ALBERT

Description: Introduction: Acute myeloid leukemia (AML) developing secondary after other hematologic diseases, or therapy related after cytotoxic treatment for solid tumors or rheumatologic diseases (s/tAML) is clinically, genetically & prognostically distinct from de novo diseases. Data indicate that s/tAML patients (pts) have inferior outcome compared to de novo cases after chemotherapy & therefore often require consolidation therapy using allogeneic stem cell transplantation (HSCT). Leukemic stem cells (LSC) initiate & maintain AML. They are also believed to exist within the CD34+/CD38- &/or high GPR56 expressing bone marrow (BM) population, which have been shown to impact adversely on outcome. The prognostic impact of LSC markers in de novovs s/tAML after HSCT with non-myeloablative conditioning intensity - where the therapeutic approach also relies on immunological graft-versus-leukemia effects - is unknown. Methods: We analyzed 379 AML pts who received an allogeneic peripheral blood HSCT in complete remission (CR, 82%) or CR with incomplete peripheral recovery (CRi, 18%) between 1999 & 2018 after non-myeloablative (3x30 mg/m2 Fludarabine & 2 Gy total body irradiation) conditioning. At diagnosis, cytogenetic & flow cytometric analyses were performed centrally. For pts with pre-treatment BM available the mutation status of CEBPA, NPM1 & presence of FLT3-ITD by fragment analyses as well as expression levels of GPR56 by qPCR were assessed. Using a next-generation targeted amplicon sequencing approach we analyzed a panel comprising 54 recurrently mutated (mut) genes in myeloid malignancies on the MiSeq platform (Illumina). Median follow up after HSCT was 3.7 years. Results: 229 pts (60%) had de novo & 150 pts (40%) had AML secondary to myelodysplastic syndrome (MDS, n=82), myeloproliferative neoplasm (MPN, n=22) or MDS/MPN (n=10), or therapy related after Non-Hodgkin lymphoma (n=9), solid tumors (n=25) or rheumatologic diseases (n=2). At diagnosis, s/tAML pts had lower white blood counts (P=.03), lower blasts in BM (P

Description: Introduction: Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disease characterized by impairment of the phagocyte NADPH-oxidase complex, resulting in deficient microbial killing and life-threatening bacterial and fungal infections. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative approach, but it can be complicated by graft failure, graft versus-host disease (GvHD) and transplant-related mortality (TRM). In order to define prognostic risk factors in this setting, the IEWP of the EBMT performed a large retrospective registry study on 600 pediatric and adult patients with CGD undergoing allo-HSCT. Patients and Methods: We analyzed the outcome of patients with CGD who received allo-HSCT in EBMT centers between 1993 and 2017. The main end-points of the study were overall survival (OS) and event-free survival (EFS; events were death and primary or secondary engraftment failure) according to patient's age, donor type, stem cell source and conditioning regimen. One patient died before allo-HSCT and was excluded from analysis. Results: We studied 536 children (aged 〈 18 years) and 63 adults (aged ≥ 18 years) affected by CGD. The median follow-up was 45.37 months (IQR 15.8-81.8). Genetic results were available for 307 patients: inheritance was X-linked (75%) or autosomal recessive (25%). Median age at transplant was 7.2 years (range: 0.12-48.56). Conditioning regimen was Busulfan/Fludarabine (n=244; 41%), Busulfan/Cyclophosphamide (n=104; 17%), Treosulfan/Fludarabine (n=76; 13%), Treosulfan/Fludarabine/Thiotepa (n=52; 9%) or other drug combinations (n=123; 20%). Donors were human leukocyte antigen (HLA) matched related (MFD, 10/10; n=211, 40%), matched unrelated (MUD, 10/10 or 6/6 in UCB; n=201; 38%), mismatched related (MMFD, ≥ 9/10; n= 27; 5%) or mismatched unrelated (MMUD, ≥ 9/10 or 5/6 in UCB; n= 83; 16%). Stem cell source was bone marrow (BM; n=408; 69%), peripheral blood (PB; n=153; 26%) or umbilical cord blood (UCB; n=27; 5%). Donor engraftment occurred in 516 evaluable patients (88%), while primary or secondary engraftment failure occurred in 68 patients (12%). Seventy-nine patients (13%) died after allo-HSCT. The 2 year Kaplan-Meier estimate of OS and EFS were 87.1% (95% CI, 84.2-89.9) and 77.8% (95% CI, 74.2-81.4), respectively (Fig A). The 2-year cumulative incidence of grade II-IV acute GvHD, chronic GvHD and extensive chronic GvHD was 18.6% (95%, 15.1-22.2), 16.2 % (95%, 18.8-19.7) and 5.5% (95%, 3.4-7.7), respectively. A univariate cox model with spline term demonstrated that older age at transplant was associated with an increased risk of death (p=0.002). Children undergoing allo-HSCT had a superior 2y OS (88.1%; 95% CI 85.2-91.0), compared to adults (78.2%; 95% CI, 67.7-88.7), p=0.03 (Fig B). Patients undergoing allo-HSCT from a MFD had a superior EFS (86.5%; 95% CI 81.5-91.4) compared to MUD (73.3%; 95% CI 66.7-79.9), MMUD (78.2%; 95% CI 69-87.5) and MMFD (59.7; 95% CI 40.4-79.1), p〈 0.001 (Fig C). Patients receiving BM grafts had superior 2y EFS (81.0%; 95% CI 76.9-85.1) compared to PB (72.5%; 95% CI 64.7-80.4) and UCB (66.7%; 95% CI 48.9-84.4), p=0.04. The pattern of disease inheritance and the choice of conditioning regimen didn't have an impact on outcome (Fig D). Fifty-three patients with graft failure underwent a second allo-HSCT and the 2y OS in this group was 82.1% (95% CI, 71.5-92.7). Year of transplantation didn't have an influence on outcome. Conclusion: This is the largest study describing the outcome of allo-HSCT in children and adults affected by CGD. We demonstrate an excellent outcome, with a low incidence of graft failure, TRM and GvHD. Older patients with CGD have reduced survival after allo-HSCT, indicating that transplant should be considered at a younger age. The use of a MMFD is associated with poorer outcome; indication to transplant in this setting should be carefully evaluated by the treating physicians. Disclosures Chiesa: Bluebird Bio: Consultancy; Gilead: Consultancy. Kalwak:medac: Other: travel grants; Sanofi: Other: travel grants. Sykora:Aventis-Behring: Research Funding; medac: Research Funding. Locatelli:Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; bluebird bio: Consultancy; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Wynn:Orchard SAB: Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Equity Ownership; Chimerix: Research Funding; Genzyme: Honoraria; Bluebird Bio: Consultancy; Orchard Therapeutics: Consultancy; Chimerix: Consultancy. Zecca:Chimerix: Honoraria. Veys:Pfizer: Honoraria; Servier: Research Funding; Novartis: Honoraria. Slatter:Medac: Other: Travel assistance.

