ALBERT

Description: Abstract 921 Down Syndrome (DS, trisomy 21) is associated with increased incidence of acute myeloid leukemia, specifically megakaryoblastic leukemia (DS-AMKL), and the pre-leukemic condition, transient myeloproliferative disorder (DS-TMD). Both AMKL and TMD are invariantly associated with amino-terminal truncating, somatic mutations in the transcription factor Gata1 (termed Gata1s). It has been proposed that Gata1s cooperates with an underlying disturbance of hematopoiesis in trisomy 21 to generate these conditions. Initial support for this model came from reports of enhanced myeloid and erythroid progenitors in trisomy 21 fetal livers in the absence of Gata1 mutations. Since mouse models of trisomy 21 do not exhibit hematopoietic abnormalities in fetal liver or develop TMD, we have sought to establish a human platform for assessment of hematopoiesis in trisomy 21. To this end, we have performed in vitro differentiation of human pluripotent cells that have been carefully controlled to minimize effects of inherent individual or clonal variation that often confound studies with such cells. We have used two different types of pluripotent human cell lines in these studies. We generated trisomy 21 induced pluripotent cells (iPS) by expressing reprogramming factors in human fibroblasts. Upon progressive passage of trisomy 21 iPS cells, we observed the segregation of disomic cells at low frequency. Taking advantage of this phenomenon, we isolated isogenic passage-matched disomic and trisomic iPS clones in order to mitigate clone-to-clone variation and performed in vitro differentiation experiments. To validate observations from 4 disomic and 4 trisomic isogenic clones, we also assayed 2 independent trisomic iPS lines, and 2 trisomic human ES lines, along with appropriate disomic controls. Human pluripotent cells were subjected to differentiation as embryoid bodies with successive addition of growth factors. Initially, cells were treated with BMP4, Activin A and FGF to promote mesoderm formation. After 4 days, VEGF, IL-6, IL-3, IL-11 and SCF were added, and after 4 more days, EPO and TPO were added for the duration of differentiation. As results were consistent for iPS and hES cells, we summarize the differences between normal and trisomic hematopoiesis as follows. During in vitro differentiation, we observed that trisomy 21 cells gave rise to elevated numbers of multilineage hematopoietic progenitor cells. Colony forming assays performed with cells isolated from Day 10 (D10) of differentiation revealed that trisomic clones exhibited greater colony-forming potential for CFU-E, CFU-G, and CFU-M colonies. Furthermore, enhanced CFU-meg forming potential was observed, and trisomic cells also formed megakaryocyte colonies that were larger than disomic controls. FACS analysis identified a CD235+ population of cells that is enhanced 4-fold in trisomic cells at D10; prior to D10, no differences in CD31/CD34+ progenitor populations were observed. From D10-20 of differentiation, we observed ∼3-fold increases in CD235+ and CD41+ cells in trisomic cells, representing cells presumably committed to either the erythroid or megakaryocytic lineage. Quantitative RT-PCR of sorted CD235+ populations indicated that γ-globin is the predominant β-like globin expressed in erythroid cells. Hence, under the conditions of in vitro differentiation we have employed, fetal liver-type hematopoiesis is highly favored. As this stage is likely to represent the target for effects of somatic mutations in Gata1 and cooperating genes, the experimental system is well suited for further dissection of the pathogenesis of DS-AMKL. In conclusion, using hES and isogenic iPS cells, we have observed that trisomy 21 leads to a disturbance of hematopoietic development, characterized by expansion of a common myeloid progenitor population. These results are reminiscent of observations that have been reported for trisomy 21 fetal liver. Our studies further establish that trisomy 21 results in a cell autonomous defect in hematopoiesis. The robust in vitro assay we have established can now be used to further investigate i) molecular targets responsible for perturbed hematopoiesis in trisomy 21 and ii) the effect of Gata1s mutation in concert with trisomy 21. The use of isogenic disomic and trisomic cells provides a powerful approach to reducing potential artifacts due to inherent clonal variation of pluripotent cell lines. Disclosures: Daley: iPierian, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Epizyme, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Verastem, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Solasia, KK: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; MPM Capital, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees.

