Abstract: Introduction The Blood and Marrow Transplant Clinical Trials Network study (BMT CTN 1102, NCT02016781) was a multicenter, biologic assignment trial in older adults aged 50-75 with higher risk de novo MDS (IPSS Intermediate-2 or High) who were candidates for reduced-intensity conditioning (RIC) allogeneic HCT. The trial compared outcomes of those with a suitable HLA-identical sibling or unrelated donor (Donor arm) to those where no donor was identified (No Donor arm) within a search window of 90 days. The trial reported a survival benefit for patients in the Donor arm compared to the No Donor arm [Nakamura et al, JCO 2021, in press]. Here, we compare the health-related quality of life (QOL) for patients between the two arms through 36 months after enrollment. We also describe the predictors and trajectories of QOL. Methods English and Spanish-speaking subjects were invited to complete patient-reported outcome (PRO) measures, including the Functional Assessment of Cancer Therapy - General (FACT-G), the SF-36 yielding a Physical Component Score (PCS) and Mental Component Score (MCS), and the EQ-5D, at enrollment and every 6 months until 24 months, then 36 months after enrollment. Validation studies indicate a clinically meaningful difference of 5 points for FACT-G, PCS, and MCS and 2 points for associated subscales. To account for the missingness of assessments, including those missing due to death, we compared each score between arms using an inverse probability weighted - independent estimating equation (IPW-IEE) model, which models the scores in surviving patients while using IPW to account for baseline variables and follow-up outcomes that impact the likelihood of missingness. Since 4 scores were evaluated, a Bonferroni corrected significance level of 1.25% = 5% / 4 was used. Cox regression models were used to evaluate the impact of QOL measures on overall and leukemia free survival. The IPW-IEE models adjust for baseline score and follow-up assessment time as well as age, race/ethnicity, performance status, IPSS score, duration of disease, and response to prior hypomethylating therapy; the Cox models adjusted for the 6 latter variables and treatment arm. Trajectories of QOL are shown by plotting mean +/- standard error by group over time. Results Between January 2014 and November 2018, 384 subjects (median age 66.7 years, range: 50.1-75.3) were enrolled at 34 centers and biologically assigned to Donor (n=261) or No Donor arm (n=123) by 90 days from enrollment. For the Donor arm the median duration from registration to HCT was 3.9 months (range 0.3-20.7). Completion rates were generally high at 65-78% of eligible survivors at each timepoint. At enrollment, 204 subjects (78.2%) in the Donor arm and 85 subjects (69.1%) in the No Donor arm completed at least one QOL form, with 4 patients unable to complete due to language (non-English or Spanish speaking). While there were some small differences at 18 months favoring the Donor arm, no clinically significant differences in PRO scores or subscales were seen between the arms at any timepoint (Figure 1) or in the scores over time. In general, similar trajectories for the Donor arm were seen for each PRO, with most decreasing or stable from baseline to 6 months and improving thereafter. Compared to published averages of U.S cancer populations, FACT-G means in both arms were higher beginning at 18 months. Baseline and 6-month PRO scores were the strongest predictors of later PRO scores despite adjusting for patient demographic and clinical factors. Overall survival was predicted by baseline FACT-G & lt;70 (HR=1.61, p & lt;.01) and PCS scores & lt;40 (HR=1.82, p & lt;0.001), while leukemia-free survival was predicted by baseline FACT-G & lt;70 (HR=1.61, p & lt;0.01) and PCS & lt;40 (HR=1.80, p & lt;0.002). No associations of PROs with AML transformation, relapse, or acute or chronic GVHD were found. Non-compliance with biologic assignment was less likely in Donor arm compared to No Donor, but baseline QOL was not a confounding factor. Conclusion In older adults with MDS, the survival advantage