Description: Background: The StiL NHL1-2003 trial demonstrated that Bendamustine-Rituximab (B-R) is a highly effective treatment for patients with WM achieving a median PFS of 69.5 months. Rituximab (R) maintenance is part of a standard treatment for follicular lymphoma. In WM, however, the role of R maintenance is unclear. In this study we compared the effect of 2 years R maintenance vs. observation after first-line treatment with B-R in patients with previously untreated WM. Methods: Patients needed to have advanced stage of disease with indication for treatment (e.g. B-symptoms, anemia, hyperviscosity syndrome, etc.). Primary endpoint was progression free survival (PFS). Secondary endpoints included response rates, overall survival (OS), and toxicity. All patients were treated with up to 6 cycles of B-R plus 2 additional R cycles. Only patients responding to B-R were randomized to either R maintenance (q 2 months for 2 years) or observation. Results: Of 293 registered patients, 5 were excluded due to lack of data and other reasons. Median time of follow-up was 70.2 months at the time of this analysis (July 2019). 257 of 288 patients with a median age of 67 years were evaluable for response evaluation. The median baseline value of IgM was 31.3 g/l, and of Hb 10.1 g/dl. Median PFS for all patients (intention to treat) was 78.0 months. The median OS was not yet reached, with an estimated 5-year-survival of 78%. A total of 38 secondary malignancies were recorded, with 1 AML during observation and 1 MDS in R maintenance. 235 patients (91.4%) responded to B-R induction, with the majority of patients (231, 89.9%) achieving a partial remission. Of 218 randomized patients, 109 (50%) were randomized to R maintenance and 109 (50%) to observation. Median age of randomized patients was 67 years, patient characteristics were comparable for both groups. The 2-year R maintenance provided a better disease control with a median PFS of 101 months in the R maintenance group compared to the median PFS of 83 months in the observation group, however, this difference was not statistically significant with a hazard ratio of 0.80 (95% CI 0.51 - 1.25, p = 0.32). The median PFS of the group of all patients receiving treatment with B-R induction only was 65.3 months and is consistent with the results of the previous StiL NHL1-2003 trial (69.5 months). This group of 179 patients includes both non-randomized patients (B-R non-responder, not randomized for any reason) and patients randomized to observation. There was no difference in OS with the median not yet reached for both R maintenance and observation. Conclusions: We confirmed that induction with B-R is a highly effective treatment for WM. After a median observation time of 5.9 years the results could not demonstrate an improvement in PFS or OS after a 2-year R-maintenance when compared with observation after B-R induction in patients with WM. Disclosures Rummel: Sandoz: Honoraria; Janssen: Honoraria; Celgene: Honoraria; Roche Pharma AG: Honoraria, Research Funding. Hensel:Roche: Honoraria, Other: travel expenses. Buske:Hexal: Honoraria, Speakers Bureau; Roche: Honoraria, Research Funding, Speakers Bureau; Bayer: Research Funding; Janssen: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria; Celltrion: Honoraria, Speakers Bureau; Amgen: Research Funding. Schmidt:Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: 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; Incyte: 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; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Hexal: Honoraria, Membership on an entity's Board of Directors or advisory committees; Biotest: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees. Willenbacher:IQVIA: Membership on an entity's Board of Directors or advisory committees; oncotyrol: Employment, Research Funding; European Commission: Research Funding; Gilead Science: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sandoz: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Tirol Program: Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria; Sanofi: Membership on an entity's Board of Directors or advisory committees; Fujimoto: Consultancy, Honoraria; Myelom- und Lymphomselbsthilfe Österreich: Consultancy, Honoraria. Dürig:Celgene: Consultancy, Other: Travel or accommodations, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support. Barth:Takeda: Honoraria; Lilly Pharma: Honoraria; Roche: Honoraria; Medac: Honoraria; Hexal: Honoraria. Hinke:Roche: Honoraria. Greil:Genentech: Honoraria, Research Funding; Eisai: Honoraria; Celgene: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Janssen-Cilag: Honoraria; Amgen: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Ratiopharm: Research Funding; Boehringer Ingelheim: Honoraria; AstraZeneca: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; MSD: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Gilead: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Pfizer: Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Mundipharma: Honoraria, Research Funding; Merck: Consultancy, Honoraria, Research Funding; Sandoz: Honoraria; Roche: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Sanofi Aventis: Honoraria; GSK: Research Funding; Daiichi Sankyo: Consultancy, Honoraria.