Description: The ataxia telangiectasia and RAD3-related (ATR) protein kinase is a component of the cellular DNA damage response pathway and promotes cell survival by signalling repair of collapsed replication forks generated by replication stress. We hypothesised that inhibition of ATR potentiates the anti-leukaemic activity of chain terminating nucleoside analogues used in the treatment of acute myeloid leukaemia (AML). We used VE-821 and its derivative VX-970 (Vertex Pharmaceuticals, Abingdon, UK) as potent and specific inhibitors of ATR kinase activity to examine the effects of ATR inhibition in AML cell lines, primary AML cells and AML xenografts. Co-treatment with 1mM VE-821 did not consistently potentiate the anti-proliferative effects of cytarabine, clofarabine or fludarabine in a panel of AML cell lines. However, there was consistent potentiation of hydroxyurea and gemcitabine in all 7 AML cell lines tested. Treatment with hydroxyurea, which induces replication stress via depletion of dNTPs, resulted in phosphorylation of CHK1, a downstream target of ATR. CHK1 phosphorylation was attenuated when 1mM VE-821 was co-administered with hydroxyurea. Exposure of cells to gemcitabine or hydroxyurea slowed transit through S phase, which was pronounced in combination with VE-821. HL-60 AML cell clones expressing either a constitutively active or inducible shRNA construct targeting ATR had reduced ATR protein expression compared to control cells and were significantly more sensitive to the anti-proliferative effects of gemcitabine and hydroxyurea, but not to cytarabine, clofarabine or fludarabine. The growth inhibitory effects of hydroxyurea and gemcitabine were also significantly potentiated by VE-821 in primary AML patient samples, which included three adult patients with de novo AML and a paediatric patient with therapy-related AML. In contrast, ATR inhibition did not potentiate the inhibitory effects of hydroxyurea or gemcitabine in primary bone marrow cells from healthy donors ex vivo. We next sought to determine whether ATR inhibition potentiated hydroxyurea and gemcitabine in an orthotopic mouse model of AML. MV4-11 AML cells engineered to express firefly luciferase (MV4-11 pSLIEW) were intrafemorally transplanted into immunodeficient Rag2-/- gc-/- mice. Bioluminescent imaging via IVIS Spectrum (PerkinElmer, Buckinghamshire, UK) demonstrated localised femoral engraftment first detectable 4-5 days post-injection, with luciferase signal developing in other parts of the body (liver, ovaries) between days 15 and 18 in untreated mice. Treatment was initiated 7 days post-injection when disease was localised to the femur and prior to emergence of disseminated luciferase signal. Single agent hydroxyurea (250mg per kg, IP days 0-4 and 7-11) conferred some early disease control compared to controls as determined by luciferase total body flux measured on day 14, but this was not statistically significant (p=0.18) and did not affect overall survival (mean 35 days for controls and 37 days for hydroxyurea, p=0.47). Monotherapy with VX-970 (60 mg per kg, orally on days 0-4 and 7-11) also conferred early disease control compared to vehicle-treated mice (p=0.18), and resulted in significantly longer overall survival (mean 40 days, p=0.017). Combination treatment with hydroxyurea and VX-970 did not result in more effective early disease control or improved overall survival compared to monotherapy with either agent. Treatment with gemcitabine monotherapy (100 mg per kg, intraperitoneal injection on days 0, 3, 7 and 10) conferred significant early disease control (p=0.002) and significantly improved overall survival compared to controls (mean survival 73 days, p

