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Resume Contexte Le Centre d’investigations cliniques de l’Hopital Saint-Louis (CIC-1427) est une structure dediee qui accueille des patients inclus dans des essais cliniques essentiellement de phases precoces (premiere administration chez l’homme, phases I et II). Ces patients sont accueillis dans des locaux autorises et valides par l’Agence regionale de sante (ARS). En mars 2020, face a la pandemie de la COVID-19 et aux mesures de confinement national de la population decidees, par le gouvernement francais, le CIC-1427 a du adapter rapidement ses procedures de fonctionnement pour assurer la securite des patients et de son personnel. Objectif Assurer une prise en charge optimale des patients inclus dans les essais cliniques de phases precoces, tout en respectant les bonnes pratiques cliniques (BPC) et les bonnes pratiques professionnelles des CIC (BPP des CIC), les exigences des promoteurs de chaque protocole, la securite des patients et du personnel multidisciplinaire (infirmiers, aide-soignants [AS], assistants de recherche clinique [ARC], coordonnateur d’etudes cliniques [CEC]), chefs de projets, cadre de sante et medecins investigateurs), dans le contexte de la crise sanitaire liee a la COVID-19. Methodes et resultats De par son activite, necessitant des tâches en presentiel, chaque personnel de l’equipe specialisee en recherche clinique du CIC-1427 a du adapter son activite quotidienne aux contraintes de la crise sanitaire. De nouvelles procedures specifiques ont ete rapidement elaborees, pour faire face a la pandemie. La plupart des visites medicales sur site ont ete remplacees par des teleconsultations avec bilans biologiques dans les laboratoires de proximite, les « remote monitoring » ont remplace les visites de monitoring sur site, les traitements ont ete envoyes au domicile de chaque patient via des coursiers apres accord des CPP (Comite de protection des personnes) de chaque protocole. Les visites indispensables ont pu etre maintenues sur site grâce a l’implication sans faille de notre equipe soignante et sous condition de mise en place d’un protocole sanitaire adapte. Conclusion Grâce a l’implication de l’ensemble de notre equipe de recherche multidisciplinaire, et malgre les difficultes rencontrees, chaque patient a pu beneficier d’un suivi personnalise et poursuivre son traitement protocolaire. Les procedures mises en place ont egalement permis la collecte d’un maximum de donnees de securite et d’efficacite pour les promoteurs des essais cliniques et le respect des bonnes pratiques reglementaires. L’ensemble de ces mesures prises dans le contexte de l’urgence sanitaire, lors de la premiere vague epidemique, ont permis d’aborder plus sereinement la suite de l’epidemie.

Introduction Les maladies auto-immunes et inflammatoires (MAI) sont associees a un sur-risque de survenue de neoplasies myeloproliferatives (NMP) [1] . Chez les patients presentant un syndrome myelodysplasique (SMD) ou une leucemie myelomonocytaire chronique (LMMC), les mutations des regulateurs epigenetiques TET2 et IDH1/2 etaient significativement plus frequentes chez les patients porteurs de MAI comparativement a une cohorte temoin de patients SMD/LMMC sans MAI [2] . Dans le contexte des NMP, le phenotype des MAI associees et leur statut mutationnel ont ete peu decrits. Les objectifs de notre etude etaient de decrire les caracteristiques cliniques et genetiques des patients presentant une NMP avec une MAI et d’evaluer leur impact pronostique. Patients et Methodes Dans notre centre, 1541 patients ont ete diagnostiques d’une NMP selon les criteres OMS, entre janvier 2011 et janvier 2021. Des analyses moleculaires par sequencage haut debit (NGS) ciblant un panel de 36 genes mutes dans les NMP ont ete realisees pour 998 d’entre eux, au diagnostic ou durant le suivi. Tous les cas de MAI ont ete revus par un interniste et les diagnostics evalues selon les criteres internationaux correspondants. Les diagnostics de MAI post-interferon ont ete exclues. Resultats Notre cohorte comprenait 522 (34 %) polyglobulie de Vaquez (PV), 709 (46 %) thrombocytemie essentielle (TE) et 229 (15 %) myelofibrose primitive (MFP). Cent (6.6 %) patients presentaient une MAI associee et les 1441 patients restants ont constitue notre population temoin. L’âge median de nos patients dans la cohorte globale etait de 54 ans [IQR 40.4–63.2] et il y avait une predominance de femmes dans le groupe avec MAI associee (66 (66 %) versus 769 (53 %), p = 0.019). Il n’y avait pas de difference significative entre les 2 groupes concernant les sous-types de NMP, les mutations « driver » (JAK2, MPL et CALR) ou encore l’hemogramme au diagnostic des NMP. L’incidence d’episodes thrombotiques ou hemorragiques etait aussi similaire dans les 2 groupes (44 (44 %) versus 564 (39 %), p = 0.356). Le diagnostic de MAI etait anterieur a celui de NMP dans 34 % des cas, concomitant dans 12 % et ulterieur dans 31 %. Sur les 100 MAI, 45 etait des maladies auto-immunes specifiques d’organe, principalement des thyroidites auto-immunes, 13 rhumatismes inflammatoires chroniques, 9 connectivites, 8 dermatoses inflammatoires, 7 vascularites et 18 inclasses. Au total, 70 % des maladies auto-immunes remplissaient leurs criteres de classification. Parmi les patients ayant beneficie d’une analyse moleculaire, 62 % avaient une mutation additionnelle a la mutation « driver ». Les mutations de TET2 etaient plus frequemment retrouvees chez les patients avec une MAI associee (24 (34 %) versus 205 (22 %), OR = 1.84 95 %CI [1.08–3.07], p = 0.028), mais elle n’etait pas associee a un sous-type de MAI particulier. Il existait une tendance a une surrepresentation des mutations IDH1/2 dans le groupe MAI (4 (6 %) versus 27 (3 %), OR = 2.02 95 %CI[0.74–5.51], p = 0.27), bien que non statistiquement significatif. Nous n’avons pas retrouve d’autres mutations de facteurs epigenetiques, de transcription, d’epissage ou de mutation a haut risque moleculaire, associees preferentiellement au groupe NMP avec MAI associee. Apres un suivi median de 8.3 ans dans la cohorte globale, la presence d’une MAI n’avait pas d’impact defavorable sur la survie globale (p = 0.82), ni sur la survenue de myelofibrose secondaire (p = 0.98), ou la survenue de transformation en SMD/LAM (p = 0.53). Conclusion Au sein de cette large cohorte retrospective de NMP decrite sur le plan clinique et moleculaire, la prevalence de MAI est de 6.6 %, similaire a celle de la population generale. Une sur-prevalence de la mutation de TET2 a ete mise en evidence dans le groupe de patients presentant une MAI associee. Nos resultats suggerent une susceptibilite genetique commune, secondaire a la mutation de regulateur epigenetique comme TET2, potentiellement responsable des phenotypes inflammatoire et hematologique.