Description: Hematopoietic stem cell transplantation is a potent curative treatment option for patients suffering from high-risk AML and MDS. However, not in all of our patients a suitable HLA-matched donor could be identified in time. To evaluate the feasibility and outcome of T-cell-replete (TCR) HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) utilizing post-transplantation high-dose cyclophosphamide (PTCY) in the context of sequential therapy in patients with high-risk, relapsed/refractory and progressive AML and MDS, we retrospectively analyzed the course of 64 patients (AML n=61, MDS n=3; median age: 50 years; male n=30) transplanted between 2009 and 2015 at our center. Disease was advanced in 55 patients including 24 patients with relapse after a first allogeneic transplantation. 54 patients presented with active disease at time of haplo-HSCT. Donors (median age: 38 years; male n=30) were fully HLA-haplotype mismatched (5/10 HLA-loci) in 48 cases (77%). All patients received sequential therapy prior to haplo-HSCT combining cytoreductive chemotherapy (clofarabine n=34; FLAMSA n=25; FLAG-Ida n=2; others n=3) and reduced-intensity conditioning (RIC) which was started after three days of rest thereafter. Conditioning was drug-based in 42 patients receiving fludarabine, cyclophosphamide (CY) and melphalan (110 mg/m2) while it was TBI-based in the others (n=22) consisting of fludarabine and CY plus either 4 (n=20) or 2 Gy TBI (n=2). Post-grafting immunosuppression was high-dose CY given on day + 3 and +4, tacrolimus and mycophenolate mofetil (both started on day +5) in all patients. Unstimulated bone marrow was the graft source in 37 patients. One graft rejection was observed after conditioning with 2 Gy TBI. Neutrophil/platelet engraftment was achieved in 49/58 evaluable patients at a median of 16 (range: 14-27) and 20 (range: 13-74) days, respectively. Acute GvHD grade II-IV occurred in 19 patients (30 %) while it was severe (grade III-IV) in only 3 (5 %). Chronic GvHD was most frequently mild (n=9) to moderate (n=8); one severe chronic GvHD occurred. Severe (grade III-IV) mucositis, hemorrhagic cystitis and hand-foot syndrome/rash were observed in 10, 5 and 2 patients, respectively; no patient developed VOD. Kidney failure requiring hemodialysis occurred in 7 patients. CMV reactivation was observed in 28 of 47 patients at risk (59 %) and EBV in 3, while only one patient developed CMV disease (pneumonia) and no patient developed PTLD. Probable or proven (n=2) invasive aspergillosis was diagnosed in 10 patients. One-year non-relapse mortality was 27.5 % (95% CI 17-41). After a median follow up of 21 months (range: 3-64), estimated one-year overall survival (OS) was 55 % (95 % CI 41-66), and one-year disease-free survival (DFS) was 43 % (95 % CI 26-51). At two-years after sequential haplo-HSCT OS and DFS were both 39 % (95 % CI 26-51). In summary, sequential therapy in the setting of RIC-TCR haplo-HSCT using PTCY is well tolerated with low rates of GvHD and acceptable NRM in patients with high-risk AML and MDS, while providing an effective anti-leukemic activity in advanced disease. Results are comparable to data of a historical cohort of patients with high-risk AML and MDS undergoing sequential therapy using the FLAMSA-RIC protocol in a HLA-matched setting, as reported by our group previously. Thus, we suggest that donor availability can be expanded in patients with high-risk and advanced AML/MDS who lack a conventional donor or need promptly access to a donor due to aggressive disease. Disclosures Hausmann: Sanofi-Aventis: Other: advisory board. Tischer:Sanofi-Aventis: Other: advisory board. Off Label Use: clofarabine in adults; efficacy is shown in myeloid blasts;.