Description: In the donor versus no donor analysis of the UKALL12/E2993 trial in adult acute lymphoblastic leukaemia (ALL), there was a significant improvement in overall survival (OS) and reduction in relapse in the donor arm. However the OS benefit did not extend to older patients in whom myeloablative allogeneic hematopoietic cell transplant (alloHCT) related mortality was 35% at 2 years and outweighed the reduction in relapse risk. The overall outcome of older patients in this trial was poor, with patients 〉40 and 50 years having 23% and 15% 5 year survival respectively. In our current UK National Cancer Research Institute UKALL14 study all patients 〉40 years in CR, regardless of Philadelphia (Ph+) status and other high risk factors, are considered "high risk" and recommended a reduced intensity conditioned (RIC) alloHCT with a matched sibling (sib) or 8/8 matched unrelated donor (MUD) after a 2 course induction and high dose methotrexate. The primary endpoint is event free survival (EFS). We report here the early outcome of 88 patients with at least day 100 follow up (FU) (median FU 18 months) who received RICalloHCT on trial. Conditioning was with fludarabine 30mg/m2 d -6 to -2, melphalan 140 mg/m2 d -2 and alemtuzumab 30mg d -2 to-1 (MUD) or d-1 (sib). Graft versus host disease (GVHD) prophylaxis was ciclosporin A only. Nine patients did not receive alemtuzumab as per protocol. Multilineage chimerism (MC) and minimal residual disease (MRD) were assessed 3 monthly post alloHSCT. Escalating doses of donor lymphocyte infusions (DLI) were given for T-cell mixed chimerism or MRD, starting dose 1 x 106 CD3 cells/kg, escalating by half log increments every 3 months. Of 511 registered patients, 306 were 〉40 years old; 127 of those have completed RIC allograft, 88 of whom have sufficient FU to report. Median age was 51.5 years (range 41 to 64). Donor was sib in 24 and MUD in 64 patients, respectively. Median WBC at diagnosis was 7 x 109/l (0.6-557). Forty one of 77 (53%) evaluable patients had high risk cytogenetics, 22 (25%) were Ph+. Twelve of 56 (21%) with MRD data were MRD +ve pre-alloHCT. Post-alloHCT, myeloid engraftment occurred in 86/88 patients at a median of 13 days, 2 had missing data. Acute graft versus host disease (GVHD) occurred at grade 1 in 30 patients (34%) and grade 2-3 in 8 patients (9%). Thirty patients developed chronic GVHD (34% of 87/88 patients surviving to D100), 13 limited and 17 extensive. Of 12 patients who suffered transplant-related mortality (TRM), 6 died of infection (one post-transplant lymphoproliferative disease), 4 of organ toxicity and 2 of GVHD. TRM was not associated with age or donor type. Sixteen patients relapsed at a median time of 317 days (range 110-1034). Of those, 9 (of 15 with data) had high risk cytogenetics (EFS, p=0.38) and 6 (of 11 with data) were MRD +ve pre-alloHCT (EFS, HR 3.35, p=0.047). Twenty seven patients in total received 67 DLI (median maximum dose 3 x 106 CD3 cells/kg): 15 for mixed chimerism, 4 for rising MRD and 8 for both. Five patients (19%) developed post-DLI GVHD at grade 1 (n=4) and grade 2 (n=1). MC data is available for 36 patients receiving alemtuzumab and is shown in figure 1 where dark grey bars represent full and light grey bars mixed chimerism, respectively. DLI are denoted by black dashes. Mixed chimerism was seen in 22 of 36 patients (61%) who received alemtuzumab and so far 26 of 36 have achieved full donor chimerism (median 9 months), 10 after DLI (38%). Figure 2 shows Kaplan Meier curves of OS 76% (64-84, 95% CI) and EFS 68% (55-77)at 18 months. This is the first prospective study of RIC alloHCT in older adults with ALL; these early results demonstrate its feasibility within a large, multicentre trial. T-cell mixed chimerism was common at 1st MC assessment but early data indicate that conversion to full donor chimerism with DLI is a safe and realistic possibility. The impact of mixed chimerism (and pre-emptive DLI) on relapse remain to be evaluated. Severe GVHD and TRM were relatively low, such that the EFS of chemotherapy then RIC alloHCT, albeit with short-term FU, may be higher than expected for chemotherapy alone in this age group. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Copland: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fielding:Amgen: Consultancy, Honoraria.

