Chemo-Enzymatic Fluorescence Labeling Of Genomic DNA For Simultaneous Detection Of Global 5-Methylcytosine And 5-Hydroxymethylcytosine.

5-Methylcytosine and 5-hydroxymethylcytosine are epigenetic modifications involved in gene regulation and cancer. We present a new, simple, and high-throughput platform for multi-color epigenetic analysis. The novelty of our approach is the ability to multiplex methylation and de-methylation signals in the same assay. We utilize an engineered methyltransferase enzyme that recognizes and labels all unmodified CpG sites with a fluorescent cofactor. In combination with the already established labeling of the de-methylation mark 5-hydroxymethylcytosine via enzymatic glycosylation, we obtained a robust platform for simultaneous epigenetic analysis of these marks. We assessed the global epigenetic levels in multiple samples of colorectal cancer and observed a 3.5-fold reduction in 5hmC levels but no change in DNA methylation levels between sick and healthy individuals. We also measured epigenetic modifications in chronic lymphocytic leukemia and observed a decrease in both modification levels (5-hydroxymethylcytosine: whole blood 30 %; peripheral blood mononuclear cells (PBMCs) 40 %. 5-methylcytosine: whole blood 53 %; PBMCs 48 %). Our findings propose using a simple blood test as a viable method for analysis, simplifying sample handling in diagnostics. Importantly, our results highlight the assay's potential for epigenetic evaluation of clinical samples, benefiting research and patient management.

Antiphospholipid antibodies in convalescent plasma of donors recovered from mild COVID-19 infection.

BACKGROUND AND OBJECTIVES: Passive immunization by the infusion of convalescent plasma (CP) obtained from patients who have recently recovered from COVID-19, thus having antibodies to severe acute respiratory syndrome coronavirus 2, is a potential strategy to reduce the severity of illness. A high prevalence of antiphospholipid antibodies (APLA) in patients with COVID-19 has been reported during the pandemic, raising a concern whether the use of CP could increase the risk of thrombosis in transfused patients. We aimed to evaluate the prevalence of APLA in COVID-19 CP (CCP) in order to assess the potential prothrombotic influence of transfused CCP to COVID-19 patients. MATERIALS AND METHODS: We studied the prevalence of APLA in 122 CCP samples collected from healthy donors who recovered from mild-COVID-19 at two time periods: September 2020-January 2021 (defined as 'early period' samples) and April-May 2021 (defined as 'late period' samples). Thirty-four healthy subjects unexposed to COVID-19 were used as controls. RESULTS: APLA were present in 7 of 122 (6%) CCP samples. One donor had anti-ß2-glycoprotein 1(anti-ß2GP1) IgG, one had anti-ß2GP1 IgM and five had lupus anticoagulant (LAC) using silica clotting time (SCT), all in 'late period' donors. In the control group, one subject had anti-ß2GP1 IgG, two had LAC using dilute Russell viper venom time (dRVVT) and four had LAC SCT (both LAC SCT and LAC dRVVT in one subject). CONCLUSION: The low prevalence of APLA in CCP donors reassures the safety of CCP administration to patients with severe COVID-19.

Haematological patients' perception of home transfusions: Effect of the COVID-19 pandemic.

BACKGROUND AND OBJECTIVES: The COVID-19 pandemic has led to a growing interest in hospital-at-home programmes, including home transfusion services. We studied whether the pandemic had influenced patients' perception of home transfusions. MATERIALS AND METHODS: We conducted a survey among haematology patients who receive transfusions in the hospital day care facility. Patients were asked about the burden of day care transfusions and whether they would prefer receiving home transfusions. The survey was conducted during the COVID-19 pandemic, and the results were compared with a survey performed before the pandemic (baseline). RESULTS: Sixty patients were included in the COVID-19 cohort and 31 patients in the baseline cohort. There was a non-significant decrease in the proportion of patients willing to receive home transfusions during the pandemic compared with baseline (35% vs. 47%, respectively, p = 0.28). More patients in the COVID-19 cohort were afraid to receive home transfusions (60% compared with 48% at baseline, p = 0.29), and fewer patients believed that hospital transfusion impaired their quality of life (19% compared with 36% at baseline, p = 0.09). These unexpected results may be partly attributed to the shorter time needed to arrive at the hospital during the pandemic and a greater fear of having transfusion-related adverse effects at home. CONCLUSIONS: Our results show that the pandemic did not increase the willingness of patients to receive home transfusions, with a non-significant drift towards refusal of home transfusions. Patients' opinions should be taken into consideration when planning for future home transfusion services, by creating a comprehensive approach to patients' needs.