Description: In recent years expression levels of several genes & microRNAs (miR) were identified as strong prognostic markers, capable to refine AML risk stratification. So far technical difficulties, including the limitations of established methods for comparable, absolute quantification & the lack of defined cut points prevented translation of these findings into clinical practice. Innovative digital droplet PCR (ddPCR) is a novel technique with high sensitivity, specificity that allows absolute quantification - without the need for standard curves - & promises better inter-laboratory comparability. In AML pts, high miR-155 expression levels associate with the presence of FLT3-ITD & independently predict inferior outcome. Here, for the first time we applied ddPCR for absolute quantification of pre-miR-155 to define an absolute cut point to discriminate between high & lowexpressers, which was then validated in a second set of AML pts. We analyzed a homogeneous test set of 71 AML pts treated between January 2000 & June 2012 in our institution. All pts received cytarabinebased induction therapies & were consolidated with allogeneic hematopoietic stem cell transplantation (HCT) after non-myeloablativeconditioning (NMA; consisting of fludarabine[30mg / m² at days -4 to -2] & 2Gy total body irradiation [day 0]). At NMA-HCT ptswere in first (n=43; 60.6%) or second complete remission (CR; n=16; 22.5%) or CR with incomplete recovery (n=12; 16.9%). At diagnosis, cytogenetics & mutation status of the NPM1, CEBPA, IDH1, IDH2 & DNMT3A gene & presence of FLT3-ITD or FLT3-TKD mutation were assessed. The expression of the pre-miR-155 stem loop was measured using an EvaGreen-based ddPCR assay & normalized to the absolute copy numbers of ABL1. The R Package OptimalCutpointswas used to determine a cut point of 1.104 copies pre-miR-155 per 100 ABL1 copies to discriminate between high (n =29; 40.8%) & low (n =42; 59.2 %) miR-155 expressers. High miR-155 expressers, more often had a FLT3-ITD (p=.039) & less frequently a mutation in the FLT3-TKD (p=.010). No significant association was found for other clinical or biological markers at diagnosis. In the test set, pts with more than 1.104 copies pre-miR-155 per 100 ABL1 copies at diagnosis had a significant shorter event-free survival (EFS; p=.03, figure 1A) & overall survival (OS; p=.009, figure 1B). To validate these findings, we used a second set of 71 pts (median age 63.4y [range 37.1 to 74.7]) with a median follow-up of 3.7y for pts alive that all received cytarabinebased induction therapies & NMA-HCT as consolidation. The ptsin the validation set also did not differ significantly in the analyzed clinical or molecular characteristics (i.e. white blood count, hemoglobin, platelets, blasts in bone marrow or peripheral blood at diagnosis, remission status at HCT [CR1 vs. CR2 vs. CRi], ELN genetic group, mutational status of FLT3-TKD, NPM1, CEBPA, DNMT3A, IDH1 or IDH2 & presence of FLT3-ITD). Using the determined cut point of 1.104 copies pre-miR-155 / 100 ABL1 copies in the test set, patients in the validation set were divided in 39 patients (54.9%) with a high miR-155 expression & 32 (45.1%) with a low miR-155 expression. Pts with high miR-155 expression in the validation set had shorter EFS (p=.11, figure 2A) by trend & a significant shorter OS (p=.05, figure 2B). In conclusion, ddPCRis a novel, feasible method that allows absolute quantification of miRexpression. We defined an absolute cut point of 1.104 copies pre-miR-155 per 100 ABL1 copies for the prognosticator miR-155 in AML without the need for standard curves. Pts with pre-miR-155 expression above the cut point had a significant shorter EFS & OS. Remarkably, using a second clinically comparable set, we were able to validate our test set findings. Future studies are planned to confirm the clinical impact of pre-miR-155 expression levels at diagnosis, as well as the identified absolute pre-miR-155 / ABL1 copy number cut point to distinguish high from low miR-155 expressers. Figure 1 Test Set Figure 1. Test Set Figure 2 Validation Test Figure 2. Validation Test Disclosures Poenisch: Mundipharma: Research Funding.

Description: Introduction Hepatic veno-occlusive disease, also called sinusoidal obstruction syndrome (VOD/SOS), is a potentially life-threatening complication of conditioning for hematopoietic stem cell transplantation (HSCT) and is associated with patient and transplant-related risk factors, such as prior therapies, underlying diagnoses, and conditioning regimen. Unpredictable in its occurrence and severity, VOD/SOS is clinically characterized by painful hepatomegaly, hyperbilirubinemia, ascites, and weight gain. Overall estimated prevalence is 14% post-HSCT, while rates in some high-risk populations (eg, osteopetrosis or prior gemtuzumab ozogamicin) are 〉60% (Wadleigh M et al. Blood. 2003;102:1578-82; Corbacioglu S et al. Bone Marrow Transplant. 2006;38:547-53). Evidence suggests that defibrotide stabilizes endothelial cells, with direct and endothelial-cell mediated restoration of the thrombo-fibrinolytic balance. Defibrotide is approved in the European Union for the treatment of severe hepatic VOD/SOS in patients receiving HSCT, and is available in the United States through an expanded-access study. In a previously reported randomized clinical trial, defibrotide prophylaxis for VOD/SOS in high-risk pediatric patients undergoing HSCT reduced the overall incidence of VOD/SOS by day +30 post-HSCT. Here we report novel subgroup analyses of VOD/SOS incidence from this trial in patients with specific VOD/SOS risk factors at baseline. Methods This was a phase 3, multicenter, open-label, randomized, controlled trial in patients aged 5% weight gain. Patients were randomized to standard care with or without defibrotide prophylaxis dosed at 25 mg/kg/day in 4 divided infusions of 6.25 mg/kg. Osteopetrosis was a stratification variable. Defibrotide began the same day as HSCT conditioning and continued for 30 days post-HSCT, or ≥14 days for patients discharged from hospital before day +30 post-HSCT. Control patients who developed VOD/SOS received defibrotide treatment. The primary endpoint was incidence of VOD/SOS at day +30 post-HSCT. Results