Description: Background After European Medicines Agency (EMA) approval of axicabtagene ciloleucel and tisagenlecleucel for the treatment of relapsed/refractory (r/r) high-grade lymphoma in 2018, England was one of the first European countries granting fully funded access to these CD19 CAR-T therapies. Both products are available through the National Health Service England (NHSE) Cancer Drug Fund until their cost-effectiveness has been determined. The NHSE CAR-T program has been set up in a structure aiming to implement robust and transparent criteria for patient selection and to ensure equity of treatment access: CAR-T slots are approved by a weekly National CAR-T Clinical Panel (NCCP), consisting of independent clinical experts, patient representatives, and delegates from each CAR-T centre; treatment is delivered in 7 geographically spread commissioned CAR-T centres (Birmingham, Bristol, King's College Hospital London, University Hospital London, The Christie Manchester, Manchester Royal Infirmary, Newcastle). Here, we report prospective data on the first 122 lymphoma patients approved by the NCCP. Methods Patients with r/r high-grade lymphoma referred to the NCCP between December 2018 and July 2019 and deemed eligible for treatment with CD19 CAR-T were analysed. Eligibility was assessed in the CAR-T centre's tumor board, based on organ function and fitness (performance status 0/1), absence of active CNS disease, and biopsy confirmation of r/r high-grade lymphoma. The final decision on patient eligibility was made by consensus through the NCCP independent clinical panel. CAR-T product selection for each patient was done by the CAR-T centre, mainly on the basis of manufacturing slot availability. Results 122 patients were approved for treatment with CD19 CAR-T therapy by the panel. CAR-T centres selected 76 patients for axicabtagene ciloleucel and 46 for tisagenlecleucel. Patients' median age was 56 years (range 18-75). 62% were male. 87 (71%) patients had de novo diffuse large B-cell lymphoma, 29 (24%) transformed lymphoma (23 from follicular- and 6 from marginal zone lymphoma), and 6 (5%) primary mediastinal B-cell lymphoma. 96 (79%) patients had biopsy confirmation of disease prior to submission. 71 (58%) patients had received 2 prior lines of therapy for high-grade lymphoma, 51 (42%) patients 3 or more treatment lines (maximum 6). 5 patients had previous allogeneic, 19 previous autologous transplant. 88% of patients (107/122) were refractory to the last line of treatment (stable- or progressive disease (PD) or relapse within 6 months). Among 122 patients, 112 completed leukapheresis, 3 are awaiting the procedure, and 7 patients did not proceed (6 due to PD, 1 opted for radical radiotherapy). 57 of 112 patients were infused at the time of abstract submission, 42 are awaiting CAR-T infusion. 10 patients did not proceed to infusion due to disease progression and clinical deterioration (3 with CNS relapse), 2 due to manufacturing failure. One patient achieved a complete response following bridging therapy and is currently monitored. 84% (88/105) patients received bridging therapy between the time of NCCP approval and CAR-T infusion (median 64 days), 62 had chemotherapy, 9 radiotherapy, and 17 steroids only. Details on bridging therapy, treatment-related toxicities and outcomes will be provided at the meeting, by which time approximately 62 patients will have completed their 3 months PET response assessment. Conclusion NHSE has successfully implemented a national structure for providing licenced CAR-T products in England, enabling equity of access and oversight on capacity and patient outcomes, which can serve as a model for newly licenced, cost-intense and complex cell- and gene therapies in the future. The prospective and centralised nature of this dataset offers a true reflection of the real-world patient population undergoing CAR-T therapy in England. Disclosures Kuhnl: Kite Gilead: Honoraria. Roddie:Gilead: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Novartis: Consultancy. Menne:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Kyowa Kirin: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau. Sanderson:Kite/Gilead: Honoraria. Osborne:Novartis: Other: Travel; Pfizer: Honoraria, Speakers Bureau; MSD: Consultancy; Takeda: Consultancy, Honoraria, Other: Travel, Speakers Bureau; Roche: Consultancy, Honoraria, Other: Travel, Speakers Bureau; Servier: Consultancy; Gilead: Consultancy. Radford:AstraZeneca: Equity Ownership, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; ADC Therapeutics: Consultancy, Research Funding; GSK: Equity Ownership; Seattle Genetics: Consultancy, Honoraria. Patten:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria; Roche: Honoraria, Research Funding. O'Reilly:Kite Gilead: Honoraria. Bloor:Abvie, Gilead, Novartis, Autolus, Celgene, etc: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational grant. Rowntree:Novartis: Consultancy. Bowles:Abbvie: Research Funding; Janssen: Research Funding. Collins:Gilead: Consultancy, Honoraria. McMillan:BMS: Honoraria; Celgene: Honoraria, Speakers Bureau; F. Hoffmann-La Roche Ltd: Honoraria, Speakers Bureau; Gilead: Honoraria; Novartis: Honoraria; Sandoz: Honoraria; Pfizer: Honoraria, Research Funding; MSD: Honoraria.

