7023 Background: SEL24/MEN1703, a dual PIM/FLT3 kinase inhibitor, in the dose escalation (DE) DIAMOND-01 trial (CLI24-001, NCT03008187), showed an acceptable safety profile up to the recommended dose (RD) of 125 mg along with initial evidence of single agent activity and meaningful target engagement in heavily pre-treated patients (pts) with AML (Solomon et al, EHA 2020; Tomirotti et al, ASH 2020). Here we present updated data including pts enrolled in the Phase II, cohort expansion (CE) of the study. Methods: DIAMOND-01 trial enrolled pts unsuitable for chemotherapy having relapsed or refractory (R/R) (DE and CE) or previously untreated (DE) AML. Previous targeted therapies – except PIM inhibitors – were allowed. SEL24/MEN1703 was given orally, QD, 14 days ON / 7 days OFF until progression/unacceptable toxicity. The DE tested MEN1703 escalating doses from 25 to 150 mg, whereas in the CE the RP2D (125 mg) was administered. The key objectives of the CE were the confirmation of the safety profile determined in the DE along with further investigation of single agent activity. Adverse events (AEs) were graded according to NCI-CTCAE v.4.03; responses assessed as per ELN 2017 criteria. Results: As of January 21, 2021 (cut-off date), n = 48 pts were treated across DE (n = 25) and CE (n = 23). Median age was 69 (25-84) years. Overall, 20 (43%) and 15 (32%) pts had non de novo AML and primary refractory AML, respectively. Adverse karyotype was reported in 7 (15%) pts. Most frequently reported mutations were FLT3/ITD (23%, n = 11), DNMT3A (15% n = 7), NPM1 (15%, n = 7), IDH1 (13%, n = 6) and IDH2 (4%, n = 2), CEBPA (4%, n = 2), FLT3/TKD (2%, n = 1). Median number of cycles was 2 (1-8). At the RD (n = 30), most frequent serious treatment-emergent AEs (serious TEAEs) were pneumonia (23%), sepsis and febrile neutropenia (13%) and pulmonary mycosis (10%) whereas most frequent G≥3 TEAEs were febrile neutropenia and pneumonia (23%), leukocytosis (20%) and neutrophil count decrease, platelet count decrease, lymphocyte count decrease and sepsis (13%). Responses occurred in 2 pts in the CE, both with IDH1 mutant disease (naïve to IDH inhibitors) who achieved complete remission with incomplete hematologic recovery (CRi). Both responses occurred by Cycle 3, with a duration of 79 (ongoing at cut-off date) and 43 days, respectively. Across DE and CE, 4 CR/CRi occurred, three of which in pts with IDH mutations. A total of 3 out of 6 pts with IDH mutations treated at doses ≥75 mg achieved CR/CRi, including a CR in a patient with IDH2 mutant AML relapsed on Enasidenib. Conclusions: SEL24/MEN1703 confirmed a manageable safety profile at RD and showed preliminary single agent efficacy in R/R AML, particularly clustering in pts with IDH mutant disease either naïve or previously exposed to IDH inhibitors. These results warrant further investigation of SEL24/MEN1703 in AML, with potential focus in the IDH mutated subset. Clinical trial information: NCT03008187.

Abstract Bst1/CD157 is a GPI-anchored transmembrane protein encoded by a member of the CD38 NADase/ADP-ribosyl cyclase gene family, which is expressed on some blood cells of the myeloid lineage, such as monocytes and neutrophils. The antigen is found to be highly expressed, at diagnosis and relapse, in primary samples derived from Acute Myeloid Leukemia (AML) patients, showing the brightest expression in monocyte-oriented blasts. Moreover, CD157 is expressed in high and low-risk Myelodysplastic Syndrome (MDS) patients. MEN1112/OBT357, is a humanized de-fucosylated monoclonal antibody, in clinical development (clinicaltrials.gov identifier: NCT02353143), that is characterized by high affinity and specificity against CD157, inducing potent in vitro Antibody-Dependent Cell-mediated Cytotoxicity (ADCC). The de-fucosylation improved the binding of MEN1112/OBT357 to both high and low-affinity alleles of FcγRIIIa/CD16a, allowing stronger recognition by NK cells. Since no Complement-Dependent Cytotoxicity (CDC) activity was detected, the MEN1112/OBT357 mechanism of action should mainly rely on immune effector cells. Indeed, in an in vitro reporter assay, MEN1112/OBT357 significantly triggered ADCC activity against AML target cell lines with different expression of CD157. Since the ex vivo sensitivity assay is considered a pharmacologically and clinically relevant model to evaluate the preclinical efficacy of therapeutic antibodies in AML (1), MEN1112/OBT357 activity was tested in 38 AML primary samples, demonstrating promising efficacy in an autologous setting, both in peripheral blood and bone marrow samples, in comparison to healthy donor blood samples and independently from FcγRIIIa polymorphisms. A similar activity was also observed in CD157 positive MDS primary samples. Since Myeloid-Derived Suppressor Cells (MDSCs) have been described to be increased in the bone marrow of both AML and MDS patients and their presence to be associated with resistance to chemotherapy (2, 3), we investigated CD157 expression in MDSCs, demonstrating a high expression of the antigen in the bone marrow and peripheral blood of AML patients. Importantly, we confirmed in ex vivo experiments, the depletion of these immunosuppressive cells by MEN1112/OBT357. Overall, our data demonstrate that MEN1112/OBT357 is a novel antibody with potent ex vivo activity against blast cells in AML and MDS patients, suggesting a potential contribution of MEN1112/OBT357 in altering the immunosuppressive environment in the bone marrow niche. References 1. Swords RT et al. Leukemia Research 2018 2. Sun H. et al. Int J Hematology 2015 3. Kittang A.O. et al. Oncoimmunology 2016 Citation Format: Corrado Carrisi, Daniela Bellarosa, Diego Bisignano, Adriano Venditti, Francesco Buccisano, Giuseppe Sconocchia, Andrea Coppola, Anna Aureli, Alessio Fiascarelli, Alessandro Bressan, Simone Baldini, Andrea Pellacani, Monica Binaschi. MEN1112/OBT357, a first-in-class humanized de-fucosylated monoclonal antibody targeting CD157 positive cells in acute myeloid leukemia and myelodysplastic syndrome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1170.