The intent-to-treat population included 356 patients: 180 randomized to defibrotide prophylaxis and 176 in the control group. Mean (SD) age was 6.6 (5.3) years, and 40.7% of patients were female. Demographic and clinical characteristics, including VOD/SOS risk factors (Table), were well-matched in the defibrotide and control groups. The most common risk factors among all patients were conditioning with busulfan and melphalan (58%), preexisting liver disease (27%), and second myeloablative transplantation (13%). VOD/SOS occurred by day +30 post-HSCT in 22 (12%) patients in the defibrotide prophylaxis group vs 35 (20%) patients in the control group. For the stratification variable, osteopetrosis, rates of VOD/SOS were 14% in the defibrotide prophylaxis arm and 67% in the control arm (Table). Differences in rates of VOD/SOS were lowest for adrenoleukodystrophy (no cases) and prior abdominal irradiation (11% vs 13%, respectively) (Table). Conclusions Across risk-factor subgroups, the rate of VOD/SOS was lower in patients receiving defibrotide compared with controls (except adrenoleukodystrophy: no VOD/SOS in either group). In particular, rates of VOD/SOS by day +30 were reduced by ≥50% in the defibrotide arm vs the control arm among patients with osteopetrosis, hemophagocytic lymphohistiocytosis, second myeloablative transplantation, and prior gemtuzumab treatment. Although the total numbers of patients with these risk factors were small, these between-group differences are of clinical interest and should be further explored. Table. Risk Factor Defibrotide (n=180) Control (n=176) Total n VOD/SOS incidence (n=22; 12.2%) n (%*) Total n VOD/SOS incidence (n=35; 20.0%) n (%*) Adrenoleukodystrophy 1 0 (0) 1 0 (0) Osteopetrosis 7 1 (14) 6 4 (67) Prior abdominal irradiation 9 1 (11) 8 1 (13) Hemophagocytic lymphohistiocytosis 10 0 (0) 15 6 (40) Prior gemtuzumab 11 2 (18) 5 2 (40) Allogeneic HSCT for leukemia 17 2 (12) 11 2 (18) Second myeloablative transplantation 25 2 (8) 23 4 (17) Pre-existing liver disease 41 6 (15) 54 12 (22) Busulfan/melphalan conditioning 106 15 (14) 99 17 (17) *Percent of patients with VOD/SOS. Support: Jazz Pharmaceuticals Disclosures Corbacioglu: Gentium S.p.A.: Consultancy, Honoraria. Off Label Use: Defibrotide is an investigational treatment for hepatic veno-occlusive disease/sinusoidal obstruction syndrome in the United States.. Bader:Amgen: Consultancy; Medac: Other: Institutional grants; Neovii: Other: Institutional grants; Riemser: Other: Institutional grants; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy.

Description: Background: Tumor heterogeneity has been documented in several malignancies and is generally associated with more aggressive disease and poorer prognosis. While heterogeneity has been documented in acute myeloid leukemia (AML), risk prognosis in AML is currently assessed by cytogenetics and the presence of recurrent mutations in genes such as FLT3 and NPM1, which are typically tested on a single gene basis. Prior approaches to identify molecular clonality have been laborious and therefore of limited clinical utility. The advent of next generation sequencing (NGS), however, allows for the rapid assessment of subclones within tumor populations. Currently, the prognostic significance of tumor heterogeneity in AML is not well defined. Therefore, this pilot study assessed the clinical significance of molecular clonality in AML using data generated by an NGS platform. Methods: We selected patients with de novo AML who had blood or bone marrow submitted for sequencing at initial diagnosis. Patients who subsequently elected for comfort measures only without receiving AML-directed therapy were excluded. Study patients were sequenced with a 25 gene NGS panel on the Ion Torrent platform. This panel included genes that have been shown to be frequently mutated in AML and which lead to increased cellular proliferation or impaired differentiation, with particular emphasis on therapeutic and prognostic mutations. Germline mutations, identified by allelic fraction and/or minor allele frequency, were excluded. Remaining somatic mutations were analyzed with software employing a variational Bayesian algorithm to predict tumor heterogeneity such that patients were assessed for the presence of tumor heterogeneity (≥2 predicted clones) at the time of diagnosis. Heterogeneity was recorded and compared to several clinical parameters, including post-chemotherapy survival at 120 days, patient age, gender, karyotype, and association with the recurrent genetic mutations NPM1, FLT3-ITD, and CEBPA. Results: Twenty patients met the study criteria of de novo AML and elected to receive therapy. The mean age at diagnosis was 59 years (38-77 years); overall survival was 75% at 120 days. Half of the patients (n=10) were determined to have ≥2 clones. Patients with either a complex karyotype or the FLT3-ITD mutation were classified as high risk (n=11). While survival at 120 days was lower in the high risk group (64%) compared to normal risk subjects (89%), this difference did not reach statistical significance (p=0.19). By contrast, patients with tumor heterogeneity (≥2 clones) had significantly lower 120 day survival (50%) when compared to AML patients with a single clone (100%) (p=0.01). There was no correlation between patients with multiple clones and high risk classification (p=0.18). Conclusions: These pilot data present some of the first prospective evidence that heterogeneity detected by NGS is an adverse prognostic indicator for early survival in de novo AML post-chemotherapy. This finding may not be surprising given that the presence of tumor heterogeneity has been shown to confer adverse prognostic risk in several solid malignancies. Still, this early impact of molecular clonality in AML may have important consequences on choice of therapy. Further prospective studies are needed to confirm our findings and to determine the long-term outcomes in AML patient subsets, as well as examining whether a distinct approach to therapy in AML patients with clonal heterogeneity leads to improved early survival. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures No relevant conflicts of interest to declare.

