JAK2V617F-dependent down regulation of SHP-1 expression participates in the selection of myeloproliferative neoplasm cells in the presence of TGF-ß.

Myeloproliferative neoplasms (MPNs) are characterized by an increased production of blood cells due to the acquisition of mutations such as JAK2V617F. TGF-ß, whose secretion is increased in MPN patients, is known to negatively regulate haematopoietic stem cell (HSC) proliferation. Using an isogenic JAK2V617F or JAK2 wild-type UT-7 cell line we observed that JAK2V617F cells resist to TGF-ß antiproliferative activity. Although TGF-ß receptors and SMAD2/3 expressions are similar in both cell types, TGF-ß-induced phosphorylation of SMAD2/3 is reduced in UT-7 JAK2V617F cells compared with JAK2 WT cells. We confirmed that JAK2V617F mutated cells are resistant to the antiproliferative effect of TGF-ß in a competitive assay as we observed a positive selection of JAK2V617F cells when exposed to TGF-ß. Using cell lines, CD34-positive cells from MPN patients and bone marrow cells from JAK2V617F knock-in mice we identified a down regulation of the SHP-1 phosphatase, which is required for the regulation of HSC quiescence by TGF-ß. The transduction of SHP-1 cDNA (but not a phosphatase inactive cDNA) restores the antiproliferative effect of TGF-ß in JAK2V617F mutated cells. Finally, SC-1, a known agonist of SHP-1, antagonized the selection of JAK2V617F mutated cells in the presence of TGF-ß. In conclusion, we show a JAK2-dependent down regulation of SHP-1 in MPN patients' cells which is related to their resistance to the antiproliferative effect of TGF-ß. This may participate in the clonal selection of cancer cells in MPNs.

Comparative clinical and molecular landscape of primary and secondary myelofibrosis: Superior performance of MIPSS70+ v2.0 over MYSEC-PM.

Comparative clinical characteristics, molecular landscape and prognosis scoring for primary (PMF) and secondary myelofibrosis (SMF).

Reduced murine double minute 2 and 4 protein, but not messenger RNA, expression is associated with more severe disease in myelodysplastic syndromes and acute myeloblastic leukaemia.

The human homologues of murine double minute 2 (MDM2) and 4 (MDM4) negatively regulate p53 tumour suppressor activity and are reported to be frequently overexpressed in human malignancies, prompting clinical trials with drugs that prevent interactions between MDM2/MDM4 and p53. Bone marrow samples from 111 patients with acute myeloblastic leukaemia, myelodysplastic syndrome or chronic myelomonocytic leukaemia were examined for protein (fluorescence-activated cell sorting) and messenger RNA (mRNA) expression (quantitative polymerase chain reaction) of MDM2, MDM4 and tumour protein p53 (TP53). Low protein expression of MDM2 and MDM4 was observed in immature cells from patients with excess of marrow blasts (>5%) compared with CD34+ /CD45low cells from healthy donors and patients without excess of marrow blasts (<5%). The mRNA levels were indistinguishable in all samples examined regardless of disease status or blast levels. Low MDM2 and MDM4 protein expression were correlated with poor survival. These data show a poor correlation between mRNA and protein expression levels, suggesting that quantitative flow cytometry analysis of protein expression levels should be used to predict and validate the efficacy of MDM2 and MDM4 inhibitors. These findings show that advanced disease is associated with reduced MDM2 and MDM4 protein expression and indicate that the utility of MDM2 and MDM4 inhibitors may have to be reconsidered in the treatment of advanced myeloid malignancies.

Dasatinib plus Peg-Interferon alpha 2b combination in newly diagnosed chronic phase chronic myeloid leukaemia: Results of a multicenter phase 2 study (DASA-PegIFN study).

Superior rates of deep molecular response (DMR) have been reported with the combination of tyrosine kinase inhibitors and pegylated-interferon-alpha (Peg-IFN) in patients with newly diagnosed chronic phase-chronic myeloid leukaemia (CP-CML). In this setting, this study investigated the efficacy and safety of dasatinib combined to Peg-IFN-α2b (Dasa-PegIFN, NCT01872442). A total of 79 patients (age ≤65 years) started dasatinib; 61 were eligible for Peg-IFNα-2b add-on therapy at month 3 for a maximum 21-months duration. Dasatinib was continued thereafter. The primary endpoint was the cumulative rate of molecular response 4.5 log (MR4.5 ) by 12 months. The results are reported for the 5-year duration of the study. Grade 3 neutropenia was frequent with the combination but did not induce severe infection (one of grade 3). Other adverse events were generally low grade (4% of grade 3-4) and expected. Seventy-nine per cent and 61% of patients continued the Peg-IFN until months 12 and 24, respectively. Overall, at these time points, MR4.5 rates were 25% and 38%, respectively. Thereafter, 32% and 46% of patients achieved a sustained (≥2 years) MR4.5 or MR4 , respectively. This work established the feasibility and high rates of achievement of early and sustained DMR (a prerequisite for treatment-free-remission) with dasatinib and Peg-IFNα-2b combination as initial therapy.

