Induction of Fetal Hemoglobin Synthesis By Crispr/Cas9-Mediated Disruption of the β-Globin Locus Architecture

Abstract Naturally occurring, large deletions in the β-globin locus result in increased fetal hemoglobin (HbF) expression (HPFH, Hereditary Persistence of Fetal Hemoglobin), a condition that mitigates the clinical severity of Sickle Cell Disease (SCD) and β-thalassemia. Here, we integrated BCL11A and GATA1 transcription factor binding site analysis and HPFH mutational data to identify potential HbF silencers in the β-globin locus. Based on this analysis, we designed a CRISPR/Cas9 strategy to disrupt: (i) a 3.5-kb δγ-intergenic region that is specifically deleted in individuals with HPFH. This region contains BCL11A and GATA1 binding sites in adult, HbF-negative primary erythroblasts, thus representing a potential HbF silencer; (ii) a 7.2-kb region, encompassing the 3.5-kb δγ-intergenic element, which is the minimal naturally occurring deletion associated with HPFH ("Corfù" deletion; Chakalova et al., Blood, 2005); (iii) a 13.6-kb genomic region commonly deleted in HPFH, which includes the δ- and β-globin genes and putative intergenic HbF silencers. Targeted deletion or inversion of the 13.6-kb genomic region caused a substantial increase in γ-globin mRNA levels, re-activation of HbF synthesis and a concomitant decrease in HbA expression in adult human erythroid cells (HUDEP-2). Interestingly, deletion of the Corfù region or of the 3.5-kb putative HbF silencer, increased γ-globin gene transcription but failed to produce accumulation of γ-globin mRNA, suggesting a post-transcriptional regulation of γ-globin synthesis in the presence of an intact and active β-globin gene. We then tested re-activation of HbF synthesis in primary adult hematopoietic stem/progenitor cells differentiated towards the erythroid lineage in liquid and clonogenic cultures. Targeting the 13.6-kb genomic region resulted in a high proportion of γ-globin expressing primary erythroblasts, with HbF representing up to 50% of total hemoglobin. Cell morphology, erythroid marker profile, total hemoglobin levels and erythroid maturation were unaffected, consistent with the asymptomatic phenotype of adult HPFH carriers. These data suggest that this region could serve as target for therapeutic genome editing for HbF induction in β-hemoglobinopathies. Overall, this study contributes to the knowledge of the mechanisms underlying fetal to adult Hb switching, and provides clues for a genome editing approach to the treatment of SCD and β-thalassemia. Disclosures Cradick: CRISPR Therapeutics: Employment. Lundberg:CRISPR Therapeutics: Employment, Equity Ownership. Porteus:CRISPR Therapeutics: Consultancy, Equity Ownership. Mavilio:Adverum Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Membership on an entity's Board of Directors or advisory committees; CRISPR Therapeutics: Consultancy, Research Funding.

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Novel Protein Agonist of Thrombopoiesis Acts Via a Physiocrine Pathway Distinct From That of Thrombopoietin

Blood ◽

10.1182/blood.v118.21.2376.2376 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2376-2376

Author(s):

Minh-Ha T Do ◽

Wei Zhang ◽

Kyle Chiang ◽

Chi-Fang Wu ◽

Chulho Park ◽

...

Keyword(s):

Bone Marrow ◽

Board Of Directors ◽

Employment Equity ◽

Advisory Committees ◽

Platelet Production ◽

Platelet Counts ◽

Normal Platelet ◽

Naturally Occurring ◽

Equity Ownership

Abstract Abstract 2376 Thrombopoietin (TPO) is recognized as the main regulator of platelet production, yet its genetic ablation in mice does not completely obliterate thrombopoiesis, suggesting that alternate pathways could lead to platelet formation. We recently identified a naturally-occurring protein that acts as a potent agonist of platelet production by a mechanism distinct from that of TPO. This protein belongs to a novel class of human extracellular signaling proteins called physiocrines that are generated from tRNA synthetases by alternative splicing or proteolysis. Physiocrines interact with several classes of receptors through unique mechanisms to modulate cellular differentiation and tissue homeostasis in normal and pathological processes. The newly identified thrombopoietic physiocrine, termed ATYR0030, is an engineered version of a naturally-occurring physiocrine derived from the tyrosyl tRNA synthetase (YRS). In vivo, systemic administration of ATYR0030 or YRS physiocrine to rats led to an increase in platelets counts comparable to that seen with TPO treatment, but with a greater effect in animals with low baseline platelet levels. When injected into normal animals preselected for low platelet counts, ATYR0030 treatment resulted in an increase in platelets up to, but not beyond, normal levels (Figure 1), suggesting a role in platelet homeostasis and differentiating its effects from the known activity of TPO. Intravenous administration of ATYR0030 also accelerated recovery of platelet counts in carboplatin-treated rats, indicating a possible role in bone marrow reconstitution after chemical insult. Consistent with homeostatic properties, no toxicity was seen in a repeat-dose 28-day non-GLP safety study in rats dosed up to 100-fold above the efficacious range. Histopathology assessment revealed no tissue abnormalities, no increase in bone marrow reticulin and no hyperplasia of myeloid precursors. Clinical chemistry and hematology parameters were in the normal range with a modest increase in platelet counts, as anticipated in animals with normal platelet levels. Our in vitro data suggest that ATYR0030 may play a role in megakaryopoiesis by facilitating cell migration and adhesion to the vasculature. In contrast to TPO, ATYR0030 does not directly signal through the TPO receptor and does not activate the JAK/STAT pathway but rather appears to engage specific G-protein coupled receptors. In vitro, ATYR0030 does not stimulate proliferation of cultured M07e human megakaryoblasts or primary bone marrow cells isolated from AML patients (Figure 2). The parent synthetase is present in human platelets and is secreted in response to platelet activation, perhaps providing a feedback mechanism to stimulate the release of new platelets. In an effort to link the biological activity of ATYR0030 and the role that the parent synthetase plays in human physiology, we have begun to analyze samples from patients with abnormal platelets counts to determine circulating levels of the parent synthetase. The unique thrombopoietic activity of ATYR0030 may lead to an orthogonal approach to restoring normal platelet levels in thrombocytopenic patients who currently have limited treatment options. For example, in the myelodysplastic syndrome population, TPO-receptor agonists carry a risk of stimulating blast proliferation and accelerating disease progression to acute myeloid leukemia (AML). The distinct proliferation profile of ATYR0030 may translate into important safety benefits by reducing the risk of progression to AML. In addition, the potential role of ATYR0030 in regulating platelet homeostasis may provide a greater safety margin in the normalization of platelet levels, thereby also limiting the risk of thrombosis. Leveraging the therapeutic potential of this thrombopoietic physiocrine may lead to the development of a novel treatment option with a favorable safety profile. Disclosures: Do: aTyr Pharma: Employment, Equity Ownership, Patents & Royalties. Zhang:aTyr Pharma: Employment, Equity Ownership. Chiang:aTyr Pharma: Employment, Equity Ownership. Wu:aTyr Pharma: Employment, Equity Ownership, Patents & Royalties. Park:aTyr Pharma: Equity Ownership. Yang:aTyr Pharma: Consultancy, Equity Ownership, Patents & Royalties, Research Funding. Kunkel:aTyr Pharma: Consultancy, Stock Ownership. Ashlock:aTyr Pharma: Employment, Equity Ownership. Mendlein:aTyr Pharma: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Belani:Atyr Pahrma: Consultancy, Equity Ownership, Patents & Royalties. Vasserot:aTyr Pharma: Employment, Equity Ownership, Patents & Royalties. Watkins:aTyr Pharma: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