BACKGROUND. SEL24/MEN1703 is a first-in-class, orally available, dual PIM/FLT3 kinase inhibitor investigated in unselected AML patients in the First-in-Human, Dose Escalation (DE) and Cohort Expansion (CE) CLI24-001 trial (DIAMOND-01, ClinicalTrials.gov identifier: NCT03008187). The study has completed both the DE and CE part showing an acceptable safety profile up to the recommended dose (RD), with initial evidence of single agent efficacy particularly clustering in patients with IDH mutant disease. Previous studies conducted on a limited number of patients in the DE cohort indicated pS6, a downstream target in the PIM/FLT3 signaling pathway, as a biomarker of target engagement.

BACKGROUND. SEL24/MEN1703 is a first-in-class, orally available, dual PIM/FLT3 kinase inhibitor investigated in unselected AML patients in the First-in-Human, Dose Escalation (DE) and Cohort Expansion (CE) DIAMOND trial (clinicaltrials.gov identifier: NCT03008187). The study has completed the DE part showing an acceptable safety profile up to the recommended dose (RD), with initial evidence of single agent efficacy1. Preclinical studies conducted in vitro - using a panel of 26 AML cell lines harboring different genetic alterations - and in vivo - in xenograft mouse model bearing MOLM-16 cell line - showed a direct correlation between the activity of SEL24/MEN1703 and the inhibition of S6 phosphorylation (pS6) protein, a downstream target of PIM/FLT3 signaling pathway. AIM. To assess the degree of target engagement and its preliminary correlation with the anti-leukemic effect of SEL24/MEN1703 in samples collected from patients enrolled in the DE part of DIAMOND trial. METHODS. S6 phosphorylation has been longitudinally monitored in the DIAMOND study through an optimized assay for multiparametric analysis of phospho-protein activation. The assay allows a quantitative assessment of pS6 at single cell level among blast cells as well as the identification of blast subpopulations in both peripheral blood (PB) and bone marrow (BM). Blast counts were monitored to assess whether the target engagement did translate into blast count reduction. RESULTS. Two cohorts of patients, treated at 100 mg (one dose level below RD) and 125 mg (RD) were analyzed, for a total of n=9 evaluable patients on PB and n=7 on BM. At screening we observed a heterogeneous positivity for pS6 marker in blast cells (range: 1%-53 %) both in PB and in BM, consistent with the unselected AML patient population recruited in the trial. Overall, 7/9 PB and 4/7 BM samples showed pS6 inhibition in blast cells at the end of the Cycle 1 in comparison with screening (range: 70%-94% and 26%-76% in PB and BM, respectively) (Figure 1). In the cohort treated at 100 mg such strong pathway inhibition did not correlate with blast count reduction. Interestingly, in samples from a patient treated at 125 mg who harbored the highest burden of pS6+ blast cells (>25%), a correlation between pathway inhibition and blast count reduction was observed suggesting that a higher burden of blasts with activated pS6 might be more sensitive to the inhibition of the pathway (Figure 1). CONCLUSIONS. The longitudinal PD assessment through the modulation of pS6 activation by flow cytometry confirmed that meaningful target engagement was achieved, both in PB and BM, in patients treated with SEL24/MEN1703 at 100 and 125 mg. Preliminary data suggest that the FLT3/PIM pathway inhibition might be associated with blast count reduction, particularly in case of high baseline activation of pS6. Longitudinal monitoring of PD will be continued in the CE part of DIAMOND trial. REFERENCES. 1. Solomon et al, EHA 2020 Disclosures Tomirotti: Menarini Ricerche: Current Employment. Bellarosa:Menarini Ricerche: Current Employment. Walter:Genentech: Consultancy; Selvita: Research Funding; StemLine: Research Funding; Daiichi: Consultancy; Celgene: Consultancy, Research Funding; Boston Biomedical: Consultancy; BiVictriX: Consultancy; BioLineRx: Consultancy, Research Funding; Astellas: Consultancy; Arog: Research Funding; Argenx: Consultancy; Aptevo: Consultancy, Research Funding; Amphivena: Current equity holder in publicly-traded company; Amgen: Consultancy, Research Funding; Agios: Consultancy, Research Funding; Seattle Genetics: Research Funding; Race Oncology: Consultancy; Pfizer: Consultancy, Research Funding; New Link Genetics: Consultancy; Macrogenics: Research Funding; Kite: Consultancy; Jazz: Consultancy, Research Funding; ImmunoGen: Research Funding. Ravandi:Abbvie: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria. Brzózka:Ryvu Therapeutics: Current Employment. Baldini:Menarini Ricerche: Current Employment. Salerno:Menarini Richerce: Current Employment. Binaschi:Menarini Ricerche: Current Employment. Laurent:Menarini Ricerche: Current Employment. Pellacani:Menarini Ricerche: Current Employment.