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Contexte Le Centre d’investigations cliniques de l’Hôpital Saint-Louis (CIC-1427) est une structure dédiée qui accueille des patients inclus dans des essais cliniques essentiellement de phases précoces (première administration chez l’homme, phases I et II). Ces patients sont accueillis dans des locaux autorisés et validés par l’Agence régionale de santé (ARS). En mars 2020, face à la pandémie de la COVID-19 et aux mesures de confinement national de la population décidées, par le gouvernement français, le CIC-1427 a dû adapter rapidement ses procédures de fonctionnement pour assurer la sécurité des patients et de son personnel. Objectif Assurer une prise en charge optimale des patients inclus dans les essais cliniques de phases précoces, tout en respectant les bonnes pratiques cliniques (BPC) et les bonnes pratiques professionnelles des CIC (BPP des CIC), les exigences des promoteurs de chaque protocole, la sécurité des patients et du personnel multidisciplinaire (infirmiers, aide-soignants [AS], assistants de recherche clinique [ARC], coordonnateur d’études cliniques [CEC]), chefs de projets, cadre de santé et médecins investigateurs), dans le contexte de la crise sanitaire liée à la COVID-19. Méthodes et résultats De par son activité, nécessitant des tâches en présentiel, chaque personnel de l’équipe spécialisée en recherche clinique du CIC-1427 a dû adapter son activité quotidienne aux contraintes de la crise sanitaire. De nouvelles procédures spécifiques ont été rapidement élaborées, pour faire face à la pandémie. La plupart des visites médicales sur site ont été remplacées par des téléconsultations avec bilans biologiques dans les laboratoires de proximité, les « remote monitoring » ont remplacé les visites de monitoring sur site, les traitements ont été envoyés au domicile de chaque patient via des coursiers après accord des CPP (Comité de protection des personnes) de chaque protocole. Les visites indispensables ont pu être maintenues sur site grâce à l’implication sans faille de notre équipe soignante et sous condition de mise en place d’un protocole sanitaire adapté. Conclusion Grâce à l’implication de l’ensemble de notre équipe de recherche multidisciplinaire, et malgré les difficultés rencontrées, chaque patient a pu bénéficier d’un suivi personnalisé et poursuivre son traitement protocolaire. Les procédures mises en place ont également permis la collecte d’un maximum de données de sécurité et d’efficacité pour les promoteurs des essais cliniques et le respect des bonnes pratiques réglementaires. L’ensemble de ces mesures prises dans le contexte de l’urgence sanitaire, lors de la première vague épidémique, ont permis d’aborder plus sereinement la suite de l’épidémie.

Myeloproliferative neoplasms (MPNs) are the most frequent underlying causes of splanchnic vein thromboses (SVTs). MPN patients with SVTs (MPN-SVT) often have a unique presentation including younger age, female predominance, and low Janus kinase 2 (JAK2) mutation allele burden. This study aimed at identifying risk factors for adverse hematologic outcomes in MPN-SVT patients. We performed a retrospective study of a fully characterized cohort of MPN-SVT patients. The primary outcome was the incidence of evolution to myelofibrosis, acute leukemia, or death. Eighty patients were included in the testing cohort. Median follow-up was 11 years. Most of the patients were women with a mean age of 42 years and a diagnosis of polycythemia vera. The primary outcome was met in 13% of the patients and was associated with a JAK2V617F allele burden ≥50% (odds ratio [OR], 14.7) and presence of additional mutations in genes affecting chromatin/spliceosome (OR, 9). We identified high-risk patients (29% of the cohort) as those harboring at least 1 molecular risk factor: JAK2-mutant allele burden ≥50%, presence of chromatin/spliceosome/TP53 mutation. High-risk patients had worse event-free survival (81% vs 100%; P = .001) and overall survival at 10 years (89% vs 100%; P = .01) than low-risk patients. These results were confirmed in an independent validation cohort of 30 MPN-SVT patients. In conclusion, molecular profiling identified MPN-SVT patients with dismal outcome. In this high-risk population, a disease-modifying therapy should be taken into consideration to minimize the probability of transformation.