Description: Numerous molecular approaches have been taken to elucidate the regulation of the human β-like globin genes, and particularly the “fetal” (γ- to β-) globin switch, given the role of fetal hemoglobin (HbF) levels on disease severity in the β-hemoglobin disorders. Despite these efforts, no developmental stage-specific nuclear regulators of HbF expression have been identified and validated. Recent genome-wide single nucleotide polymorphism (SNP) association studies by us and others have revealed novel loci that are significantly associated with HbF levels in normal, sickle cell, and thalassemia populations. One variant, lying within intron 2 of the chromosome 2 gene BCL11A, accounts for 〉10% of the variation in HbF levels. We have now tested the hypothesis that BCL11A, a zinc-finger transcription factor, serves as a stage-specific regulator of HbF expression, rather than merely a genetic marker of HbF status. We found that BCL11A is expressed as two major isoforms (termed XL and L) in human erythroid progenitors. The level of BCL11A expression is inversely correlated with the expression of the HbF gene, γ-globin, in human erythroid cell types representative of different developmental stages. Expression of BCL11A is negligible in embryonic, and high in adult, erythroid cells. Correlation of SNP genotypes with levels of BCL11A RNA in cells derived from individuals of known genotypes indicates that the “high HbF” genotype is associated with reduced BCL11A expression. To better characterize its potential role in erythropoiesis and globin gene regulation, we identified interacting protein partners of BCL11A in erythroid cells through affinity purification and protein microsequencing. We found that the BCL11A protein exists in complexes with the nucleosome remodeling and histone deacetylase (NuRD) corepressor complex, as well as the erythroid transcription factors GATA-1 and FOG-1. Taken together, the genetic, developmental, and biochemical data are most consistent with a model in which BCL11A functions as a repressor of γ-globin gene expression. To directly test this possibility, we modulated expression of BCL11A in primary human erythroid precursors expanded from adult CD34+ progenitors. Transient or persistent knockdown of BCL11A accomplished by siRNA or lentiviral shRNA delivery, respectively, led to robust induction of γ-globin gene expression. Importantly, down-regulation of BCL11A expression did not alter the differentiation state or global transcriptional profile of the cells, suggesting an effect on a limited number of targets, including the γ-globin gene. In summary, these studies establish BCL11A as a potent regulator of human globin switching. As an adult-stage repressor, BCL11A represents a primary target for therapy aimed at reactivating HbF expression in patients with β-hemoglobin disorders. Our studies illustrate the power of an integrative approach to reveal the functional connection between a common genetic variant and a trait that serves as a prominent modifier of disease severity.

Description: UKALL14 (NCT01085617) randomised 655 patients aged 25-65 years with B-precursor ALL, irrespective of Philadelphia chromosome (Ph) status or cell surface CD20 expression to determine if the addition of four doses of rituximab to standard induction chemotherapy (SOC+R) resulted in improved event free survival (EFS). Patients were recruited between Dec 2010 - Jul 2017 and the primary analysis population comprises 577 patients recruited after an April 2012 amendment in which the SOC therapy was altered. The trial was powered with an 84% chance to detect a 12% improvement in EFS (Hazard ratio (HR): 0.71). Secondary endpoints included complete remission (CR), OS, non-relapse mortality, levels of minimal residual disease (MRD) after induction and relationship of response to CD20 expression. SOC consisted of daunorubicin 30mg/m2, vincristine 1.4mg/m2, dexamethasone 4 day blocks of 10mg/m2 starting d1, 8, 15 and 22. Pegylated asparaginase 1000IU/m2 was added on d4 and 18 (d18 only if 〉40 years) for Ph- ALL and continuous daily imatinib 600mg for Ph+ ALL. Intrathecal MTX was given on d14. Rituximab 375mg/m2 was given on d3,10,17 and 24. Two patients did not start trial treatment, both were in the SOC+R arm. Analysis is by intention-to-treat. There were 288 patients in the SOC arm and 289 in the SOC+R arm, 273 (95.5%) of whom received all 4 doses of rituximab. The arms were well-balanced for risk characteristics. Of