Introduction SEL24/MEN1703 is a potent dual inhibitor of proviral integration site for Moloney murine leukemia virus (PIM) and FMS-like tyrosine kinase 3 (FLT3) with increased activity in both primary Acute Myeloid Leukemia (AML) cells and AML cell lines, irrespectively of FLT3 mutational status, when compared to either FLT3 or PIM single agent inhibitors. PIM kinases are thought to be major drivers of resistance to FLT3 inhibitors and their inhibition in relapsed samples restores cell sensitivity to these agents. Thus, simultaneous PIM and FLT3 inhibition represents a promising strategy in AML therapy. In addition, the broader spectrum of activity of SEL24/MEN1703, which goes beyond PIM/FLT3 inhibition, warrants the compound investigation in AML patients regardless of the genetic aberrations of FLT3. Methods CLI24-001 is a First-in-Human, single-arm, phase I/II trial with a dose-escalation (DE) part followed by a cohort expansion (CE) part in patients with AML (excluding Acute Promyelocytic Leukemia) -newly diagnosed, relapsed or refractory - that are unsuitable for intensive chemotherapy and meet the main inclusion criterion of white blood count (WBC) of ≤30 x 109/L (hydroxyurea/leukapheresis permitted to lower WBC). In both study parts, patients are eligible regardless of mutational status and prior exposure to FLT3 inhibitors; however, prior treatment with PIM inhibitors is not allowed. SEL24/MEN1703 is given orally, QD, for 14 days in a 21-day cycle to be repeated until disease progression, or unacceptable toxicity or withdrawal of patient consent. Bayesian modified toxicity probability interval model was implemented in the DE part after achieving 5 incremental dose levels in order to provide the most accurate identification of the Recommended Phase 2 Dose (RP2D). Also, during the DE part, a new oral formulation was introduced and compared to the original one by repeating the 100 mg dose level in order to avoid a subsequent formal bioequivalence study in patients. The primary objective of the study is to identify the RP2D of SEL24/MEN1703 in the DE part that will be further characterized in the CE part for next steps of clinical development. Key secondary objectives include the characterization of pharmacokinetics (PK) and efficacy assessment of SEL24/MEN1703 given as single agent; exploratory objectives include the assessment of relevant biomarkers (e.g. pS6) in peripheral blood and bone marrow, and their correlation with PK at different time points. Correlation of clinical activity and the cell surface antigen CD25 will be also explored. Study update Currently, the study is enrolling at 5 US sites and will be extended both in the US and EU. The recruitment started in March 2017 and, as of July 26th, 2019, 24 patients received SEL24/MEN1703 at dose levels ranging from 25 to 150 mg. Patients had a median age of 69 (25-84) years and a median of 3 (0-8) prior treatments for AML. Adverse prognostic factors such as primary refractory AML, unfavorable cytogenetics and prior MDS history accounted for 45.8%, 37.5%, 33.% of study patients, respectively. The most frequently reported mutations were FLT3-ITD (20.8% of patients) and those of DNMT3A and IDH1 (16.7% each). Conclusions This is the first trial testing a dual PIM/FLT3 inhibitor with the potential to overcome FLT3 inhibitor resistance, but also to be active in AML regardless of FLT3 mutational status. Ongoing adjustment of the DE design, including the switch to an optimized oral formulation, has been performed to obtain more robust data on the RP2D (ClinicalTrials.gov Identifier: NCT03008187). Disclosures Nazha: Incyte: Speakers Bureau; Tolero, Karyopharma: Honoraria; MEI: Other: Data monitoring Committee; Novartis: Speakers Bureau; Jazz Pharmacutical: Research Funding; Abbvie: Consultancy; Daiichi Sankyo: Consultancy. Strickland:Astellas Pharma: Consultancy; Sunesis Pharmaceuticals: Research Funding; AbbVie: Consultancy; Jazz: Consultancy; Kite: Consultancy; Pfizer: Consultancy. Walter:Boehringer Ingelheim: Consultancy; Agios: Consultancy; Amgen: Consultancy; Amphivena Therapeutics: Consultancy, Equity Ownership; Aptevo Therapeutics: Consultancy, Research Funding; Argenx BVBA: Consultancy; Astellas: Consultancy; BioLineRx: Consultancy; BiVictriX: Consultancy; Jazz Pharmaceuticals: Consultancy; Kite Pharma: Consultancy; New Link Genetics: Consultancy; Pfizer: Consultancy, Research Funding; Race Oncology: Consultancy; Seattle Genetics: Research Funding; Boston Biomedical: Consultancy; Covagen: Consultancy; Daiichi Sankyo: Consultancy. Valimberti:Menarini Ricerche S.p.A: Employment. Tagliavini:Menarini Ricerche S.p.A: Employment. Mazzei:Menarini Ricerche S.p.A.: Employment. Fiesoli:Menarini Ricerche S.p.A.: Employment. Scartoni:Menarini Ricerche S.p.A.: Employment. Bellarosa:Menarini Ricerche S.p.A.: Employment. Binaschi:Menarini Ricerche S.p.A.: Employment. Chrom:Selvita S.A.: Employment. Baldini:Menarini Ricerche S.p.A.: Employment. Brzózka:Selvita S.A.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Capriati:Menarini Ricerche S.p.A.: Employment. Pellacani:Menarini Ricerche S.p.A.: Employment; Amgen: Equity Ownership. Ravandi:Macrogenix: Consultancy, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cyclacel LTD: Research Funding; Xencor: Consultancy, Research Funding; Menarini Ricerche: Research Funding; Selvita: Research Funding.

