Treatment-free remission after a second TKI discontinuation attempt in patients with Chronic Myeloid Leukemia re-treated with dasatinib - interim results from the DAstop2 trial

Tyrosine kinase inhibitor (TKI) discontinuation in chronic myeloid leukemia (CML) has become part of routine care for patients with a sustained deep molecular response (DMR). Approximately 50% experience a molecular relapse upon TKI cessation. Most of them quickly regain DMR upon TKI resumption. Whether these patients can achieve a second treatment-free remission (TFR) remains unclear. DAstop2 (ClinicalTrials.gov ID: NCT03573596) is a prospective study including patients with a failed first TFR attempt re-treated with any TKI for ≥ one year. Upon entering the study, patients received the TKI dasatinib for additional two years. Patients with sustained DMR for ≥1 year qualified for a second TKI stop. Ninety-four patients were included between Oct 2017-Dec 2021. At the time of data analysis, 62 patients had attempted a 2nd stop. After a median follow-up of 27 months from 2nd stop, TFR rates were 61, 56 and 46% at 6, 12 and 24 months respectively. No progression to advanced stage disease was seen and 87% had re-achieved MR4 within a median of 3 months from TKI re-initiation. In summary, we show that a 2nd TFR attempt after dasatinib treatment is safe, feasible and TFR rates seem in the range of those reported in trials of a first TKI stop.

Role of red cell mass evaluation in myeloproliferative neoplasms with splanchnic vein thrombosis and normal hemoglobin value: a study of the France Intergroupe des Syndromes myeloprolifératifs

Not available.

Distinct clinico-molecular arterial and venous thrombosis scores for myeloproliferative neoplasms risk stratification

Current recommended risk scores to predict thrombotic events associated with myeloproliferative neoplasms (MPN) do not discriminate between arterial and venous thrombosis despite their different physiopathology. To define novel stratification systems, we delineated a comprehensive landscape of MPN associated thrombosis across a large long-term follow-up MPN cohort. Prior arterial thrombosis, age >60 years, cardiovascular risk factors and presence of TET2 or DNMT3A mutations were independently associated with arterial thrombosis in multivariable analysis. ARTS, an ARterial Thrombosis Score, based on these four factors, defined low- (0.37% patients-year) and high-risk (1.19% patients-year) patients. ARTS performance was superior to the two-tiered conventional risk stratification in our training cohort, across all MPN subtypes, as well as in two external validation cohorts. Prior venous thrombosis and presence of a JAK2V617F mutation with a variant allelic frequency ≥50% were independently associated with venous thrombosis. The discrimination potential of VETS, a VEnous Thrombosis Score based on these two factors, was poor, similar to the two-tiered conventional risk stratification. Our study pinpoints arterial and venous thrombosis clinico-molecular differences and proposes an arterial risk score for more accurate patients' stratification. Further improvement of venous risk scores, accounting for additional factors and considering venous thrombosis as a heterogeneous entity is warranted.

[Optimizing the use of bosutinib in patients with chronic-phase chronic myeloid leukemia: Recommendations of a panel of experts from the Fi-LMC (French CML working group)]

The treatment of chronic myeloid leukemia relies on orally available tyrosine kinase inhibitors targeting the BCR::ABL1 oncoprotein. Bosutinib is a second generation adenosine triphosphate-competitive inhibitor approved for use in frontline adult chronic phase-chronic myeloid leukemia and all phases-chronic myeloid leukemia in the second line setting or beyond. Its efficacy was demonstrated in several pivotal clinical trials at 400mg once daily in the first line context and at 500mg once daily beyond first line. Bosutinib-related adverse events frequently occur early after treatment initiation and include gastro-intestinal symptoms and cytolytic hepatitis. These drug-related adverse events must be properly managed in order to preserve safety, efficacy and treatment acceptability. The French chronic myeloid leukemia study group gathered a panel of experts in hematology, pharmacology and hepatology in order to elaborate practical recommendations on the management of bosutinib treatment. These recommendations aim at optimizing the short and long-term tolerance and benefit/risk balance of bosutinib, mainly focusing at gastro-intestinal and liver toxicities.

First-line second generation tyrosine kinase inhibitors in patients with newly diagnosed accelerated phase chronic myeloid leukemia

Accelerated phase (AP) CML at onset and have poorer prognosis than CP-CML. We hypothesize that off-license use of second generation TKI (TKI2) as front-line therapy might counterbalance this poor prognosis, with limited toxicity. In "real-life" conditions, newly diagnosed patients meeting the ELN cytological criteria for AP-CML or harboring ACA and treated with first-line TKI2 were included in this retrospective multicenter observational study. We enrolled 69 patients [69.5 % male, median age 49.5 years, median follow-up 43.5 months], segregated into hematologic AP [HEM-AP (n = 32)] and cytogenetically defined AP [ACA-AP (n = 37)]. Hematologic parameters were worse in HEM-AP [spleen size (p = 0.014), PB basophils (p < .001), PB blasts (p < .001), PB blasts+promyelocytes (p < .001), low hemoglobin levels (p < .001)]. Dasatinib was initiated in 56 % patients in HEM-AP and in 27 % in ACA-AP, nilotinib in 44 % and 73 % respectively. Response and survival do not differ, regardless of the TKI2: 81 % vs 84.3 % patients achieved CHR, 88 % vs 84 % CCyR, 73 % vs 75 % MMR respectively. The estimated 5-year PFS 91.5 % (95%CI: 84.51-99.06 %) and 5-year OS 96.84 % (95%CI: 92.61-100 %). Only BM blasts (p < 0.001) and BM blasts+promyelocytes (p < 0.001) at diagnosis negatively influenced OS. TKI2 as front-line therapy in newly diagnosed AP-CML induce excellent responses and survival, and counterbalance the negative impact of advanced disease phase.

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 (MR^4.5 ) 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, MR^4.5 rates were 25% and 38%, respectively. Thereafter, 32% and 46% of patients achieved a sustained (≥2 years) MR^4.5 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.

Calcific tendinopathy: an unexpected side effect of tyrosine kinase inhibitor?

Musculoskeletal (MSK) pains have been reported during TKI treatment or after its discontinuation in patients with chronic myeloid leukemia (CML). We hypothesized that MSK pains originate from calcific tendinopathy according to preliminary clinical observations. We conducted a retrospective study including CML patients divided into three groups: patients with MSK pain during TKI treatment; asymptomatic patients during TKI treatment; patients with MSK pain after TKI discontinuation. Patients with MSK pain were clinically evaluated, and the presence of calcific deposits was assessed in X-rays of both shoulders and pelvis. Forty-five patients were included; 14 described MSK pain during TKI treatment and 12 after TKI discontinuation. A diagnosis of rotator cuff tendinopathy was retained for 57.7% of patients and of gluteus tendinopathy in 19.2%. The prevalence of calcifications in shoulders and/or hips was 64.3% in symptomatic patients receiving TKIs, 63.2% in asymptomatic patients and 75.0% in patients with MSK pain after TKI treatment.