note, 63.9% (SOC) and 62.6% (SOC+R) were aged over 40 years at randomisation and 86 patients in each arm (29.9% and 29.8%, respectively) had Ph+ ALL. CR rate, 92.7% SOC and 94.8% SOC+R, did not differ between the arms. There was no difference in the MRD response between the arms, whether assessed as positive vs. negative or as a continuous variable; 121 (42.2%) of patients were MRD negative at induction completion in the SOC arm vs. 120 (41.8%) in the SOC+R arm. Likewise, the rate of severe/adverse events and non-relapse mortality did not differ between arms. At a median follow-up of 50.5 months (7 days - 83.6 months), 3 year EFS for SOC is 41.9% (95% CI: 35.8 - 48.0) versus SOC+R 48.7% (42.4 - 54.8), Hazard Ratio(HR) 0.88 (0.71 - 1.11), p=0.28, see figure1a. Pre-planned subgroup analyses by cytogenetic ("high risk" was defined as t(9;22), t(4;11), low hypodiploidy/near triploidy and complex karyotype) and other risk groups (age, presenting WBC) as well as by cell surface CD20 expression did not reveal any significant interactions. However, we did find that % blasts expressing CD20 was an independent poor prognostic factor; Youden's cut-off, to determine the best cut-off for a continuous variable, suggested a % CD20 expression of 11.7% as the optimal cut-off. EFS HR for 10-20% CD20 was 1.74 (0.98-3.10) and 〉20% was 2.20 (1.27 - 3.81), compared to

Description: Introduction Patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) who are not eligible for autologous stem cell transplant (ASCT) have a poor prognosis. Tafasitamab (MOR208) is an Fc-enhanced, humanized, monoclonal antibody that targets CD19, which is broadly expressed across B-cell malignancies, including DLBCL. Lenalidomide (LEN) is an immunomodulatory drug with antiproliferative and antiangiogenic effects. Combined tafasitamab + LEN has shown enhanced activity in in vitro and in vivo lymphoma models. L-MIND (NCT02399085) is an ongoing, open-label, single-arm, Phase II study of tafasitamab + LEN in patients with R/R DLBCL who are ineligible for ASCT. Here, we present results from prespecified patient subgroup analyses from L-MIND. Methods Patients aged ≥18 years with R/R DLBCL (1-3 prior systemic therapies, including ≥1 CD20-targeting regimen) with an Eastern Cooperative Oncology Group performance status 0-2, and who were ineligible for ASCT were enrolled. Patients received 28-day cycles of tafasitamab (12 mg/kg intravenously), once weekly during Cycles 1-3 with a loading dose on Cycle 1 Day 4, then every 2 weeks during Cycles 4-12. LEN (25 mg orally) was administered on Days 1-21 of Cycles 1-12. After Cycle 12, progression-free patients received tafasitamab every 2 weeks until disease progression. The primary endpoint is objective response rate (ORR; partial response [PR] + complete response [CR]), assessed centrally by an independent review committee (IRC) per International Working Group criteria 2007, incorporating PET-based imaging. Secondary endpoints include ORR (investigator-assessed), duration of response (DOR), progression-free survival (PFS), overall survival (OS), safety and biomarker analyses. Results Of 81 patients enrolled, 80 patients received tafasitamab + LEN and were included in the full analysis set (FAS) for efficacy (data cut-off 30 Nov 2018). Median follow-up was 17.3 months. In the FAS, ORR was 60.0% (95% confidence interval [CI]: 48.4-70.8) (Figure 1A). The CR rate was 42.5% (n=34/80), of which 88.2% (n=30/34) were PET-confirmed. Median time to response (PR or CR) was 2.0 months and median time to CR was 7.1 months. Median DOR was 21.7 months (95% CI: 21.7-not reached [NR]); median PFS was 12.1 months (95% CI: 5.7-NR); and median OS was NR (95% CI: 18.3-NR) with a median follow-up of 19.6 months. The 12-month DOR and OS rates were 71.6% (95% CI: 55.1-82.9) (Figure 1B) and 73.7% (95% CI: 62.2-82.2) (Figure 1C), respectively. In the subgroup analysis, patients with CR as best objective response (BOR) had better outcomes than those with PR: median DOR, NR (95% CI: 21.7-NR) vs 4.4 months (95% CI: 2.0-9.1); 12-month DOR rate, 93.2% (95% CI: 75.4-98.3) vs 14.4% (95% CI: 1.1-43.7); and 12-month OS rate, 97.1% vs 76.9%. Patients with one prior line of therapy had a trend for better outcomes than those with ≥2 prior lines: ORR, 70.0% vs 50.0%; and 12-month OS rate, 86.9% vs 60.1%. However, the 12-month DOR rate was similar regardless of the number of prior lines (one prior line: 70.5% [95% CI: 47.2-85.0] vs ≥2 prior lines: 