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Crispr-Cas9 Saturating Mutagenesis Reveals an Achilles Heel in the BCL11A Erythroid Enhancer for Fetal Hemoglobin Induction (by Genome Editing)

Blood ◽

10.1182/blood.v126.23.638.638 ◽

2015 ◽

Vol 126 (23) ◽

pp. 638-638 ◽

Cited By ~ 4

Author(s):

Daniel E. Bauer ◽

Matthew C. Canver ◽

Elenoe C. Smith ◽

Falak Sher ◽

Luca Pinello ◽

...

Keyword(s):

Board Of Directors ◽

Genome Editing ◽

Genetic Variants ◽

Research Funding ◽

Gene Editing ◽

Fetal Hemoglobin ◽

Erythroid Cell ◽

Erythroid Cells ◽

Advisory Committees ◽

Hbf Level

Abstract Common genetic variation associated with fetal hemoglobin (HbF) level and β-hemoglobin disorder clinical severity marks an erythroid enhancer within the BCL11A gene. The 12 kb intronic enhancer contains three ~1 kb erythroid DNase I hypersensitive sites (DHSs), termed +55, +58, and +62. Here we utilized a human adult-stage erythroid cell line to show by CRISPR-Cas9 mediated targeted deletion that the composite enhancer is required both for BCL11A expression and HbF repression. Because deletion of the entire enhancer is currently too inefficient to consider for a gene editing approach to hemoglobin disorders, we sought to define the critical features of the enhancer in its natural genomic context. We designed and synthesized a tiling pooled guide RNA (gRNA) library to conduct saturating mutagenesis of the enhancer sequences in situ using the CRISPR-Cas9 gene editing platform. The gRNAs direct Cas9 cleavage and non-homologous end-joining repair at discrete sites throughout the enhancer. By comparing the representation of lentiviral gRNA integrants in high and low HbF pools of the adult erythroid cells, we generated a functional map approaching nucleotide resolution of sequences within the enhancer influencing BCL11A regulation. We observed several discrete enhancer regions required for maximal expression. The largest effect was observed by producing mutations within a narrow functional core of the +58 DHS. These sequences include a GATA1 motif conserved among vertebrates located within a primate-specific context. This region constitutes an Achilles Heel for functional inactivation of the enhancer. We also identified rare genetic variants within the +58 DHS core in individuals with sickle cell disease that are associated with HbF level, independent of all known associations of common genetic variants. In parallel, we performed a similar saturating CRISPR mutagenesis screen of the corresponding murine Bcl11a enhancer. To our surprise, despite low-resolution evidence of conservation by primary sequence homology, syntenic genomic position, and shared chromatin signature, the mouse enhancer sequence determinants of BCL11A expression showed substantial functional divergence. The +58 orthologous sequences were dispensable whereas the +62 orthologous sequences were critically required in murine adult erythroid cells. These results were validated by producing targeted deletions in mouse and human adult erythroid cell lines. Furthermore we subjected cells to individual gRNAs to correlate individual nucleotide disruptions with loss of BCL11A expression. To substantiate the tissue-restricted effect of the enhancer mutations, we generated transgenic mice with deletion of the Bcl11a enhancer and found these sequences were dispensable for expression in developing neurons and B-lymphocytes (unlike conventional Bcl11a knockout) but essential for appropriate hemoglobin switching in vivo. We showed that in primary CD34+ hematopoietic stem and progenitor derived human erythroid precursors that delivery of an individual gRNA and Cas9 is sufficient to produce robust reinduction of HbF. These results validate the BCL11A erythroid enhancer as a promising therapeutic target. Our findings define the most favorable regions for generation of indel mutations in the BCL11A erythroid enhancer as a therapeutic genome editing strategy for HbF reinduction for the β-hemoglobin disorders. Disclosures Bauer: Biogen: Research Funding; Editas Medicine: Consultancy. Zhang:Editas Medicine: Membership on an entity's Board of Directors or advisory committees; Horizon Discovery: Membership on an entity's Board of Directors or advisory committees. Orkin:Editas Medicine: Membership on an entity's Board of Directors or advisory committees; Biogen: Research Funding; Pfizer: Research Funding; Sangamo Biosciences: Consultancy.

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Interim Results from a Phase 1/2 Clinical Study of Lentiglobin Gene Therapy for Severe Sickle Cell Disease

Blood ◽

10.1182/blood.v128.22.1176.1176 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1176-1176 ◽

Cited By ~ 19

Author(s):

Julie Kanter ◽

Mark C. Walters ◽

Matthew M. Hsieh ◽

Lakshmanan Krishnamurti ◽

Janet Kwiatkowski ◽

...