Adverse events associated with JAK inhibitors in 126,815 reports from the WHO pharmacovigilance database

Increasing number of Janus kinase (JAK) inhibitors have been approved for chronic haematopoietic neoplasms and inflammatory/autoimmune diseases. We aimed to assess safety of the first three approved JAK inhibitors: ruxolitinib, tofacitinib and baricitinib. In this retrospective observational study, pharmacovigilance data were extracted from the World Health Organization database. Adverse events are classified according to Medical Dictionary for Regulatory Activities hierarchy. Until February 28, 2021, all Individual Case Safety Reports [ICSRs] with the suspected drug ruxolitinib, tofacitinib or baricitinib were included. Disproportionality analysis was performed and the information component (IC) was estimated. Adverse events were considered a significant signal if the lower end of the 95% credibility interval of the IC (IC025) was positive. We identified 126,815 ICSRs involving JAK inhibitors. Ruxolitinib, tofacitinib and baricitinib were associated with infectious adverse events (IC025 1.7, especially with viral [herpes and influenza], fungal, and mycobacterial infectious disorders); musculoskeletal and connective tissue disorders (IC025 1.1); embolism and thrombosis (IC025 0.4); and neoplasms (IC025 0.8, especially malignant skin neoplasms). Tofacitinib was associated with gastrointestinal perforation events (IC025 1.5). We did not find a significant increase in the reporting of major cardiovascular events. We identified significant association between adverse events and ruxolitinib, tofacinitib and baricitinib in international pharmacovigilance database.

Determinants of SARS-CoV-2 waning immunity in allogeneic hematopoietic stem cell transplant recipients

Hematopoietic stem cell transplant (HSCT) recipients are at high-risk for severe COVID-19 and have altered immune responses to vaccination. We sought to evaluate the dynamics of immune response to BNT162b2 mRNA vaccine in HSCT recipients. We systematically proposed vaccination with BNT162b2 to HSCT recipients and gave a third vaccine dose to those showing titers of IgG(S-RBD) below 4160 AU/mL 1 month following the second dose. We then quantified anti-SARS-CoV-2 antibodies dynamics in 133 of these HSCT recipients (88 after two and 45 after three vaccine doses) 6 months after the first vaccine dose. Mean IgG(S-RBD) titer at 6 months was significantly lower than the peak value measured 1 month after a second (p < 0.001) or third (p < 0.01) vaccine dose. IgG(S-RBD) titers at 6 months were strongly correlated to peak values (p < 0.001) and a peak titer above 10,370 AU/mL predicted persistent protection at 6 months. Seventy-two percent (96/133) of patients retained protective antibody levels at 6 months. Immunosuppressive drugs and low lymphocyte counts in peripheral blood correlated with lower IgG(S-RBD) titers at 6 months. Four patients (3%) developed PCR-documented SARS-CoV-2 infection and one died.

Long-term outcome of imatinib 400 mg compared to imatinib 600 mg or imatinib 400 mg daily in combination with cytarabine or pegylated interferon alpha 2a for chronic myeloid leukaemia: results from the French SPIRIT phase III randomised trial

The STI571 prospective randomised trial (SPIRIT) French trial is a four-arm study comparing imatinib (IM) 400 mg versus IM 600 mg, IM 400 mg + cytarabine (AraC), and IM 400 mg + pegylated interferon alpha2a (PegIFN-α2a) for the front-line treatment of chronic-phase chronic myeloid leukaemia (CML). Long-term analyses included overall and progression-free survival, molecular responses to treatment, and severe adverse events. Starting in 2003, the trial included 787 evaluable patients. The median overall follow-up of the patients was 13.5 years (range 3 months to 16.7 years). Based on intention-to-treat analyses, at 15 years, overall and progression-free survival were similar across arms: 85%, 83%, 80%, and 82% and 84%, 87%, 79%, and 79% for the IM 400 mg (N = 223), IM 600 mg (N = 171), IM 400 mg + AraC (N = 172), and IM 400 mg + PegIFN-α2a (N = 221) arms, respectively. The rate of major molecular response at 12 months and deep molecular response (MR4) over time were significantly higher with the combination IM 400 mg + PegIFN-α2a than with IM 400 mg: p = 0.0001 and p = 0.0035, respectively. Progression to advanced phases and secondary malignancies were the most frequent causes of death. Toxicity was the main reason for stopping AraC or PegIFN-α2a treatment.

Dasatinib dose optimisation based on therapeutic drug monitoring reduces pleural effusion rates in chronic myeloid leukaemia patients

Dasatinib is a second-generation BCR-ABL1 tyrosine kinase inhibitor approved for patients with chronic myeloid leukaemia (CML). Dasatinib 100 mg per day is associated with an increased risk of pleural effusion (PlEff). We randomly evaluated whether therapeutic drug monitoring (TDM) may reduce dasatinib-associated significant adverse events (AEs) by 12 months (primary endpoint). Eligible patients started dasatinib at 100 mg per day followed by dasatinib (C)min assessment. Patients considered overdosed [(C)min ≥ 3 nmol/l) were randomised between a dose-reduction strategy (TDM arm) and standard of care (control arm). Out of 287 evaluable patients, 80 patients were randomised. The primary endpoint was not met due to early haematological AEs occurring before effective dose reduction. However, a major reduction in the cumulative incidence of PlEff was observed in the TDM arm compared to the control arm (4% vs. 15%; 11% vs. 35% and 12% vs. 39% at one, two and three years, respectively (P = 0·0094)). Molecular responses were superimposable in all arms. Dasatinib TDM during treatment initiation was feasible and resulted in a significant reduction of the incidence of PlEff in the long run, without impairing molecular responses. (NCT01916785; https://clinicaltrials.gov).

Eurados review of retrospective dosimetry techniques for internal exposures to ionising radiation and their applications

This work presents an overview of the applications of retrospective dosimetry techniques in case of incorporation of radionuclides. The fact that internal exposures are characterized by a spatially inhomogeneous irradiation of the body, which is potentially prolonged over large periods and variable over time, is particularly problematic for biological and electron paramagnetic resonance (EPR) dosimetry methods when compared with external exposures. The paper gives initially specific information about internal dosimetry methods, the most common cytogenetic techniques used in biological dosimetry and EPR dosimetry applied to tooth enamel. Based on real-case scenarios, dose estimates obtained from bioassay data as well as with biological and/or EPR dosimetry are compared and critically discussed. In most of the scenarios presented, concomitant external exposures were responsible for the greater portion of the received dose. As no assay is available which can discriminate between radiation of different types and different LETs on the basis of the type of damage induced, it is not possible to infer from these studies specific conclusions valid for incorporated radionuclides alone. The biological dosimetry assays and EPR techniques proved to be most applicable in cases when the radionuclides are almost homogeneously distributed in the body. No compelling evidence was obtained in other cases of extremely inhomogeneous distribution. Retrospective dosimetry needs to be optimized and further developed in order to be able to deal with real exposure cases, where a mixture of both external and internal exposures will be encountered most of the times.