Venetoclax combinations induce high response rates in newly diagnosed acute myeloid leukemia patients ineligible for intensive chemotherapy in routine practice.

Combinations of the BCL-2 inhibitor, venetoclax, with either hypomethylating agents (HMA) or low dose cytarabine (LDAC), have shown promising results in clinical trials of AML patients unfit for intensive therapy. We report on the efficacy and safety of venetoclax combinations in AML patients treated outside of clinical trials. Complete remission (CR) + CR with incomplete count recovery (CRi) were achieved in 61% of patients, with similar CR+CRi rates in with secondary AML, and in patients who were previously treated with HMA (61% and 43%, respectively). Relapse occurred in 25% of patients, with a median event-free survival (EFS) of 11.7 months (95% CI, 10.09-13.35) in responding patients. At a median follow up of 8.7 months, the median overall survival (OS) was 9.8 months (95% CI 6.42-13.3) in the entire cohort. In multivariate analysis adverse karyotype was the only negative predictor of CR/CRi (p = .03), while both ECOG performance status (PS) and adverse karyotype were significantly associated with shorter OS (p = .023 and .038, respectively). Median OS was higher in patients achieving CR/CRi and in patients proceeding to allogeneic stem cell transplantation (allo-SCT). Treatment was well tolerated, with side effects similar to those described in the randomized clinical trials. Tumor lysis syndrome (TLS) occurred in 12% of patients. Our data support the efficacy and safety of venetoclax combinations in newly diagnosed AML patients not eligible for intensive therapy. According to our data, secondary AML patients could benefit from venetoclax combinations similarly to de-novo AML patients, and allo-SCT could be offered to selected patients achieving CR/CRi.

BNT162b2 COVID-19 vaccine is significantly less effective in patients with hematologic malignancies.

Patients with hematologic malignancies have an increased risk of severe COVID-19 infection. Vaccination against COVID-19 is especially important in these patients, but whether they develop an immune response following vaccination is unknown. We studied serologic responses to the BNT162b2 vaccine in this population. A lower proportion of patients were seropositive following vaccination (75%) than in a comparison group (99%; p < 0.001), and median (interquartile range [IQR]) antibody titers in patients were lower (90 [12.4-185.5] and 173 [133-232] AU/ml, respectively; p < 0.001). Older age, higher lactate dehydrogenase, and number of treatment lines correlated with lower seropositivity likelihood and antibody titers, while absolute lymphocyte count, globulin level, and time from last treatment to vaccination correlated with higher seropositivity likelihood and antibody titers. Chronic lymphocytic leukemia patients had the lowest seropositivity rate followed by indolent lymphoma. Patients recently treated with chemo-immunotherapy, anti-CD20 antibodies, BCL2, BTK or JAK2 inhibitors had significantly less seropositive responses and lower median (IQR) antibody titers (29%, 1.9 [1.9-12] AU/ml; 0%, 1.9 [1.9-1.9] AU/ml; 25%, 1.9 [1.9-25] AU/ml; 40%, 1.9 [1.9-92.8] AU/ml; and 42%, 10.9 [5.7-66.4] AU/ml, respectively; p < 0.001). Serological response to BNT162b2 vaccine in patients with hematologic malignancies is considerably impaired, and they could remain at risk for severe COVID-19 infection and death.

Management and Outcome of Venous Thrombosis in Patients with Myeloproliferative Neoplasms: Data from the Israeli MPN Working Group.