Keyword(s):

Gene Therapy ◽

Board Of Directors ◽

Research Funding ◽

Phase 1 ◽

Globin Gene ◽

Advisory Committees ◽

Cell Dose ◽

Cd34 Cells ◽

Equity Ownership

Abstract β-globin gene transfer into hematopoietic stem cells (HSCs) has the potential to reduce or eliminate the symptoms and long-term complications of severe sickle cell disease (SCD). LentiGlobin Drug Product (DP) is a gene therapy product containing autologous CD34+ cells transduced with the BB305 lentiviral vector. BB305 encodes a human β-globin gene containing a single point mutation (AT87Q) designed to confer anti-sickling properties similar to those observed in fetal hemoglobin (γ-globin). In two ongoing studies, subjects with transfusion-dependent β-thalassemia (Studies HGB-204 and HGB-205) or SCD (Study HGB-205) receiving LentiGlobin DP have demonstrated sustained expression of 3-9 g/dL therapeutic hemoglobin (HbAT87Q) and have shown marked improvements in clinical symptoms 1 year post-treatment. Study HGB-206 is a multi-center, Phase 1/2 safety and efficacy study of LentiGlobin DP in adults with severe SCD. We previously (ASH 2015) presented results from 2 subjects, who had 3 and 6 months of follow-up after LentiGlobin treatment. We now present data from 7 treated subjects, 4 of whom have ≥6 months of follow-up data. Subjects (≥18 years of age) with severe SCD (history of recurrent vaso-occlusive crisis [VOC], acute chest syndrome, stroke, or tricuspid regurgitant jet velocity of >2.5 m/s) were screened for eligibility. Following bone marrow harvest (BMH), CD34+ cells were transduced with the BB305 vector. Subjects underwent myeloablative conditioning with busulfan prior to infusion of the transduced cells. Safety assessments include adverse events (AEs), integration site analysis (ISA) and surveillance for replication competent lentivirus (RCL). After infusion, subjects are monitored for hematologic engraftment, vector copy number (VCN), HbAT87Q expression, and other laboratory and clinical parameters. As of July 2016, 7 subjects with severe SCD (median age: 26 years, range 18-42 years) have received LentiGlobin DP in this study. All subjects successfully underwent BMH, with a median of 2 harvests required (range 1-4). Fifteen Grade 3 AEs in 5 subjects were attributed to BMH: pain (n=10), anemia (n=3) and VOC (n=2); all resolved with standard measures. Table 1 summarizes cell harvest, DP characteristics, and lab results. The median LentiGlobin DP cell dose was 2.1x10e6 CD34+ cells/kg (range 1.6-5.1) and DP VCN was 0.6 (0.3-1.3) copies/diploid genome. Median post-infusion follow-up as of July 2016 is 7.1 months (3.7-12.7 months). All subjects successfully engrafted after receiving LentiGlobin DP, with a median time to neutrophil engraftment of 22 days (17-29 days). The toxicity profile observed from start of conditioning to latest follow-up was consistent with myeloablative conditioning with single-agent busulfan. To date, there have been no DP-related ≥Grade 3 AEs or serious AEs, and no evidence of clonal dominance or RCL. The BB305 vector remains detectable at low levels in the peripheral blood of all subjects infused, with median VCN 0.08 (0.05-0.13, n=7) at last measurement. All subjects express HbAT87Q, with a median of 0.4g/dL (0.1-1.0 g/dL, n=7) at 3 months; most subjects demonstrated modest increases over time, and the 2 subjects with the longest follow-up expressed 0.31 and 1.2 g/dL HbAT87Q at 9 months. All 4 subjects with ≥6 months of follow-up experienced multiple VOCs in the 2 years prior to study entry (2-27.5 VOCs annually). Since LentiGlobin DP infusion, 3 of these 4 subjects have had fewer VOCs, although this trend may be confounded by the short follow-up, the effects of transplant conditioning, and/or post-transplant RBC transfusions. The decrease in VCN between DP and peripheral cells contrasts with previous reports of successful LentiGlobin gene therapy in ongoing studies HGB-204 and HGB-205. The relatively low in vivo VCN in this study appears to result in the lower HbAT87Q expression seen to date. We are exploring multiple hypotheses as to the etiology of the VCN drop between DP and peripheral blood, including the adverse impact of sickle marrow pathology on HSCs, the adequacy of myeloablation, and the magnitude of the transduced cell dose. We will provide an update on study data and ongoing efforts to increase in vivo VCN in patients with SCD, such as increasing the transduced cell dose through alternate HSC procurement methods or enhancing the DP VCN through manufacturing improvements. Disclosures Kanter: Novartis: Consultancy. Walters:Bayer HealthCare: Honoraria; AllCells, Inc./LeukoLab: Other: Medical Director ; ViaCord Processing Laboratory: Other: Medical Director ; Leerink Partners, LLC: Consultancy; Kiadis Pharma: Honoraria; bluebirdBio, Inc: Honoraria. Kwiatkowski:Ionis pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Shire Pharmaceuticals: Consultancy; Sideris Pharmaceuticals: Consultancy; Apopharma: Research Funding; Luitpold Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. von Kalle:bluebird bio: Consultancy; GeneWerk: Equity Ownership. Kuypers:Children's Hospital Oakland Research Institute: Employment; bluebird bio: Consultancy. Leboulch:bluebird bio: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding. Joseney-Antoine:bluebird bio: Employment, Equity Ownership. Asmal:bluebird bio: Employment, Equity Ownership. Thompson:bluebird bio: Consultancy, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Amgen: Research Funding; Baxalta (now part of Shire): Research Funding; ApoPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mast: Research Funding; Eli Lily: Research Funding.

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HQK-1001 Is Well Tolerated and Augments Hemoglobin F and Hemoglobin Levels In Patients with Beta Thalassemia Intermedia

Blood ◽

10.1182/blood.v116.21.4280.4280 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4280-4280

Author(s):

Suthat Fuchareon ◽

Adlette C. Inati ◽

Noppadol Siritanaratkul ◽

Suzanne Koussa ◽

Ali Taher ◽

...

Keyword(s):