Low-dose tyrosine kinase inhibitors before treatment discontinuation do not impair treatment-free remission in chronic myeloid leukemia patients: Results of a retrospective study

BACKGROUND

Long-term treatment-free remission (TFR) represents a new goal for chronic myeloid leukemia (CML). In clinical practice, tyrosine kinase inhibitor (TKI) dose reductions can be considered a means of preventing adverse effects and improving quality of life. We hypothesized that administration of low-dose TKIs before treatment discontinuation does not impair TFR in patients with CML who have a deep molecular response (DMR, ≥MR⁴ ).

METHODS

We conducted a retrospective analysis of 77 patients with CML who discontinued treatment with TKIs. Twenty-six patients had been managed with low-dose TKIs before stopping treatment. Patients were to be exposed to TKIs for ≥5 years and to low-dose TKIs for ≥1 year and in DMR for ≥2 years. The loss of major molecular response (MMR) was considered a trigger for restarting therapy.

RESULTS

In the low-dose group, 61.5% of patients received second-generation TKIs, and dose reduction was ≥50% for 65.4% of patients. With a median follow-up of 61.5 months, TFR at 12 months was 56.8% in the full-dose TKI group and 80.8% in the low-dose group, and TFR at 60 months was 47.5% and 58.8%, respectively. The median time to molecular recurrence (≥MMR) from TKI discontinuation in the entire cohort was 6.2 months. All patients quickly achieved MMR after resuming TKI therapy. Results appear independent of both dose reduction and potential pretreatment with interferon-α.

CONCLUSION

This retrospective study shows that TFR was not impaired by low-dose TKI regimens before TKI cessation in Patients with CML. Nevertheless, prospective randomized clinical trials must be undertaken to analyze the probability of successful TFR in patients managed with TKI dose de-escalation strategies before TKI discontinuation.

Deer keds on wild ungulates in northern Italy, with a taxonomic key for the identification of Lipoptena spp. of Europe

Deer keds (Lipoptena spp.) are blood-sucking ectoparasites of domestic and wild animals, and also accidentally of humans. In Europe, five Lipoptena spp. have been recorded, although the lack of specific taxonomic keys has often led to mistaken identification or to missing data. The present study aimed to develop an identification key of the European species and also to identify Lipoptena spp. found on wild ungulates in northern Italy. In total, 390 hippoboscids were collected from Rupicapra rupicapra, Capreolus capreolus, Cervus elaphus and Ovis aries musimon in an Alpine area of Italy. After morphological identification, 140 specimens were subjected to phylogenetic analysis based on mitochondrial (CO1) and nuclear (CAD) gene sequences. Despite the expected presence of slight morphological variations, all specimens examined were identified both microscopically and molecularly as Lipoptena cervi (100% identity for both CO1 and CAD genes). The massive increase in wild ungulate populations can favour the possibility of detecting other species of Lipoptena. The identification keys proposed in the present study may help with monitoring the presence of Lipoptena species, particularly in European countries where this ectoparasite is neglected and for which various data (from diffusion to control methods) are still missing.

Innate T-αβ lymphocytes as new immunological components of anti-tumoral "off-target" effects of the tyrosine kinase inhibitor dasatinib

Kinase inhibitors hold great potential as targeted therapy against malignant cells. Among them, the tyrosine kinase inhibitor dasatinib is known for a number of clinically relevant off-target actions, attributed in part to effects on components of the immune system, especially conventional T-cells and natural killer (NK)-cells. Here, we have hypothesized that dasatinib also influences non-conventional T-αβ cell subsets known for their potential anti-tumoral properties, namely iNKT cells and the distinct new innate CD8 T-cell subset. In mice, where the two subsets were originally characterized, an activated state of iNKT cells associated with a shift toward an iNKT cell Th1-phenotype was observed after dasatinib treatment in vivo. Despite decreased frequency of the total memory CD8 T-cell compartment, the proportion of innate-memory CD8 T-cells and their IFNγ expression in response to an innate-like stimulation increased in response to dasatinib. Lastly, in patients administered with dasatinib for the treatment of BCR-ABL-positive leukemias, we provided the proof of concept that the kinase inhibitor also influences the two innate T-cell subsets in humans, as attested by their increased frequency in the peripheral blood. These data highlight the potential immunostimulatory capacity of dasatinib on innate T-αβ cells, thereby opening new opportunities for chemoimmunotherapy.

P11.39 Chloroquine as an anti-glioblastoma therapeutic: repurposing of an old drug

BACKGROUND

Glioblastoma (GBM) is the most common and aggressive type of primary brain tumour in adults. These tumours depict anarchic proliferation and brain infiltration as well as radio- and chemoresistant profiles. The complete surgical resection is unachievable and responses to standard therapy are transitory. Recurrence is thus inevitable and patient prognosis is generally less than 15 months. Transforming growth factor-beta (TGF-β) holds a substantial role in supporting the GBM phenotype. We showed that TGF-β 1 expression levels correlate with overall and progression-free survival in newly diagnosed GBM patient. We also observed that chloroquine (CQ) can reduce the production of TGF-β together with proliferation, invasion, radioresistance and radio-induced invasion in vitro. Unfortunately, little is known regarding the ability of CQ to penetrate the blood-brain barrier (BBB). Therefore, our objective is to determine whether intravenous (IV) or intra-arterial (IA) infusions of CQ and hydroxychloroquine (HCQ), a pharmacological analog of CQ, can yield therapeutic brain concentrations.

MATERIAL AND METHODS

To assess BBB penetration, the brain, plasma and cerebrospinal fluid (CSF) concentrations of CQ/HCQ were measured by LCMS/MS at different timepoints post-IV or post-IA infusions with 20 mg/kg of CQ/HCQ in tumour-free Wistar rat. For the survival studies, We implanted 10’000 F98 murin glioblastoma cells in the right putamen of Fischer rats. Ten days post-implantation, IA and IV infusion were accomplished through cannulations of the external right carotid and tail vein respectively.

RESULTS

With IV injections, CQ/HCQ brain concentrations 15 minutes post-injection reached 15.76 mg/g (0.18 µM) and 1.67 mg/g (0.078 µM) respectively. However, following IA infusions, we observed a 1.74 and 20.9 fold increase (20 mg/kg HCQ) as well as 7.1 and 84.7-fold-increase (20 mg/kg CQ) in contra- and ipsilateral brain concentrations respectively. Although brain concentrations gradually decreased over time post-IA infusions, the ipsilateral hemisphere CQ concentration was still 82.81 mg/g (34.52 µM) after 6 hours. Whereas plasma concentrations were very similar following IV and IA infusions, both molecules barely accumulated in the CSF and only when using IA infusions. The median survival of the control group (IA phosphate-buffered saline) and the group treated with 20 mg/kg CQ IV were 23.5 days and 24.5 days respectively. However, rats injected with 20 mg/kg CQ IA had a median survival of 28.5 days.

CONCLUSION

These results suggest that IA CQ could be used to abrogate the GBM phenotype. As TGF-β is associated with resistance to both radio- and chemotherapy, we plan to characterize the combination of IA infusions of CQ in combination with radiation or chemotherapy (carboplatin).

