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Background. - It is known that patients with COVID-19 are at increased risk of thrombosis. Although COVID-19 infection primarily affects the lower respiratory tract system, emerging reports suggest direct and indirect cardiovascular complications. However, the key mechanisms under thrombosis development at great arterial vessels are still unclear.Case presentation. – We report the cases of 4 patients who were admitted to our hospital and suffered from arterial thrombotic complications. All of them were older than 60 years and only 1 did not have cardiovascular risk factors. It should be noted that days prior to the diagnosis of arterial thrombosis, 3 of the 4 patients were under anticoagulant treatment. It is also interesting that in contrast to already known typical microvascular locations, our patients suffered from large arterial vessels thrombosis. Furthermore, none of them would present with severe respiratory symptoms. Conclusions. – The underlying mechanism of COVID-19-associated arterial thrombosis remains unclear and might be independent of the cytokine storm that occurs in patients with COVID-19-associated venous thrombosis. Also, the role of anti-platelets agents as prophylactic treatment in high-risk patients remains unclear. Multicenter clinical trials are necessary to clarify these issues.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection produces higher morbidity and mortality in hematological malignancies, but evidence in acute myeloid leukemia (AML) is scarce. A multicenter observational study was conducted to determine the clinical outcomes and assess the impact of therapeutic approaches in adult AML patients with SARS-CoV-2 infection in the first wave (March-May 2020). Overall, 108 patients were included: 51.9% with active leukemia and 70.4% under therapeutic schedules for AML. Signs and symptoms of SARS-CoV-2 were present in 96.3% of patients and 82.4% received specific treatment for SARS-CoV-2. The mortality rate was 43.5% and was correlated with age, gender, active leukemia, dyspnea, severe SARS-CoV-2, intensive care measures, neutrophil count, and D-dimer levels. A protective effect was found with azithromycin, lopinavir/ritonavir, and normal liver enzyme levels. During the SARS-CoV-2 first wave, our findings suggested an increased mortality in AML in a short period. SARS-CoV-2 management could be guided by risk factors in AML patients.

Background and objective SARS-CoV-2 infection has bimodal distribution in Europe with a first wave in March to June 2020 and a second in September 2020 to February 2021. We compared the frequency, clinical characteristics and outcomes of adults with acute lymphoblastic leukemia (ALL) and infection in the first vs. second pandemic waves in Spain. Patients and Methods In this prospective study the characteristics of ALL and COVID-19 infection, comorbidities, treatment and outcome in the two periods were compared. The study ended when vaccination against SARS-CoV-2 was implemented in Spain. Results Twenty eight patients were collected in the first wave and 24 in the second. The median age was 46.5 years (range 20–83). Patients from the first wave had a trend to more severe ALL (higher frequency of patients under induction or submitted to transplantation or under immunosuppressive therapy). No significant differences were observed in need for oxygen support, intensive care unit (ICU) requirement, days in ICU and time to COVID-19 infection recovery. Seventeen patients (33%) died, with death attributed to COVID infection in 15 (29%), without significant differences in the 100 day overall survival (OS) probabilities in the two waves (68% ± 17% vs. 56% ± 30%). The only prognostic factor for OS identified by was the presence of comorbidities at COVID-19 infection (HR: 5.358 [95% CI: 1.875- 15.313]). Conclusion The frequency and mortality of COVID-19 infection were high in adults with ALL, without changes over time, providing evidence in favor of vaccination priority for these patients., Microabstract The characteristics and outcome of ALL in adults with COVID-19 infection in the first two waves of the pandemic in Spain were compared. The frequency and mortality of COVID-19 infection were high in adults with ALL, without changes over time. Comorbidities at COVID-19 infection was the only prognostic factor for survival.

© The Author(s) 2021., This study reports on 382 COVID-19 patients having undergone allogeneic (n = 236) or autologous (n = 146) hematopoietic cell transplantation (HCT) reported to the European Society for Blood and Marrow Transplantation (EBMT) or to the Spanish Group of Hematopoietic Stem Cell Transplantation (GETH). The median age was 54.1 years (1.0–80.3) for allogeneic, and 60.6 years (7.7–81.6) for autologous HCT patients. The median time from HCT to COVID-19 was 15.8 months (0.2–292.7) in allogeneic and 24.6 months (−0.9 to 350.3) in autologous recipients. 83.5% developed lower respiratory tract disease and 22.5% were admitted to an ICU. Overall survival at 6 weeks from diagnosis was 77.9% and 72.1% in allogeneic and autologous recipients, respectively. Children had a survival of 93.4%. In multivariate analysis, older age (p = 0.02), need for ICU (p < 0.0001) and moderate/high immunodeficiency index (p = 0.04) increased the risk while better performance status (p = 0.001) decreased the risk for mortality. Other factors such as underlying diagnosis, time from HCT, GVHD, or ongoing immunosuppression did not significantly impact overall survival. We conclude that HCT patients are at high risk of developing LRTD, require admission to ICU, and have increased mortality in COVID-19., JA acknowledges the support of the UK NIHR Imperial College Biomedical Research Centre.