The BCR-ABL-negative myeloproliferative neoplasms (MPN) are associated with high incidence of venous thrombosis and a significant rate of recurrent events, but there is no consensus regarding their management. In this retrospective study, we analyzed 96 patients with MPN-related venous thrombosis. The index venous thrombosis occurred at a median age of 58 years (IQR 37-71), with 58% of the events involving unusual sites. Patients who were on antiplatelet agents at the time of index thrombosis tended to be older than patients who were not receiving antiplatelets at the time of index thrombosis. The majority of index thromboses occurring after the diagnosis of MPN had uncontrolled blood counts at the time of event and were not receiving antithrombotic agents. Following the thrombotic episode, 75% of patients received long-term anticoagulation. At a median follow-up of 3.4 years, the recurrence rate was 14%. Thrombophilia was significantly more prevalent among patients with recurrent thrombosis compared to patients without recurrence (p < 0.01). Patients who developed a recurrent event early were more likely to have thrombophilia (either inherited or antiphospholipid antibodies), and controlled blood counts, and were likely to receive anticoagulation at the time of recurrence compared to patients with later recurrences. Thrombophilia may contribute to venous thrombosis recurrence, especially early after the index venous thrombosis. Suboptimal anticoagulation and blood count control are factors associated with late venous thrombosis recurrence.

Willingness and concerns of transfusion-dependent hematological patients toward the option of home transfusion therapy.

BACKGROUND: One of the main obstacles of providing home-based palliative care to transfusion-dependent hematology patients is the lack of home transfusions services. While healthcare professionals are concerned with safety and cost of home transfusions, the attitude of the patients toward home transfusions are mostly unknown. AIM: To obtain quantitative data regarding the willingness and concerns of transfusion-dependent patients with hematological diseases toward the option of home transfusions. DESIGN: A cross sectional survey including a self-administered questionnaire in one of the three main spoken languages in Israel was administered to patients in 17 hospital hematology outpatient clinics between May 2019 and March 2020. RESULTS: About 52% of 385 patients that participated in the survey preferred home transfusions to hospital transfusions. Gender, age, education, or type of disease were not associated with preference for home transfusions, nor were hospital location or its size. The likelihood to prefer home transfusions was significantly higher among the Hebrew-speakers and those who had not experienced adverse effects previously. The most significant factor associated with preference of home transfusions was a perceived negative effect of hospital-based transfusion on quality of life. The main reason to reject home transfusions was fear of possible adverse effects and concerns over losing contact with the medical staff at the treating hospital. CONCLUSION: These data suggest that a significant portion of transfusion-dependent patients in Israel view home transfusions as a preferred treatment option and that its successful implementation requires maintaining ongoing contact with the treating hospital.

Safety and efficacy of blinatumomab: a real world data.

Despite improvement in survival of newly diagnosed adult precursor B-acute lymphoblastic leukemia/lymphoma (B-ALL), the results of relapsed/refractory disease are poor. Blinatumomab, a bispecific monoclonal antibody directed against CD19/CD3 show clinical activity against relapsed/refractory B-ALL and in minimal residual disease (MRD)-positive patients.We report our "real-world" experience with blinatumomab in patients with relapsed/refractory B-ALL.Twenty-one patients, at a median age 52 years with median disease duration of 10 months, were included. Indications for treatment were hematological relapse (n = 17), MRD positivity (n = 2), inability to continue intensive chemotherapy (n = 1), and bridging to a second alloSCT (n = 1). Blinatumomab was given as first salvage in 11 patients and after at least one prior salvage treatment in eight.Complete response (CR) was newly achieved in 47% and was maintained in 75% of patients with baseline CR. At a median follow-up of 12.4 months, 13 patients were alive, and 11 in CR. Median leukemia-free survival was 8.7 months, and median overall survival was 15.2 months. Median leukemia-free survival and overall survival were not reached in patients proceeding to alloSCT compared to 5.1 and 15.2 months, respectively, for patients who did not receive stem cell transplantation.Treatment was well tolerated with neurological events reported in two patients (10%) and GI events in three patients (14%). Cytokine storm was reported in four patients (19%).In conclusion, treatment with blinatumomab is effective and tolerable in adult patients with relapsed/refractory B-ALL outside of a clinical trial stetting.