p53 activation during ribosome biogenesis regulates normal erythroid differentiation.

The role of ribosome biogenesis in erythroid development is supported by the recognition of erythroid defects in ribosomopathies in both Diamond-Blackfan anemia and 5q- syndrome. Whether ribosome biogenesis exerts a regulatory function on normal erythroid development is still unknown. In the present study, a detailed characterization of ribosome biogenesis dynamics during human and murine erythropoiesis showed that ribosome biogenesis is abruptly interrupted by the decline in ribosomal DNA transcription and the collapse of ribosomal protein neosynthesis. Its premature arrest by the RNA Pol I inhibitor CX-5461 targeted the proliferation of immature erythroblasts. p53 was activated spontaneously or in response to CX-5461, concomitant to ribosome biogenesis arrest, and drove a transcriptional program in which genes involved in cell cycle-arrested, negative regulation of apoptosis, and DNA damage response were upregulated. RNA Pol I transcriptional stress resulted in nucleolar disruption and activation of the ATR-CHK1-p53 pathway. Our results imply that the timing of ribosome biogenesis extinction and p53 activation is crucial for erythroid development. In ribosomopathies in which ribosome availability is altered by unbalanced production of ribosomal proteins, the threshold downregulation of ribosome biogenesis could be prematurely reached and, together with pathological p53 activation, prevents a normal expansion of erythroid progenitors.

Revisiting Diagnostic performances of serum erythropoïetin level and JAK2 mutation for polycythemias: analysis of a cohort of 1090 patients with red cell mass measurement.

We assessed the diagnostic performances of erythropoietin and JAK2 mutations in 1,090 patients with suspected polycythemia who were referred for red cell mass (RCM) measurement. In patients with a high haematocrit and/or haemoglobin level, a low erythropoietin level (<=3·3 mUI/ml) and JAK2 mutation showed comparable positive predictive value (PPV) for true polycythemia (RCM>=125%), 92·1% and 90% respectively. A very-low erythropoietin level (<=1·99 mUI/ml) had a PPV of 100% for polycythemia vera (PV) diagnosis. We confirmed the correlations between RCM, erythropoietin and JAK2 variant allelic frequency in PV patients. This study prompts the need to revisit the role of EPO in PV diagnostic criteria.

Insights into the Potential Mechanisms of JAK2V617F Somatic Mutation Contributing Distinct Phenotypes in Myeloproliferative Neoplasms.

Myeloproliferative neoplasms (MPN) are a group of blood cancers in which the bone marrow (BM) produces an overabundance of erythrocyte, white blood cells, or platelets. Philadelphia chromosome-negative MPN has three subtypes, including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The over proliferation of blood cells is often associated with somatic mutations, such as JAK2, CALR, and MPL. JAK2V617F is present in 95% of PV and 50-60% of ET and PMF. Based on current molecular dynamics simulations of full JAK2 and the crystal structure of individual domains, it suggests that JAK2 maintains basal activity through self-inhibition, whereas other domains and linkers directly/indirectly enhance this self-inhibited state. Nevertheless, the JAK2V617F mutation is not the only determinant of MPN phenotype, as many normal individuals carry the JAK2V617F mutation without a disease phenotype. Here we review the major MPN phenotypes, JAK-STAT pathways, and mechanisms of development based on structural biology, while also describing the impact of other contributing factors such as gene mutation allele burden, JAK-STAT-related signaling pathways, epigenetic modifications, immune responses, and lifestyle on different MPN phenotypes. The cross-linking of these elements constitutes a complex network of interactions and generates differences in individual and cellular contexts that determine the phenotypic development of MPN.

Should Transplantation Still Be Considered for Ph1-Negative Myeloproliferative Neoplasms in Transformation?