Polycythemia vera is characterized by the acquisition of the JAK2V617F mutation. Recommended treatments include hydroxyurea and interferon-alpha. Several groups have reported a reduction in the JAK2 mutant allele burden in interferon-treated patients, but significance of this observation is questioned. We characterized the activity of ropeginterferon alpha-2b, a novel form of interferon-alpha recently shown to be safe and efficacious in polycythemia vera. Ropeginterferon was able to inhibit the proliferation of the HEL, UKE-1, and UT-7 JAK2-mutant cell lines while sparing JAK2-wild-type UT-7 and normal CD34+ cells growth. In vitro treatment of erythroid progenitors derived from PV patients showed that ropeginterferon could considerably inhibit the growth of endogenous erythroid colonies, a hallmark of polycythemia vera. Finally, we could study in sequential samples the clonal architecture of erythroid progenitors derived from patients included in a randomized study comparing hydroxyurea to ropeginterferon. After 1 year of treatment with ropeginterferon, the ratio of JAK2-mutated to wild-type colonies grown from bone marrow progenitors was reduced by 64%, compared to 25% in patients receiving hydroxyurea. This study shows that ropeginterferon has a potent targeted activity against JAK2-mutant cells and is able to drastically reduce the proportion of malignant progenitors in patients treated with this drug.

Introduction: Although myeloproliferative neoplasms (MPN) are driven by three mutually exclusive driver mutations (JAK2, CALR and MPL), targeted deep sequencing studies identified multiple additional somatic mutations potentially impacting MPN evolution. Presence of a high molecular risk (HMR: ASXL1, EZH2, SRSF2 and IDH1/2) or a TP53 mutations has been associated with adverse prognosis. However, to date, the effect of clonal evolution (CEv) on MPN patients' outcome has not been evaluated, as most of the studies assessed mutational-based prognosis stratification from single baseline molecular genotyping. The objective of our study was to describe the clinical and molecular characteristics of patients with CEv in a large cohort of MPN patients and analyze its impact on patients' outcome. Methods: A total of 1538 consecutive patients were diagnosed with MPN according to WHO criteria and followed in our hospital between January 2011 and January 2021. From this large retrospective cohort, we included in this study 446 patients who had at least 2 molecular analyses during the chronic phase of MPN, performed at diagnosis and/or during follow-up using next generation sequencing (NGS), targeting a panel of 36 genes involved in myeloid malignancies. Significant variants were retained with a sensitivity of 1%. CEv was defined as the acquisition of a new additional non-driver mutation between baseline and subsequent NGS evaluation. Statistical analyses were performed using the STATA software (STATA 17.0 for Mac Corporation, College Station, TX). Results: The median age at MPN diagnosis in our whole cohort was 51 years [IQR 41 - 60]. Our cohort included 167 (37%), 205 (46%) and 64 (14%) patients with polycythemia vera, essential thrombocythemia and primary myelofibrosis (MF) respectively. With a median interval of 1.6 years [IQR 1.0 - 2.8] between the first and the second NGS analysis in the whole cohort, CEv occurred in 128 patients (29%). Patients with CEv were significantly older compared to patients without CEv (n=318) (p=0.03). MPN diagnosis, the type of driver mutation and complete blood counts at MPN diagnosis did not differ between the 2 groups. Eighty-one (63%) and 198 (62%) patients with or without CEv respectively had at least one additional non-driver mutation at baseline NGS (p=0.59), while the rate of HMR (n=25 (20%) versus n=79 (25%)) or TP53 (n=7 (5%) versus n=20 (6%)) mutations at baseline NGS did not differ between the 2 groups. Thirty six out of 128 (28%) of patients with CEv had more than 1 acquired mutation. Most recurrently acquired mutations involved the epigenetic regulators TET2 and DNMT3A that were mutated in respectively 33% and 25% of patients with CEv (Figure 1A). Moreover, 38% of CEv patients acquired HMR (ASXL1 (14%), EZH2 (6%), SRSF2 (3%), IDH1/2 (2%)) or TP53 (13%) mutations. After a median follow up of 10.8 years [IQR 6.6 - 17.2] in the whole cohort representing a total of 5635 patient years, 32 (7%) patients died, and 11 (2.5%) and 11 (2.5%) patients with at least 2 NGS performed during MPN chronic phase transformed respectively into secondary MF or myelodysplastic syndrome / acute myeloid leukemia (MDS/AML). Interestingly, CEv (HR 11.27, 95%CI [5.09; 24.96], p Conclusion: Our study on a large retrospective clinically and biologically annotated real-life cohort of MPN patients with long-term follow up shows that CEv independently adversely impacts OS, MDS/AML and secondary MF free survivals. CEv occurred in a clinically relevant proportion of MPN patients (28%) and was associated with patients' age. Acquired mutations mainly involved epigenetic regulators, HMR and TP53 genes. These results suggest that serial molecular monitoring using NGS could be routinely implemented in MPN patients follow up, to assess more accurately disease evolution and potentially update therapeutic management. Figure 1 Figure 1. Disclosures Raffoux: PFIZER: Consultancy; CELGENE/BMS: Consultancy; ABBVIE: Consultancy; ASTELLAS: Consultancy. Kiladjian: Novartis: Membership on an entity's Board of Directors or advisory committees; Taiho Oncology, Inc.: Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; PharmaEssentia: Other: Personal fees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees. Benajiba: Gilead: Research Funding; Pfizer: Research Funding.