Description: Pediatric non-Down Syndrome acute megakaryoblastic leukemia (AMKL), a disease where megakaryocyte (MK) maturation is blocked, has a very poor prognosis. In 13% of AMKL cases of this type, the transcriptional co-factor MRTFA is expressed as part of a fusion protein. Normally, MRTFA levels increase in hematopoietic cells during megakaryopoiesis, making it likely that expression of MRTFA as part of a fusion protein leads to aberrant gene regulation, which results in leukemia. However, the mechanism by which megakaryopoiesis is blocked in AMKL is unknown. Therefore, we sought to parse out the role of MRTFA in normal megakaryopoiesis, so that we could better understand the cause for maturation block in leukemia. MRTFA is a co-factor of serum response factor (SRF). Knockout of either SRF or MRTFA in mice decreases MK maturation causing thrombocytopenia; and MRTFA overexpression (MRTFAOE) promotes MK maturation of primary human bone marrow (BM) cells in vitro. Our novel study shows that genomic regulation by MRTFA promotes MK maturation. In the human erythroleukemia (HEL) cell line, MRTFAOE enhances phorbol ester (TPA)-induced megakaryopoiesis, mimicking the effects of MRTFA on primary MK maturation. TPA-induced HEL cells with MRTFAOE achieve significantly higher 8N and 16N ploidy (p 〈 0.001, N = 4), compared to those without MRTFAOE. To identify the mechanisms underlying megakaryocytic differentiation, we bioinformatically analyzed anti-SRF chromatin immunoprecipitation (ChIP)-sequencing [approx. 15 million reads/sample] and RNA-sequencing data [approx. 20 million reads/sample], from non-induced and TPA-induced HEL cells, with and without MRTFAOE (N = 2/condition). We identified SRF peaks that change during TPA-induction, with and without MRTFAOE, and analyzed the strength of their binding and motif status. MRTFOE not only increased SRF binding to the genome during MK maturation (p ≤ 10-8), but preferentially retained binding at genomic CArG (CC[W]6GG) motifs, where SRF binds to in association with either MRTFA or specific ETS proteins (ELK1, ELK4). We then analyzed upregulated and downregulated genes during TPA-induction, with and without MRTFAOE, and identified those that had associated SRF peaks. As expected, TPA-induction upregulated megakaryocytic and cytoskeletal genes (VWF, ACTN1, CORO1A) and downregulated erythroid genes (KLF1, GYPB, GYPE). Interestingly, TPA-induction with MRTFAOE increased the number of upregulated genes by 27% and the number of downregulated genes by 10%. In TPA-induced cells, MRTFAOE increased the percentage of differentially expressed genes that had SRF peaks (25% versus 11% for upregulated genes, and 9% versus 4% for downregulated genes), further highlighting the direct role that MRTFA plays in MK maturation. Also, genes upregulated by TPA-induction alone have both ETS and CArG motifs, whereas those upregulated by TPA-induction with MRTFAOE lack ETS binding motifs, suggesting that MRTFAOE skews SRF binding toward CArG motifs. With anti-MRTFA ChIP-PCR in HEL cells, we confirmed the novel finding that along with SRF, MRTFA binds to regions associated with megakaryocytic and cytoskeletal genes (XRK6, CORO1A). Therefore, SRF and MRTFA together regulate expression of genes that are important for normal megakaryopoiesis, which explains why lack of these proteins adversely affects megakaryopoiesis in mice. We asked whether our findings in HEL cells were applicable to the more clinically relevant primary human BM cells. Anti-SRF and anti-MRTFA ChIP-PCR on day 0 primary human cells (CD34+ cells) and day 8 differentiated cell subpopulations (CD41+CD42-, CD41+CD42+) confirmed that both SRF and MRTFA have increased binding during megakaryopoiesis at target sites associated with upregulated genes, such as CORO1A, TNS1, and XRK6 (p 〈 0.001). Therefore, we illustrated that transcriptional regulation by SRF/MRTFA function similarly in human BM cells undergoing megakaryopoiesis. We show for the first time that MRTFA increases both the genomic association and activity of SRF, and upregulates genes that enhance primary human megakaryopoiesis. These findings suggest that aberrant expression of MRTFA as a fusion protein in AMKL may disrupt essential transcriptional regulation via the SRF/MRTFA axis, resulting in blocked MK maturation. This forms a crucial reference point for future studies to understand the altered SRF/MRTFA function in AMKL. Disclosures No relevant conflicts of interest to declare.