BCR-ABL-negative myeloproliferative neoplasms (MPNs) in transformation have a dismal prognosis, and allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered the sole curative therapeutic option. We retrospectively analyzed 53 molecularly annotated patients treated at Saint Louis Hospital, Paris, diagnosed with MPN in transformation between 2008 and 2018. The median patient age was 65 years, and the median interval between MPN diagnosis and MPN transformation was 46 months. The median overall survival (OS) of the entire cohort after transformation was 7.1 months. OS was better for patients treated with hypomethylating agents (HMAs) or with chemotherapy compared than for those treated by best supportive care or single-agent targeted therapy (median, 9.1 months versus 1.5 months; P < .001). Patients treated with chemotherapy more often achieved complete remission compared with those treated with HMAs (68% versus 29%; P = .02), and were more often candidates for transplantation (59% versus 14%; P = .02), but the median OS was similar in the 2 groups. We then compared the outcomes in transplant recipients and nonrecipients using the Mantel-Byar methodology and found that allo-HSCT did not improve survival. In multivariate analysis, independent factors in prognosis were performance status at transformation (P < .01), initial treatment with HMAs or chemotherapy (P = .02), and the ability to achieve complete remission during follow-up (P < .01). Our data demonstrate that the indication for allo-HSCT for high-risk MPN should be discussed before transformation, because transplantation rescues few patients after transformation.

Synergistic effects of PRIMA-1Met (APR-246) and 5-azacitidine in TP53-mutated myelodysplastic syndromes and acute myeloid leukemia.

Myelodysplastic syndromes and acute myeloid leukemia with TP53 mutations are characterized by frequent relapses, poor or short responses, and poor survival with the currently available therapies including chemotherapy and 5-azacitidine (AZA). PRIMA-1Met(APR-246,APR) is a methylated derivative of PRIMA-1, which induces apoptosis in human tumor cells through restoration of the transcriptional transactivation function of mutant p53. Here we show that low doses of APR on its own or in combination with AZA reactivate the p53 pathway and induce an apoptosis program. Functionally, we demonstrate that APR exerts these activities on its own and that it synergizes with AZA in TP53-mutated myelodysplastic syndromes (MDS)/acute myeloid leukemia (AML) cell lines and in TP53-mutated primary cells from MDS/AML patients. Low doses of APR on its own or in combination with AZA also show significant efficacy in vivo Lastly, using transcriptomic analysis, we found that the APR + AZA synergy was mediated by downregulation of the FLT3 pathway in drug-treated cells. Activation of the FLT3 pathway by FLT3 ligand reversed the inhibition of cell proliferation by APR + AZA. These data suggest that TP53-mutated MDS/AML may be better targeted by the addition of APR-246 to conventional treatments.

Longer treatment duration and history of osteoarticular symptoms predispose to tyrosine kinase inhibitor withdrawal syndrome.

The effectiveness of tyrosine kinase inhibitors (TKIs) has made it possible to consider treatment discontinuation in chronic myeloid leukaemia (CML) patients that achieve an excellent response. However, a few of the patients included in the Europe Stop Tyrosine Kinase Inhibitors (EURO-SKI) trial reported musculoskeletal pain shortly after stopping TKIs, considered as a withdrawal syndrome (WS). To identify factors that may predispose to TKI WS, we analysed the pharmacovigilance declarations for the 6 months after stopping TKIs in a large cohort of CML (n = 427) that combined the French patients included in the STop IMatinib 2 (STIM2; n = 224) and EURO-SKI (n = 203) trials. Among these patients, 23% (99/427) developed TKI WS after stopping imatinib (77/373; 20·4%), nilotinib (12/29; 41·4%) or dasatinib (10/25; 40%). WS concerned mainly the upper body joints, and required multiple symptomatic treatments in 30% of patients. Univariate and multivariate analyses identified two risk factors: duration of TKI treatment [risk ratio (RR) = 1·68 (1·02-2·74)] with a 93-month cut-off time, and history of osteoarticular symptoms [RR = 1·84 (1·04-3·28)]. These findings confirm that WS is a TKI class effect. CML patients should be carefully screened before treatment initiation to identify pre-existent osteoarticular symptoms. Moreover, before TKI discontinuation, patients should be informed of the possibility of WS, particularly after a long treatment period.

Next-generation sequencing for JAK2 mutation testing: advantages and pitfalls.