SEL24/MEN1703 is a first-in-class, orally available, dual PIM/FLT3 kinase inhibitor currently investigated in patients with Acute Myeloid Leukemia (AML) in the first-in-human study CLI24-001 (NCT03008187). PIM and FLT3 kinases are considered to play an important role in AML and are inhibited by SEL24/MEN1703. Moreover, there is evidence that inhibition of PIM kinases might contribute to overcoming acquired resistance induced by approved FLT3 inhibitors1. In AML, different signal transducers in the FLT3 pathway are substrates of kinases. Therefore, their phosphorylation levels might be modulated by kinase inhibitors and may be exploited as a potential pharmacodynamic biomarker in clinical development. In particular, phosphorylation of S6, 4E-BP1, and STAT5 is regulated by both FLT3 and PIM1/2. Thus, the objective of this investigation was to identify the most promising pharmacodynamic biomarker/s for implementation in the clinical trials of SEL24/MEN1703. Initially, we assessed the in vitro cytotoxic effect of SEL24/MEN1703 in a panel of 26 AML cell lines harboring different genetic mutations, to identify suitable cell lines for subsequent experiments. In the selected panel of AML cell lines, SEL24/MEN1703 resulted in the inhibition of phosphorylation of S6, 4-EBP1 and STAT5 as measured by immunoblotting. Notably, the reduction in phosphorylated S6 (pS6) in response to SEL24/MEN1703 was particularly evident. Since SEL24/MEN1703 displays a broad cytotoxic activity in AML cell lines, we clustered sensitive and resistant cell lines considering 0.5 μM as the IC50 cut-off value. Then, we investigated the relationship between SEL24/MEN1703 cytotoxic activity in AML cell lines and the inhibition of the above mentioned phosphorylated proteins in a 24-hour cytotoxic assay, showing a correlation between IC50 and the reduction of pS6 (Pearson correlation coefficient: -0.6905, R2= 0.477). To further confirm the in vitro data, SEL24/MEN1703 ability to modulate phosphoproteins was assessed also in xenograft mice bearing MOLM-16 cell line. The phosphorylation status of S6, 4E-BP1 and STAT5 was analyzed by immunoblot in tumor tissues from mice treated at 25 mg/kg of SEL24/MEN1703 at baseline and at 4, 8, and 16 hours after treatment. Results showed that also in vivo, SEL24/MEN1703 administration resulted in a decrease of pS6, with maximum reduction in this parameter observed 4 hours after the administration of the investigational compound. Based on these results, pS6 was identified as the pharmacodynamic biomarker to be implemented in the CLI24-001 clinical trial. Among different available methods, flow cytometry was selected as the preferred platform to analyze patient samples, because of its ability to provide quantitative assessment of cellular events and pharmacodynamic evaluation in a selected, relevant cell subpopulation, such as the AML blast cells. The assessment of pS6 in the clinical trial is planned both at baseline and at cycle 1 day 14 for whole blood and bone marrow. In addition, pS6 levels will be measured in whole blood at additional time points during treatment cycles. We have implemented the measurement of pS6 in the CLI24-001 trial, and pS6 levels as well as their relationship with the main pharmacokinetic parameters in patients treated with SEL24/MEN703 at 100 and 125 mg will be presented. 1Green A.S. et al., Pim kinases modulate resistance to FLT3 tyrosine kinase inhibitors in FLT3-ITD acute myeloid leukemia, Sci Adv, 2015 Disclosures Tomirotti: Menarini Ricerche S.p.A.: Employment. Merlino:Menarini Ricerche S.p.A.: Employment. Fiascarelli:Menarini Ricerche S.p.A.: Employment. Baldini:Menarini Ricerche S.p.A.: Employment. Tagliavini:Menarini Ricerche S.p.A: Employment. Borella:Menarini Ricerche S.p.A.: Employment. Mazan:Selvita S.A.: Employment. Brzózka:Selvita S.A.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Bressan:Menarini Ricerche S.p.A.: Employment. Pellacani:Menarini Ricerche S.p.A.: Employment; Amgen: Equity Ownership. Salerno:Menarini Ricerche S.p.A.: Employment. Binaschi:Menarini Ricerche S.p.A.: Employment. Bellarosa:Menarini Ricerche S.p.A.: Employment.

TPS7062 Background: FLT3-ITD is one of the most common genetic lesions in acute myeloid leukemia (AML). PIM kinases are oncogenic FLT3-ITD targets expressed in AML cells and increased PIM kinase expression is found in relapse samples from AML patients treated with FLT3 inhibitors. In addition, inhibition of PIM kinases restores sensitivity to FLT3 inhibitors and dual FLT3/PIM inhibition eradicates FLT3-ITD+ cells including primary AML cells. SEL24/MEN1703, a potent PIM/FLT3 dual inhibitor, demonstrates a significantly broader spectrum of activity in AML cell lines and primary AML blasts, irrespective of FLT3 status, compared to monotherapy with either FLT3 or PIM inhibitors such as quizartinib or AZD1208. Methods: CLI24-001 is a First in Human, open label, non-randomized, multi-center, Phase I/II dose-escalation and cohort expansion study of SEL24/MEN1703 in AML patients (excluding APL) not suitable for chemotherapy. SEL24/MEN1703 is given orally, QD, for 14 days in a 21-day cycle with cycles repeated until disease progression or unacceptable toxicity. Dose escalation follows a 3+3 design to identify the recommended phase 2 dose (RP2D). In the phase 2 part/cohort expansion, subjects will receive SEL24/MEN1703 at the RP2D, to further investigate the safety profile and signs of antileukemic activity. In both study parts, patients are eligible regardless of mutational status and/or prior exposure to FLT3 inhibitors; prior treatment with PIM inhibitors is not allowed. Main inclusion criteria comprise a white blood count (WBC) of ≤30 x 109/L (hydroxyurea/leukoapheresis permitted to lower WBC). Key secondary objectives include pharmacokinetics (PK) and single agent efficacy. The study is enrolling at 5 US sites and will be extended, both in US and EU, in the cohort expansion part. This is the first trial testing a dual PIM/FLT3 inhibitor with the potential to be active in AML regardless of FLT3 status andwith a potential to overcome FLT3 inhibitor resistance. (Sci Adv. 2015;1:e1500221; Oncotarget. 2018 Mar 30;9(24):16917-16931) Clinical trial information: NCT03008187.

