Abstract: New-onset autoimmune hemolytic anemia (AIHA) occurs in 2% to 6% of pediatric patients post–hematopoietic stem cell transplantation (HSCT) and is a significant complication. Incomplete immune recovery following HSCT may predispose to immune dysregulation including autoimmune cytopenias. We describe an innovative therapy for AIHA refractory to proteasome inhibition. In potentially life-threatening AIHA in the context of HSCT, daratumumab may be an effective rescue therapy.

Abstract: The histone demethylating enzyme LSD1 has emerged as a promising epigenetic target in the treatment of acute myeloid leukemia (AML). Inhibition of LSD1 has been shown to induce differentiation and facilitate the responsiveness of AML cells to all-trans retinoic acid (ATRA). As it remains unclear how LSD1 inhibition induces differentiation, we have now used a murine leukemia model based on retroviral overexpression of Hoxa9 and Meis1 to study the effect of of both genetic inactivation as well as pharmacological inhibition of LSD1. We transformed bone marrow cells from conditional LSD1 knock-out (KO) mice to confirm the responsiveness of Hoxa9/Meis1-induced leukemias to an inhibition of LSD1. Marked granulocytic differentiation was observed in these cells upon induction of the LSD1 KO. The cells also showed a decrease in expression of c-Kit by 53 %. Furthermore the cells acquired the mature granulocytic marker Ly6G. We also found an increased sensitivity to a treatment with ATRA upon induction of the LSD1 KO. We then transplanted Hoxa9/Meis1-transformed cells from conditional LSD1 KO mice into lethally irradiated mice and induced the LSD1 KO 20 days after transplantation by treatment with tamoxifen. This extended the survival of mice from a median of 48 days for control-treated mice (N=5) to a median of 78 days for tamoxifen-treated mice (N=5) (p=0.0021). We then treated Hoxa9/Meis1-transformed myeloid progenitors with three irreversible (tranylcypromine, trans-N-((2-methoxypyridin-3-yl)methyl)-2-phenylcyclopropan-1-amine (ORY86, AW69), (1S,2R)-2-phenyl-N-(piperidin-4-ylmethyl)cyclopropanamine (AW84)) and three reversible LSD1 inhibitors (MS120 (=Namoline), MS142, SP2509) alone or in combination with ATRA. We observed signs of granulocytic differentiation with the irreversible inhibitors and a reduction in c-Kit expression from 92% to 25% after treatment with AW69. Colony formation of Hoxa9/Meis1-transformed myeloid progenitors was reduced by 70% compared to control cells after treatment with AW69 for 96 hrs. Treatment with AW69 and AW84 also enhanced the response of leukemia cells to ATRA by enhancing the anti-proliferative effect and by reducing colony formation by 99% in Hoxa9/Meis1 cells in the combination. The reversible LSD1 inhibitors exhibited only minor effects on differentiation even when used at effective concentrations. We also analyzed the effect of LSD1 inhibition on leukemia-initiating cell frequency. We therefore treated Hoxa9/Meis1-transformed myeloid progenitors with AW69 in vitro for a total of 96 hrs and then assessed the LIC frequency in a limiting-dilution assay. In this assay, AW69 induced a striking reduction in LIC frequency from 1/40 (95 % CI 1/10.7 to 1/175) to 1/3200 (95 % CI 1/835.5 to 1/12101) (p 〈 0.001). As the differentiating effect of LSD1 inhibition in our model was limited to the irreversible inhibitors we then wanted to investigate if the effect was due to interference with the enzymatic activity of LSD1. We therefore used the combination of Hoxa9 and Meis1 to transform cells from mice carrying a conditional knock-in (KI) of an enzymatically inactive form of LSD1 (LSD1mut) and assessed its consequence both in vitro and in vivo. Similar to the effect seen with the conditional KO we observed granulocytic differentiation upon induction of the conditional LSD1mut KI as well as a downregulation of c-Kit expression. However, we did not find a survival benefit in vivo upon induction of the conditional LSD1mut KI, but observed a more differentiated immunophenotype in the developing leukemias. In summary, LSD1 depletion or inhibition using tranylcypromine or its derivatives induces granulocytic differentiation, reduces LIC frequency and induces a survival benefit in Hoxa9/Meis1-driven AML. Our data further suggest that these effects of LSD1 inhibition are mediated by interfering with both enzymatic and scaffolding functions of LSD1. Disclosures Lübbert: Ratiopharm: Other: Study drug valproic acid; Janssen-Cilag: Other: Travel Funding, Research Funding; Celgene: Other: Travel Funding. Berg:Astellas: Other: Travel Funding; Alexion: Other: Travel Funding; Celgene: Other: Travel Funding.

Abstract: 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.