Background. Donor specific antibodies (DSAs) are preformed IgG antibodies with specificity against HLA molecules not shared with the donor that can lead to graft failure (GF) in the setting of mismatched HSCT. The aim of this study is to report the experience of the Spanish Group of Hematopoietic Transplant (GETH-TC) in patients with DSAs undergoing haplo-HSCT. Methods. Patients undergoing haplo-HSCT in centers from the GETH-TC from 2013 to 2021 were included in the study. DSAs were analyzed with a solid-phase single-antigen immunoassay (Luminex®); monitoring was performed prior to desensitization, prior to infusion and after infusion. Desensitization strategies used depended on center experience, immunofluorescence intensity, complement fixation and type of antibodies. Results. 59 haplo-HSCT with DSAs were performed in 57 patients in 13 centers. Characteristics of the population are shown in Table 1. 53 (93%) patients were female (91% with prior pregnancies). All patients lacked a suitable alternative donor. 51 (89%) received peripheral blood as stem cell source. Conditioning was myeloablative in 58% and all patients received post-transplant cyclophosphamide based GVHD prophylaxis; 3 (5%) patients received also ATG. 28 (49%) patients presented anti-HLA class I DSAs 22 of them with >5000MFI), 14 (25%) presented anti-HLA class II (6 with >5000MFI) and 15 (26%) presented both anti-HLA class I and II DSAs (13 with >5000MFI). Five patients did not receive desensitization treatment, 4 of them with After a median follow-up of 24 months, 2-year OS and EFS were 52% and 42%, respectively. 2-year cumulative incidence of relapse at was 14% and NRM was 41%. Cumulative incidence of grade II-IV aGVHD at day 180 was 13% and chronic GVHD was 25%. Conclusions. The use of desensitization treatment guided by DSAs intensity kinetics constitute an effective approach with high rates of engraftment for patients with DSAs in need for an haplo-HSCT lacking an alternative suitable donor, including non-malignant disorders. Figure 1 Figure 1. Disclosures Bailen: Pfizer, Kite-Gilead, Gilead: Honoraria. Oarbeascoa: Gilead: Honoraria, Speakers Bureau. Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria.

Background: Pyruvate kinase deficiency (PKD) is a rare inherited hemolytic anemia caused by mutations in the PKLR gene resulting in decreased red cell pyruvate kinase activity and impaired erythrocyte metabolism. Manifestations include anemia, reticulocytosis, splenomegaly and iron overload, and may be life-threatening in severely affected individuals. PKD represents a significant unmet medical need as current treatments are palliative and limited to blood transfusions, chelation therapy, and splenectomy which are associated with significant side effects. Preclinical studies in a clinically relevant PKD murine model have demonstrated that infusion of gene-modified Lin− bone marrow (BM) cells may ameliorate PKD phenotype. Based on compelling preclinical data, a global Phase 1 clinical trial RP-L301-0119 (NCT04105166) is underway to evaluate the feasibility and safety of lentiviral mediated gene therapy in adult and pediatric subjects with severe PKD. Methods: Six adult and pediatric patients with severe PKD (defined as severe and/or transfusion-dependent anemia despite prior splenectomy) will be enrolled. Peripheral blood (PB) hematopoietic stem cells (HSCs) are collected on 2 consecutive days via apheresis after mobilization with granulocyte-colony stimulating factor (G-CSF) and plerixafor. HSCs are enriched, transduced with PGK-coRPK-WPRE lentiviral vector (LV), and cryopreserved. Following release testing of the investigational product (IP), RP-L301, myeloablative therapeutic drug monitoring (TDM) busulfan is administered over 4 days. RP-L301 is then thawed and infused. Patients are followed for safety assessments, including replication competent lentivirus (RCL) and insertion site analysis (ISA), and for efficacy parameters including PB and BM genetic correction, decrease in transfusion requirements, clinically significant improvement in anemia, and reduction of hemolysis for 2 years post-infusion. Results: As of May 2021, 2 adult patients with severe anemia have received RP-L301. Patient 1 (age 31 years) received 3.9x106 CD34+ cells/kg with mean vector copy number (VCN) of 2.73. Patient 2 (age 47 years) received 2.4x106 CD34+ cells/kg with mean VCN of 2.08. Despite baseline hemoglobin (Hb) levels in the 7.0-7.5 g/dL range, both patients displayed normal-range hemoglobin (Hb), improved hemolysis markers, and have required no red blood cell transfusions post-engraftment at 9- and 6- months follow-up. Both report improved quality of life. PB mononuclear cell VCNs for both patients were >2.0 at last evaluated timepoint (6- and 3-months post-treatment, respectively). No serious adverse events have been attributed to RP-L301. Updated safety and efficacy data will be presented. Conclusions: Hematopoietic stem cell mobilization using G-CSF and plerixafor is feasible and effective in adult PKD patients. RP-L301 was successfully manufactured to meet the required specifications for the Phase 1 clinical study and administered without short-term infusion related complications. Efficacy was demonstrated by normalized Hb associated with engraftment confirmed by PB and BM VCN. Disclosures Shah: OrchardTherapeutics: Membership on an entity's Board of Directors or advisory committees, Other: Dr. Shah currently serves on the medical advisory board for Orchard Therapeutics . Navarro: Rocket Pharmaceuticals, Inc.: Current equity holder in publicly-traded company, Other: Dr. Navarro has licensed medicinal products and receives research funding and equity from Rocket Pharmaceuticals, Inc., Patents & Royalties, Research Funding. Sevilla: Miltenyi: Consultancy; Novartis: Consultancy; Amgen: Consultancy; Rocket Pharmaceuticals, Inc.: Consultancy, Other: J.Sevilla is an inventor on patents on lentiviral vectors filed by CIEMAT, CIBERER and Fundación Jiménez Díaz, and may be entitled to receive financial benefits from the licensing of such patents.; SOBI: Consultancy. Glader: Agios: Consultancy. Quintana Bustamante: Rocket Pharmaceuticals, Inc.: Current equity holder in publicly-traded company. Beard: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Law: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Zeini: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Choi: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Nicoletti: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Rao: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Bueren: Rocket Pharmaceuticals, Inc.: Consultancy, Other: J.Bueren is an inventor on patents on lentiviral vectors filed by CIEMAT, CIBERER and Fundación Jiménez Díaz, may be entitled to receive financial benefits from the licensing of such patents and receives funding for research., Patents & Royalties, Research Funding. Schwartz: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Segovia: Rocket Pharmaceuticals, Inc.: Consultancy, Research Funding.

