut-off value with higher specificity, considering that the BM examination is not a screening test. A cut-off value for Mo1% of >88.5% (Figure 1B) gave a sensitivity of 77.1% (95% CI: 60.98%, 87.93%) and specificity of 88.9% (95% CI: 74.69%, 95.59%) (Figure 1A). A Mo2% cut-off value of <12.25% (Figure 1C) gave a sensitivity of 78.8% (95% CI: 62.25%, 89.32%) with a specificity of 80.6% (95% CI: 64.97%, 90.25%) (Figure 1A). Eight patients with CMML were misclassified by the Mo1/Mo2 criteria. Conclusion: Our study confirms that analysis of monocyte subsets on BM samples provides good discrimination of CMML cases when compared to normal controls. There was significant overlap with other MN samples. FMR may be a useful adjunct to BM morphology in cases with subtle dysplasia. Further study is required to understand the overlap in monocyte phenotype between CMML and other myeloid neoplasms. Disclosures Allen: Amgen: Other: Travel Support; Roche: Other: Travel Support; Novartis: Other: Travel Support. Hahn:Roche: Honoraria; Astra Zeneca: Honoraria.

Heterozygous germ line CSF3R variants as risk alleles for development of hematologic malignancies

AbstractColony-stimulating factor 3 receptor (CSF3R) encodes the receptor for granulocyte colony-stimulating factor (G-CSF), a cytokine vital for granulocyte proliferation and differentiation. Acquired activating heterozygous variants in CSF3R are the main cause of chronic neutrophilic leukemia, a hyperproliferative disorder. In contrast, biallelic germ line hypomorphic variants in CSF3R are a rare cause of severe congenital neutropenia, a hypoproliferative condition. The impact of heterozygous germ line CSF3R variants, however, is unknown. We identified CSF3R as a new germ line hematologic malignancy predisposition gene through analysis of 832 next-generation sequencing tests conducted in 632 patients with hematologic malignancies. Among germ line CSF3R variants, 3 were abnormal in functional testing, indicating their deleterious nature. p.Trp547* was identified in 2 unrelated men with myelodysplastic syndromes diagnosed at 76 and 33 years of age, respectively. p.Trp547* is a loss-of-function nonsense variant in the extracellular domain that results in decreased CSF3R messenger RNA expression and abrogation of CSF3R surface expression and proliferative responses to G-CSF. p.Ala119Thr is a missense variant found in 2 patients with multiple myeloma and acute lymphoblastic leukemia, respectively. This variant is located between the extracellular immunoglobulin-like and cytokine receptor homology domains and results in decreased G-CSF sensitivity. p.Pro784Thr was identified in a 67-year-old man with multiple myeloma. p.Pro784Thr is a missense variant in the cytoplasmic domain that inhibits CSF3R internalization, producing a gain-of-function phenotype and G-CSF hypersensitivity. Our findings identify germ line heterozygous CSF3R variants as risk factors for development of myeloid and lymphoid malignancies.

Update on CML-Like Disorders

Chronic myeloid leukemia (CML) is defined for many years as BCR-ABL1 positive disease, but older publications refer to a poor prognosis, clinically heterogeneous entity termed ‘BCR-ABL1 negative CML’ constituting about 5% of CML cases. Apart from very rare CML cases with cytogenetically cryptic, atypical variant BCR-ABL1 fusions that had been inadvertently missed during the diagnostic work up, most of these cases would now be classified as a subtype of myelodysplastic/myeloproliferative neoplasm (MDS/MPN), such as atypical CML (aCML), chronic myelomonocytic leukemia (CMML), or chronic neutrophilic leukemia (CNL). A minority would be classified as systemic mastocytosis with associated hematological neoplasm (SM-AHN), myeloid/lymphoid neoplasms associated with eosinophilia and rearrangement of PDGFRA, PDGFRB, FGFR1 or with PCM1-JAK2 (MLN-eo), or chronic eosinophilic leukemia not otherwise specified (CEL-NOS).1

Pathological studies of chronic neutrophilic leukaemia involving skin

目的： 探讨慢性中性粒细胞白血病累及皮肤的临床病理学特点。 方法： 收集1例慢性中性粒细胞白血病患者的临床资料，描述其皮肤斑块的大体和镜下形态学特点、聚合酶链反应（PCR）法检测集落刺激因子3受体T618I突变情况。 结果： 本例为62岁男性患者，反复白细胞升高5年，骨髓及血细胞形态学检查显示以中、晚、杆状、分叶核粒细胞为主，BCR-ABL融合基因为阴性。晚期出现皮肤斑块和皮疹。镜下见真皮内大量成熟分叶核中性粒细胞浸润伴核碎裂，未见围皮肤附件分布表现，未侵犯毛囊、皮脂腺等皮肤附件。皮肤标本检测到集落刺激因子3受体T618I突变，进一步证实这些貌似正常的中性粒细胞为肿瘤性病变。 结论： 慢性中性粒细胞白血病极其罕见，多在血液科诊断，本例因病变累及皮肤而偶然为病理医师所见，在临床病史不明的情况下极易漏诊、误诊，希望能引起病理医师的关注和重视。.