TPS3100 Background: Defucosylated mAbs enhance antibody dependent cell-mediated cytotoxicity (ADCC) through an improved affinity for Fc receptors. MEN1112/OBT357 is a humanized, defucosylated mAb targeting Bst1/CD157, a GPI-anchored transmembrane protein highly expressed on blasts of AML patients either at primary diagnosis or relapse. Preclinical findings show that MEN1112/OBT357 has the potential to exert powerful ADCC against AML (Aud et al ASH 2014; Venditti et al ASH 2014). Methods: Multi-center, non-randomized, 3+3 dose escalation/expansion cohort trial of MEN1112/OBT357 intended to recruit approximately 50 adult patients (pts) with R/R AML. Refractory pts must have failed ≥ 1 cycle of cytotoxic chemotherapy or hypomethylating agents. A baseline WBC count ≤ 10 x 109/L is required (pre-treatment with hydroxyurea is permitted). Main exclusion criteria are acute promyelocytic leukemia, hematopoietic stem cell transplant within 3 months prior to screening and active central nervous system involvement. MEN1112/OBT357 is given intravenously at 5 incremental doses on Days 1, 8, and 15 in a 21-day cycle for a total of 2 cycles; monthly maintenance is allowed in pts achieving clinical benefit. Primary objective is to identify dose limiting toxicities and maximum tolerated dose of MEN1112/OBT357 in pts with R/R AML; secondary objectives include (1) clinical pharmacokinetics, (2) potential immunogenicity, (3) clinical activity (complete- and composite complete remission rate, best response rate, overall survival) in treated pts and (4) its correlation with target expression/saturation, natural killer cells status, ex vivo activity at baseline and clinical/biological AML features. AEs will be graded according to NCI CTCAE v. 4.03 guidelines. Study variables will be presented by dose-cohort and overall using appropriate descriptive statistics. Efficacy will be evaluated in each cohort in pts completing the first cycle and with ≥ 1 post-cycle assessment using modified IWG 2003 criteria. The individual study duration is 6 months. The enrolment began on December 2014. Clinical trial information: NCT02353143 Clinical trial information: NCT02353143.

BACKGROUND Serum uric acid (sUA) control is of key relevance in tumor lysis syndrome (TLS) prevention as it correlates with both TLS and renal event risk. We sought to determine whether febuxostat fixed dose achieves a better sUA control than allopurinol while preserving renal function in TLS prevention. PATIENTS AND METHODS Patients with hematologic malignancies at intermediate to high TLS risk grade were randomized to receive febuxostat or allopurinol, starting 2 days before induction chemotherapy, for 7-9 days. Study treatment was blinded, whereas daily dose (low/standard/high containing allopurinol 200/300/600 mg, respectively, or fixed febuxostat 120 mg) depended on the investigator's choice. The co-primary end points, sUA area under curve (AUC sUA1-8) and serum creatinine change, were assessed from baseline to day 8 and analyzed through analysis of covariance with two-sided overall significance level of 5%. Secondary end points included treatment responder rate, laboratory and clinical TLS incidence and safety. RESULTS A total of 346 patients (82.1% intermediate TLS risk; 82.7% assigned to standard dose) were randomized. Mean AUC sUA1-8 was 514.0 ± 225.71 versus 708.0 ± 234.42 mgxh/dl (P < 0.0001) in favor of febuxostat. Mean serum creatinine change was -0.83 ± 26.98% and -4.92 ± 16.70% for febuxostat and allopurinol, respectively (P = 0.0903). No differences among secondary efficacy end points were detected. Drug-related adverse events occurred in 6.4% of patients in both arms. CONCLUSION In the largest adult trial carried out in TLS prevention, febuxostat achieved a significant superior sUA control with one fixed dose in comparison to allopurinol with comparable renal function preservation and safety profile. CLINICAL TRIAL REGISTRATION NCT01724528.

Background Febuxostat, a potent and selective xanthine oxidase inhibitor, showed a significantly superior serum uric acid (sUA) control during chemotherapy (CT) in comparison to Allopurinol (Spina M. et al, ASCO 2014 and Annals of Oncology in press) when given as 120 mg oral fixed daily dosed and has been recently approved in the European Union (EU) for the prevention and treatment of hyperuricemia in adult patients undergoing CT for hematologic malignancies (HM) at intermediate- high Tumor Lysis Syndrome (TLS) risk, with recognition of the high relevance of its clinical benefit. Some pediatric HM are highly prone to develop TLS; an age-appropriate drug formulation for TLS prophylaxis is lacking in this population, resulting in an unmet medical need that Febuxostat is going to address. The similarities between adult and pediatric patients in terms of TLS pathogenesis, clinical manifestations and current management allow using pharmacokinetic (PK) information to extrapolate clinical efficacy and safety from adult to pediatric patients, as well as within the different pediatric ages (EMEA/CHMP/EWP/147013/2004).