Introduction: Auto-immune and Inflammatory Diseases (AID) have been associated with myeloproliferative neoplasms (MPN) in a large population-based study (Kristinsson et al. Haematologica 2010). In myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML), epigenetic regulators TET2 and IDH1/2 were more frequently mutated in patients with AID, suggesting potentially common pathogenesis pathways (Zhao et al. Leukemia 2021). However, in the context of MPN, AID specific features remain poorly characterized, and no study has reported to date the mutational landscape of MPN patients with AID. The objectives of our study were to describe the clinical and molecular characteristics of MPN patients with associated AID and evaluate its impact on patient's outcome. Methods: A total of 1541 patients were diagnosed with MPN according to WHO criteria between January 2011 and January 2021 in our center, of whom 998 had a molecular analysis by next generation sequencing (NGS) targeting a panel of 36 genes involved in MPN, performed at diagnosis and/or during follow-up. AID diagnosis was based on international criteria, and all cases have been reviewed by internal medicine experts. Patients with AID induced by interferon-alpha treatment were not included. Results: The median age of our whole cohort was 51.3 years IQR[40.4-63.2]. Our cohort included 522 (34%), 709 (46%) and 229 (15%) diagnosis of polycythemia vera (PV), essential thrombocytemia (ET) and primary myelofibrosis (MF) respectively. A total of 100 patients (6.6%) had AID and were compared to the remaining 1441 MPN patients without AID. There were more females (66 (66%) versus 769 (53%), p=0.019) within the AID group compared to non-AID patients. MPN subtype, driver mutation, complete blood counts at diagnosis did not differ between the two groups. Occurrence of thrombosis and hemorrhage episodes did not vary either (44 (44%) versus 564 (39%), p=0.356). AID diagnosis was prior to MPN in 34% of cases, concomitant in 12% and posterior in 31% of cases. AID diagnosis included 45 (45%) organ-specific AID (mainly autoimmune thyroiditis, n=34), 13 (13%) inflammatory arthritis, 9 (9%) connective tissue diseases, 8 (8%) inflammatory dermatosis, 7 (7%) systemic vasculitis and 18 (18%) unclassified AID (Figure 1A). The AID fulfilled the required classification criteria in 70 (70%) cases, while complete criteria were not reached in 30 (30%) cases. The median interval of time between MPN diagnosis and NGS was 7.2 years IQR[2.1-13.3] in the whole cohort. Among patients with available molecular analysis, 44 (62%) and 571 (62%) patients had at least one additional non-driver mutated gene in the AID and control groups respectively. Interestingly, TET2 mutations were more frequent in MPN patients with AID (24 (34%) versus 205 (22%), OR=1.84 95%CI[1.08-3.07], p=0.028, Fig 1B). The prevalence of TET2 mutations did not significantly differ between the AID categories. When focusing on IDH1/2 mutations, as they act on the same biological epigenetic pathway as TET2, IDH1/2 mutations were more frequent in the AID cohort although not statistically significant (4 (6%) versus 27 (3%), OR=2.02 95%CI[0.74-5.51], p=0.27). No other mutations including other epigenetic factors, splicing regulators, transcription factors or high molecular risk mutations, were significantly associated with AID. After a median follow up of 8.3 years IQR[3.7-14.3] in the whole cohort, 10 (10%) and 122 (8%) patients died in the AID and control groups respectively. The presence of AID did not impact overall survival (p=0.82), secondary myelofibrosis free (p=0.98) or MDS/AML transformation free (p=0.53) survivals. Conclusion Our study reports on a large retrospective clinically and molecularly annotated cohort the prevalence of AID in MPN patients (6.6%). This prevalence did not differ from that of the general population. Interestingly, our data emphasize a high prevalence of TET2 mutations in patients with both AID and MPN, compared to MPN patients without AID. Although other studies are warranted to better define the causal relationship between MPN and AID, our results may suggest a common pathophysiology as it has been proposed in MDS patients, based on shared genetic susceptibilities with mutations in TET2 that could occur within early hematopoietic progenitors and give rise to both the inflammatory phenotype and myeloid malignancy. DE and LPZ contributed equally to this work. Figure 1 Figure 1. Disclosures Fenaux: Celgene/BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Syros Pharmaceuticals: Honoraria. Ades: Novartis: Honoraria; Takeda: Honoraria; Abbvie: Honoraria; JAZZ: Honoraria; Celgene: Honoraria, Research Funding. Raffoux: PFIZER: Consultancy; CELGENE/BMS: Consultancy; ABBVIE: Consultancy; ASTELLAS: Consultancy. Kiladjian: Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Taiho Oncology, Inc.: Research Funding; PharmaEssentia: Other: Personal fees. Benajiba: Pfizer: Research Funding; Gilead: Research Funding.