associated with Donor availability and HCT does not come at the cost of worse QOL in comparison to the No Donor arm. Baseline PRO scores were the strongest independent predictors of subsequent QOL outcomes and survival, even after controlling for clinical and patient-level factors. These results should reassure older patients and clinicians who prefer curative approaches to MDS. Figure 1 Figure 1. Disclosures Cutler: Mallinckrodt: Consultancy; Editas: Consultancy; CareDx: Consultancy; Kadmon: Consultancy; Pfizer: Consultancy; Incyte: Consultancy; Cimeio: Consultancy; Deciphera: Consultancy; Omeros: Consultancy; Syndax: Consultancy; Mesoblast: Consultancy; Jazz: Consultancy. Saber: Govt. COI: Other. Lee: Takeda: Research Funding; Syndax: Research Funding; Pfizer: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kadmon: Research Funding; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Janssen: Other; Incyte: Research Funding; AstraZeneca: Research Funding; Amgen: Research Funding. Shaw: mallinkrodt: Other: payments; Orca bio: Consultancy. Horowitz: Magenta: Consultancy, Research Funding; Astellas: Research Funding; Jazz Pharmaceuticals: Research Funding; GlaxoSmithKline: Research Funding; Genentech: Research Funding; CSL Behring: Research Funding; Gamida Cell: Research Funding; Allovir: Consultancy; Daiicho Sankyo: Research Funding; Amgen: Research Funding; bluebird bio: Research Funding; Chimerix: Research Funding; Actinium: Research Funding; Medac: Research Funding; Kiadis: Research Funding; Xenikos: Research Funding; Vor Biopharma: Research Funding; Bristol-Myers Squibb: Research Funding; Regeneron: Research Funding; Pharmacyclics: Research Funding; Pfizer, Inc: Research Funding; Orca Biosystems: Research Funding; Omeros: Research Funding; Novartis: Research Funding; Miltenyi Biotech: Research Funding; Mesoblast: Research Funding; Kite/Gilead: Research Funding; Janssen: Research Funding; Sanofi: Research Funding; Seattle Genetics: Research Funding; Shire: Research Funding; Sobi: Research Funding; Stemcyte: Research Funding; Takeda: Research Funding; Tscan: Research Funding; Vertex: Research Funding.

Abstract: Patient outcomes for steroid-dependent or -refractory chronic graft-versus-host diesease (cGVHD) are poor, and only ibrutinib has been US Food and Drug Administration (FDA) approved for this indication. cGVHD is often driven by the germinal center (GC) reaction, in which T follicular helper cells interact with GC B cells to produce antibodies that are associated with disease pathogenesis. The transcriptional corepressor B-cell lymphoma 6 (BCL6) is a member of the Broad-complex, Tramtrack, and Bric-abrac/poxvirus and zinc finger (BTB/POZ) transcription factor family and master regulator of the immune cells in the GC reaction. We demonstrate that BCL6 expression in both donor T cells and B cells is necessary for cGVHD development, pointing to BCL6 as a therapeutic cGVHD target. A small-molecule BCL6 inhibitor reversed active cGVHD in a mouse model of multiorgan system injury with bronchiolitis obliterans associated with a robust GC reaction, but not in cGVHD mice with scleroderma as the prominent manifestation. For cGVHD patients with antibody-driven cGVHD, targeting of BCL6 represents a new approach with specificity for a master GC regulator that would extend the currently available second-line agents.

Abstract: Background: The nuclear export protein, XPO1 is overexpressed in all types of malignant lymphoma. The SINE selinexor (KPT-330) is a slowly reversible XPO1 antagonist that forces the nuclear retention and activation of over 10 tumor suppressor proteins (TSP) such as p53, IkB, FOXO and p21. In addition, selinexor inhibits the nuclear export and the translation of oncogenic mRNAs such as c-myc and Bcl-XL levels. Together these effects result in apoptosis of cancer cells in preclinical models of both T- and B- cell NHL. In DLBCL cell lines (n=10), selinexor induced potent cytotoxicity against both germinal center (GCB) and nonGCB including those with high MYC and/or BCL2/6 protein levels. Methods: Selinexor was administered