Introduction and objective. SARS-CoV-2 pandemic has deeply impacted in Spain. In cancer patients (pts) the lethality has been higher than in normal population, but, little is known on the impact in adults with ALL. Our objective was to analyze the frequency, clinical characteristics and outcome of adult ALL patients infected by SARS-CoV-2. Methods. Between March 1, 2020 and May 31, 2020 (the period of the peak of COVID-19 infection in Spain) two registries from the PETHEMA (Programa Español de Tratamientos en Hematologia) and GETH (Grupo Español de Trasplante Hematopoyético y Terapia Celular) groups were activated to recruit adult patients with ALL and COVID-19 infection confirmed by PCR. The PETHEMA registry was based on ASH proposal (www.ashresearchcollaborative.org/covid-19-registry) and the GETH registry was specifically performed for hematological diseases and COVID-19 infection. Both registries were merged for this study. Eighty-four Spanish centers were contacted and weekly reminds were sent until May 19, 2020. The demographic and clinical characteristics of ALL and COVID-19 infection, the comorbidities, the treatment and outcome were collected. The study was closed for follow in July 10, 2020. Results. Fifty-six of 84 centers answered the survey and 28 patients with ALL and COVID-19 infection were identified in 17 of them, especially on March (n=11) and April (n=15). Median age was 46 (range 20-78) yrs. and 19 were aged over 40 yrs. Fifteen pts were male, 1 was active smoker and 9 showed one or more comorbidities (chronic liver disease [n=2] diabetes [n=1], hypertension [n=5], cardiopathy [n=2], prior malignancy [n=1] and hypogammaglobulinemia [n=1]). ALL was of B-cell precursors in 18 pts (Ph+ in 6) and T in 10. Twenty-six pts were on treatment of LAL (induction [n=10], consolidation [n=3], maintenance [n=1], HSCT [n=5], rescue [n=6], and palliative [n=1]). Eight patients were previously submitted to allogeneic HSCT, CAR T [n=1] or immunotherapy with monoclonal antibodies (inotuzumab, n=4) and 21 were receiving immunosuppressive drugs (corticosteroids in 11, fludarabine in 4, among others). Eleven pts showed neutropenia Conclusion. The frequency of adult patients with ALL and COVID-19 infection can be considered high, given the low incidence of adult ALL. COVID-19 infection was frequent in patients with advanced age and on ALL therapy. The frequency of severe COVID-19 infection and the mortality were high. Supported in part by 2017 SGR288 (GRC) Generalitat de Catalunya and "la Caixa" Foundation. Disclosures Ribera: Pfizer, Amgen, Ariad, Novartis:Consultancy, Speakers Bureau;Pfizer, Amgen:Research Funding.Barba:Amgen, Celgene, Novartis, Pfizer:Speakers Bureau;Amgen, Celgene, Gilead, Jazz Pharmaceuticals, Novartis, Pfizer, Shire:Consultancy.