Background: Although patients with MPN may achieve complete hematological remission (CHR) with cytoreductive therapy (CRT), lifelong treatment represents a major burden for these chronically ill patients. IFN has emerged as a major MPN therapy thought to positively alter the natural history of MPN and appears to be the only drug that can provide long-term CHR after discontinuation in some patients (Hasselbalch HC et al., Seminars in Immunopathology, 2019). In this study, we aimed to identify clinical and molecular factors associated with long-term CHR after IFN treatment discontinuation and to compare clinical outcome of patients who discontinued therapy, to patients who continued IFN treatment despite achieving a CHR. Methods: All MPN patients followed between January 2000 and May 2020 in our institution who received at least 3 months of IFN were included. Logistic regression analysis was performed to identify variables associated with long-term CHR after discontinuation. Cumulative incidence of relapse was calculated from time of IFN discontinuation, considering death without relapse as a competitive event. Overall survival (OS) and thrombotic/hemorrhagic events free survival (EFS) curves were estimated using the Kaplan-Meier method and compared by cause-specific hazard Cox models. Results: 381 patients treated with IFN were included in the study. Median age at MPN diagnosis was 44 years [interquartile range: 33-54]. 171 had polycythemia vera (PV), 169 essential thrombocythemia (ET) and 34 primary myelofibrosis (PMF). JAK2V617F was the most frequent driver mutation (78.8% of patients), while CALR and MPL were mutated in 15.5%, and 2.9% of patients respectively. Median driver variant allele frequency (VAF) at time of IFN therapy initiation was 34% [12; 51]. Reasons to start IFN included age younger than 50 years in 44.9%, intolerance/resistance to previous therapies in 17.8% or pregnancy in 1.8% patients. CHR was achieved with IFN in 77.2% of patients. After a median follow-up of 72.4 months [28.4; 119.7] from IFN initiation, 131 patients were still on IFN treatment, while 250 patients had discontinued therapy. No significant difference was observed between continued and discontinued IFN patients in terms of MPN subtype, initial clinical, biological or molecular characteristics. Reasons for discontinuation were toxicity in 128 (50.4%), prolonged hematological CHR in 76 (29.9%), failure in 16 (6.3%) and other in 30 (11.8%) patients. At time of IFN discontinuation, 170 (66.9%) patients were in CHR and the median driver mutation VAF was 12% [3; 35]. Of note, IFN was re-introduced in 61 patients who lost CHR with a second CHR rate of 83.6%, arguing for the absence of development of IFN resistance in post-discontinuation relapses. In multivariate logistic regression analysis, stopping for prolonged CHR (OR 3.52, 95%CI [1.18; 10.56], p=0.024) was associated with a higher CHR without CRT rate, while VAF ≥ 10% at time of IFN discontinuation (OR 0.26, 95%CI [0.1; 0.65], p=0.004) was associated with lower long-term CHR without CRT. Accordingly, VAF ≥ 10% at time of IFN discontinuation (HR 3.06 [1.59; 5.90], p=0.001) was independently associated with a higher cumulative incidence of relapse after IFN discontinuation (Figure A). Driver VAF at IFN discontinuation time was available for 117 patients. 53 patients (45.3%) had a driver VAF < 10% at IFN discontinuation. Finally, we compared discontinued IFN patients who stopped IFN for CHR (n=76) to patients who obtained CHR and are still on IFN therapy (n=116). Hematological transformation could not be evaluated due to very low incidence of events: 2 patients from each group progressed to myelofibrosis while leukemic progression was only observed in 1 patient. Importantly, OS (HR 0.23, 95%CI [0.5; 1.14], p=0.07) and EFS (HR 0.53, 95%CI [0.19; 1.45], p=0.217) were not significantly different between patients who discontinued and those who continued IFN. Conclusion: Overall, our study demonstrates that IFN discontinuation represents a safe strategy in MPN patients who achieved CHR, and particularly in patients with a driver VAF lower than 10% at time of discontinuation. Importantly, relapsed patients did not develop IFN resistance. Our data contributes to set the frame for future clinical trials evaluating the possibility of IFN treatment holidays in good responding MPN patients. Disclosures Benajiba: Gilead Foundation: Research Funding. Kiladjian:Abbvie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees.

Introduction: Ruxolitinib (RUX) is a JAK 1/2 inhibitor approved for the treatment of intermediate and high-risk primary or secondary MF. In addition to the intrinsic immune system modulation in MF patients, JAK inhibition exerts an immunosuppressive effect that may increase the risk of infections (Heine A et al., Blood, 2013). We aimed to investigate the association between treatment with RUX and infectious complications in a large monocentric cohort of MF patients. Methods: We performed a retrospective study including all patients diagnosed with primary, post-polycythemia vera or post-essential thrombocythemia MF in our MPN clinic between January 2011 and April 2020. Patients were considered RUX treated when exposed to treatment for at least two consecutive months. Clinical and biological characteristics at time of MF diagnosis and follow-up were collected from medical charts and electronic medical records. We used logistic regression models to identify specific infection subtypes associated with RUX treatment. Univariate and multivariate analysis assessing the impact of categorical and continuous variables on infectious events cumulative incidence were performed using Cox models. Results: 213 MF patients were included in the study. 114 (51.1%) patients were treated with RUX while 99 didn't receive RUX. Overall 102 patients exhibited a total of 231 infectious episodes. To search for factors associated with occurrence of infectious events, we evaluated the characteristics of MF, potential clinical and biological immune suppression factors (immunosuppressive treatment, prior non-MPN cancer, diabetes, hepatic/renal failure, neutropenia, lymphopenia, hypo-gammaglobulinemia, complement deficiency, prior history of infection), use of infection prophylaxis and RUX treatment using Cox models. In this cohort of MF patients, we found that RUX treatment (HR 5.91, 95%CI[3.48; 10.04], p 2 (HR 4.91, 95%CI[2.62; 9.21], p 41 (22.2%) and 16 (34.0%) infections were of grade 3-4, 61 (33.1%) and 19 (40.4%) required hospitalization, while 8 (4.3%) and 2 (4.2%) resulted in patients' death, in RUX treated and RUX naïve patients, respectively (all non-significantly different). Bacterial infections represented 48.0%, viral infections 16.0% and fungal infections 4.8% of the total infectious events. The most frequently infected sites were lungs/respiratory tract (28.1%) and skin/soft tissue (24.2%). RUX treatment was significantly associated with recurrence of HSV-1/2 or VZV (OR 7.57, 95%CI[1.01-57.30], p=0.050), and skin/soft tissue infections including the above herpetic recurrences (OR 3.33, 95%CI[1.13-9.78], p=0.029). 17 (14.9%) patients presented with HSV/VZV recurrence in the RUX treated group compared to 1 (1.0%) in non-treated patients (Figure B). We then thought to evaluate the impact of potential infections risk factors in RUX treated patients at time of treatment initiation in order to inform clinicians' therapeutic decision and follow-up guidance. For this analysis, we evaluated the characteristics of MF, potential clinical and biological immune suppression factors, treatment lines prior to RUX, dose and cumulative exposition to RUX. No clinical or biological factor was significantly associated with the overall risk of infectious events. However, hypo-gammaglobulinemia at time of RUX initiation was independently associated with HSV and/or VZV recurrence (HR 4.57, 95%CI[1.29-16.16], p=0.018). The higher rate of infections in RUX treated patients was associated with a not statistically significant trend towards shorter OS (HR 1.97, 95%CI[0.98; 3.94], p=0.055). Conclusion: This retrospective study shows an association between the occurrence of infectious complications and Ruxolitinib treatment in MF patients, and in particular, a higher incidence of HSV/VZV recurrence and skin/soft tissue infection. Patients with hypo-gammaglobulinemia at time of RUX initiation were at higher risk of HSV/VZV recurrence, suggesting that protein electrophoresis should be performed prior to treatment initiation and primary antiviral prophylaxis proposed to patients with hypo-gammaglobulinemia. Disclosures Rea: BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kiladjian:AbbVie: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees. Benajiba:Gilead Foundation: Research Funding.