Background: Tumor lysis syndrome (TLS) is an oncologic emergency characterized especially by elevated serum uric acid (sUA). Febuxostat (FEB) is an orally administerd selective xanthine oxidase inhibitor to reduce sUA.Methods: This was a randomized, double blind phase III trial of FEB vs Allopurinol (ALL) in terms of control of sUA level and preservation of renal function in patients undergoing chemotherapy (CT) for hematologic malignancies at intermediate to high risk of TLS. Patients were stratified according to TLS risk and sUA level to FEB or ALL starting from 2 days prior CT and continued for 7-9 days. Assigned treatment was blinded, while daily dose level (low/standard/high containing ALL 200/300/600 mg or fixed FEB 120) was upon investigator's choice. Primary endpoints were sUA area under the curve (AUC sUA1-8) and change in serum creatinine (sC) level both from baseline to Day 8, analyzed through ANCOVA including treatment and stratification factors as covariates. Secondary endpoints were response rate (sUA ≤ 7.5 mg/dL from CT start to Day 8), incidence of laboratory and clinical TLS and safety. The study was run in 79 sites in Europe and Brazil (NCT01724528).Results: 346 patients were included with similar baseline demographics in both groups. 82.1% of patients were at intermediate risk of TLS, 87.6% had a baseline sUA ≤ 7.5 mg/dl and 82.7% received standard dose level. Intention to treat (ITT) analysis: mean AUC sUA1-8 (mgxh/dl) was significantly lower in FEB arm (514.0 +/- 225.71 vs 708.0 +/- 234.42; p <0.0001). No significant difference in mean sC change(%) occurred between FEB and ALL arms (-0.83 +/- 26.98 vs -4.92 +/- 16.70 respectively, p = 0.0903). No significant difference was detected among secondary efficacy endpoints. Incidence of all adverse events (AEs) and related AEs was 67.6% vs 64.7% and 6.4% vs 6.4% in FEB and ALL arm, respectively.Conclusions: In this largest TLS prevention trial FEB proved to be significantly superior over ALL with a 28% lower exposure to sUA during CT, moreover without requirement for any dose adjustment in patients with preexisting mild or moderate renal impairment. FLORENCE study results were the basis for the FEB European approval for the TLS prevention and treatment granted in May 2015. Background: Tumor lysis syndrome (TLS) is an oncologic emergency characterized especially by elevated serum uric acid (sUA). Febuxostat (FEB) is an orally administerd selective xanthine oxidase inhibitor to reduce sUA. Methods: This was a randomized, double blind phase III trial of FEB vs Allopurinol (ALL) in terms of control of sUA level and preservation of renal function in patients undergoing chemotherapy (CT) for hematologic malignancies at intermediate to high risk of TLS. Patients were stratified according to TLS risk and sUA level to FEB or ALL starting from 2 days prior CT and continued for 7-9 days. Assigned treatment was blinded, while daily dose level (low/standard/high containing ALL 200/300/600 mg or fixed FEB 120) was upon investigator's choice. Primary endpoints were sUA area under the curve (AUC sUA1-8) and change in serum creatinine (sC) level both from baseline to Day 8, analyzed through ANCOVA including treatment and stratification factors as covariates. Secondary endpoints were response rate (sUA ≤ 7.5 mg/dL from CT start to Day 8), incidence of laboratory and clinical TLS and safety. The study was run in 79 sites in Europe and Brazil (NCT01724528). Results: 346 patients were included with similar baseline demographics in both groups. 82.1% of patients were at intermediate risk of TLS, 87.6% had a baseline sUA ≤ 7.5 mg/dl and 82.7% received standard dose level. Intention to treat (ITT) analysis: mean AUC sUA1-8 (mgxh/dl) was significantly lower in FEB arm (514.0 +/- 225.71 vs 708.0 +/- 234.42; p <0.0001). No significant difference in mean sC change(%) occurred between FEB and ALL arms (-0.83 +/- 26.98 vs -4.92 +/- 16.70 respectively, p = 0.0903). No significant difference was detected among secondary efficacy endpoints. Incidence of all adverse events (AEs) and related AEs was 67.6% vs 64.7% and 6.4% vs 6.4% in FEB and ALL arm, respectively. Conclusions: In this largest TLS prevention trial FEB proved to be significantly superior over ALL with a 28% lower exposure to sUA during CT, moreover without requirement for any dose adjustment in patients with preexisting mild or moderate renal impairment. FLORENCE study results were the basis for the FEB European approval for the TLS prevention and treatment granted in May 2015.

e20677 Background: Harmonization of clinical practice and standard of care allow multicenter pivotal trials to be successfully run both in EU and NOEU Countries, with patients’ recruitment increasing in favor of NOEU sites. Comparative data on the performance of EU vs. NOEU investigators in terms of compliance to study protocol and data collection are now offered by the FLORENCE study (a pivotal phase III study of Febuxostat vs. Allopurinol for TLS prevention in hematologic malignancies; NCT01724528) that included 75 European sites distributed in both EU (HR, CZ, DE, HU, IT, PL, RO, ES) and NOEU (RU, RS, UA) contributing with 193 and 152 randomized patients (0.35 and 0.44 patients/month/site), respectively. Methods: Compliance of sites to FLORENCE was evaluated by counting all protocol violations (APVs) and major protocol violations (MPVs) weighted for the number of randomized patients grouped by EU and NOEU sites. Distribution of APVs and MPVs was compared using a Chi Square test at 5% significant level. Additionally, distribution of the most affected MPVs subcategories, namely eligibility of randomized patients, errors in treatment intake, use of prohibited medications, compliance to stratification factors/safety data recording (SFSDR), compliance to scheduled Visits/Assessments (SVAs) and timely reporting of serious adverse events (weighted for the number of patients as per APVs and MPVs) was compared using a Fisher’s Exact test at 5% significant level. Results: APVs were 815, 32.4% in NOEU vs. 67.6% in EU sites (p = .0686). MPVs were 68, 17.7% in NOEU vs. 82.3% in EU (p < .0001), however the difference was due to only two MPVs subcategories, namely compliance to SFSDR (12.5% vs. 87.5% for NOEU and EU sites respectively; p = .0056) and to SVAs (4.2% vs. 95.8% for NOEU and EU sites respectively; p = .0001). Conclusions: Overall compliance to FLORENCE study was high with limited MPVs; NOEU sites had less MPVs affecting compliance to SFSDR and to SVAs, which may reflect difference in assigned site resources. The FLORENCE study provides the first evidence that NOEU and EU sites run a multicenter pivotal trial with high and almost comparable study compliance Clinical trial information: NCT01724528.