Board Of Directors ◽

Research Funding ◽

Globin Gene ◽

Beta Thalassemia ◽

Thalassemia Intermedia ◽

Employment Equity ◽

Advisory Committees ◽

Hemoglobin F ◽

Pharmacodynamic Effects ◽

Equity Ownership

Abstract Abstract 4280 Beta thalassemia intermedia syndromes are serious conditions for which there is no satisfactory therapy to correct the underlying globin chain imbalance. Some agents that induce fetal globin gene expression have ameliorated anemia in thalassemia patients by reducing the imbalance in alpha: non-alpha globin synthesis, but none have been broadly accepted or are currently approved by regulatory authorities. HQK-1001 is an oral agent that targets the fetal globin gene promoter, thereby increasing fetal hemoglobin (HbF) expression. It has been well tolerated in single dose and multiple dose escalation clinical studies in healthy volunteers. We now report the results of a randomized, double blind, placebo-controlled, multiple ascending dose Phase I/II trial in 21 adult patients with beta thalassemia intermedia (BTI), including 14 with HbE/ß0 thalassemia and 7 with ß+/ß0 thalassemia (including 12 different beta globin gene mutations). Study medication was taken as a single daily dose for 8 weeks. Four ascending dose levels (10, 20, 30, and 40 mg/kg/day) were sequentially evaluated in 4 dose level cohorts after the preceding dose and schedule were determined safe by an independent and unblinded Safety Monitoring Committee. HQK-1001 was well-tolerated. Adverse events in treated subjects included headache, upper respiratory infection and nausea, but the rates of such events were not markedly different than those observed in the placebo-treated subjects. The 20 mg/kg dose was associated with a 10% mean increase above baseline in HbF, (p< 0.001). Total hemoglobin (Hgb) increased by a mean of 1.1 gram/dL in 3 of 6 treated BTI patients with Mediterranean mutations. F-cells increased over the study period with maximal increases often observed 2 weeks following therapy. Doses higher than 20 mg/kg were not associated with the same magnitude of pharmacodynamic effects. These observations indicate that HQK-1001 is well-tolerated at doses associated with favorable pharmacodynamic effects on Hgb and HbF. These findings with brief treatment provide a rationale for conducting larger and longer studies in BTI patients. Disclosures: Fuchareon: HemaQuest Pharmaceuticals, Inc: Honoraria, Research Funding. Inati:HemaQuest Pharmaceuticals, Inc: Honoraria, Research Funding. Boosalis:HemaQuest Pharmaceuticals, Inc: Equity Ownership, Research Funding. Thein:HemaQuest Pharmaceuticals, Inc: Research Funding. Wallis:HemaQuest Pharmaceuticals: Consultancy, Equity Ownership. Bobbitt:HemaQuest Pharmaceuticals, Inc: Employment, Equity Ownership, Patents & Royalties. Thomson:HemaQuest Pharmaceuticals: Employment, Equity Ownership. Johnson:HemaQuest Pharmaceuticals: Employment, Equity Ownership. Berenson:HemaQuest Pharmaceuticals, Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Perrine:HemaQuest Pharmaceuticals, Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding.

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Multiplex CRISPR/Cas9 Genome Editing Targeting the BCL11A/HBG Axis Maximizes Fetal Hemoglobin Reinduction but Generates Chromosomal Translocations Which Persist In Vivo

Blood ◽

10.1182/blood-2020-138539 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 47-48

Author(s):

Clare Samuelson ◽

Olivier Humbert ◽

Stefan Radtke ◽

Haiying Zhu ◽

Mallory J Llewellyn ◽

...

Keyword(s):

Bone Marrow ◽

Board Of Directors ◽

Genome Editing ◽

Chromosomal Translocation ◽

Fetal Hemoglobin ◽

Secondary Malignancy ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Immunodeficient Mice

Sickle cell disease and β-thalassemia are among the most common monogenic disorders globally, causing significant morbidity and early mortality. The only curative option available is allogeneic hematopoietic stem cell transplantation, which is limited by a lack of matched donors and risks, including graft versus host disease and secondary malignancy. Retroviral gene transfer is being explored in clinical trials, but an alternative approach is more targeted CRISPR/Cas9 genome editing, to recapitulate naturally occurring hereditary persistence of fetal hemoglobin (HPFH) which ameliorates disease. HbF reinduction is achieved by disrupting either transcription factor binding sites within the HBG promoter, or an erythroid enhancer sequence within the HbF repressor, BCL11A. Results from preclinical studies have suggested that HbF levels may remain suboptimal when each locus is targeted individually. We thus investigated the feasibility of a dual editing approach, targeting both loci simultaneously or sequentially, to maximize HbF production. G-CSF-mobilized human peripheral blood hematopoietic stem and progenitor cells (HSPCs) underwent CRISPR/Cas9 genome editing at either HBG promoter, BCL11A erythroid enhancer, or both loci targeted either simultaneously or sequentially. Immunodeficient mice were transplanted with edited cells. HSPCs cultured in differentiation media demonstrated comparable levels of editing at each locus in the single edited arms (by TIDE).The dual editing approach did not impair editing efficiency at each site when conducted sequentially and only slightly reduced efficiency in the simultaneously-edited reactions. HbF reinduction was also greatest in sequentially double-edited reactions, with HbF/HbA ratio as high as 3.9 times that seen in mock reactions by flow cytometry and 4.1 times by HPLC. In single-edited arms, HbF reinduction was slightly greater with HBG promotor than BCL11A erythroid enhancer editing. Two separate chromosomal translocation events encompassing both loci were detected in each double-edited arm and quantified using digital droplet PCR. Both were more frequent in simultaneous (mean of 1.0% and 0.6%) than sequential reactions (means <0.2%, n=3, p=0.0420 and p=0.0296). Analysis of single BFU-E colonies grown on methocult media revealed markedly different indel patterns at the 2 target loci. Concurrent hemoglobin fraction analysis of these clonal populations by HPLC demonstrated greatest HbF proportion in double-edited colonies. Where ≥60% editing was reported at both loci mean HbF was 71.3%, compared to 47.1% with ≥60% editing at HBG only, and 29.6% with ≥60% editing at BCL11A only (p=0.0373). Following transplant into mice, engraftment and lineage differentiation were comparable among all experimental arms. At necropsy, bone marrow populations of human CD45+ cells, CD34+CD38low HSPCs and, within these, HSC-enriched CD90+CD45RA- subpopulation, were present at comparable levels indicating that the dual editing approach did not impair engraftment. Translocation events were detected, albeit at frequencies of less than 0.25%, in the bone marrows of all 4 mice transplanted with simultaneously dual-edited cells and in 5 of 6 mice transplanted with sequentially dual-edited cells. Bone marrow cells cultured ex vivo demonstrated greatest HbF from mice transplanted with sequentially double-edited cells. In summary, we present evidence of maximized HbF reinduction with sequentially applied multiplex genome editing at BCL11A erythroid enhancer and HBG promoter, with no impairment of engraftment or differentiation. However, chromosomal translocation events were consistently seen in double-edited reactions, even when edits at each locus were applied sequentially, and persisted in vivo after engraftment, thus rendering this approach inappropriate for clinical applications. However, multiplex editing and targeting both the BCL11A erythroid enhancer and HBG promoter to maximize fetal hemoglobin induction may be a promising strategy for alternative platforms such as base editors which are expected to greatly reduce or completely eliminate the occurrence of translocations. Disclosures Radtke: Forty Seven INC: Consultancy. Kiem:Enochian: Membership on an entity's Board of Directors or advisory committees; Umoja: Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics: Consultancy; Homology Medicines: Membership on an entity's Board of Directors or advisory committees; CSL: Consultancy; Vor Biopharma: Membership on an entity's Board of Directors or advisory committees; Rocket Pharma: Membership on an entity's Board of Directors or advisory committees.