Introduction: Myeloproliferative neoplasms (MPN) are the most frequent underlying causes of splanchnic vein thromboses (SVT), including Budd-Chiari syndrome (BCS), portal, splenic and mesenteric vein thromboses. This subgroup of MPN patients with SVT (MPN/SVT) has been shown to have distinct clinical and molecular features like younger age and lower JAK2V617Fmutant allele burden (the most predominant driver mutation in MPN/SVT patients) and are often considered as early stages of MPN. However, there is no study that has investigated the contribution of NGS data to the risk stratification of these MPN/SVT patients. Main objective of this study was to evaluate the impact of the presence of additional mutations to the driver mutation in the long term outcome of MPN patients with SVT. Patients and methods: Over the past 10 years, a total of 286 patients with SVT have been referred to our center for diagnostic assessment of an underlying MPN. Among them, a diagnosis of MPN (WHO criteria) was finally made in 197. Full molecular analyses by NGS was available in 61 of these MPN/SVT patients. The molecular profiling of patients was performed using a Capture-based custom NGS panel provided by Sophia Genetics. This panel comprised the coding sequences of 36 genes involved in MPN. Bioinformatics analysis was performed by Sophia Genetics, with a detection limit of variants set at 1%. We compared (i) MPN/SVT patients to our local cohort of 1371 MPN patients without SVT with full NGS data available; (ii) MPN/SVT patients with and without additional mutation to the driver mutation. Results: Median follow-up of MPN/SVT patients was 11 years, 62% were females, 33% had BCS and 67% portal vein thrombosis (Table 1). All patients received anticoagulants and 58 (95%) a cytoreductive therapy after the diagnosis of MPN. The type of MPN was polycythemia vera in 69%, essential thrombocythemia in 25% and myelofibrosis in 6%. The driver mutation was JAK2V617F in 57 (93%), and CALR mutation in 4 patients, respectively, and no patient had MPL mutation. By NGS, an additional mutation was identified in 27 (44%) patients, while 34 patients had only the driver mutation. The most frequent additional mutations were in TET2 (23%), ASXL1 (8%), DNMT3A (7%), IDH1/2 (5%), and LNK (5%) genes. EZH2, SRSF2 and TP53 mutations were found in only 1 patient, respectively. When compared to NGS data from 1371 MPN patients, there was no significant difference in the frequency of each additional mutation, except a slightly lower incidence of ASXL1 mutations in MPN/SVT patients (8% vs 23% in MPN patients, p=0.07). Of note, MPN/SVT patients were younger at MPN diagnosis than the control MPN cohort (44 vs 61 years, p< 10-5). Clinical characteristics were not significantly different between MPN/SVT patients with and without additional mutations (Table 1), including age at SVT or at MPN diagnosis, type of MPN or type of SVT, use of cytoreductive therapy, and median follow-up (11 years in both groups). In contrast, MPN/SVT patients with additional mutations had a significantly higher median JAK2V617F mutant allele burden than those with only JAK2 mutation (34% vs 11%, p=0.003, Figure 1); and higher risk of hematological transformation to myelofibrosis or acute leukemia or death (30% vs 6%, p=0.017). Only few patients experienced recurrence of thrombosis during follow up, with no difference according to the mutational profile (3 (11%) and 6 (17%) in patients with and without additional mutations, respectively). Conclusion: This is to our knowledge the first study assessing the impact of molecular abnormalities in the long term outcome of MPN/SVT patients showing a possible prognostic role for NGS data in these patients. Our results suggest that MPN/SVT patients with only JAK2V617F mutation and a low mutant allele burden (below 50%) are at low risk of adverse hematological outcome. In contrast, NGS may identify a group of patients with additional mutations at very high long term risk of unfavorable hematological evolution (30% transformation or death after 11 years of median follow-up, that is unexpected in such a young MPN population). In this group, a disease modifying therapy like interferon or other targeted therapies should be proposed when possible to reduce this risk of transformation. Disclosures Kiladjian: Novartis: Honoraria, Research Funding; Celgene: Consultancy; AOP Orphan: Honoraria, Research Funding.