Transfusion MedicineVolume 24, Issue 2 p. 125-126 LETTER TO THE EDITOR Romiplostim before splenectomy in a patient with aggressive non-Hodgkin lymphoma and poor response to platelet transfusions S. Baldini, Corresponding Author S. Baldini Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, Italy Correspondence: Dr. Simone Baldini, MD, Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, viale Morgagni 85, 50134 Florence, Italy. Tel.: +390557947476; fax: +39055412098; e-mail: [email protected]Search for more papers by this authorV. Carrai, V. Carrai Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this authorB. Puccini, B. Puccini Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this authorL. Rigacci, L. Rigacci Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this authorR. Alterini, R. Alterini Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this authorA. Bosi, A. Bosi Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this author S. Baldini, Corresponding Author S. Baldini Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, Italy Correspondence: Dr. Simone Baldini, MD, Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, viale Morgagni 85, 50134 Florence, Italy. Tel.: +390557947476; fax: +39055412098; e-mail: [email protected]Search for more papers by this authorV. Carrai, V. Carrai Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this authorB. Puccini, B. Puccini Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this authorL. Rigacci, L. Rigacci Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this authorR. Alterini, R. Alterini Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this authorA. Bosi, A. Bosi Haematology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, 50134 Florence, ItalySearch for more papers by this author First published: 07 February 2014 https://doi.org/10.1111/tme.12106Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume24, Issue2April 2014Pages 125-126 RelatedInformation

Allopurinol for tumor lysis syndrome (TLS) prophylaxis is mostly given at 300 mg daily, but the exact dose is variable and depends on physician’s choice. In order to assess which baseline factors mostly drive the choice, we performed an analysis of the FLORENCE study database. FLORENCE is a double-blinded randomized trial, the largest one in TLS prophylaxis, conducted in 11 European countries (Croatia, Czech Republic, Germany, Hungary, Italy, Poland, Romania, Russia, Serbia, Spain, Ukraine) and Brazil, with this latter country accounting only for 1 patient. Patients with hematologic malignancies (HM) were stratified according to TLS risk (intermediate or high; Cairo et al, British Journal of Haematology, 2010) and serum uric acid (sUA) level (≤ or > 7.5 mg/dl) and randomized at one-to-one ratio to receive TLS prophylaxis with febuxostat or allopurinol. At randomization, 341 patients were blindly assigned by the physician to receive standard or high daily dose level of study drug, containing either allopurinol 300/600 mg or fixed febuxostat 120 mg, respectively. A total of 286 (84%) patients were assigned to receive standard dose level, 253 (88%) and 33 (12%) of which were at intermediate and high TLS risk, respectively. By contrast, in a total of 55 (16%) patients the high dose level of treatment was chosen, 28 (51%) and 27 (49%) of which were at intermediate and high TLS risk, respectively. In order to identify which factors might have influenced the physician’s choice, an analysis of variance (ANOVA) model was used considering the dose level as dependent variable and each of the following variables as covariates (one at a time): TLS risk grade (intermediate or high), sUA level (≤ or > 7.5 mg/dL), type of HM (acute leukemia or chronic lymphocytic leukemia / non Hodgkin lymphoma), presence/absence of high disease burden (defined as bulky disease for lymphomas or white blood cells count ≥ 100 x 10 9 /L for leukemias), lactate dehydrogenase level ( Disclosures Baldini: MENARINI RICERCHE: Employment. Off Label Use: Febuxostat in Tumor Lysis Syndrome prophylaxis. Rossi: MENARINI RICERCHE: Employment. Spina: MENARINI RICERCHE: Membership on an entity9s Board of Directors or advisory committees. Federico: MENARINI RICERCHE: Membership on an entity9s Board of Directors or advisory committees. Nagy: MENARINI RICERCHE: Consultancy. Jordan: MENARINI RICERCHE: Consultancy. Aurer: MENARINI RICERCHE: Consultancy. Ribera: MENARINI RICERCHE: Consultancy. Borsaru: MENARINI RICERCHE: Consultancy. Glushko: MENARINI RICERCHE: Consultancy. Grosicki: MENARINI RICERCHE: Consultancy. Rego: MENARINI RICERCHE: Consultancy. Nizzardo: MENARINI RICERCHE: Employment. Scartoni: MENARINI RICERCHE: Employment. Scordari: MENARINI RICERCHE: Employment. Matera: MENARINI RICERCHE: Employment. Maggi: MENARINI RICERCHE: Employment. Capriati: MENARINI RICERCHE: Employment. Simonelli: MENARINI RICERCHE: Employment.

9641^ Background: Tumor lysis syndrome (TLS) is an oncologic emergency characterized especially by elevated serum uric acid (sUA). FEB is an orally administerd selective xanthine oxidase inhibitor to reduce sUA. Methods: This was a randomized, double blind phase III trial of FEB vs ALL in terms of control of sUA level and preservation of renal function in patients undergoing chemotherapy (CT) for hematologic malignancies at intermediate to high risk of TLS. Patients werestratified according to TLS risk and sUA level to FEB or ALL starting from 2 days prior CT and continued for 7-9 days. Assigned treatment was blinded, while daily dose level (low/standard/high containing ALL 200/300/600 mg or fixed FEB 120) was upon investigator’s choice. Primary endpoints were sUA area under the curve (AUC sUA1-8) and change in serum creatinine (sC) level both from baseline to Day 8, analyzed through ANCOVA including treatment and stratification factors as covariates. Secondary endpoints were response rate (sUA ≤ 7.5 mg/d...