Sustained treatment-free remission in chronic myeloid leukaemia is associated with an increased frequency of innate CD8(+) T-cells

Immunological mechanisms of treatment-free remission (TFR) in chronic myeloid leukaemia (CML) are poorly defined and, to date, no correlation between successful TFR and CD8(+) T-cell subsets has been found. We analysed a new identified human subset of CD8(+) T-cells, namely innate CD8(+) T-cells, in CML patients with TFR ≥ 2 years. We demonstrated a dramatic increase of functionally active innate CD8(+) T-cells in these patients as compared to control subjects and patients in remission under tyrosine kinase inhibitors. Moreover, we found a positive correlation between frequencies of innate CD8(+) T-cells and natural killer cells, possibly representing a new innate biomarker profile of successful TFR.

BIODOSIMETRY AND BIODOSIMETRY NETWORKS FOR MANAGING RADIATION EMERGENCY

Biological dosimetry enables individual dose reconstruction in the case of unclear or inconsistent radiation exposure situations, especially when a direct measurement of ionizing radiation is not or is no longer possible. To be prepared for large-scale radiological incidents, networking between well-trained laboratories has been identified as a useful approach for provision of the fast and trustworthy dose assessments needed in such circumstances. To this end, various biodosimetry laboratories worldwide have joined forces and set up regional and/or nationwide networks either on a formal or informal basis. Many of these laboratories are also a part of global networks such as those organized by World Health Organization, International Atomic Energy Agency or Global Health Security Initiative. In the present report, biodosimetry networks from different parts of the world are presented, and the partners, activities and cooperation actions are detailed. Moreover, guidance for situational application of tools used for individual dosimetry is given.

Ponatinib evaluation and safety in real-life chronic myelogenous leukemia patients failing more than two tyrosine kinase inhibitors: the PEARL observational study

Ponatinib represents a remarkable progress in the treatment of heavily pretreated chronic myelogenous leukemia (CML) and de novo Philadelphia chromosome-positive ALL patients despite significant toxicity in clinical trials. To date, "real-life" data remain few and the use of ponatinib in this setting and its consequences remain mostly unknown. We report, within a national observational study, the use of ponatinib in unselected CML patients who had previously failed ≥2 lines of tyrosine kinase inhibitor (TKI) therapy (or one line if an Abelson (ABL)^T315I mutation was identified), in real-life conditions (2013-2014) in a compassionate program. Our analysis has been focused on 48 chronic phase CML patients recorded. With a median follow-up of 26.5 months since ponatinib initiation, the overall survival (OS) rates (80.5% at 3 years) and cumulative incidence of major molecular response (81.8% at 18 months) were similar to those of the phase II study, with no influence of BCR-ABL mutations nor the reason of ponatinib prescription. A specific subanalysis of the preexisting cardiovascular risk factors and events occurring on ponatinib is described. These events occurred after a median time on ponatinib of 5.8 months (excluding hypertension) and were observed in 29/48 patients (47%), even in those already on anti-aggregants/coagulants. The majority were not severe and resolved, but two cases were fatal. Other hematological or nonhematological nonvascular adverse events were similar to those previously described in trials. This observational study reports similar rates of survival, molecular responses, and a slight increase in the cardiovascular toxicity of ponatinib in real-life conditions, prompting improved control of cardiovascular risk factors and selection of patients.

P53 activation inhibits all types of hematopoietic progenitors and all stages of megakaryopoiesis

TP53 also known as p53 is a tumor suppressor gene mutated in a variety of cancers. P53 is involved in cell cycle, apoptosis and DNA repair mechanisms and is thus tightly controlled by many regulators. Recently, strategies to treat cancer have focused on the development of MDM2 antagonists to induce p53 stabilization and restore cell death in p53 non-mutated cancers. However, some of these molecules display adverse effects in patients including induction of thrombocytopenia. In the present study, we have explored the effect of SAR405838 not only on human megakaryopoiesis but also more generally on hematopoiesis. We compared its effect to MI-219 and Nutlin, which are less potent MDM2 antagonists than SAR405838. We found that all these compounds induce a deleterious effect on all types of hematopoietic progenitors, as well as on erythroid and megakaryocytic differentiation. Moreover, they inhibit both early and late stages of megakaryopoiesis including ploidization and proplatelet formation. In conclusion, MDM2 antagonists induced a major hematopoietic defect in vitro as well as an inhibition of all stages of megakaryopoiesis that may account for in vivo thrombocytopenia observed in treated patients.

Benefits and pitfalls of pegylated interferon-α2a therapy in patients with myeloproliferative neoplasm-associated myelofibrosis: a French Intergroup of Myeloproliferative neoplasms (FIM) study

We have previously described the safety and efficacy of pegylated interferon-α2a therapy in a cohort of 62 patients with myeloproliferative neoplasm-associated myelofibrosis followed in centers affiliated to the French Intergroup of Myeloproliferative neoplasms. In this study, we report their long-term outcomes and correlations with mutational patterns of driver and non-driver mutations analyzed by targeted next generation sequencing. The median age at diagnosis was 66 years old, the median follow-up since starting pegylated interferon was 58 months. At the time of analysis, 30 (48.4%) patients were alive including 16 still being treated with pegylated interferon. The median survival of patients with intermediate and high-risk prognostic Lille and dynamic International Prognostic Scoring System scores treated with pegylated interferon was increased in comparison to that of historical cohorts. In addition, overall survival was significantly correlated with the duration of pegylated interferon therapy (70 versus 30 months after 2 years of treatment, P<10⁻¹²). JAK2^V617F allele burden was decreased by more than 50% in 58.8% of patients and two patients even achieved complete molecular response. Next-generation sequencing analyses performed in 49 patients showed that 28 (57.1%) of them carried non-driver mutations. The presence of at least one additional mutation was associated with a reduction of both overall and leukemia-free survival. These findings in a large series of patients with myelofibrosis suggest that pegylated interferon therapy may provide a survival benefit for patients with intermediate- or high-risk Lille and dynamic International Prognostic Scoring System scores. It also reduced the JAK2^V617F allele burden in most patients. These results further support the use of pegylated interferon in selected patients with myelofibrosis.

Symptom burden profile in myelofibrosis patients with thrombocytopenia: Lessons and unmet needs

Myelofibrosis is a myeloproliferative neoplasm associated with progressive cytopenias and high symptom burden. MF patients with thrombocytopenia have poor prognosis but the presence of thrombocytopenia frequently precludes the use of JAK2 inhibitors. In this study, we assessed quality of life and symptom burden in 418 MF patients with (n=89) and without (n=329) thrombocytopenia using prospective data from the MPN-QOL study group database, including the Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) and Total Symptom Score (MPN10). Thrombocytopenia, defined as platelet count <100×10⁹/L (moderate 51-100×10⁹/L; severe ≤50×10⁹/L), was associated with anemia (76% vs. 45%, p<0.001), leukopenia (29% vs. 11%, p<0.001), and need for red blood cell transfusion (35% vs. 19%, p=0.002). Thrombocytopenic patients had more fatigue, early satiety, inactivity, dizziness, sad mood, cough, night sweats, itching, fever, and weight loss; total symptom scores were also higher (33 vs. 24, p<0.001). Patients with severe thrombocytopenia were more likely to have anemia (86% vs. 67%, p=0.04), leukopenia (40% vs. 20%, p=0.04), and transfusion requirements (51% vs. 20%, p=0.002) but few differences in symptoms when compared to patients with moderate thrombocytopenia. These results suggest that MF patients with thrombocytopenia experience greater symptomatic burden than MF patients without thrombocytopenia and may benefit from additional therapies.