Introduction Eculizumab (Ecu) is the standard treatment for paroxysmal nocturnal hemoglobinuria (PNH), as it results in sustained control of intravascular hemolysis and prevention of thrombosis, and significant improvement of long-term survival. However, the hematological benefits remain heterogeneous among patients, and most response analyses are restricted to transfusion independence. In the era of new anti-complement therapies, we found appropriate to investigate in detail the quality of hematological response of Ecu-treated PNH patients. Methods We have recently proposed (Risitano et al, Frontiers in Immunology 2019) a classification of hematological response to anti-complement therapies based on hemoglobin (Hb) levels and laboratory markers of hemolysis. Six distinct categories were determined (Table 1): i. complete response (no transfusion requirement with normal stable Hb and no evidence of hemolysis); ii. major response (no transfusion requirement with normal Hb but evidence of residual intravascular or extravascular hemolysis); iii. good response (no transfusion requirement with persistent chronic mild anemia); iv. partial response (persistent chronic moderate anemia and/or with occasional red blood cell transfusions); v. minor response (3-6 red blood cell transfusions every 6 months); vi. no response (>6 blood cell transfusions every 6 months). Here we have retrospectively exploited this classification to assess hematological response in a large cohort of 93 PNH patients evaluated in six international reference PNH centers (Paris, Naples, London, Florence, São Paulo, and Ribeirão Preto). Results Forty-two patients were male and 51 were female; the median age at diagnosis (treatment starting) was 36 years (range, 12 to 74 years). All the patients have started Ecu treatment for hemolytic PNH; 57% of patients had classic PNH, whereas 30% and 13% had aplastic anemia (AA)/PNH or intermediate PNH (Peffault de Latour et al, Blood 2006), respectively. Two-thirds of patients had been receiving red blood cell (RBC) transfusion before starting Ecu; the mean treatment duration was 97 months (range 6-179). The majority of patients (87%) received Ecu at the standard schedule of 900 mg every 2 weeks; due to chronic, residual, intravascular hemolysis 13% were treated with higher doses (1200 mg) or with shorter administration interval (10-12 days). Hematological responses were evaluated early during the treatment course (at 6 and 12 months), and then later during the last 6 months of treatment (Figure 1). After 6 (n=80) and 12 months (n=79) of Ecu, respectively, rates of hematological response were as follows: complete response 9% and 10%, major response 4% and 6%, good response 34% and 47%, partial response 34% and 28%, minor response 14% and 6% and no response 6% and 3%. In 83 patients treated for more than 18 months late response rates also were evaluated; most patients responded and the rates of hematological response during the last 6 months of treatment were as follows: complete response, 11%; major response, 6%; good response, 41%; partial response, 29%; minor response, 7% and no response, 6%. Breakthrough episodes were recorded in 21% of patients (equally split between pharmacokinetic and pharmacodynamic ones); thromboembolic events and AA were seen in 2% and 3% of patients, respectively. These data suggest that, albeit individual and unpredictable, the extent of the hematological benefit of Ecu in most PNH patient can be determined quite early in the treatment course, after a minimum of 12 months. Conclusion This is the first attempt to classify hematological response to Ecu based on Hb levels and residual hemolysis. The proposed classification allows the identification of distinct patient subgroups with different medical needs, as well as of meaningful clinical goals for future anti-complement therapies. In our cohort, about 60% of patients are well controlled with Ecu, even if less than 20% of patients reach normal Hb values; about 40% of patients remain anemic, and this represents a goal for future therapies in PNH. This classification is helpful to characterize more precisely the clinical response, which should be assessed after 1 year of treatment. Even if it should be validated in independent, larger cohorts, this classification represents a useful tool to design future trials, and to compare the clinical results of the novel anti-complement agents in development for PNH. Disclosures Notaro: Alexion: Membership on an entity's Board of Directors or advisory committees, Other: letture fees. Scheinberg:Pfizer,: Speakers Bureau; Celgene: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kulasekararaj:Alexion: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Achilleon: Consultancy; Ra Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Akari Therapeutics: Consultancy. Risitano:Biocryst: Membership on an entity's Board of Directors or advisory committees; Samsung: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Ra Pharma: Research Funding; Samsung: Membership on an entity's Board of Directors or advisory committees; Achillion: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Apellis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion: Honoraria, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Ra Pharma: Research Funding; Alnylam: Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alnylam: Research Funding; Amyndas: Consultancy; Achillion: Research Funding; Amyndas: Consultancy; Biocryst: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Apellis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion: Honoraria, Research Funding, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees. Peffault de Latour:Pfizer: Consultancy, Honoraria, Research Funding; Alexion: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Research Funding.

Introduction Fin 2016, un dispositif medical (DM) de prelevement de BOM motorise a ete reference dans notre hopital. Par rapport a la technique de BOM manuelle, pratiquee jusqu’alors dans notre etablissement, la litterature montre de meilleures performances de ce DM en termes de qualite de prelevement, de confort du patient et du manipulateur. Toutefois, il engendre un surcout significatif (108 vs 29 €). Notre objectif a ete de maitriser les utilisations de ce DM en definissant les indications, qui justifient le recours a une technique motorisee et de comparer la qualite des prelevements obtenus par les 2 techniques. Materiels et methode Un groupe de travail pluridisciplinaire constitue de medecins hematologues et de pharmaciens s’est reuni, afin de mettre en place un circuit de dispensation controlee, puis de janvier 2017 a mars 2018, les dispensations ont ete suivies en vue d’une analyse comparative des prelevements. Resultats et discussion Une ordonnance nominative standardisee a ete etablie : elle comporte les 3 indications validees sur la base des difficultes de prelevement (et donc de l’inconfort du patient et du manipulateur) auxquelles elles sont associees, a savoir myelofibrose, patients d’Afrique sub-saharienne et obesite. Le dispositif motorise a ete utilise dans 14 % des BOM et 100 % (71/71) des dispensations ont ete effectuees dans le cadre des indications retenues. 73 % (11/15) des medecins ont utilise ce DM une fois et 20 % (3/15) plus de trois fois. Les analyses anatomo-pathologiques ne montrent pas de superiorite de la technique motorisee. Conclusion Le support de prescription etabli a donc permis de mettre a disposition ce DM, tout en maitrisant les couts. Les premieres utilisations confirment un ressenti ameliore du confort du patient et du manipulateur, mais l’existence de biais (niveaux d’apprentissage et pathologies differents) ne permet pas de trancher concernant la qualite des prelevements. Une comparaison des prelevements motorises et manuels d’un meme manipulateur sur une meme pathologie est donc envisagee.