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2'-O-Methoxyethyl Splice-Switching Oligos to Reverse Splicing from IVS2-745 β-Thalassemia Patient Cells: A Foundation for Potential Therapies

Blood ◽

10.1182/blood-2019-127017 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2244-2244

Author(s):

Valentina Ghiaccio ◽

Alisa Dong ◽

Irene Motta ◽

Shuling Guo ◽

Raechel Peralta ◽

...

Keyword(s):

Board Of Directors ◽

Splice Site ◽

Globin Gene ◽

Mrna Translation ◽

Aberrant Splice ◽

Splice Sites ◽

Globin Mrna ◽

Aberrant Splicing ◽

Advisory Committees ◽

Intron 2

The β thalassemia trait is associated with over 300 mutations in the β-globin gene that lead to reduced (β+ allele) or absent (β0 allele) synthesis of the β globin chain. A subset of these mutations affect the canonic splicing of the β globin mRNA. Such mutations activate aberrant splice sites, which lead to an altered splicing pathway and consequently affects protein synthesis. The (C>G) IVS-2-745 mutation is common in South Eastern Europe, Cyprus, Lebanon, India, Malaysia, and Indonesia. This mutation, located within intron 2 of the β-globin gene, creates an aberrant 5' splice site at nucleotide 745 of intron 2 and activates a cryptic 3' splice site within the same intron. Portions of the intronic sequence are incorrectly retained in the spliced mutant mRNA. The mutation results in a premature stop codon that prevents proper mRNA translation and causes a β‐globin deficiency, resulting in β‐thalassemia. The IVS-2-745 allele has the functional splice sites preserved, but produces a significantly reduced level of correctly spliced β-globin mRNA and results in only marginal synthesis of HbA. Therefore, the IVS-2-745 mutation in homozygosity leads to severe transfusion-dependent thalassemia major. Taking advantage of conserved canonical splice sites in defective β‐globin genes, such as IVS-2-745, recently developed approaches show that by targeting the aberrant splice sites it is possible to circumvent the aberrant splice site and restore the normal β-globin splicing pattern. We sought to use uniform 2'-O-methoxyethyl (2'-MOE) splice switching oligos (SSOs) to reverse aberrant splicing in the pre-mRNA for the IVS-2-745 mutation. Using these SSOs, we show effective aberrant-to-wild-type splice switching. This leads to an increase in adult hemoglobin (HbA) by up to 80% in erythroid cells from patients with the IVS-2-745 mutation. Furthermore, we demonstrate a restoration of the balance between β-like- and α-globin chains, and up to an 87% reduction in α-heme aggregates. While examining the potential benefit of 2'-MOE-SSOs in a sickle/IVS-2-745-thalassemic genotype setting, we found that use of these oligos restored production of HbA and reduced HbS synthesis, which ultimately lessened cell sickling under hypoxic conditions. We confirmed increased WT β-globin expression in specimens treated with 2'-MOE-SSOs with semi- and quantitative methods (RT and Q-PCR), and further supported this evidence using a direct quantification method (ddPCR). Compared to treated specimens heterozygous for IVS-2-745 , homozygous specimens showed elevated WT HbA, reflecting the additive effect of targeting the aberrant splicing of both alleles as opposed to a single IVS-2-745 allele. In fact, while 2'-MOE-SSOs significantly reduced aberrant splicing, leading to a consequent 60% increase in HbA levels in specimens from patients with a β0/IVS-2-745 genotype, the same oligos produced a more robust effect in specimens with a homozygous IVS-2-745 genotype, resulting in an 80% increase in HbA levels. This level of increase could potentially be curative for patients with this particular genotype. Moreover, we compared the effect of 2'-MOE-SSOs treatment to a lentiviral vector carrying a WT β-globin gene. In this comparative assay, β0/IVS-2-745 cells treated with 2'-MOE-SSOs or the lentivector (with 1.13 copies integrated per genome) lead to a similar increase in HbA (50%). This suggests that the oligo-based technology is a competitive approach and a viable alternative to gene addition therapy to overcome anemia in IVS-2-745 β-thalassemia. In summary, 2'-MOE-SSOs are promising therapeutic tools for certain forms of β-thalassemia caused by aberrant splicing. Their ability to correct the underlying splicing defect offers a pharmacological treatment that is direct, specific, and accessible. In comparison, gene therapy approaches utilizing gene addition or editing are primarily available in advanced medical care environment resulting in an unfulfilled demand in regions where such conditions are not readily available. The restoration of target gene activity reported here suggests that this treatment strategy could be applicable to other forms of thalassemia resulting from mutations affecting splicing. This could have, with an effective method of delivery, potential clinical utility in helping patients reduce their transfusion dependence or even achieving transfusion independence. Disclosures Dong: Aruvant Sciences INC: Employment. Motta:Sanofi-Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees. Guo:Ionis Pharmaceutical, INC: Employment, Other: shareholders. Peralta:Ionis Pharmaceutical, Inc: Employment. Freier:Ionis Pharmaceuticals: Employment. Watt:Ionis Pharmaceuticals: Employment. Manwani:Novartis: Consultancy; Pfizer: Consultancy; GBT: Consultancy, Research Funding. Cappellini:Genzyme/Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Honoraria; Vifor Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; CRISPR Therapeutics: Membership on an entity's Board of Directors or advisory committees. Abdulmalik:The Children's Hospital of Philadelphia: Patents & Royalties: Provisional Patent. Rivella:Meira GTx, Ionis Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Disc medicine, Protagonist, LIPC, Meira GTx: Consultancy.

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Phase 1/2 Clinical Trial of HQK-1001, An Oral Fetal Hemoglobin Stimulant, In Sickle Cell Anemia

Blood ◽

10.1182/blood.v116.21.943.943 ◽

2010 ◽

Vol 116 (21) ◽

pp. 943-943 ◽

Cited By ~ 1

Author(s):

Abdullah Kutlar ◽

Kenneth I. Ataga ◽

Marvin Reid ◽

Loray A Blair-Britt ◽

Elliott Vichinsky ◽

...