orally for 4-10 doses in a 28-day cycle in this phase 1 study. Serial tumor biopsies were performed. Response evaluation was performed in cycle 1 and 2 and then every 2 cycles. All pts had heavily pretreated NHL with documented progressive disease (PD) on study entry. Results: 58 pts (34 males 24 females; median age 62 yrs; ECOG PS 0/1/2: 19/35/4; median prior regimens: 3) received selinexor across 13 dose levels (3 to 80 mg/m2). The recommended Phase 2 dose is 60 mg/m2 based on results across all Phase 1 studies. Grade 3/4 events ( 〉 5%) include thrombocytopenia (31%), neutropenia (22%), fatigue (10%), and anemia (7%). The most common Grade 1/2 AEs were: nausea (66%), anorexia (47%), fatigue (40%), and vomiting (40%) that were manageable with supportive care and were seen less frequently following cycle 1. Increases in XPO1 mRNA levels were observed at all doses and sustained for 4-48 hours, supporting twice weekly dosing. Tumor biopsies confirmed TSP nuclear localization, c-myc reductions, and apoptosis induction of cancer cells. Objective responses were observed in all classes of NHL studied (Table 1). An objective response rate (ORR) of 31% was observed across all NHL types. An ORR of 40% was observed in pts with rel/ref aggressive B-NHL (DLBCL, Follicular NHL grade 3b (FLgrd3b) and transformed NHL) at doses ³60 mg/m2 vs an ORR of 33% at 23-50 mg/m2 and 25% at ²20 mg/m2. Across all NHL types, time to best response was delayed, including 5 complete responses (CR) (4 in DLBCL and 1 T-NHL). Nine pts out of 34 have remained on therapy for 〉 6-23 months without clinically significant cumulative toxicities or major organ dysfunction. Conclusions: Selinexor treatment is generally well tolerated with supportive care and can be given over a prolonged period. Durable single agent activity in pts with heavily pretreated NHL has been observed. Phase 2 studies in DLBCL, Richter's transformation and T-NHL of single agent selinexor as well as in combination with other agents including CD20 antibodies are expected to begin in the near future. Abstract 396. Table 1 Cancer Type Selinexor Dose (mg/m2) N* ORR (%) CR (%) PR (%) SD (%) PD (%) WC/NE (%) Aggressive B-NHL (DLBCL, FLgrd3b, Transformed) ≤20 4 1 (25%) -- 1 (25%) 1 (25%) 2 (50%) -- 20 – 50 21 7 (33%) 4 (19%) 3 (14%) 5 (24%) 6 (29%) 3 (14%) ≥60* 10 4 (40%) -- 4 (40%) 4 (40%) -- 2 (20%) Follicular & Other Indolent NHL ≤30 4 -- -- -- 4 (100%) -- -- ≥35 4 2 (50%) -- 2 (50%) 1 (25%) -- 1 (25%) Mantle Cell Lymphoma ≤30 2 1 (50%) -- 1 (50%) 1 (50%) -- -- ≥35 2 -- -- -- -- 1 (50%) 1 (50%) T-Cell Lymphoma ≤30 4 -- -- -- 2 (50%) -- 2 (50%) ≥35 1 1 (100%) 1 (100%) -- -- -- -- Richter's Transformation ≤30 3 1 (33%) -- 1 (33%) 2 (67%) -- -- ≥35 3 1 (33%) -- 1 (33%) -- -- 2 (67%) TOTAL 58 18 (31%) 5 (9%) 13 (22%) 20 (34%) 9 (16%) 11 (19%) * First pt in this population was dosed on 23-July-2012 ORR=Objective Response Rate; CR=Complete Response; PR=Partial Response; SD=Stable Disease; PD=Progressive Disease; WC=Withdrew Consent; NE=Non-Evaluable Disclosures Byrd: Pharmacyclics, Genentech: Research Funding. Porcu:Infinity: Research Funding; Seattle genetics: Research Funding; Actelion: Honoraria; Celgene: Honoraria; United States Cutaneous Lymphoma Consortium: Membership on an entity's Board of Directors or advisory committees; Cutaneous Lymphoma Foundation: Membership on an entity's Board of Directors or advisory committees. Stone:AbbVie, Inc: Consultancy; Agios: Consultancy; Amgen: Consultancy; Celator: Consultancy; Celgene: Consultancy; Roche: Consultancy. Baz:Celgene: Research Funding; Millennium: Research Funding; Bristol Myers Squibb: Research Funding; Karyopharm: Research Funding; Sanofi: Research Funding. Flinn:AstraZeneca: Research Funding. Kukreti:Celgene: Honoraria. Landesman:Karyopharm Therapeutics: Employment. Klebanov:Karyopharm Therpeutics: Employment. Shacham:Karyopharm Therapeutics: Employment. Saint-Martin:Karyopharm Therpeutics: Employment. Marshall:Karyopharm Therpeutics: Employment. McCartney:Karyopharm Therpeutics: Employment. McCauley:Karyopharm Therapeutics: Employment, Equity Ownership. Carlson:