72.7% [95% CI: 46.3-87.6]). For patients who were refractory to primary therapy or their last line of therapy, similar ORRs were observed to non-refractory patients (60.0% vs 60.0%); 12-month DOR was similar regardless of refractory status to last therapy; and 12-month OS rates were higher in non-refractory patients (Figure 1C). As expected, patients with a low/low-intermediate International Prognostic Index (IPI) score had better outcomes than those with an intermediate-high/high score: ORR, 70.0% vs 50.0%; 12-month DOR rate, 86.5% vs 50.4%; and 12-month OS rate, 87.0% vs 59.9%. Based on Hans algorithm, encouraging outcomes were reported in patients with germinal center B-cell (GCB) DLBCL (n=37), and outcomes were even better in those with non-GCB DLBCL (n=21): ORR, 48.6% vs 71.4%; median DOR, NR vs 21.7 months; 12-month DOR rate, 53.5% vs 83.1%; and 12-month OS rate, 65.4% vs 84.2%. Conclusions Tafasitamab + LEN combination followed by tafasitamab monotherapy shows encouraging activity with durable responses in ASCT-ineligible patients with R/R DLBCL. L-MIND includes a substantial number of poor prognosis patient subgroups. While the influence of these risk factors is evident, the clinical activity of tafasitamab + LEN in these difficult-to-treat patients is promising, particularly in those who were refractory to prior therapies. Disclosures Duell: Regeneron Pharmaceuticals, Inc.: Research Funding. Maddocks:Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; Merck: Research Funding; BMS: Research Funding. González-Barca:Janssen: Consultancy, Honoraria; Kiowa: Consultancy; Celtrion: Consultancy; Celgene: Consultancy; AbbVie: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Takeda: Honoraria. Jurczak:TG Therapeutics: Research Funding; Roche: Research Funding; Takeda: Research Funding; Servier: Research Funding; Celtrion: Research Funding; Novo Nordisk: Research Funding; Incyte: Research Funding; Bayer: Research Funding; Loxo: Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: 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; Gilead: Research Funding; Sandoz: Membership on an entity's Board of Directors or advisory committees, Research Funding; MorphoSys: Research Funding. Liberati:Incyte: Consultancy; Janssen: Honoraria; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Bristol & Mayer: Honoraria. de Vos:Bayer: Consultancy; Verastem: Consultancy; Portola Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Nagy:Janssen: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Gaidano:AbbVie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sunesys: Consultancy, Honoraria; Astra-Zeneca: Consultancy, Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Abrisqueta:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, expenses, Speakers Bureau; Roche: Consultancy, Honoraria, Other: Travel, Accommodations, expenses, Speakers Bureau; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, expenses, Speakers Bureau. André:Takeda: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers-Squibb: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Roche: Other: Travel grants, Research Funding; Amgen: Other: Travel grants, Research Funding; Johnson & Johnson: Research Funding; Takeda Millenium: Research Funding; Chugai: Research Funding; Celgene: Other: Travel grants, Research Funding. Dreyling:Celgene: Other: Scientific advisory board, Research Funding, Speakers Bureau; Gilead: Other: Scientific advisory board, Speakers Bureau; Janssen: Other: Scientific advisory board, Research Funding, Speakers Bureau; Mundipharma: Other: Scientific advisory board, Research Funding; Novartis: Other: Scientific advisory board; Roche: Other: Scientific advisory board, Research Funding, Speakers Bureau; Sandoz: Other: Scientific advisory board; Acerta: Other: Scientific advisory board; Bayer: Other: Scientific advisory board, Speakers Bureau. Menne:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Kyowa Kirin: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau. Dirnberger-Hertweck:MorphoSys: Employment. Weirather:MorphoSys: Employment. Ambarkhane:MorphoSys: Employment. Salles:Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Other: Educational events; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Roche, Janssen, Gilead, Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Epizyme: Consultancy, Honoraria; Novartis, Servier, AbbVie, Karyopharm, Kite, MorphoSys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria.