Keyword(s):

Board Of Directors ◽

Sickle Cell ◽

Research Funding ◽

Phase 1 ◽

Fetal Hemoglobin ◽

Employment Equity ◽

Advisory Committees ◽

Equity Ownership ◽

Dose Levels ◽

Peak Increase

Abstract Abstract 943 Definitive therapies to reduce the underlying pathology in sickle cell syndromes are still needed, particularly non-cytotoxic therapeutics which could be used either alone or in combination with hydroxyurea. Increased fetal hemoglobin (HbF) levels correlate with reduction in organ damage and improved patient survival. An oral, promoter-targeted fetal globin gene stimulant, HQK-1001, which also prolongs erythroid survival and proliferation, has demonstrated favorable pharmacokinetic (PK) and safety profiles in normal volunteers in a Phase 1 clinical trial. Accordingly, a randomized, blinded dose-ranging Phase 1/2 trial was performed in 24 adult patients with sickle cell disease (including HbSS or S/ß thalassemia). The study therapeutic was administered once daily for two 6-week cycles of daily therapy with a 2 week treatment break between the two cycles. Three dose levels (10, 20, 30 mg/kg/dose) were studied sequentially, with 4 placebo treated subjects. 21 patients were evaluable. Five patients received active drug at the lower two dose levels; 7 patients received active study drug at the 30 mg/kg dose level. HQK-1001 was well-tolerated with no significant drug-related adverse events. Increases in HbF levels were observed at all dose levels with the highest effects observed at 30 mg/kg, where 5 of 7 treated patients responded with a mean peak increase of 2.6% HbF (absolute 0.2 g/dl, p=0.04) above baseline. HbF increased both in patients who did, and who did not, take concomitant hydroxyurea. A mean peak increase in total hemoglobin of 1.3 g/dL (range 0.9 to 2.4) above baseline was also observed in these HQK-1001-treated patients. F-reticulocytes and F-cells increased by 20–33% and 6–18%, respectively, in the 5 responders at the 30 mg/kg dose level. LDH declined in 4 of 5 responding subjects receiving 30 mg/kg doses. Fetal globin mRNA increased by 4- to 9-fold over baseline throughout the study period in treated patients and was still increasing at the end of the dosing period, implying that HbF expression had not yet peaked. Other fetal globin inducing agents, such as hydroxyurea require 6–9 months of treatment for optimal effects on HbF to be achieved. Therefore, the findings of HbF induction and rises in total Hgb in 70% of subjects with short treatment duration in the current study indicate that longer trials of HQK-1001 are warranted to evaluate potential therapeutic effects on HbF expression and anemia more definitively in sickle cell disease. Disclosures: Kutlar: HemaQuest Pharmaceuticals, Inc: Research Funding. Vichinsky:HemaQuest Pharmaceuticals, Inc: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding. Neumayr:Novartis : Honoraria, one time honoraium 10/09; NIH: Research Funding. Labotka:HemaQuest Pharmaceuticals, Inc: Research Funding. Keefer:HemaQuest Pharmaceuticals, Inc: Research Funding. Shen:HemaQuest Pharmaceuticals, Inc: Research Funding. Boosalis:HemaQuest Pharmaceuticals, Inc: Equity Ownership, Research Funding. Thomson:HemaQuest Pharmaceuticals: Employment, Equity Ownership. Bobbitt:HemaQuest Pharmaceuticals, Inc: Employment, Equity Ownership, Patents & Royalties. Wallis:HemaQuest Pharmaceuticals: Consultancy, Equity Ownership. Johnson:HemaQuest Pharmaceuticals: Employment, Equity Ownership. Berenson:HemaQuest Pharmaceuticals, Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Perrine:HemaQuest Pharmaceuticals, Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding.

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Re-Creating Hereditary Persistence of Fetal Hemoglobin (HPFH) to Treat Sickle Cell Disease (SCD) and β-Thalassemia

Blood ◽

10.1182/blood.v128.22.4708.4708 ◽

2016 ◽

Vol 128 (22) ◽

pp. 4708-4708

Author(s):

Michelle I Lin ◽

Elizabeth J Paik ◽

Bibhu P Mishra ◽

Song Chou ◽

Ying Zhang ◽

...

Keyword(s):

Board Of Directors ◽

Genetic Variants ◽

Fetal Hemoglobin ◽

Employment Equity ◽

Advisory Committees ◽

Human Cd34 ◽

Cas9 Protein ◽

Hereditary Persistence ◽

Equity Ownership ◽

Cas9 Mrna

Abstract Hereditary persistence of fetal hemoglobin, a naturally occurring condition that substantially ameliorates disease in SCD and β-thalassemia, is associated with genetic variation at the β-globin locus. Our strategy is to use the CRISPR-Cas9 system to re-create specific genetic variants associated with HPFH in CD34+ hematopoietic stem and progenitor cells (HSPCs) and demonstrate their causal relationship to elevated fetal hemoglobin (HbF) levels as a potential therapeutic strategy to treat SCD and β-thalassemia. The CRISPR-Cas9 system has been adapted to achieve site-directed DNA cleavage by guide RNAs (gRNAs) and the Cas9 endonuclease. We have identified highly potent single gRNAs (sgRNAs) that can target regions within the β-globin locus associated with HPFH. The sgRNAs, when combined and delivered as dual sgRNAs, resulted in deletions that mimic naturally occurring deletions associated with HPFH. We have also optimized transfection dose and ratio of these sgRNAs with either Cas9 mRNA or Cas9 protein into primary human CD34+ HSPCs from mobilized peripheral blood of healthy donors and can achieve greater than 85% transfection rate with minimal cell loss (85-95% viability). We found that sgRNAs delivered with Cas9 protein resulted in better cell viability than when delivered with Cas9 mRNA especially at higher doses, while attaining the same rates of editing efficiency. Lastly, erythroid differentiation of CD34+ HSPCs demonstrated significant increase in γ-globin gene expression level by qRT-PCR as well as HbF protein levels, measured by FACS and LC/MS. In conclusion, we have optimized sgRNA and Cas9 transfection into primary human CD34+ HSPCs. We have identified sgRNAs that are highly effective in targeting the β-globin locus and employed forward genetics to re-create genetic variants associated with HPFH in HPSCs. We have demonstrated the causal relationship of different HPFH genetic variants to elevation of HbF, and obtained comparative data on upregulation of HbF in erythroid cells differentiated from edited CD34+ HSPCs. Our findings provide a viable therapeutic strategy using CRISPR-Cas9 for the treatment of β-hemoglobinopathies. Disclosures Lin: CRISPR Therapeutics: Employment. Paik:CRISPR Therapeutics: Employment. Mishra:CRISPR Therapeutics: Employment. Chou:CRISPR Therapeutics: Employment. Zhang:CRISPR Therapeutics: Employment, Equity Ownership. Tomkinson:CRISPR Therapeutics: Employment. Pettiglio:CRISPR Therapeutics: Employment. Sanginario:CRISPR Therapeutics: Employment. Woo:CRISPR Therapeutics: Employment. Lee:CRISPR Therapeutics: Employment. Allen:CRISPR Therapeutics: Employment. Cradick:CRISPR Therapeutics: Employment. Chakraborty:CRISPR Therapeutics: Employment. Porteus:CRISPR Therapeutics: Consultancy, Equity Ownership. Mavilio:Adverum Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Membership on an entity's Board of Directors or advisory committees; CRISPR Therapeutics: Consultancy, Research Funding. Cowan:CRISPR Therapeutics: Employment, Equity Ownership. Novak:CRISPR Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Lundberg:CRISPR Therapeutics: Employment, Equity Ownership.