Platelets from Calreticulin mutated essential thrombocythemia patients are less reactive than JAK2 V617F mutated platelets.

Both JAK2V617F and calreticulin (CALR) mutated essential thrombocythemia (ET) patients have different clinical characteristics, with lower thrombosis risk in patients with CALR mutations. To elucidate the mechanism for this lower risk we studied platelet function in ET patients with either JAK2V617F or a CALR mutation. Platelet activation state was similar in ET and healthy controls at baseline using P-selectin and PAC1 flow cytometry analysis. However, CALR mutated platelets were significantly less activated following ADP stimulation, compared to control or JAK2 mutated platelets (P < .001). In live-cell imaging of platelet attachment to immobilized fibrinogen by Interference Reflection Microscopy (IRM), the number of attached CALR mutated platelets was lower compared to control and JAK2 mutated platelets, with lower fractions of platelets achieving the fully spread state (90%, 78% and 54% of adherent cells for control, JAK2 and CALR mutated subjects, respectively). Compared to controls, ET patients, regardless of the mutation type, had increased numbers of immature platelets (IP) and leukocyte platelet aggregates (LPA), as well as plasma sP-selectin. These were all correlated with the platelet count and not to the state of platelet activation. We also found that intracellular free Ca2+ was increased in resting ET compared to control platelets. Note, CALR had a more dispersed localization in activated ET platelets compared to healthy controls, and mutated CALR interact physically with TpoR in CALR mutated platelets. We hypothesize that defects in platelet activation and spreading in CALR mutated patients can explain, at least in part, the lower thrombotic tendency in CALR mutated ET patients.

Splanchnic vein thromboses associated with myeloproliferative neoplasms: An international, retrospective study on 518 cases.

Myeloproliferative Neoplasms (MPN) course can be complicated by thrombosis involving unusual sites as the splanchnic veins (SVT). Their management is challenging, given their composite vascular risk. We performed a retrospective, cohort study in the framework of the International Working Group for MPN Research and Treatment (IWG-MRT), and AIRC-Gruppo Italiano Malattie Mieloproliferative (AGIMM). A total of 518 MPN-SVT cases were collected and compared with 1628 unselected, control MPN population, matched for disease subtype. Those with MPN-SVT were younger (median 44 years) and enriched in females compared to controls; PV (37.1%) and ET (34.4%) were the most frequent diagnoses. JAK2V617F mutation was highly prevalent (90.2%), and 38.6% of cases had an additional hypercoagulable disorder. SVT recurrence rate was 1.6 per 100 patient-years. Vitamin K-antagonists (VKA) halved the incidence of recurrence (OR 0.48), unlike cytoreduction (OR 0.96), and were not associated with overall or gastrointestinal bleeding in multivariable analysis. Esophageal varices were the only independent predictor for major bleeding (OR 17.4). Among MPN-SVT, risk of subsequent vascular events was skewed towards venous thromboses compared to controls. However, MPN-SVT clinical course was overall benign: SVT were enriched in PMF with lower IPSS, resulting in significantly longer survival than controls; survival was not affected in PV and slightly reduced in ET. MPN-U with SVT (n = 55) showed a particularly indolent phenotype, with no signs of disease evolution. In the to-date largest, contemporary cohort of MPN-SVT, VKA were confirmed effective in preventing recurrence, unlike cytoreduction, and safe; the major risk factor for bleeding was esophageal varices that therefore represent a major therapeutic target.

Midostaurin in combination with intensive chemotherapy is safe and associated with improved remission rates and higher transplantation rates in first remission-a multi-center historical control study.