BACKGROUND: Older patients with acute myeloid leukaemia (AML) who are unsuitable for standard induction therapy have limited treatment options. While DNMT3A, TET2, IDH1/2 and TP53 mutations have been previously associated to better response to hypomethylating agents, there are no molecular biomarkers for low-dose cytarabine (LDAC)-based regimens. AIMS: To predict outcome in AML older patients at diagnosis based on mutation status in the context of FLUGAZA trial. FLUGAZA trial was focus on >65 years AML de novo patients comparing azacytidine vs. fludarabine and LDAC (FLUGA Scheme). METHODS: We analyzed bone marrow (BM) samples at diagnosis from 209 out of 285 AML patients treated according Flugaza trial (NCT02319135), azacytidine-arm (n=97) and FLUGA-arm (n=112). In this trial, patients were randomized to receive 3 induction cycles with fludarabine and cytarabine (FLUGA) followed by 6 consolidation cycles with reduced intensity FLUGA, vs 3 induction cycles with 5-azacytidine (AZA) followed by 6 consolidation cycles with AZA. Median age at diagnosis was 75 years (65-90). Both treatment groups were balanced for age, leucocytes count, baseline BM blasts, karyotype risk (ELN), and FLT3-internal tandem duplication and NPM1 gene mutations. Mutational profile analysis was carried out by NGS targeted gene sequencing (Ion Torrent S5XL System-Thermo Fisher Scientific) using a 43 genes custom panel implicated in leukemia prognosis. RESULTS: We detected 893 variants, 247 Indels and 646 SNVs. 206 (23.1%) of them were included as pathogenic or like-pathogenic by clinvar database. Ninety-five percent of patients (n=203) had at least one detectable mutation, and the median number of mutations was 4 (range = 0-8 mutations). The most common gene mutations were TET2 (N=55), FLT3 (n=52), SRSF2 (n=49), TP53 (n=45), DNMT3A (n=45), ASXL1 (n=45), RUNX1 (n=43), IDH2 (n=36), IDH1 (n=34), NPM1, (n=33) and NRAS (n=23). This mutational landscape is different to previous published in younger patients (Grimwade, Blood 2016), with higher number of patients with mutations in TP53 (21.5 vs 8%), SRSF2 (23.9 vs 2%), IDH1 (16.3 vs 7%) and IDH2 (17.2 vs 9%) and lower number of patients with mutation in NMP1 (15.8 vs 33%). The median OS of global series was 6 months (range 0-40). Multivariate Cox regression in the global series showed that NRAS and TP53 mutations predict reduced OS (Table 1). Distribution of mutations between both arms was not homogeneous (Figure 1) and NRAS (p=0.012) was more frequent among patients randomized to the FLUGA-arm. However, TP53 mutation frequency distribution was homogeneous: 23.7% in AZA-arm and 19.6% in FLUGA-arm (p=NS). In the AZA-arm, patient´s age was the only variable associated with not achieving composite complete remission (CR plus CR with incomplete recovery) and TET2 and EZH2 mutations were predictors to achieve composite CR. In the FLUGA-arm, TP53 and NRAS mutations were associated with not reaching composite CR (table 2). In the AZA-arm, cytogenetic was the only variable associated with risk of early death. In the FLUGA-arm, leucocyte count, TP53 and NRAS mutations were associated with risk of early death (table 3). In the AZA-arm, BCORL1 mutations (4.1%) were the only variable associated with high risk of relapse. In the FLUGA-arm, BCOR (7.1%) and TP53 (19.6%) mutations were associated with high risk of relapse (table 4). CONCLUSION The mutational profile of AML in elderly patients is different from the previously published in young patients. We have confirmed that a molecular pattern can identify patients with poor prognosis in elderly AML patients. NRAS and TP53 mutations confer a poor prognosis in LDAC (FLUGA-arm) patients, but this effect disappeared in the AZA-arm. BCOR and BCORL1 mutations were associated to a reduced DFS. These results confirm that azacytidine could be more efficacious than LDAC treatment for older patients with AML and mutations in TP53, NRAS, TET2 and EZH2. The percentage of patients who presented mutations in these genes amounted to 77% in this AML series. The study is registered at www.ClinicalTrials.gov as NCT02319135. This study was supported by the Subdirección General de Investigación Sanitaria (ISCIII, Spain) grants PI13/02387 and PI16/01530. Disclosures Salamero: Celgene: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; Daichii Sankyo: Honoraria. Paiva:Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche, and Sanofi; unrestricted grants from Celgene, EngMab, Sanofi, and Takeda; and consultancy for Celgene, Janssen, and Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau. Fernandez:Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees; Incyte: 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, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Pyruvate kinase deficiency (PKD) is an autosomal recessive disorder caused by mutations in the PKLR gene that lead to a reduction of the erythroid pyruvate kinase (RPK) protein activity, which causes an energetic imbalance in PKD erythroid cells. This disease is associated with reticulocytosis, splenomegaly and iron overload, and may be life-threatening in severely affected patients. In selected cases, allogeneic Hematopoietic Stem Cell Transplantation has been shown to correct the disorder. Therefore, autologous HSCT of genetically corrected cells will offer a durable and curative therapeutic option. In fact, a global Phase I clinical trial (clinicaltrials.gov #NCT04105166) is underway to evaluate the feasibility and safety of lentiviral mediated gene therapy with severe PKD. Looking for a guided integration of the exogenous therapeutic DNA sequences, herein we conducted a gene editing approach to correct PKD in human Hematopoietic Stem Cells (HSCs). We developed a knock-in approach to insert either a TurboGFP expression cassette or a promotor-less therapeutic codon optimized RPK cDNA (coRPK) at the genomic starting site of the PKLR gene, a gene editing strategy that will correct most of the mutations present in PKD patients. This gene editing approach combines RNP nucleofection and adeno-associated viral vector (AAV6) mediated delivery of homologous donors. In order to assess the safety of the proposed gene editing approach, we performed GUIDE-Seq and rhAmpSeqTM analyses of different single guide RNAs targeting the PKLR starting site. We found PKLR sgRNAs that showed a high targeting efficiency, up to 40% targeted hematopoietic progenitors (in vitro semisolid colony forming units) and a safety profile, with no off-targets detected above threshold values (0.1%) and in the absence of cellular toxicity, when applied to healthy cord blood CD34+ (CB-CD34+) cells. These gene-edited CB-CD34+ cells engrafted efficiently in both primary and secondary immunodeficient NSG recipient mice, demonstrating the gene editing in long-term hematopoietic repopulating HSCs. Furthermore, we evaluated the therapeutic potential of this gene editing strategy to restore the energetic imbalance in erythroid cells derived from PKD patients. CD34+ cells from 4 different PKD patients, were purified, nucleofected with PKLR sgRNA and transduced with AAV-coRPK donor. In vitro differentiated erythroid cells derived from edited PKD CD34+ expressed coRPK mRNA and restored their energetic defect up to normal values obtained in in vitro differentiated erythroid cells from healthy donor cells. Moreover, gene edited mobilized Peripheral Blood CD34+ (mPB-CD34+) cells from a PKD patient engrafted efficiently in immunodeficient NBSGW mice, having human cells that showed the specific integration of coRPK donor 2 months post-transplant. Overall, these results demonstrate the feasibility and safety of PKLR gene editing in human HSPCs and, therefore, its potential clinical application for the treatment of PKD patients. Disclosures Dever: Integral Medicines: Current Employment. Turk:Integrated DNA Technologies, Inc. (IDT): Current Employment, Current equity holder in publicly-traded company. Bianchi:Agios Pharmaceuticals: Other: Scientific Advisor. Behlke:Integrated DNA Technologies, Inc. (IDT): Current Employment, Current equity holder in publicly-traded company. Bueren:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from this company., Patents & Royalties, Research Funding. Segovia:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from the Company., Patents & Royalties, Research Funding.