Incidence and predictors of portal and splenic vein thrombosis after pure laparoscopic splenectomy

BACKGROUND

Optimal modalities for diagnosis, treatment, and surveillance of portal or splenic vein thrombosis have not yet been defined. The present retrospective study aimed to investigate the role of computed tomography performed systematically before and after laparoscopic splenectomy to assess the incidence of portal or splenic vein thrombosis, predictors, and outcomes.

METHODS

Computed tomography scans were obtained from 170 patients undergoing elective laparoscopic splenectomy between 2005 and 2015. Pre- and postoperative splenic vein diameter was measured at the splenoportal junction and at a distance of 2, 4, 6 cm from it. Univariate and multivariate analyses were used to identify portal or splenic vein thrombosis risk factors and predictors of treatment outcome.

RESULTS

Overall, 68.2% of patients had benign hematologic diseases; 64.1% showed splenomegaly. Portal or splenic vein thrombosis occurred in 53.5% of patients (91/170), of whom 49.5% were asymptomatic. Preoperative splenic vein diameter measurements at 2, 4, and 6 cm from the splenoportal junction were significantly greater in portal or splenic vein thrombosis patients than in no-portal or splenic vein thrombosis patients. Patients with splenic vein diameter ≥8 mm at all measured sites had a greater risk of developing portal or splenic vein thrombosis (P = .009; odds ratio, 2.57; 95% confidence interval, 1.26-5.23). The majority of thromboses involved the distal splenic vein (45.1%, 41/91), and 41.7% of patients had thromboses located in multiple sites. Fully 71.4% showed complete resolution of portal or splenic vein thrombosis. Thrombus location at a single site predicted a favorable treatment outcome (P < .0001).

CONCLUSION

Portal or splenic vein thrombosis is a frequent complication of splenectomy that occurs asymptomatically in half of cases. Computed tomography could have an important role in identifying patients at risk of developing portal or splenic vein thrombosis as well as in predicting portal or splenic vein thrombosis resolution.

The Hypothesis of the Human iNKT/Innate CD8(+) T-Cell Axis Applied to Cancer: Evidence for a Deficiency in Chronic Myeloid Leukemia

We recently identified a new human subset of NK-like [KIR/NKG2A(+)] CD8(+) T cells with a marked/memory phenotype, high Eomesodermin expression, potent antigen-independent cytotoxic activity, and the capacity to generate IFN-γ rapidly after exposure to pro-inflammatory cytokines. These features support the hypothesis that this new member of the innate T cell family in humans, hereafter referred to as innate CD8(+) T cells, has a role in cancer immune surveillance analogous to invariant natural killer T (iNKT) cells. Here, we report the first quantitative and functional analysis of innate CD8(+) T cells in a physiopathological context in humans, namely chronic myeloid leukemia (CML), a well-characterized myeloproliferative disorder. We have chosen CML based on our previous report that IL-4 production by iNKT cells was deficient in CML patients at diagnosis and considering the recent evidence in mice that IL-4 promotes the generation/differentiation of innate CD8(+) T cells. We found that the pool of innate CD8(+) T cells was severely reduced in the blood of CML patients at diagnosis. Moreover, like iNKT and NK cells, innate CD8(+) T cells were functionally impaired, as attested by their loss of antigen-independent cytotoxic activity and IFN-γ production in response to innate-like stimulation with IL-12 + IL-18. Remarkably, as previously reported for IL-4 production by iNKT cells, both quantitative and functional deficiencies of innate CD8(+) T cells were at least partially corrected in patients having achieved complete cytogenetic remission following tyrosine kinase inhibitor therapy. Finally, direct correlation between the functional potential of innate CD8(+) T and iNKT cells was found when considering all healthy donors and CML patients in diagnosis and remission, in accordance with the iNKT cell-dependent generation of innate CD8(+) T cells reported in mice. All in all, our data demonstrate that CML is associated with deficiencies of innate CD8(+) T cells that are restored upon remission, thereby suggesting their possible contribution to disease control. More generally, our study strongly supports the existence of an innate iNKT/innate CD8(+) T-cell axis in humans and reveals its potential contribution to the restoration of tumor immune surveillance.

Pioglitazone together with imatinib in chronic myeloid leukemia: A proof of concept study

BACKGROUND

We recently reported that peroxisome proliferator‐activated receptor γ agonists target chronic myeloid leukemia (CML) quiescent stem cells in vitro by decreasing transcription of STAT5. Here in the ACTIM phase 2 clinical trial, we asked whether pioglitazone add‐on therapy to imatinib would impact CML residual disease, as assessed by BCR‐ABL1 transcript quantification.

METHODS

CML patients were eligible if treated with imatinib for at least 2 years at a stable daily dose, having yielded major molecular response (MMR) but not having achieved molecular response 4.5 (MR^4.5) defined by BCR‐ABL1/ABL1^IS RNA levels ≤ 0.0032%. After inclusion, patients started pioglitazone at a dosage of 30 to 45 mg/day in addition to imatinib. The primary objective was to evaluate the cumulative incidence of patients having progressed from MMR to MR^4.5 over 12 months.

RESULTS

Twenty‐four patients were included (age range, 24‐79 years). No pharmacological interaction was observed between the drugs. The main adverse events were weight gain in 12 patients and a mean decrease of 0.4 g/dL in hemoglobin concentration. The cumulative incidence of MR^4.5 was 56% (95% confidence interval, 37%‐76%) by 12 months, despite a wide range of therapy duration (1.9‐15.5 months), and 88% of 17 evaluable patients who were still on imatinib reached MR^4.5 by 48 months. The cumulative incidence of MMR to MR^4.5 spontaneous conversions over 12 months was estimated to be 23% with imatinib alone in a parallel cohort of patients.

CONCLUSION

Pioglitazone in combination with imatinib was well tolerated and yielded a favorable 56% rate. These results provide a proof of concept needing confirmation within a randomized clinical trial (EudraCT 2009‐011675‐79). Cancer 2017;123:1791–1799. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Pioglitazone is a peroxisome proliferator‐activated receptor gamma agonist that is able to target quiescent chronic myeloid leukemia stem cells. The combination of imatinib and pioglitazone was well tolerated in vivo and induced a cumulative incidence of conversion to molecular response 4.5 (MR4.5) of 56% by 12 months in 24 CML patients who had a major molecular response under imatinib alone.