The addition of midostaurin, a FLT3-inhibitor, to intensive chemotherapy (IC) was previously shown to improve outcome of younger patients with FLT3-mutated AML. The toxicity and efficacy of adding midostaurin to IC in patients not originally included in the RATIFY study or with intensified daunorubicin dosing are unknown. We conducted a retrospective, multi-center, historical-control study to characterize the safety and efficacy of adding midostaurin to IC in a "real-world" setting. Sixty-nine adult patients were included in the analysis (midostaurin n = 34, historical controls n = 35) with a mean follow-up of 18.4 (± 15) months. Median age of patients was 60 (range 26-82) years; 32% and 20% of patients were > 65 and 70 years, respectively. No differences in baseline characteristics were noted between the groups. Midostaurin was administered with 90 mg/m2 daunorubicin in 29% of patients; One-third of patients experienced dose reductions/interruptions during midostaurin therapy. Overall toxicity was comparable between the midostaurin and control groups.CR/CRi rates were higher in patients treated with midostaurin compared with controls (80% vs. 57%, p = 0.047) and significantly more patients in the midostaurin group were transplanted in first remission (95% vs. 68%, p = 0.04).Median OS and DFS were higher in the midostaurin vs. control group (not reached vs. 11 months (p = 0.085) and 13 vs. 6 months (p = 0.09), respectively). In our analysis, midostaurin was not associated with increased toxicity including in older patients, in those with secondary AML or when administered with intensified daunorubicin dosage. Higher remission rates in the midostaurin group and increased transplantation rates in first CR were associated with a trend towards better outcomes.

[CURRENT CRITERIA FOR THE DIAGNOSIS OF MYELOPROLIFERATIVE NEOPLASMS - WHAT IS IMPORTANT TO KNOW?]

INTRODUCTION: The understanding of the basic molecular mechanisms of myeloproliferative neoplasms in the last few years led to updating of their diagnostic criteria in the recent classification of myeloid and lymphoid neoplasms by the WHO, which was published in 2017. The major changes relating to the diagnosis of myeloproliferative neoplasms include lowering of the hemoglobin threshold and mandatory bone marrow biopsy as major criteria for the diagnosis of polycythemia vera, as well as adding acquired mutation in either CALR or MPL in addition to the common JAK2V617F mutation as a major criterion for diagnosing essential thrombocythemia or myelofibrosis. We review the newest discoveries on the pathogenesis of myeloproliferative neoplasms, highlighting the relevant new additions to their diagnostic criteria, and relevant therapeutic considerations.

Management of extreme thrombocytosis in myeloproliferative neoplasms: an international physician survey.

Extreme thrombocytosis (ExT) has been associated with an increased bleeding risk in myeloproliferative neoplasm (MPN) patients and is included in the high risk category in treatment guidelines. Treatment of patients with ExT has not been studied in prospective trials. To study physicians' approaches to ExT, we distributed a web based questionnaire with clinical case scenarios to 202 members of MPN working groups. Cases included low thrombotic risk essential thrombocythemia (ET) with either JAK2V617F or CALR mutation, polycythemia vera with ExT either with or without leukocytosis, an ET patient needing urgent orthopedic surgery, and a poorly controlled ET patient with acute cerebral venous sinus thrombosis. Responses were received from 90 physicians (45 %) and were variable in most case scenarios. Country of practice had the most significant influence on physician response. The USA and Israel physicians responded similarly in most cases and differently to the Europe physicians. Treatment of asymptomatic JAK2V617F positive ET and target platelet count on cytoreduction were significantly influenced by physician years of experience. Responses were not influenced by the volume of MPN practice or by whether MPN was considered a major interest by the physician. Our results show a lack of consensus on how to manage MPN patients with ExT. Randomized controlled trials properly designed to address these questions are needed.

Sensitive Replicate Real-Time Quantitative PCR of BCR-ABL Shows Deep Molecular Responses in Long-Term Post-Allogeneic Stem Cell Transplantation Chronic Myeloid Leukemia Patients.

Real-time quantitative PCR (RT-qPCR) is commonly used for follow-up of chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors, but its current sensitivity does not allow detection of very low BCR-ABL levels. Therefore RT-qPCR negativity is not synonymous with complete molecular response. Replicate RT-qPCR had shown increased sensitivity in tyrosine kinase inhibitor-treated patients and was, therefore, used here to evaluate whether RT-qPCR-negative post-allogeneic stem cell transplantation (SCT) patients harbor detectable disease. Samples from 12 patients were tested at 2 time points using 82 replicates of BCR-ABL RT-qPCR. One patient (38 months after SCT) had detectable transcripts at baseline and none at the follow-up test, done at a median of 107 months after SCT. This suggests cure from CML in the majority of allogeneic SCT patients who have no transcripts detectable by replicate RT-qPCR for BCR-ABL.