The JAK2V617F mutation is part of the major criteria for diagnosis of myeloproliferative neoplasms (MPN). Allele-specific quantitative PCR (qPCR) is the most prevalent method used in laboratories but with the advent of next-generation sequencing (NGS) techniques, we felt necessary to evaluate this approach for JAK2 mutations testing. Among DNA samples from 427 patients analyzed by qPCR and NGS, we found an excellent concordance between both methods when allelic burden was superior to 2% (the detection limit of our NGS assay). Only one sample among 298 was found negative by NGS while allelic burden by qPCR was 3%. Because NGS detection limit is higher, sensitivity was lower as exemplified by 21 samples found negative whereas qPCR measured allelic burdens between 0.1 and 1%. Importantly, quantitative data of samples found positive by both techniques were highly correlated (R2 = 0.9477). We also evaluated 40 samples tested for JAK2 exon 12 mutations by HRM. The concordance with NGS was of 100%. Using NGS, the full coding region of JAK2 was analyzed leading to identification of several variants outside of exon 12 and 14 which were previously described or not. Interestingly, we found one somatic mutation (c.1034A>T p.H345L) which induced constitutive activation of the JAK/STAT pathway leading to an increased proliferation of BaF/3 cells with low-dose EPO. This study showed that NGS is a robust method highly correlated to qPCR, although less sensitive, but providing the opportunity to identify other JAK2 variants with potential impact on disease initiation or evolution.

Non-adherence to treatment with cytoreductive and/or antithrombotic drugs is frequent and associated with an increased risk of complications in patients with polycythemia vera or essential thrombocythemia (OUEST study).

The purpose of this study was to identify the incidence, causes and impact of non-adherence to oral and subcutaneous chronic treatments for patients with polycythemia vera or essential thrombocythemia. Patients receiving cytoreductive drugs for polycythemia vera or essential thrombocythemia were recruited at our institution (Observatoire Brestois des Néoplasies Myéloprolifératives registry). They completed a one-shot questionnaire designed by investigators (Etude de l'Observance Thérapeutique et des Effets Secondaires des Traitements study). Data about complications (thrombosis, transformation and death) at any time in the patient's life (before diagnosis, up until consultation and after the completion of the questionnaire) were collected. Sixty-five (22.7%) of 286 patients reported poor adherence (<90%) to their treatment with cytoreductive drugs and 46/255/18%) also declared non-adherence to antithrombotic drugs. In total, 85/286 patients (29.7%) declared they did not adhere to their treatment. Missing an intake was rare and was mostly due to forgetfulness especially during occupational travel and holidays. Patients who did not adhere to their treatment were characterized by younger age, living alone, having few medications but a high numbers of pills and determining their own schedule of drug intake. Having experienced thrombosis or hematologic evolution did not influence the adherence rate. Non-adherence to oral therapy was associated with a higher risk of phenotypic evolution (7.3 versus 1.8%, P=0.05). For patients treated for polycythemia vera or essential thrombocythemia, non-adherence to cytoreductive and/or antithrombotic therapies is frequent and is influenced by age, habitus and concomitant treatments, but not by disease history or treatment side effects. Phenotypic evolution seems to be more frequent in the non-adherent group.

Emergence of MPLW515 mutation in a patient with CALR deletion: Evidence of secondary acquisition of MPL mutation in the CALR clone.

Myeloproliferative neoplasms are characterized by transduction pathway recognized as mutually exclusive molecular abnormalities such as BCR-ABL translocation, JAK2V617F or JAK2 exon 12 mutations, MPL w515, and CALR mutations. However, in some rare cases, associations of such mutations are found in 1 patient. This can be related to 2 pathologies (at least 2 different clones harboring 2 mutations) or associated mutations in 1 clone. We describe here such an association of CALR and MPL mutations in a patient harboring the second mutation in a subclone during the phenotypic evolution of the myeloproliferative neoplasms.

Second tyrosine kinase inhibitor discontinuation attempt in patients with chronic myeloid leukemia.