Associations between gender, disease features and symptom burden in patients with myeloproliferative neoplasms: an analysis by the MPN QOL International Working Group

The myeloproliferative neoplasms, including polycythemia vera, essential thrombocythemia and myelofibrosis, are distinguished by their debilitating symptom profiles, life-threatening complications and profound impact on quality of life. The role gender plays in the symptomatology of myeloproliferative neoplasms remains under-investigated. In this study we evaluated how gender relates to patients' characteristics, disease complications and overall symptom expression. A total of 2,006 patients (polycythemia vera=711, essential thrombocythemia=830, myelofibrosis=460, unknown=5) were prospectively evaluated, with patients completing the Myeloproliferative Neoplasm-Symptom Assessment Form and Brief Fatigue Inventory Patient Reported Outcome tools. Information on the individual patients' characteristics, disease complications and laboratory data was collected. Consistent with known literature, most female patients were more likely to have essential thrombocythemia (48.6% versus 33.0%; P<0.001) and most male patients were more likely to have polycythemia vera (41.8% versus 30.3%; P<0.001). The rate of thrombocytopenia was higher among males than females (13.9% versus 8.2%; P<0.001) and males also had greater red-blood cell transfusion requirements (7.3% versus 4.9%; P=0.02) with shorter mean disease duration (6.4 versus 7.2 years, P=0.03). Despite there being no statistical differences in risk scores, receipt of most therapies or prior complications (hemorrhage, thrombosis), females had more severe and more frequent symptoms for most individual symptoms, along with overall total symptom score (22.8 versus 20.3; P<0.001). Females had particularly high scores for abdominal-related symptoms (abdominal pain/discomfort) and microvascular symptoms (headache, fatigue, insomnia, concentration difficulties, dizziness; all P<0.01). Despite complaining of more severe symptom burden, females had similar quality of life scores to those of males. The results of this study suggest that gender contributes to the heterogeneity of myeloproliferative neoplasms by influencing phenotypic profiles and symptom expression.

Uncoupling of the Hippo and Rho pathways allows megakaryocytes to escape the tetraploid checkpoint

Megakaryocytes are naturally polyploid cells that increase their ploidy by endomitosis. However, very little is known regarding the mechanism by which they escape the tetraploid checkpoint to become polyploid. Recently, it has been shown that the tetraploid checkpoint was regulated by the Hippo-p53 pathway in response to a downregulation of Rho activity. We therefore analyzed the role of Hippo-p53 pathway in the regulation of human megakaryocyte polyploidy. Our results revealed that Hippo-p53 signaling pathway proteins are present and are functional in megakaryocytes. Although this pathway responds to the genotoxic stress agent etoposide, it is not activated in tetraploid or polyploid megakaryocytes. Furthermore, Hippo pathway was observed to be uncoupled from Rho activity. Additionally, polyploid megakaryocytes showed increased expression of YAP target genes when compared to diploid and tetraploid megakaryocytes. Although p53 knockdown increased both modal ploidy and proplatelet formation in megakaryocytes, YAP knockdown caused no significant change in ploidy while moderately affecting proplatelet formation. Interestingly, YAP knockdown reduced the mitochondrial mass in polyploid megakaryocytes and decreased expression of PGC1α, an important mitochondrial biogenesis regulator. Thus, the Hippo pathway is functional in megakaryocytes, but is not induced by tetraploidy. Additionally, YAP regulates the mitochondrial mass in polyploid megakaryocytes.

EOMESODERMIN-EXPRESSING INNATE-LIKE CD8+ T CELLS IN HUMANS ARE IMPAIRED IN CHRONIC MYELOID LEUKEMIA PATIENTS AT DIAGNOSIS

Starting with our recent identification in healthy individuals of a new distinct CD8+ T cell subset harboring Eomes and exhibiting a marked “innate” (panKIR/NKG2A+) phenotype, we present here the first report on this unique T cell population in a physiopathological context, namely chronic myelogenous leukemia (CML), a clonal myeloproliferative disorder. The current first-line therapies for this hematopoietic malignancy are tyrosine kinase inhibitors such as Imatinib (IM). Knowing that the generation of innate Eomes-expressing CD8+ T cells in mice depends on PLZF-expressing NKT cells and that iNKT cells are functionally deficient in CML, we surmised that panKIR/NKG2A+Eomes+ CD8+ T cells could be altered during CML. Accordingly, in CML patients at diagnosis, the pool of blood KIR/NKG2A(+)Eomes(+) CD8(+) T cells was found to be severely reduced. Moreover, like for iNKT and NK cells, the functions of these innate-like CD8(+) T cells were impaired, as attested by their lost of potent antigen-independent cytotoxic activity and IFN-γ production in response to innate-like stimulation by IL-12+IL-18. Remarkably, both innate-like CD8(+) T cells and iNKT cells returned to normal after complete CML remission upon IM therapy, supporting evidence for an iNKT cell-dependent generation of circulating KIR/NKG2A+Eomes+ CD8+ T cells in CML patients, as in mice. Our study reveals a possible contribution of iNKT/innate-like CD8(+) T cells as a new innate immune axis to tumor control in CML.

Symptomatic Profiles of Patients With Polycythemia Vera: Implications of Inadequately Controlled Disease

Purpose

Polycythemia vera (PV) is a myeloproliferative neoplasm (MPN) associated with disabling symptoms and a heightened risk of life-threatening complications. Recent studies have demonstrated the effectiveness of JAK inhibitor therapy in patients with PV patients who have a history of prior hydroxyurea (HU) use (including resistance or intolerance), phlebotomy requirements, and palpable splenomegaly. We aimed to determine how these features contribute alone and in aggregate to the PV symptom burden.

Patients and Methods

Through prospective evaluation of 1,334 patients with PV who had characterized symptom burden, we assessed patient demographics, laboratory data, and the presence of splenomegaly by disease feature (ie, known HU use, known phlebotomy requirements, splenomegaly).

Results

The presence of each feature in itself is associated with a moderately high symptom burden (MPN symptom assessment form [SAF] total symptom score [TSS] range, 27.7 to 29.2) that persists independent of PV risk category. In addition, symptoms incrementally increase in severity with the addition of other features. Patients with PV who had all three features (PV-HUPS) faced the highest total score (MPN-SAF TSS, 32.5) but had similar individual symptom scores to patients with known HU use (PV-HU), known phlebotomy (PV-P), and splenomegaly (PV-S).

Conclusion

The results of this study suggest that patients with PV who have any one of the features in question (known HU use, known phlebotomy, or splenomegaly) have significant PV-associated symptoms. Furthermore, it demonstrates that many PV symptoms remain severe independent of the number of features present.

Evidence for eomesodermin-expressing innate-like CD8(+) KIR/NKG2A(+) T cells in human adults and cord blood samples

Polyclonal CD8(+) T cells, with a marked innate/memory phenotype, high eomesodermin (Eomes) expression, and the capacity to generate IFN-γ rapidly without prior exposure to antigen, have been described in mice. However, even though a pool of human CD8(+) T cells expressing killer Ig-like receptors (KIRs) was recently documented, the existence of a human equivalent of murine innate/memory CD8(+) T cells remains to be established. Here, we provide evidence for a population of KIR/NKG2A(+) CD8(+) T cells in healthy human adults sharing the same features, namely increased Eomes expression, prompt IFN-γ production in response to innate-like stimulation by IL-12+IL-18, and a potent antigen-independent cytotoxic activity along with a preferential terminally differentiated effector memory phenotype. None of the above functional characteristics applied to the KIR/NKG2A(-) fraction of the Eomes(+) CD8(+) T-cell population, thereby underlining the ability of KIR/NKG2A to distinguish between "innate/memory-like" and "conventional/memory" pools of CD8(+) T cells. Remarkably, KIR/NKG2A(+) Eomes(+) CD8(+) T cells with innate-like functions and a memory/terminally differentiated effector memory phenotype were also identified in human cord blood, suggesting that their development did not depend on cognate antigens. Taken together, our results support the conclusion that CD8(+) T cells co-expressing Eomes and KIR/NKG2A may represent a new, functionally distinct "innate/memory-like" subset in humans.