Description: Introduction: Since the seminal paper of LeBlanc in 2008, despite several negative studies, the scientific community has retained optimism with respect to the usefulness of mesenchymal stroma cells (MSCs) in refractory acute graft-versus-host disease (GvHD). A prevailing theme of past studies was that, while pediatric GvHD responded to MSCs, adult GvHD did not. As reported, we developed proprietary protocols GMP-quality MSC production from bone marrow (BM) mononuclear cells expanded in platelet lysate-enriched media. Patients and Methods: We present treatment data with MSC-FFM for 61 children/adolescents and 31 adults with either "only" steroid-refractory (SR) GvHD (27%) or GvHD which had additionally proven refractory to up to five additional lines of therapy (MR-GvHD) (73%). Pediatric patients tended to have more MR-GvHD than adults. Patients from 23 centers in 6 countries were included. Most patients had severe GvHD (37% °III, 59% °IV, Glucksberg scale). 31 patients (34%) were female,61 male (66%). 69 have a malignant disease (75%), and 23 a non-malignant (25%) disease as indication for transplantation. Donors were MSD (n=21, 23%), MUD (n=56, 61%), haploidentical (n=14, 15%), and 1 MMUD (1%). Patients received myeloablative conditioning with TBI-, Treosulfan-, Busulfan- and Fludarabine-based regimen, with serotherapy, mostly ATG. 89% of patients had had immunosuppression for GvHD prophylaxis, 13% CSA alone, 49% CSA+MTX or MMF; or others (n=15, 16%). Median onset of aGvHD was at 40 days (range: 6-280 d), another 28 days (range: 5-380) until the first infusion of MSC-FFM. Recommended dose and interval is 4 weekly doses of 1-2M MSC/kg body weight; the average patient received only 3 doses, the interval approximately staggered as recommended, with a median dose of 1.4M MSC/kg. Any reduction in GvHD activity by at least one full grade was classified as a partial (PR), absence of any degree of GvHD as a complete response (CR). Results: Day-28 response rates were 84%/25%/59% overall (OR)/CR/PR for children and 80%/35%/45% for adults resulting in a day-28 response rate for the entire cohort: 82%/28%/54%). At last follow-up (LFU) many of the pediatric responders had continued to improve from partial to complete response to response rates of 84%/59%/25% OR/CR/PR, in adults responses were largely unchanged (77%/35%/42%; LFU for the entire cohort: 81%/51%/30%). GvHD °III and °IV were equally likely to respond or resolve. Looking at response rates of SR- vs. MR-GvHD, of the SR-GvHD 96% responded (MR-GvHD: 81%), as well as early and LFU responses in SR-GvHD were more likely to be complete responses (60% and 72% for SR-GvHD, 16% and 43% for MR-GvHD, day-28 and LFU, respectively). Day-28-response was highly predictive of long-term responsiveness, in that only one non-responder on day 28 achieved a response long term, and only two initial partial responders' GvHD relapsed to the same degree of severity as before MSC treatment. The historical expected survival probability for patients with steroid-refractory severe GvHD being in the order of 20% at 6 months. The patients reported here with °III or °IV aGVHD achieved 6-month overall survival probabilities of 65% and 61%, respectively. In total 6 patients relapsed and died (of note: only 69 patients were at risk), 28 deaths were treatment-related. 6-month overall survival rates for children and adults were 68% and 54%, respectively (n.s.). In terms of adverse reactions to MSC-FFM, one case each of spontaneously remitting headache and nausea/vomiting were reported shortly after infusion of the thawed cells. Both events occurred in children and were possibly related to the rapid infusion of DMSO-containing ice-cold fluid and not the active substance. Conclusion: MSC-FFM emanates as a highly efficacious treatment for severe pediatric and adult advanced GvHD, with OR in excess of 80% and survival rates approximating those of patients without GvHD. The very low relapse mortality may suggest that severe GvHD effectively suppresses leukemic recurrence. Better and faster responses of SR- vs. MR-GvHD make a case for early treatment with MSC-FFM. Disclosures Bader: Medac: Patents & Royalties, Research Funding; Cellgene: Consultancy; Neovii: Research Funding; Riemser: Research Funding; Novartis: Consultancy, Speakers Bureau. Kuci:Medac: Patents & Royalties. Kuci:Medac: Patents & Royalties. Bug:Amgen: Honoraria; Jazz Pharmaceuticals: Other: Travel Grant; Neovii: Other: Travel Grant; Astellas Pharma: Other: Travel Grant; Janssen: Other: Travel Grant; Celgene: Honoraria; Novartis Pharma: Honoraria, Research Funding. Lang:Miltenyi Biotec: Patents & Royalties, Research Funding. Sykora:Aventis-Behring: Research Funding; medac: Research Funding. Seifried:Medac: Other: BSD owns IP and is contract manufacturer; Uniqure BV: Research Funding. Bonig:Kiadis Pharma: Consultancy.