Introduction: Pyruvate Kinase Deficiency (PKD) is a rare inherited hemolytic anemia that is caused by mutations in the PKLR gene leading to decreased red cell pyruvate kinase (RPK) activity and impaired erythrocyte metabolism. The disorder is characterized by anemia, reticulocytosis, splenomegaly and iron overload, and may be life-threatening in severely affected individuals. PKD represents a significant unmet medical need as current therapies are palliative and limited to chronic blood transfusions, iron chelation therapy, and splenectomy. The side effects of these supportive treatments include iron overload, end-organ damage and increased infection risks. AG-348, an allosteric activator of RPK, is under evaluation in clinical trials, predominantly in less severely-afflicted transfusion-independent patients. Allogeneic hematopoietic stem cell transplantation (HSCT) has been performed in selected cases and resulted in transfusion independence, suggesting that the disorder may be reversed when an adequate level of hematopoietic stem and progenitor cells (HSPCs) harboring a corrected PKLR gene engraft in the bone marrow (BM). The therapeutic efficacy of allogeneic transplant is limited by the availability of a suitable donor and transplant-associated toxicities. Preclinical studies conducted in a clinically relevant PKD murine model have demonstrated the safety and efficacy of Lin- BM cells transduced with the therapeutic lentiviral vector, PGK-coRPK-WPRE, in ameliorating the PKD phenotype. More specifically, transplantation of transduced cells resulted in increased erythrocyte survival, decreased reticulocytosis, and improvement in the secondary manifestations of hemolytic anemia, including splenomegaly and hepatic iron overload. Based on compelling preclinical data, a global Phase 1 clinical trial RP-L301-0119 (clinicaltrials.gov#NCT04105166) is underway to evaluate the feasibility and safety of lentiviral mediated gene therapy in adults and pediatric subjects with severe PKD. Methods: 6 subjects with severe PKD (defined as having a history of severe and/or transfusion-dependent anemia despite prior splenectomy) will be enrolled in the Phase 1 study; the first 2 subjects will be adults (age ≥18- Results: An adult female PKD subject (age 31 years) with significant anemia and transfusion requirement has received treatment as of July 2020. Mobilization and apheresis procedures were performed successfully and busulfan conditioning was administered at the target area under the curve (AUC). IP consisted of 3.9×106 CD34+ cells/kg body weight, with a mean vector copy number (VCN) of 2.73. Safety and preliminary efficacy results will be available at the time of presentation. Conclusions: Efficacy in pre-clinical models indicates promising potential for clinical gene therapy in severe PKDHematopoietic stem cell mobilization using G-CSF and plerixafor appears feasible and effective in adult PKD patientsIP was successfully manufactured to meet the required specifications for the Phase 1 clinical study and administered without short-term infusion related complications Disclosures Navarro: Rocket Pharmaceuticals, Inc.: Current equity holder in publicly-traded company, Other: SN has licensed medicinal products and receives research funding and equity from Rocket Pharmaceuticals, Inc., Patents & Royalties, Research Funding. Sevilla:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company. Glader:Agios Pharmaceuticals, Inc.: Consultancy. Beard:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Law:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Zeini:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Choi:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Nicoletti:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Bueren:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from this company., Patents & Royalties, Research Funding. Rao:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Schwartz:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Segovia:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from the Company., Patents & Royalties, Research Funding.

Bosutinib is a second-generation tyrosine kinase inhibitor (2GTKI) approved at 400 mg once daily (QD) as first-line therapy in patients with chronic myeloid leukemia (CML) patients and at 500 mg QD in patients who are resistant to or intolerant of prior therapy. In clinical practice, bosutinib is often given to patients who have failed imatinib, nilotinib, and dasatinib (i.e., as fourth-line treatment), despite the limited data on its clinical benefit in this setting. We have retrospectively evaluated the results of bosutinib in a series of 62 CML patients who have failed to prior treatment with all three, imatinib, nilotinib, and dasatinib. Median time on TKI treatment before bosutinib start was 105 (9–163) months, and median duration on bosutinib was 9 months (1–30). Overall, probabilities to achieve complete cytogenetic response (CCyR) and major molecular response (MMR) were 25% and 24% respectively. After a median follow-up period of 14 months, the event-free survival and progression-free survival were 68 and 85%, respectively. Sixty-four percent of patients in CCyR at the time of bosutinib start were able to achieve MMR. In contrast, patients without CCyR, probabilities to obtain CCyR and MMR were 25% and 14%. Bosutinib was well tolerated in this heavily pretreated patients’ cohort. Pleural effusions and diarrhea were the most frequent grade II–IV side effects, leading to treatment discontinuation in 16% of patients. Bosutinib is an effective treatment option for patients who have failed previous 2GTKIs due to intolerance. However, efficacy seems to be related to the molecular response that the patient achieved prior to bosutinib.