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Rapid and Robust Mobilization of CD34+ HSCs without G-CSF Following Administration of Mgta-145 Alone or in Combination with Plerixafor

Blood ◽

10.1182/blood-2019-127523 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1961-1961

Author(s):

John F. DiPersio ◽

Jonathan Hoggatt ◽

Steven Devine ◽

Lukasz Biernat ◽

Haley Howell ◽

...

Keyword(s):

Single Dose ◽

Adverse Events ◽

Board Of Directors ◽

Preliminary Data ◽

Research Funding ◽

Fold Change ◽

Employment Equity ◽

Advisory Committees ◽

Cd34 Cells ◽

Equity Ownership

Background Granulocyte colony-stimulating factor (G-CSF) is the standard of care for mobilization of hematopoietic stem cells (HSCs). G-CSF requires 4-7 days of injections and often multiple aphereses to acquire sufficient CD34+ cells for transplant. The number of CD34+ HSCs mobilized can be variable and patients who fail to mobilize enough CD34+ cells are treated with the combination of G-CSF plus plerixafor. G-CSF use is associated with bone pain, nausea, headaches, fatigue, rare episodes of splenic rupture, and is contraindicated for patients with autoimmune and sickle cell disease. MGTA-145 (GroβT) is a CXCR2 agonist. MGTA-145, in combination with plerixafor, a CXCR4 inhibitor, has the potential to rapidly and reliably mobilize robust numbers of HSCs with a single dose and same-day apheresis for transplant that is free from G-CSF. MGTA-145 plus plerixafor work synergistically to rapidly mobilize HSCs in both mice and non-human primates (Hoggatt, Cell 2018; Goncalves, Blood 2018). Based on these data, Magenta initiated a Phase 1 dose-escalating study to evaluate the safety, PK and PD of MGTA-145 as a single agent and in combination with plerixafor. Methods This study consists of four parts. In Part A, healthy volunteers were dosed with MGTA-145 (0.0075 - 0.3 mg/kg) or placebo. In Part B, MGTA-145 dose levels from Part A were selected for use in combination with a clinically approved dose of plerixafor. In Part C, a single dose MGTA-145 plus plerixafor will be administered on day 1 and day 2. In Part D, MGTA-145 plus plerixafor will be administered followed by apheresis. Results MGTA-145 monotherapy was well tolerated in all subjects dosed (Table 1) with no significant adverse events. Some subjects experienced mild (Grade 1) transient lower back pain that dissipated within minutes. In the ongoing study, the combination of MGTA-145 with plerixafor was well tolerated, with some donors experiencing Grade 1 and 2 gastrointestinal adverse events commonly observed with plerixafor alone. Pharmacokinetic (PK) exposure and maximum plasma concentrations increased dose proportionally and were not affected by plerixafor (Fig 1A). Monotherapy of MGTA-145 resulted in an immediate increase in neutrophils (Fig 1B) and release of plasma MMP-9 (Fig 1C). Neutrophil mobilization plateaued within 1-hour post MGTA-145 at doses greater than 0.03 mg/kg. This plateau was followed by a rebound of neutrophil mobilization which correlated with re-expression of CXCR2 and presence of MGTA-145 at pharmacologically active levels. Markers of neutrophil activation were relatively unchanged (<2-fold vs baseline). A rapid and statistically significant increase in CD34+ cells occurred @ 0.03 and 0.075 mg/kg of MGTA-145 (p < 0.01) relative to placebo with peak mobilization (Fig 1D) 30 minutes post MGTA-145 (7-fold above baseline @ 0.03 mg/kg). To date, the combination of MGTA-145 plus plerixafor mobilized >20/µl CD34s in 92% (11/12) subjects compared to 50% (2/4) subjects receiving plerixafor alone. Preliminary data show that there was a significant increase in fold change relative to baseline in CD34+ cells (27x vs 13x) and phenotypic CD34+CD90+CD45RA- HSCs (38x vs 22x) mobilized by MGTA-145 with plerixafor. Mobilized CD34+ cells were detectable at 15 minutes with peak mobilization shifted 2 - 4 hours earlier for the combination vs plerixafor alone (4 - 6h vs 8 - 12h). Detailed results of single dose administration of MGTA-145 and plerixafor given on one day as well as also on two sequential days will be presented along with fully characterized graft analysis post apheresis from subjects given MGTA-145 and plerixafor. Conclusions MGTA-145 is safe and well tolerated, as a monotherapy and in combination with plerixafor and induced rapid and robust mobilization of significant numbers of HSCs with a single dose in all subjects to date. Kinetics of CD34+ cell mobilization for the combination was immediate (4x increase vs no change for plerixafor alone @ 15 min) suggesting the mechanism of action of MGTA-145 plus plerixafor is different from plerixafor alone. Preliminary data demonstrate that MGTA-145 when combined with plerixafor results in a significant increase in CD34+ fold change relative to plerixafor alone. Magenta Therapeutics intends to develop MGTA-145 as a first line mobilization product for blood cancers, autoimmune and genetic diseases and plans a Phase 2 study in multiple myeloma and non-Hodgkin lymphoma in 2020. Disclosures DiPersio: Magenta Therapeutics: Equity Ownership; NeoImmune Tech: Research Funding; Cellworks Group, Inc.: Membership on an entity's Board of Directors or advisory committees; Karyopharm Therapeutics: Consultancy; Incyte: Consultancy, Research Funding; RiverVest Venture Partners Arch Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; WUGEN: Equity Ownership, Patents & Royalties, Research Funding; Macrogenics: Research Funding, Speakers Bureau; Bioline Rx: Research Funding, Speakers Bureau; Celgene: Consultancy; Amphivena Therapeutics: Consultancy, Research Funding. Hoggatt:Magenta Therapeutics: Consultancy, Equity Ownership, Research Funding. Devine:Kiadis Pharma: Other: Protocol development (via institution); Bristol Myers: Other: Grant for monitoring support & travel support; Magenta Therapeutics: Other: Travel support for advisory board; My employer (National Marrow Donor Program) has equity interest in Magenta. Biernat:Medpace, Inc.: Employment. Howell:Magenta Therapeutics: Employment, Equity Ownership. Schmelmer:Magenta Therapeutics: Employment, Equity Ownership. Neale:Magenta Therapeutics: Employment, Equity Ownership. Boitano:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Cooke:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Goncalves:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Raffel:Magenta Therapeutics: Employment, Equity Ownership. Falahee:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Morrow:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Davis:Magenta Therapeutics: Employment, Equity Ownership.