Description: Chromosomal abnormalities are established prognostic markers in adult ALL. Analysis of the UKALLXII/ECOG2993 trial (Blood, 2007;109:3189) revealed that patients (15-65 years) with BCR-ABL1, KMT2A-AFF1, low hypodiploidy (HoL) or a complex karyotype (CK) had a significantly inferior outcome in multivariable analysis. In UKALL14 (ISRCTN 66541317), all patients (25-65 years) with these genetic abnormalities were stratified to the high-risk arm to receive allogeneic stem cell transplant (alloSCT), where possible, or an unrelated transplant. Patients with BCR-ABL1 received imatinib. The objectives of this study were to determine the frequency and outcome of patients with high-risk chromosomal abnormalities and identify new high-risk genetic abnormalities by screening for novel gene rearrangements and copy number alterations. All genetic screening was performed using diagnostic marrow samples and by cytogenetics, FISH and MLPA. Survival endpoints were defined according to the trial protocol and analysed using standard statistical methods. After a median follow-up time of 3.4 years the 3 year survival rates for the whole B-cell precursor ALL cohort were: overall survival (OS) 52% (95% 48-56), event-free survival (EFS), 45% (41-49), relapse rate (RR) 34% (30-39). Among 653 patients, 319 (49%) harboured high-risk primary chromosomal abnormalities: BCR-ABL1 (197/635, 31%), KMT2A-AFF1 (49/616, 8%), HoL (49/525, 9%), and CK (21/512, 5%). The OS of patients with CK and HoL was 24% (95% CI 9-43) & 19% (9-33) which was driven by high RR: 60% (36-85) & 56% (39-75), respectively, despite alloSCT in first remission. This outcome was not obviously improved compared to UKALLXII (28% and 22%); however, the patient population was older. Patients with KMT2A-AFF1 fusion had OS and RR similar to the small number of patients (n=9) with other KMT2A fusions: 44% (29-58) & 49% (34-65) v 42% (11-71) & 56% (22-93). The outcome of BCR-ABL1 positive patients was not different from the remaining BCP-ALL patients (hazard ratios 0.92 (0.72-1.18), p=0.5 & 0.93 (0.67-1.29), p=0.7). Additional primary chromosomal abnormalities were detected as follows: ABL-class fusions (ABL1, ABL2, PDGFRB, CSF1R) (n=6, 1.3%), JAK-STAT abnormalities (P2RY8-CRLF2, IGH-CRLF2, JAK2 fusions) (n=34, 1.3%) and ZNF384 fusions (n=12, 3%). Patients with JAK-STAT abnormalities had high rates of MRD positivity post phase 2 induction (76%), high RR (62% (42-82)) and lower OS (35% (18-52)) despite 82% being stratified as high-risk. Three of the six patients with an ABL-class fusion have had an event - 2 early remission deaths and 1 relapse. In contrast, among the 12 patients with a ZNF384 fusion only 2 have relapsed (both after 3 years) and none have died. Secondary copy number alterations affecting key genes/regions were determined by MLPA in 437 samples. 270 (62%) samples harboured one or more deletion at the following frequencies: IKZF1 (n=169, 39%), CDKN2A/B (n=163, 37%), PAX5 (n=95, 22%), BTG1 (n=48, 11%), ETV6 (n=33, 8%), EBF1 (n=15, 3%), RB1 (n=31, 7%) and PAR1 (n=6, 1%). None of the individual deletions nor the number of deletions were associated with survival, either in the cohort overall or when stratified by BCR-ABL1 status. In particular, IKZF1 deletions had no impact on RR: hazard ratios = 1.04 (0.72-1.49), p=0.850 (Overall); 0.84 (0.45-1.56), p=0.584 (BCR-ABL1); 1.23 (0.51-2.98), p=0.645 (B-Other). In addition, neither of the two recently validated paediatric CNA profiles - UKALL (Blood Advances 2019, 3:148) and IKZF1plus (JCO, 2018, 36:1240) - showed a significant association with outcome in the whole cohort or any relevant subgroup, e.g. BCR-ABL1 or B-other ALL. Collectively these data indicate that primary chromosomal abnormalities remain stronger prognostic markers in adult ALL than the more recently identified secondary deletions. On the basis of these results, we propose an amendment to the genetic risk classification for adult ALL wherein groups with distinct outcomes (see figure) comprise: (1) very high risk: CK, HoL or JAK-STAT abnormalities; (2) high risk: all KMT2A fusions; (3) Tyrosine kinase sensitive: BCR-ABL1 and ABL-class fusions; (4) low risk ZNF384 fusions; (5) standard risk: all other patients. The integration of these primary genetic risk factors with other risk factor such as age, white cell count and MRD into an overall risk score is a key goal of our current work. Figure Disclosures Papaemmanuil: Celgene: Research Funding. Menne:Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Kyowa Kirin: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau. McMillan:BMS: Honoraria; Gilead: Honoraria; MSD: Honoraria; Novartis: Honoraria; Sandoz: Honoraria; F. Hoffmann-La Roche Ltd: Honoraria, Speakers Bureau; Pfizer: Honoraria, Research Funding; Celgene: Honoraria, Speakers Bureau. Rowntree:Novartis: Consultancy. Fielding:Novartis: Consultancy; Amgen: Consultancy; Pfizer: Consultancy; Incyte: Consultancy.