Nilotinib and peginterferon alfa-2a for newly diagnosed chronic-phase chronic myeloid leukaemia (NiloPeg): a multicentre, non-randomised, open-label phase 2 study

BACKGROUND

Nilotinib is now recommended for patients with newly diagnosed chronic myeloid leukaemia in chronic phase and leads to important rates of molecular response 4·5 log (MR(4·5)), allowing the prospect of therapy cessation. However, most patients do not reach this criterion and nilotinib is taken for lengthy periods, resulting in chronic or late-onset adverse events. Nilotinib combined with interferon might further increase rates of MR(4·5), avoid late side-effects, and allow therapy cessation. In a phase 2 trial we aimed to assess the feasibility, safety, and deep molecular response of the combination of nilotinib (600 mg daily) and peginterferon alfa-2a in newly diagnosed patients with chronic-phase chronic myeloid leukaemia (CML).

METHODS

In a non-randomised, open-label, phase 2 trial, we enrolled adult patients (age ≥18 years) without any organ failure who had BCR-ABL-positive, chronic-phase CML, at diagnosis. After a priming procedure with 90 μg per week of peginterferon alfa-2a alone for a month, we gave patients peginterferon alfa-2a 45 μg per week combined with nilotinib 600 mg daily until 24 months after interferon initiation. The primary endpoint was the cumulative incidence of MR(4·5) at 12 months after initiation of peginterferon alfa-2a. Data were analysed by a modified intention-to-treat principle. This trial is registered at the European Clinical Trials Database (EudraCT), number 2010-019786-28.

FINDINGS

Between March 24, 2011, and Sept 27, 2011, we enrolled 42 patients. One patient withdrew consent before receiving any study treatment so was excluded from analysis; 41 patients received treatment with peginterferon alfa-2a and nilotinib. At 12 months, seven (17%) patients had achieved MR(4·5). Haematological and hepatic adverse events were frequent-with grade 3-4 neutropenias occurring in ten (24%) patients, grade 3-4 thrombocytopenias occurring in ten (24%) patients, grade 3-4 cholestatic events occurring in seven (17%) patients, and grade 3-4 elevations in aspartate aminotransferase or alanine aminotransferase occurring in three (7% patients-particularly during the first 3 months. However, 30 (73%) patients remained on interferon therapy at 1 year. Three grade 3-4 cardiac events (7% of patients, all coronary stenoses) occurred at later timepoints.

INTERPRETATION

The combination of peginterferon alfa-2a resulted in good molecular responses in patients. Despite substantial toxic effects, most patients remained on the study drugs for more than a year. This combination should now be tested in a randomised controlled trial.

FUNDING

Novartis Pharma.

BCR-ABL-induced deregulation of the IL-33/ST2 pathway in CD34+ progenitors from chronic myeloid leukemia patients

Although it is generally acknowledged that cytokines regulate normal hematopoiesis in an autocrine/paracrine fashion, their possible role in chronic myelogenous leukemia (CML) and resistance to imatinib mesylate treatment remain poorly investigated. Here, we report that CD34(+) progenitors from patients with CML at diagnosis are selectively targeted by the cytokine/alarmin interleukin (IL)-33. Indeed, CML CD34(+) progenitors upregulate their cell surface expression of the IL-33-specific receptor chain ST2, proliferate and produce cytokines in response to IL-33, conversely to CD34(+) cells from healthy individuals. Moreover, ST2 overexpression is normalized following imatinib mesylate therapy, whereas IL-33 counteracts in vitro imatinib mesylate-induced growth arrest in CML CD34(+) progenitors via reactivation of the STAT5 pathway, thus supporting the notion that IL-33 may impede the antiproliferative effects of imatinib mesylate on CD34(+) progenitors in CML. Clinically, the levels of circulating soluble ST2, commonly considered a functional signature of IL-33 signaling in vivo, correlate with disease burden. Indeed, these elevated peripheral concentrations associated with a high Sokal score predictive of therapeutic outcome are normalized in patients in molecular remission. Finally, we evidenced a facilitating effect of IL-33 on in vivo maintenance of CD34(+) progenitors from patients with CML by using xenotransplant experiments in immunodeficient NOG mice, and we showed that engraftment of mouse BCR-ABL-transfected bone marrow progenitors was less efficient in IL-33-deficient mice compared with wild-type recipients. Taken together, our results provide evidence that IL-33/ST2 signaling may represent a novel cytokine-mediated mechanism contributing to CML progenitor growth and support a role for this pathway in CML maintenance and imatinib mesylate resistance.

Loss of major molecular response as a trigger for restarting tyrosine kinase inhibitor therapy in patients with chronic-phase chronic myelogenous leukemia who have stopped imatinib after durable undetectable disease

PURPOSE

More than half of patients with chronic-phase chronic myelogenous leukemia (CP-CML) in complete molecular response (CMR) experience molecular relapse after imatinib discontinuation. We investigated loss of major molecular response (MMR) as a criterion for resuming therapy.

PATIENTS AND METHODS

A multicenter observational study (A-STIM [According to Stop Imatinib]) evaluating MMR persistence was conducted in 80 patients with CP-CML who had stopped imatinib after prolonged CMR.

RESULTS

Median time from imatinib initiation to discontinuation was 79 months (range, 30 to 145 months);median duration of CMR before imatinib discontinuation was 41 months (range, 24 to 96 months); median follow-up after discontinuation was 31 months (range, 8 to 92 months). Twenty-nine patients (36%) lost MMR after a median of 4 months off therapy (range, 2 to 17 months). Cumulative incidence of MMR loss was estimated as 35% (95% CI, 25% to 46%) at 12 months and 36% (95% CI, 26% to 47%) at 24 months, whereas probability of losing CMR was higher. Fluctuation of BCR-ABL transcript levels below the MMR threshold (≥ two consecutive positive values) was observed in 31% of patients after imatinib discontinuation. Treatment-free remission was estimated as 64% (95% CI, 54% to 75%) at 12 and 24 months and 61% (95% CI, 51% to 73%) at 36 months. Median to time to second CMR was estimated as 7.3 months in re-treated patients.

CONCLUSION

Loss of MMR is a practical and safe criterion for restarting therapy in patients with CML with prolonged CMR.