BACKGROUND: Several studies have demonstrated that approximately one-half of patients with chronic myeloid leukemia (CML) who receive treatment with tyrosine kinase inhibitors (TKIs) and achieve and maintain a deep molecular response (DMR) are able to successfully discontinue therapy. In patients who have a molecular relapse, a DMR is rapidly regained upon treatment re-initiation. METHODS: The authors report the results from RE-STIM, a French observational, multicenter study that evaluated treatment-free remission (TFR) in 70 patients who re-attempted TKI discontinuation after a first unsuccessful attempt. After the second TKI discontinuation attempt, the trigger for treatment re-introduction was the loss of a major molecular response in all patients. RESULTS: The median follow-up was 38.3 months (range, 4.7-117 months), and 45 patients (64.3%) lost a major molecular response after a median time off therapy of 5.3 months (range, 2-42 months). TFR rates at 12, 24, and 36 months were 48% (95% confidence interval [CI], 37.6%-61.5%), 42% (95% CI, 31.5%-55.4%), and 35% (95% CI, 24.4%-49.4%), respectively. No progression toward advanced-phase CML occurred, and no efficacy issue was observed upon TKI re-introduction. In univariate analysis, the speed of molecular relapse after the first TKI discontinuation attempt was the only factor significantly associated with outcome. The TFR rate at 24 months was 72% (95% CI, 48.8%-100%) in patients who remained in DMR within the first 3 months after the first TKI discontinuation and 36% (95% CI, 25.8%-51.3%) for others. CONCLUSIONS: This study is the first to demonstrate that a second TKI discontinuation attempt is safe and that a first failed attempt at discontinuing TKI does not preclude a second successful attempt. Cancer 2017;123:4403-10. © 2017 American Cancer Society.

Clinical and molecular response to interferon-α therapy in essential thrombocythemia patients with CALR mutations.

Myeloproliferative neoplasms are clonal disorders characterized by the presence of several gene mutations associated with particular hematologic parameters, clinical evolution, and prognosis. Few therapeutic options are available, among which interferon α (IFNα) presents interesting properties like the ability to induce hematologic responses (HRs) and molecular responses (MRs) in patients with JAK2 mutation. We report on the response to IFNα therapy in a cohort of 31 essential thrombocythemia (ET) patients with CALR mutations (mean follow-up of 11.8 years). HR was achieved in all patients. Median CALR mutant allelic burden (%CALR) significantly decreased from 41% at baseline to 26% after treatment, and 2 patients even achieved complete MR. In contrast, %CALR was not significantly modified in ET patients treated with hydroxyurea or aspirin only. Next-generation sequencing identified additional mutations in 6 patients (affecting TET2, ASXL1, IDH2, and TP53 genes). The presence of additional mutations was associated with poorer MR on CALR mutant clones, with only minor or no MRs in this subset of patients. Analysis of the evolution of the different variant allele frequencies showed that the mutated clones had a differential sensitivity to IFNα in a given patient, but no new mutation emerged during treatment. In all, this study shows that IFNα induces high rates of HRs and MRs in CALR-mutated ET, and that the presence of additional nondriver mutations may influence the MR to therapy.

Lack of Transcription Factor p53 Exacerbates Elastase-Induced Emphysema in Mice.

The transcription factor p53 is overexpressed in the lung of patients with emphysema, but it remains unclear if it has a deleterious or protective effect in disease progression. We investigated the role of p53 in the elastase-induced emphysema model and the molecular underlining mechanisms. Wild-type (WT) and p53(-/-) mice were instilled with pancreatic porcine elastase. We quantified emphysema (morphometric analysis), chemokine (C-C motif) ligand 2 (CCL2), and TNF-α in bronchoalveolar lavage (BAL) (ELISA), oxidative stress markers [heme oxygenase 1 (HO1), NAD(P)H dehydrogenase quinone 1 (NQO1), and quantitative RT-PCR], matrix metalloproteinase 12 (MMP12) expression, and macrophage apoptosis (cleaved caspase-3, immunofluorescence). p53 gene expression was up-regulated in the lung of elastase-instilled mice. p53 deletion aggravated elastase-induced emphysema severity, pulmonary inflammation (macrophage and neutrophil numbers and CCL2 and TNF-α levels in BAL), and lung oxidative stress. These findings, except for the increase in CCL2, were reproduced in WT mice transplanted with p53(-/-) bone marrow cells. The increased number of macrophages in p53(-/-) mice was not a consequence of reduced apoptosis or an excess of chemotaxis toward CCL2. Macrophage expression of MMP12 was higher in p53(-/-) mice compared with WT mice after elastase instillation. These findings provide evidence that p53(-/-) mice and WT mice grafted with p53(-/-) bone marrow cells are more prone to developing elastase-induced emphysema, supporting a protective role of p53, and more precisely p53 expressed in macrophages, against emphysema development. The pivotal role played by macrophages in this phenomenon may involve the MMP12-TNF-α pathway.