Thrombopoietin receptor agonists (TRAs) offer new opportunities for the treatment of chronic immune thrombocytopenia (ITP). However, little is known about their safety and efficacy in combination with vitamin K antagonists in patients who need chronic anticoagulation. In this study, we report of a 68year-old man with chronic ITP and severe cardiac comorbidities who has achieved a 1-year follow-up of combined treatment with romiplostim and warfarin. He was affected by dilated-hypokinetic cardiopathy with chronic atrial fibrillation and was admitted to our hospital in February 2011 for progressive dyspnea and fatigue with diffuse mucocutaneous purpura. Coagulation laboratories were normal except for an international normalized ratio (INR) of 2.6, as he was on treatment with warfarin for the atrial fibrillation, and an ischemic stroke occurred 2 months before. Hematological data showed thrombocytopenia and mild leukocytosis (leukocytes 11.3 10/l with absolute neutrophil count 9.6 10/l; hemoglobin 13.5 g/dl; and platelet count 21 10/l). The patient was affected by ITP since 2008. Diagnosis of ITP was confirmed throughout by the exclusion of other causes of thrombocytopenia and with a bone marrow histological analysis showing an increased number of megakaryocytes with normal erythroid and myeloid lineages. He had received several cycles of prednisone and intravenous immunoglobulins (IVIG) for ITP. However, since about a year, IVIG were no longer effective. At the time of hospital admission, he was taking prednisone 1 mg/kg per day since 1 month, with poor tolerance due to an insulin-dependent type 2 diabetes mellitus. We stopped warfarin and administered intravenous vitamin K, achieving normalization of INR (1.1). An abdomen ultrasound scan showed a mild enlargement of the liver consistent with chronic heart failure but normal size of the spleen, whereas transthoracic echocardiography revealed a severe left ventricular systolic impairment (0.20 residual ejection fraction) and a moderate pulmonary hypertension. As thrombocytopenia prevented the use of warfarin, a transesophageal echocardiography was performed in order to evaluate the feasibility of percutaneous left atrial appendage transcatheter occlusion as a prophylaxis of cardioembolic stroke [1], but a recent left atrial appendage thrombosis was found. Thus, our patient had a chronic ITP with the loss of response to prednisone [2], but further treatment was needed to ensure a long-term control of platelet count in order to restore the anticoagulation. Splenectomy is a highly effective second-line treatment for chronic ITP but its complications also include thrombotic events and may be greater in patients older than 65 [3]. Furthermore, our patient had severe comorbidities that increased the risk of surgical and anesthesiological complications. TRAs are licensed for the treatment of chronic ITP in patients who fail to respond to splenectomy or have contraindications to it. Long-term data with romiplostim show a sustained platelet response and a significant reduction in the use of steroids, with an acceptable safety profile [4]. Nevertheless, patients treated with romiplostim in a multicenter phase III trial had a median weekly platelet count 50 10/l during quite all the treatment period, but the first quartile of the range was often below this threshold. Moreover, although non-splenectomized patients had a higher rate of durable platelet response (at least 6 weeks with platelet counts of 50 10/l or more during the last 8 weeks of treatment), no more than 61% of them achieved such end-point and the percentage only marginally improved by including patients who resorted to rescue therapies [5]. Thus, we choose to restore the anticoagulation at a higher threshold of platelet count (100 10/l) to have a broader safety margin in the case of sudden drops. Besides, as it has been shown that variations of the dosage of romiplostim are more likely to be required during the first 24 weeks of treatment and are substantial in a small number of patients, both platelet count and INR were checked weekly for such period and then every 2 weeks [4]. Romiplostim was started from 1 mcg/kg/week, adjusting dose on the basis of weekly platelet response according to the prescribing information [6]. Despite the loss of response and the poor tolerance to prednisone, we continued it until the

Immune thrombocytopenia (ITP) is an autoimmune disorder that occasionally arises with neoplasms. Although often sensitive to first-line treatment, a refractory thrombocytopenia may lead to a difficult management of the patient. A patient with primary ITP who successfully underwent surgery and chemotherapy with immunoglobulins and dexamethasone for ovarian cancer has recently been reported. We report on a 71-year-old woman who developed refractory secondary ITP concomitant with an advanced serous ovarian carcinoma. The ITP responded only to the thrombopoietin receptor agonist romiplostim with an uncommon threshold effect, enabling both palliative surgery and histological diagnosis. Although thrombopoietin receptor agonists might be useful in some circumstances, their safety and efficacy for cancer patients must still be determined. Well-designed clinical trials are urgently needed to resolve this issue.

Patients with chronic immune thrombocytopenia treated with romiplostim may benefit from a higher starting dose when a rapid increase in count is needed, but it could be avoided in those with a prompt response to the standard dosage. We hypothesized that a platelet count ≥ 20 x 109/l at baseline could distinguish subjects with such response from those with a delayed one during the early phase of treatment. Our work is a retrospective and single-institution analysis comparing the median platelet count, the median weekly dosage of romiplostim and the median number of weekly platelet counts < 50 x 109/l between patients with a baseline ≥ 20 x 109/l platelets (n=10, 2 splenectomized) and those with a lower one (n=8, 3 splenectomized) during the first month of treatment with romiplostim. The results show a higher median platelet count (79,5 vs 40,5 x 109/l, p=0,002) and a lower median dose of romiplostim (1 vs 2 mcg/kg/week, p=0,01) in subjects with a baseline ≥ 20 x 109/l platelets, who also had a trend of less weekly counts < 50 x 109/l platelets (1 vs 2, p=0,054). These data suggest that patients with ≥ 20 x 109/l platelets at baseline may achieve a prompt response with the standard dose of romiplostim, but further and larger data are needed in order to assess whether it can be considered in clinical practice.

To the editor: Elliott and colleagues have reported in a group of 73 patients with acute myeloid leukemia (AML) that the time to clearance of peripheral blood blasts (PBB) during standard induction therapy is a strong predictor of both overall (OS) and relapse-free survival (RFS).[1][1] We have