Wolverines (Gulo gulo luscus) on the Rocky Mountain slopes: natural heterogeneity and landscape alteration as predictors of distribution

A species’ occurrence can be influenced by natural and anthropogenic factors; disentangling these is a precursor to understanding the mechanisms of distribution. Anthropogenic factors may be especially important at contracting range edges. We test this premise for wolverines (Gulo gulo luscus L., 1758) at the edge of their Rocky Mountain range in Alberta, Canada, a mosaic of natural heterogeneity and extensive landscape development. As wolverines have a suspected negative response to human activity, we hypothesized their occurrence on the Rockies’ slopes is predicted by a combination of natural and anthropogenic features. We surveyed wolverines at 120 sites along a natural and anthropogenic gradient using hair trapping and noninvasive genetic tagging. We used abundance estimation, generalized linear, and hierarchical models to determine whether abundance and occurrence was best predicted by natural land cover, topography, footprint, or a combination. Wolverines were more abundant in rugged areas protected from anthropogenic development. Wolverines were less likely to occur at sites with oil and gas exploration, forest harvest, or burned areas, even after accounting for the effect of topography. The relative paucity of wolverines in human-impacted portions of this range edge suggests that effective conservation requires managing landscape development, and research on the proximal mechanisms behind this relationship.

Efficacy and safety of pegylated-interferon α-2a in myelofibrosis: a study by the FIM and GEM French cooperative groups

Myeloproliferative neoplasm-related myelofibrosis is associated with cytopenic or proliferative phases, splenomegaly and constitutional symptoms. Few effective treatments are available and small series suggested that interferon could be an option for myelofibrosis therapy. We performed a retrospective study of pegylated-interferon α-2a (Peg-IFNα-2a) therapy in myelofibrosis. Sixty-two patients treated with Peg-IFNα-2a at 17 French and Belgian centres were included. Responses were determined based on the criteria established by the International Working Group for Myelofibrosis Research and Treatment. Mean follow-up was 26 months. Sixteen of 25 anaemic patients (64%) (eight concomitantly receiving recombinant erythropoietin) achieved a complete response and transfusion-independence was obtained in 5/13 patients (38·5%). Constitutional symptoms resolved in 82% of patients. All five leucopenic patients normalized their leucocyte counts, whereas a normal platelet count was obtained in 5/8 thrombocytopenic patients. Splenomegaly was reduced in 46·5% of patients, and complete resolution of thrombocytosis and leucocytosis were observed in 82·8% and 68·8% of patients, respectively. Side effects (mostly haematological) were mainly of grade 1-2. The only factor independently associated with treatment failure was a spleen enlargement of more than 6 cm below the costal margin. In conclusion, Peg-IFNα-2a induced high response rates with acceptable toxicity in a large proportion of patients with primary and secondary myelofibrosis, especially in early phases.

Bcr/Abl-induced deregulation of the IL-33/ST2 pathway in CD34(+) progenitors from chronic myeloid leukemia patients (P6284)

Although it is generally acknowledged that cytokines regulate normal hematopoiesis in an autocrine/paracrine fashion, their possible role in chronic myeloid leukemia (CML) and resistance to imatinib mesylate (IM) treatment remain poorly investigated. Here, we report that CD34(+) progenitors from CML patients at diagnosis are selectively targeted by the cytokine/alarmin IL-33. Indeed, CML CD34(+) progenitors up-regulate their cell surface expression of the IL-33-specific receptor chain ST2, proliferate and produce cytokines in response to IL-33, conversely to CD34(+) cells from healthy individuals. Moreover, ST2 overexpression is normalized following IM therapy, while IL-33 counteracts in-vitro IM-induced growth arrest in CML CD34(+) progenitors via re-activation of the STAT5 pathway. Clinically, CML is associated with high circulating levels of soluble ST2, commonly used as a functional signature of IL-33 signaling in vivo. Taken together, our results support the hypothesis that the IL-33/ST2 pathway facilitates Bcr/Abl-induced leukemogenesis and contributes to IM resistance in CML patients.

Identification of eomesodermin-expressing innate-like T cells in adult humans (P1436)

Innate-like CD8(+) T cells have been recently described in mice. These cells express NK cell markers with high levels of the transcription factor Eomesodermin (Eomes(br)) and rapidly produce IFN-γ in response to IL-12 and IL-18 stimulation without previous exposure to antigen. To date, only a single study in human has investigated Eomes(br) innate-like T cells which were found in small numbers in fetal spleen and cord blood. In mice, their generation depends on IL-4 expressing invariant NKT (iNKT) cells. Here, we identified a similar subset of T cells, mainly CD8(+) T cells, in PBMC from healthy adult individuals that have increased expression of Eomes. They harbor a marked innate phenotype as attested by a higher frequency of perforin(+) and NK-like (CD158(+) and/or CD159(+)) cells, as compared with total T cells. Likewise, they preferentially produce IFN-γ in response to stimulation by IL-12 and IL-18. Remarkably, in patients with chronic myeloid leukemia (CML), a disease known to be associated with a deficiency in IL-4 expression by iNKT cells, the size of Eomes(br) innate-like T cells is severely impaired. and they have lost the capacity to produce IFN-γ after stimulation with IL-12 and IL-18. These impairments together with the deficiency in IL-4 expression by iNKT cells are corrected in CML patients having achieved complete remission. Altogether, these results demonstrate the presence of Eomes expressing innate-like T cells in adult human peripheral blood.

Interlaboratory comparison of dicentric chromosome assay using electronically transmitted images

The bottleneck in data acquisition during biological dosimetry based on a dicentric assay is the need to score dicentrics in a large number of lymphocytes. One way to increase the capacity of a given laboratory is to use the ability of skilled operators from other laboratories. This can be done using image analysis systems and distributing images all around the world. Two exercises were conducted to test the efficiency of such an approach involving 10 laboratories. During the first exercise (E1), the participant laboratories analysed the same images derived from cells exposed to 0.5 and 3 Gy; 100 images were sent to all participants for both doses. Whatever the dose, only about half of the cells were complete with well-spread metaphases suitable for analysis. A coefficient of variation (CV) on the standard deviation of ∼15 % was obtained for both doses. The trueness was better for 3 Gy (0.6 %) than for 0.5 Gy (37.8 %). The number of estimated doses classified as satisfactory according to the z-score was 3 at 0.5 Gy and 8 at 3 Gy for 10 dose estimations. In the second exercise, an emergency situation was tested, each laboratory was required to score a different set of 50 images in 2 d extracted from 500 downloaded images derived from cells exposed to 0.5 Gy. Then the remaining 450 images had to be scored within a week. Using 50 different images, the CV on the estimated doses (79.2 %) was not as good as in E1, probably associated to a lower number of cells analysed (50 vs. 100) or from the fact that laboratories analysed a different set of images. The trueness for the dose was better after scoring 500 cells (22.5 %) than after 50 cells (26.8 %). For the 10 dose estimations, the number of doses classified as satisfactory according to the z-score was 9, for both 50 and 500 cells. Overall, the results obtained support the feasibility of networking using electronically transmitted images. However, before its implementation some issues should be elucidated, such as the number and resolution of the images to be sent, and the harmonisation of the scoring criteria. Additionally, a global website able to be used for the different regional networks, like Share Points, will be desirable to facilitate worldwide communication.