Phase 1/2 study of nilotinib prophylaxis after allogeneic stem cell transplantation in patients with advanced chronic myeloid leukemia or Philadelphia chromosome-positive acute lymphoblastic leukemia.

BACKGROUND: Allogeneic stem cell transplantation (SCT) remains the standard treatment for advanced chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL). Relapsed disease is the major cause of treatment failure, especially when SCT is given in the setting of advanced disease. Tyrosine kinase inhibitors can be given after transplantation prophylactically or after the detection of minimal residual disease (MRD) to reduce the relapse risk. METHODS: Posttransplant nilotinib was started after the achievement of sustained engraftment and the resolution of transplant-related toxicities. Nilotinib was continued until progression or unacceptable toxicity. RESULTS: Twenty-two patients with advanced CML (n = 15) or Ph(+) ALL (n = 7) underwent SCT with human leukocyte antigen-matched siblings (n = 11), unrelated donors (n = 7), or alternative donors (n = 4). Sixteen patients were given prophylactic nilotinib maintenance, which was started at a median of 38 days after transplantation. Six patients stopped the treatment because of toxicities (mostly gastrointestinal and hepatic). After nilotinib maintenance, 11 patients achieved (n = 9) or maintained (n = 2) a complete molecular response (CMR), and only 1 of them later relapsed. Four of the 5 patients not achieving CMR relapsed. At a median follow-up of 46 months, 9 patients were alive, and 13 had died. The 2-year overall and progression-free survival rates were 55% (95% confidence interval [CI], 34%-75%) and 45% (95% CI, 25%-66%), respectively. Among the 16 nilotinib recipients, the rates were 69% (95% CI, 46%-92%) and 56% (95% CI, 32%-81%), respectively. The 2-year nonrelapse mortality and relapse rates for all patients were 32% (95% CI, 17%-58%) and 23% (95% CI, 11%-49%), respectively. CONCLUSIONS: Nilotinib is relatively safe and effective prophylactic therapy for the prevention of relapse after SCT. It may control MRD and convert patients to CMR, which is associated with prolonged survival. These observations merit further study in larger scale studies.

Salvage therapy with ARA-C and gemtuzumab ozogamicin in AML patients relapsing after stem cell transplantation.

Acute myeloid leukemia (AML) relapse is often associated with a poor outcome, especially after allogeneic stem cell transplantation (Allo-SCT). In patients relapsing early after SCT treatment, options are further limited by the fear for increased toxicity. We report our experience with ARA-C and gemtuzumab ozogamicin (GO) combination in relapsed post-SCT AML patients. Therapy consisted of ARA-C (1 gr/m(2)) for 4 days followed by one dose of GO 9 mg/m(2) on day 5 and was supported by donor stem cells when possible. Responding patients not developing graft versus host disease (GVHD) were eligible for immunotherapy with donor lymphocyte infusion (DLI) or a second Allo-SCT. Sixteen patients, median age 53 years (range 31-63), are included in this analysis. Patients underwent SCT for high-risk AML (n = 11) or AML relapse (n = 5), and 81 % had an early post-SCT relapse. Responses were achieved in 60 % of evaluable patients (CR-5 CRp-4). Median probabilities of survival (OS) and event-free survival (EFS) in the entire cohort, responding and non-responding patients were 103 and 76 days, 183 and 97 days, and 79 and 16 days, respectively. At 1-year follow-up, 25 % of patients were alive; however, all had relapse. Treatment resulted in grade 3-4 neutropenia and thrombocytopenia in all patients, and 27 % each had grade 3-4 hyperbilirubinemia or elevation of liver enzymes. One patient died during treatment due to intracranial hemorrhage. Of the six patients proceeding to second SCT or receiving DLI, three patients developed mild veno-occlusive disease (VOD). Combination therapy with ARA-C and GO after SCT results in short-term disease control and limited toxicity and could be considered for patients who are candidates for further immunotherapy.