Description: Background: Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive Non-Hodgkin lymphoma, with approximately one third of patients not responding (or relapsing) after receiving first-line (1L) therapy, typically a multi-agent chemoimmunotherapy regimen containing rituximab and doxorubicin. These patients may be treated with a second-line (2L) chemotherapy (CT) or chemoimmunotherapy (CIT) regimen, with the intention to proceed to a high-dose therapy followed by an autologous stem cell transplant (SCT). Unfortunately, a significant proportion of older patients are unable to tolerate such treatment. There is little data on treatment practices and outcomes in older DLBCL patients receiving 2L CT or CIT after failure of 1L therapy. Using electronic healthcare record data from the largest integrated health system in the United States, the Veterans Health Administration (VHA), we examined real-world outcomes of DLBCL patients ≥ 65 years of age receiving 2L CT or CIT following 1L therapy with rituximab and doxorubicin containing regimens. Methods: DLBCL patients diagnosed from 2001-2015 and treated at the VHA were identified by linking information from the VA Clinical Registry System (VACRS) in the VHA Corporate Data Warehouse (CDW) to administrative, laboratory and pharmacy data, and clinical notes in the CDW. Patients were included in the analysis if they: had no evidence of a prior malignancy, were diagnosed with DLBCL, received 1L therapy containing rituximab and doxorubicin for ≥ 21 days, then subsequently received a 2L CT or CIT, and were ≥ 65 years of age at time of 2L treatment. Patient age, gender, race/ethnicity; stage at diagnosis, lactate dehydrogenase (LDH), and Charlson Comorbidity Index (CCI) were extracted from VACRS and/or CDW. Patients were censored at end of study observation period (Dec 31, 2016) or if a second cancer diagnosis occurred following their DLBCL diagnosis. Patients were divided into 2 groups: Group 1 included patients receiving a 2L regimen that, per the National Comprehensive Cancer Network (NCCN) guidelines, is typically used with intention to proceed to high-dose therapy; Group 2 included patients receiving a regimen that, per NCCN, is used in non-candidates for high-dose therapy. Receipt of SCT was identified using ICD codes and/or clinical notes. Results: 230 DLBCL patients met our inclusion criteria. Of these, 223 (97%) were male and 171 (74%) were of non-Hispanic, white ethnicity. Baseline characteristics (at time of 1L) were as follows: 156 (68%) had stage III-IV disease, 154 (67%) had LDH 〉 ULN, and median CCI was 4 (IQR:2-5). The majority of patients (217, 94%) received RCHOP as 1L, with the remaining receiving RCHOP + etoposide (13, 6%). Two thirds of patients, (151, 66%) started 2L within 1 year of starting 1L with a median of 10.6 months between start of 1L and start of 2L. Patients were almost equally divided between the two groups, with Group 1 (109, 47%) and Group 2 (121, 53%). Of the 109 Group 1 patients, 68 (62%) received ifosfamide, carboplatin, etoposide (ICE) +/- rituximab (R), and 22 (20%) received etoposide, methylprednisolone, cytarabine, cisplatin (ESHAP) +/- R. Of the 109 Group 1 patients, 14 (13%) proceeded to SCT within VHA (SCT outside VHA was not extracted for this study). The remaining 121 Group 2 patients received 2L therapy with the following: bendamustine (B) +/- R (28, 23%), gemcitabine, oxaliplatin (Gem-Ox) +/- R (21, 17%), cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) +/- R (17, 14%), cyclophosphamide, etoposide, vincristine, prednisone (CEOP) +/- R (14, 12%), cyclophosphamide, etoposide, prednisone, procarbazine (CEPP) +/- R (12, 10%); CHOP + etoposide +/- R (6%), lenalidomide +/- R (6%). Fewer than 10 of these patients proceeded to SCT. The median OS of all patients was 8 months. Conclusions: This is the first study that details treatment practices and outcomes in a nationwide cohort of older adult patients (≥ 65 years old) with relapsed/refractory DLBCL. Approximately half of these older patients did not receive or were not candidates for regimens typically used with intent for high-dose therapy and autologous transplant. OS for the entire cohort was less than a year. Despite significant advances in available treatments for DLBCL, there remains an unmet need in treatment of relapsed/refractory DLBCL, especially in older patients who have difficulty tolerating high-dose regimens. Disclosures Halwani: Takeda: Research Funding; Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Miragen: Research Funding; Kyowa Hakko Kirin: Research Funding; Immune Design: Research Funding; Genentech, Inc.: Research Funding; Bristol-Myers Squibb: Research Funding; Amgen: Research Funding; Abbvie: Research Funding. Schulz:Genentech: Employment, Equity Ownership; Roche: Equity Ownership. Li:Roche: Equity Ownership; Genentech: Employment. Masaquel:Genentech: Employment, Equity Ownership; Roche: Equity Ownership. Halloran:Genentech, Inc.: Employment, Equity Ownership; Janssen Pharmaceuticals, Inc: Employment, Equity Ownership. Delong-Sieg:Roche: Equity Ownership; Genentech, Inc.: Employment. Sauer:Genentech: Research Funding; Abbvie: Research Funding; Pharmacyclics: Research Funding; COHRDATA: Research Funding; Amgen: Research Funding.