Background MPN-associated myelofibrosis (MF) is a condition characterized by splenomegaly, anemia, bone marrow (BM) fibrosis and debilitating symptoms. About 80% of patients (pts) harbor a driver mutations in JAK2, CALR or MPL genes that can be used as biomarkers for minimal residual disease assessment. Ruxolitinib (Rux) is a JAK inhibitor approved in intermediate or high risk (HR) MF to improve symptoms and splenomegaly but with little impact on the malignant clone and fibrosis. Interferon alpha (IFNa) can reduce mutant allele burden and fibrosis but is often poorly tolerated in highly symptomatic pts. The RUXOPEG study was designed to assess the efficacy and safety of the combination of Rux + IFNa in MF (NCT02742324). Methods RUXOPEG is a multi-center Bayesian Phase 1/2 adaptive trial. Phase 1 includes up to 9 cohorts of 3 pts with increasing doses of both drugs. Tested doses of Rux and IFNa are 10, 15 and 20 mg BID, and 45, 90 and 135 mcg/week, respectively. Phase 2 will randomize between the 2 best dose combinations selected from phase 1. Primary objective: identify the most efficacious dose combination that also satisfies safety requirements. Primary tolerance criterion is the occurrence of dose limiting toxicities (DLT) within 45 days; primary efficacy criterion is >50% reduction in spleen length within 6 months. Secondary objectives include molecular response, reduction of BM fibrosis, quality of life and symptoms evolution, event-free and overall survival. The planned total enrollment is 42 pts. Key inclusion criteria are: diagnosis of MF (WHO criteria), intermediate or HR (IPSS), need of active therapy, presence of a driver mutation. Key exclusion criteria: prior treatment (or contra-indication) with Rux or IFNa, eligibility for stem cell transplantation, inadequate liver, cardiac or renal function, autoimmune disease, history of depression. Enrolment in 5 cohorts was completed in June 2018, and the last cohort for phase 1 will be opened in August. This abstract reports the current available data for the 5 cohorts who have completed the primary endpoint, but the presentation will provide the detailed analysis of primary and secondary endpoints of phase 1, which will be available in October 2018. Results Among the 15 pts currently enrolled in phase 1, 6 were females, mean age was 60.9 years (range: 38-72), 8 had primary MF, 5 post ET and 2 post PV MF. Median spleen size was 6 cm (range 0 - 18) by palpation and 18 cm (range 10-25) by imaging. Mean (range) blood counts were: hemoglobin 12 g/dL (8.5 - 13.8), WBC 18.3 G/L (8 - 35.5), platelets 457 G/L (157 - 906) and 6 pts had circulating blasts. 12 pts had JAK2V617F and 2 had CALR mutations; karytotype was normal in 9 pts, abnormal in 5 (very HR in 3). In 10 pts analyzed by NGS so far, 8 had additional mutations (1 in 5 pts, 3 in 1, and 4 in 2) in TET2 (n= 5), ASXL1 (4), DNMT3A (2), TP53 (2), SF3B1 (1) and SRSF2 (1) genes. Safety: No DLT was observed in the 5 cohorts (primary safety criterion), the highest tested dose combination being Rux 15 mg BID + IFNa 135 mcg/week. The last cohort will test Rux 20 mg BID + IFNa 135 mcg/week. 4 serious adverse events have been reported: 1 AML transformation (very HR cytogenetics, 3% circulating blasts at baseline), 1 thrombotic event, 1 squamous cell carcinoma and 1 aggravation of Raynaud's phenomenon. Efficacy: preliminary data show a clear decrease in spleen size at 6 months (median 0 cm by palpation, range 0-9; 12.1 cm by imaging, range 10-21) and improvement in blood counts (mean, range): hemoglobin 10.5 g/dL (9.7 - 12.5), WBC 8.6 G/L (5.4 - 11.1), platelets 267 G/L (80 - 486). According to IWG criteria, all the 10 pts evaluable at time of abstract preparation responded (3 partial response, 7 hematological improvement). JAK2V617F allele burden decreased from a mean of 75% (range 43- 96) at baseline to 46% (range 24 - 84) at 6 months. Encouraging results were also found in a patient with 5 mutations (figure1) with a clear decrease in JAK2V617F, ASXL1, DNMT3A and EZH2 mutations after 12 months of treatment. Conclusion RUXOPEG is the first study to formally assess the safety and efficacy of Rux + IFNa combination in MF patients never exposed to either drugs before. The first 5 dose combinations tested showed no DLT, confirming that this combination was generally well tolerated. Preliminary efficacy results are encouraging, including in patients who received very low doses of both drugs. Full results of the 6 cohorts tested in phase 1 and doses selected for phase 2 will be presented. Disclosures Kiladjian: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding. Giraudier:Novartis: Research Funding. Cassinat:Novartis: Research Funding; AOP Orphan: Research Funding.