The role of bosutinib as rescue treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML) patients after failing three previous tyrosine kinase inhibitors (TKIs) is currently unknown. We report here the largest series (to our knowledge) of patients treated with bosutinib in fourth-line, after retrospectively reviewing 30 patients in chronic phase, and pretreated with imatinib, nilotinib, and dasatinib. With a median follow up of 11.1 months, the probability to either maintain or improve their CCyR response was 56.6% (17/30) and 11 patients (36.7%) achieved or maintained their baseline MMR. In patients not having baseline CCyR, the probabilities of obtaining CCyR, MMR, and MR4.5 were 13, 11, and 14%, respectively. The probabilities of obtaining MMR and deep molecular response MR4.5 in patients with baseline CCyR were 40.0% (6/15) and 20.0% (3/15). At 20 months, progression-free survival was 73%. Grade 3-4 hematological toxicities were more frequent in resistant than intolerant patients (45.4 vs. 0.0%). Nonhematological toxicities were also more frequent in resistant patients, being diarrhea the most conspicuous one. Bosutinib seems to be an appropriate treatment option for patients resistant or intolerant to three prior TKI's.

The role of bosutinib as rescue treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML) patients after failing three previous tyrosine kinase inhibitors (TKIs) is currently unknown. We report here the largest series (to our knowledge) of patients treated with bosutinib in fourth-line, after retrospectively reviewing 30 patients in chronic phase, and pretreated with imatinib, nilotinib, and dasatinib. With a median follow up of 11.1 months, the probability to either maintain or improve their CCyR response was 56.6% (17/30) and 11 patients (36.7%) achieved or maintained their baseline MMR. In patients not having baseline CCyR, the probabilities of obtaining CCyR, MMR, and MR4.5 were 13, 11, and 14%, respectively. The probabilities of obtaining MMR and deep molecular response MR4.5 in patients with baseline CCyR were 40.0% (6/15) and 20.0% (3/15). At 20 months, progression-free survival was 73%. Grade 3-4 hematological toxicities were more frequent in resistant than intolerant patients (45.4 vs. 0.0%). Nonhematological toxicities were also more frequent in resistant patients, being diarrhea the most conspicuous one. Bosutinib seems to be an appropriate treatment option for patients resistant or intolerant to three prior TKI's.

Introduction: Current recommendations for the treatment of AML in newly diagnosed elderly patients (≥ 65 years) include different therapeutic options (intensive or semi-intensive chemotherapy, low-dose chemotherapy, hypomethylating agents, and supportive care). Regardless of the selected treatment, the results are disappointing because of low overall survival (OS) rates and significant toxicity. Objectives: The primary objective of FLUGAZA trial is to compare the 1-year-OS in 350 patients aged ≥ 65 years diagnosed with AML assigned to azacytidine (n=175) or FLUGA (n=175) arms. Here we present the results of a pre-planned interim safety analysis for both outpatient treatment regimens. Methods Inclusion criteria: Patients diagnosed with de novo or secondary AML according to WHO classification (except for APL), previously untreated, age ≥ 65 years, ECOG 25 x109/L. Concomitant use of hydroxyurea was allowed in the AZA arm if WBC was between 15 and 50 x109/L. In patients with more than 50 x109/L WBC assigned to the AZA arm, the first induction cycle was FLUGA. An interim analysis to assess myelotoxicity, early mortality and response rate was planned in the trial when the last of the first 100 randomized patients completed the first 3 induction cycles. Results: From October 2014 to April 2016, 162 patients were enrolled in 26 Spanish centers from the PETHEMA group. Of them, 22 patients were screen failure and 16 patients did not receive the assigned treatment. The first 100 patients treated were analyzed (58 patients were assigned to AZA arm and 42 to FLUGA arm). Baseline characteristics are shown in Table 1. Median age was 75 [65;90] years in AZA arm vs. 77 [65;88] years in FLUGA arm; 36 (62%) vs. 19 (45%) males. Five patients from AZA arm (n=58) received the first cycle of FLUGA because of WBC > 50 x109/L. Outcomes: overall response rate (CR+CRu+PR) based on the best response accumulated with 3 cycles of treatment was 62% in the AZA arm and 57% in the FLUGA arm. CR+CRu was achieved in 14 patients (24%) from AZA arm and 15 (36%) from FLUGA arm. Early mortality rate (8 weeks) was 14% in AZA and 22% in FLUGA arm. Toxicities: there were no differences in hospitalization and non-hematological ≥ G3 serious adverse events (SAEs) between both arms. Overall, 71 patients (71%), 61 out of 79 (77%) vs. 41 out of 64 (64%) patients, developed neutropenia (< 0.5 x x109/L) after C1, C2 and C3, respectively. Median duration of neutropenia in the AZA arm was 14 days (6;40), 21 days (4;95) and 18 days (1;45) after in C1, C2 and C3, respectively, vs. 15 days (4;33), 15 days (3;36) and 20 days (7;41) after C1, C2 and C3, respectively, in the FLUGA arm (no statistically significant differences). Eighty-one (81%), 55 out of 79 (70%) vs. 40 out of 64 (62%) patients, developed thrombocytopenia (< 50 x109/L) after C1, C2 and C3, respectively. Median duration of thrombocytopenia was 14 days (5;29) after C1, 18 days (4;88) after C2 and 14 days (7;25) after C3 in the AZA arm; vs. 16 (3;63), 20 (6;42) and 13 days (7;56) after C1, C2 and C3, respectively, in the FLUGA arm (NS). Conclusions: Outpatient treatment with AZA or FLUGA was feasible. Both treatment arms showed a similar rate of early mortality and relatively low CR/CRu rates. The study is currently enrolling patients until the planned accrual goal (350 patients) to assess the primary end-point (1-year OS). The study is registered at www.ClinicalTrials.gov as NCT02319135. Disclosures No relevant conflicts of interest to declare.