Adaptor protein Lnk binds to and inhibits normal and leukemic FLT3.

Fms-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase with important roles in hematopoietic progenitor cell survival and proliferation. It is mutated in approximately one-third of AML patients, mostly by internal tandem duplications (ITDs). Adaptor protein Lnk is a negative regulator of hematopoietic cytokine signaling. In the present study, we show that Lnk interacts physically with both wild-type FLT3 (FLT3-WT) and FLT3-ITD through the SH2 domains. We have identified the tyrosine residues 572, 591, and 919 of FLT3 as phosphorylation sites involved in direct binding to Lnk. Lnk itself was tyrosine phosphorylated by both FLT3 ligand (FL)-activated FLT3-WT and constitutively activated FLT3-ITD. Both shRNA-mediated depletion and forced overexpression of Lnk demonstrated that activation signals emanating from both forms of FLT3 are under negative regulation by Lnk. Moreover, Lnk inhibited 32D cell proliferation driven by different FLT3 variants. Analysis of primary BM cells from Lnk-knockout mice showed that Lnk suppresses the expansion of FL-stimulated hematopoietic progenitors, including lymphoid-primed multipotent progenitors. The results of the present study show that through direct binding to FLT3, Lnk suppresses FLT3-WT/ITD-dependent signaling pathways involved in the proliferation of hematopoietic cells. Therefore, modulation of Lnk expression levels may provide a unique therapeutic approach for FLT3-ITD-associated hematopoietic disease.

OCT1 genetic variants are associated with long term outcomes in imatinib treated chronic myeloid leukemia patients.

OBJECTIVES: One third of CML patients treated with first line imatinib have suboptimal responses or treatment failures with increased risk for disease progression. Imatinib is actively transported into cells by the SLC22A1 transporter (hOCT1) and its genetic variants may affect intracellular drug import. We studied the effect of SLC22A1 genetic variants on long-term outcomes of imatinib treated patients. METHODS: A total of 167 patients, 94% in chronic phase, were analyzed for rs41267797, rs683369, rs12208357, and rs628031 variants using the Sequenom MassARRAY platform. RESULTS: Rates of CHR, MCyR, CCyR, and MMolR were not significantly different according to allelic variants. However, patients with AA or GA rs628031 genotypes had a higher incidence of poor response to imatinib compared to the GG genotype (47% compared to 29%, P = 0.06), and a higher rate of KD mutation discovery (8/16 vs. 5/27, P = 0.04), suggesting that secondary resistance was more common in these genotypes. Median EFS was shorter for rs628031 genotype AA/AG compared with the GG genotype (61 months and not reached, respectively, P = 0.05), and 5 yr OS rates were lower for patients with the rs628031 genotypes AA/AG compared with the GG genotype (88% and 97%, respectively, P = 0.03). Patients with AA/GA rs628031 and additional rare genotypes had worse EFS and OS compared to patients with only AA/GA rs628031 (P = 0.02 for EFS and 0.01 for OS). There was no difference in pretreatment SLC22A1 mRNA expression levels in patients with rs628031 genotypes GG/AA or GA. CONCLUSIONS: Studying SLC22A1 genetic variants prior to TKI initiation could influence treatment decisions.

SH2B3 (LNK) mutations from myeloproliferative neoplasms patients have mild loss of function against wild type JAK2 and JAK2 V617F.

Somatic point mutations in the PH domain of SH2B3 (LNK), an adaptor protein that is highly expressed in haematopoietic cells, were recently described in patients with myeloproliferative neoplasms. We studied the effect of these mutations on the JAK2 signalling pathway in cells expressing either wild type JAK2 or the JAK2 V617F mutation. Compared to wild type SH2B3, PH domain mutants have mild loss of function, with no evidence for a dominant-negative effect. Mutants retain binding capacity for JAK2, an established SH2B3 target, as well as for the adaptor proteins 14-3-3 and CBL. Our data suggest that the loss of SH2B3 inhibitory function conferred by the PH domain mutations is mild and may collaborate with JAK2 V617F and CBL mutations in order to promote either the development or the progression of myeloproliferative neoplasms.