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Treatment Patterns and Outcomes in Elderly Patients with Newly Diagnosed Multiple Myeloma: Results from the Connect® MM Registry

Blood ◽

10.1182/blood-2019-126205 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3129-3129

Author(s):

Hans C. Lee ◽

Sikander Ailawadhi ◽

Cristina Gasparetto ◽

Sundar Jagannath ◽

Robert M. Rifkin ◽

...

Keyword(s):

Board Of Directors ◽

Research Funding ◽

Causes Of Death ◽

Age Groups ◽

Treatment Patterns ◽

Age Group ◽

Newly Diagnosed ◽

Employment Equity ◽

Advisory Committees ◽

Equity Ownership

Background: Multiple myeloma (MM) is common among the elderly, with 35% of patients (pts) diagnosed being aged ≥75 years (y). With increasing overall life expectancy, the incidence and prevalence of newly diagnosed and previously treated MM patients ≥80 y is expected to increase over time. Because elderly pts are often excluded from clinical trials, data focused on their treatment patterns and clinical outcomes are lacking. The Connect® MM Registry (NCT01081028) is a large, US, multicenter, prospective observational cohort study of pts with newly diagnosed MM (NDMM) designed to examine real-world diagnostic patterns, treatment patterns, clinical outcomes, and health-related quality of life patient-reported outcomes. This analysis reviews treatment patterns and outcomes in elderly pts from the Connect MM Registry. Methods: Pts enrolled in the Connect MM registry at 250 community, academic, and government sites were included in this analysis. Eligible pts were adults aged ≥18 y with symptomatic MM diagnosed ≤2 months before enrollment, as defined by International Myeloma Working Group criteria; no exclusion criteria were applied. For this analysis, pts were categorized into 4 age groups: <65, 65 to 74, 75 to 84, and ≥85 y. Pts were followed from time of enrollment to the earliest of disease progression (or death), loss to follow-up, or data cutoff date of February 7, 2019. Descriptive statistics were used for baseline characteristics and treatment regimens. Survival outcomes were analyzed using Cox regression. Time to progression (TTP) analysis excluded causes of death not related to MM. Results: Of 3011 pts enrolled (median age 67 y), 132 (4%) were aged ≥85 y, and 615 (20%) were aged 75-84 y at baseline. More pts aged ≥85 y had poor prognostic factors such as ISS stage III disease and reduced hemoglobin (<10 g/dL or >2 g/dL <LLN) compared with other age groups, although no notable differences between creatinine and calcium levels were observed across age groups (Table). A lower proportion of elderly pts (75-84 and ≥85 y) received triplet regimens as frontline therapy. More elderly pts received a single novel agent, whereas use of 2 novel agents was more common in younger pts (Table). The most common frontline regimens among elderly pts were bortezomib (V) + dexamethasone (D), followed by lenalidomide (R) + D, whereas those among younger pts included RVD, followed by VD and CyBorD (Table). No pt aged ≥85 y, and 4% of pts aged 75-84 y received high-dose chemotherapy and autologous stem cell transplant (vs 61% in the <65 y and 37% in the 65-74 y age group). The most common maintenance therapy was RD in pts ≥85 y (although the use was low) and R alone in other age groups (Table). In the ≥85 y group, 27%, 10%, and 4% of pts entered 2L, 3L, and 4L treatments respectively, vs 43%, 23%, and 13% in the <65 y group. Progression-free survival was significantly shorter in the ≥85 y age group vs the 75-84 y age group (P=0.003), 65-74 y age group (P<0.001), and <65 y age group (P<0.001; Fig.1). TTP was significantly shorter in the ≥85 y group vs the <65 y group (P=0.020); however, TTP was similar among the 65-74 y, 75-84 y, and ≥85 y cohorts (Fig. 2). Overall survival was significantly shorter in the ≥85 y group vs the 75-84 y, 65-74 y, and <65 y groups (all P<0.001; Fig. 3). The mortality rate was lowest (46%) during first-line treatment (1L) in pts aged ≥85 y (mainly attributed to MM progression) and increased in 2L and 3L (47% and 54%, respectively); a similar trend was observed in the younger age groups. The main cause of death was MM progression (29% in the ≥85 y vs 16% in the <65 y group). Other notable causes of death in the ≥85 y group included cardiac failure (5% vs 2% in <65 y group) and pneumonia (5% vs 1% in <65 y group). Conclusions: In this analysis, elderly pts received similar types of frontline and maintenance regimens as younger pts, although proportions varied with decreased use of triplet regimens with age. Considering similarities in TTP across the 65-74 y, 75-84 y, and ≥85 y cohorts, these real-world data support active treatment and aggressive supportive care of elderly symptomatic pts, including with novel agents. Additionally, further clinical studies specific to elderly patients with MM should be explored. Disclosures Lee: Amgen: Consultancy, Research Funding; GlaxoSmithKline plc: Research Funding; Sanofi: Consultancy; Daiichi Sankyo: Research Funding; Celgene: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Ailawadhi:Janssen: Consultancy, Research Funding; Takeda: Consultancy; Pharmacyclics: Research Funding; Amgen: Consultancy, Research Funding; Celgene: Consultancy; Cellectar: Research Funding. Gasparetto:Celgene: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed ; Janssen: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed ; BMS: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed . Jagannath:AbbVie: Consultancy; Merck & Co.: Consultancy; Bristol-Myers Squibb: Consultancy; Karyopharm Therapeutics: Consultancy; Celgene Corporation: Consultancy; Janssen Pharmaceuticals: Consultancy. Rifkin:Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Durie:Amgen, Celgene, Johnson & Johnson, and Takeda: Consultancy. Narang:Celgene: Speakers Bureau. Terebelo:Celgene: Honoraria; Jannsen: Speakers Bureau; Newland Medical Asociates: Employment. Toomey:Celgene: Consultancy. Hardin:Celgene: Membership on an entity's Board of Directors or advisory committees. Wagner:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; American Cancer Society: Other: Section editor, Cancer journal. Omel:Celgene, Takeda, Janssen: Other: Patient Advisory Committees. Srinivasan:Celgene: Employment, Equity Ownership. Liu:TechData: Consultancy. Dhalla:Celgene: Employment. Agarwal:Celgene Corporation: Employment, Equity Ownership. Abonour:BMS: Consultancy; Celgene: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Janssen: Consultancy, Research Funding.

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