BACKGROUND: Despite the excellent prognostic of chronic myeloid leukemia (CML) patients since the introduction of tyrosine kinase inhibitors (TKIs), approximately 50% of patients that are treated with TKIs will discontinue first line treatment due to lack of efficacy or intolerance. Once patients need a second line treatment, a considerable proportion of patients will need third or even fourth line therapy during further evolution. At this moment, there is a lack of data about real benefit of this group of patients. We have recently published our experience of 30 CML patients treated with bosutinib in 4th line. We present an update of the study where we have increased the number of patients, and the follow-up. The aim of this study is to present safety and efficacy data CML chronic phase patients treated with bosutinib in 4th line. METHODS: We have collected data from 59 CML patients treated with bosutinib in 4th line after resistance or intolerance to IM, NI and DA. 51 patients have been treated under the Spanish compassionate use program (36 centers) and 10 patients were treated in a single institution from United Kingdom. Median age of patients at diagnosis was 53 years. The percentage of low, intermediate and high risk Sokal groups were 47%, 37% and 16%. Median time TKIs exposure before bosutinib was 9 years. The most common indication (30/59) was intolerant to DA and NI. Patients' dispositions and main line characteristics are shown in table 1. RESULTS: Median follow-up was 14.3 months. All patients started bosutinib at 500mg/d, median dose of was 450mg/d. Overall probabilities to either achieve or maintain previous response were 96% (57/59), 62% (37/59), 40% (24/59) and 17% (10/59) for complete hematological response (CHR), complete cytogenetic response (CCyR), major molecular response (MMR) and MR4.5 respectively. However, probabilities to obtain responses (in patients without response evaluated at baseline) were 27% (7/26), 26% (12/45) and 12% (7/55) for CCyR, MMR and MR4.5. As expected, probabilities to obtain CCyR were lower for patients resistant to DA and NI patients than for patients intolerant to DA and NI (8% VS 44%). Event free survival (EFS) and progression free survival (PFS) probabilities were 50% and 83% by 27 month. Treatment was discontinued in 20/58 (34%), most frequent reasons being adverse events 9/59(15%), lack of efficacy 5/59 (8.5%), disease progression 2/59 (3.4%) and death 1/59 (1.7%). Two patients discontinued due to stem cell transplantation. The adverse events that led to treatment discontinuation were pleural effusion (3), diarrhea (2), rash, renal impairment, auricular fibrillation and liver enzyme elevation one patient each. Overall, bosutinib was well tolerated. Grade 3-4 hematological toxicities were 3%, 6% and 6% for anemia, thromboctytopenia and neutropenia. Most common non hematological side effects were diarrhea (39%, nauseas 13% and liver alterations 14% and pleural effusion 14%. CONCLUSIONS: Little is known about the therapeutic role of Bosutinib in 4th line. The series presented here is, to our knowledge, the largest being presented. Bosutinib seems to be an appropriate treatment option for patients resistant or intolerant to three prior TKIs. | | IM+NI-I+DA-R (N=4) | IM+NI-R+DA-R (N=18) | IM+NI-I+DA-I (N=30) | IM+NI-R+DA-I (N=7) | Total (N=59) | | ------------------------------------------------ | ----------------------- | ------------------------ | ----------------------- | ------------------------ | ------------------------- | ------------------------- | | Sex, N (%) Male | 2 (50) | 11 (61.1) | 16 (53.3) | 2 (28.6) | 31 (52.5) | | Median age of diagnosis, yr (range) | 57.32 (50-64) | 49.19 (23-73) | 54.95 (21-89) | 48.87 (26-68) | 53.15 (21-89) | | Median age of Bosutinib initiation, yr (range) | 69.13 (61-70) | 62.27 (39-79) | 64.85 (25-90) | 64.79(35-74) | 63.7 (25-9) | | Median follow up, months (range) | 18.5(7.8-34.1) | 8.4(1.22-36.1) | 16.3(0.5-34.7) | 23.4(3.3-28.9) | 14.3(0.7-36.1) | | SOKAL Index at diagnosis, N (%) | High | 2(50.0) | 4 (23.5) | 1 (4.3) | 1 (20) | 8 (16.3) | | Intermediate | 1 (25.0) | 5 (29.4) | 10(43.5) | 2 (40) | 18 (36.7) | | Low | 1 (25.0) | 8 (47.1) | 12 (52.2) | 2 (40) | 23 (46.9) | | Median Time from first TKI to BOS, (yr, range) | 10.3 (4.8-11.9) | 9.3 (2.0-11.4) | 8.8 (0.7-13.6) | 8.2 (5.1-12.3) | 8.8 (0.7-13.6) | | Median duration of prior therapy, months (range) | Imatinib | 38.8 (11.8-69.8) | 32.6 (6.3-96.8) | 26.2 (1.6-102.6) | 23.1 (8.3-66.8) | 28.8 (1.6-102.6) | | Dasatinib | 21.5 (12.6-75) | 21.8 (7.7-69) | 31.4 (0.4-87.1) | 23.7 (10.3-53.6) | 23.44 (0.4-87.1) | | Nilotinib | 19.1 (2.1-46.2) | 16.7 (5-65.6) | 8.9 (0.2-58.5) | 30.9 (6.9-49.3) | 14.3 (0.2-65.6) | * BOS: bosutinib, IM, imatinib; DA, dasatinib; NI, nilotinib, I: Intolerance, R: Resistant, Yr: year Table 1. Disclosures Garcia-Gutierrez: Ariad: Consultancy; Pfizer: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Milojkovic: Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Ariad: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Boque: Novartis: Honoraria; BMS: Honoraria; Celgene: Honoraria. Casado: Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Roche: Honoraria, Research Funding. Jimenez: Pfizer: Consultancy, Honoraria. Giraldo: Pfizer: Consultancy. Steegmann: Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Ariad: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Second-generation TKIs have demonstrated efficacy and an acceptable tolerability in patients (pts) with chronic myeloid leukemia (CML); however, new data from so called “off target” side effects have been published. For example, serious concerns have been raised about cardiovascular (CV) events with ponatinib, and, in lesser degree with nilotinib (NI), impeding or difficulting the treatment in patients with previous CV risk factors. Besides, patients with previous history of pleural effusion or pulmonary hypertension should avoid dasatinib (DA) if possible. Bosutinib could be a good candidate for situations which preclude the use of other TKI’s. We have previously presented efficacy data of 29 patients treated with bosutinib in forth line. The aim of this study is to report safety data of heavily CML patients treated with bosutinib in 4th line. We have studied 30 pts previously treated with imatinib (IM), dasatinib and nilotinib and 5 pts previously treated with IM-DA or NI since 2012 under the Spanish Compassionate Use Program. Patient’s baseline characteristics and previous treatments are shown in table 1. We have classified patients in 2 groups regarding to investigator-driven cause of discontinuation: intolerant (INT) or resistant (RES). At the data cutoff on June 16, 2014, the median follow up was 11.47 months (range, 2.03-45.97 months). Median duration of BOS treatment across all cohorts was 9.23 months (range, 0.63-23.40 months). We observed no significant differences in terms of Index prognostic factors (Sokal, Hasford or Eutos), sex, median duration of TKIs treatment or comorbidities. However, patients with resistance where significantly older observed: 56 years vs. 67 years (p

Abstract 4279 Introduction: Clofarabine (CLF) is a purine nucleoside analog approved by FDA and EMA in refractory pediatric ALL patients. Phase I and II studies have reported Clofarabine activity in AML. Aims: To evaluate the experience in Spain with (CLF) in the treatment of adult AML patients, analyzing effectiveness and toxicity profile. Method: This is a multicenter retrospective study including AML patients treated in Spain with CLF by compassionate use. Main points were complete remission as IWRv2003 criteria and toxicity as CTCAE v3.0 of NCI scale. Result: Between July 2007 ans April 2011 a total of 76 AML patients were treated with CLF based chemotherapy in Spain. We obtained clinical data from 64 cases. Median age at CLF treatment 52.4 years (18–77). Male/Female: 31/33. Previous Myelodisplastic syndrome 12 (18%). Cytogenetic data was available in 58 patients (90%), and 28 of them had high-risk cytogenetic. CLF treatment: 56 patients received CLF as salvage therapy (23 in AML relapse and 33 in refractory disease), median previous lines 2 (0–7), were the remaining 8 patients were untreated patients. CLF was administered in combination with AraC in 94% patients and the 91% received a five days schedule. The most frequents CLF dose/day were: 40 mg/m2/day in 39 patients, 30 mg/m2/day in 11 patients, and 20 mg/m2/day in 9 patients. Response and outcome: Nineteen (35.8%) patients achieved complete remission and 64.1% had resistant disease. Mean survival time 14.3 ± 1.4 months. The statistical analysis shows a significant difference in the CR rate between first line therapy (CR 82%) and savage therapy in relapsed (CR 45%) and salvage therapy in refractory (CR 18%), (p0.012). Neither adverse cytogenetics nor previous MDS did influence CR. (p0.57 and p0.53 respectively). Toxicity: All patients presented grade IV hematological toxicity with grade IV neuthopenia, grade IV trombopenia and transfusion depend anemia. The incidence of extra hematological toxic effects were low, creatinine >3 mg/dL: 4 cases (6%); bilirrubine > 3mg/dL: 9 cases (14%). Eleven (17%) patients died during Induction. Conclusions(opcion1): The revised experience in Spain with CLF as compassionate used in AML confirms the effectiveness of Clofarabine as a salvage regimen. Of note was that CLF could potentially overcome some adverse known factors as cytogenetics. Disclosures: Off Label Use: Clofarabine in AML is an off-label use.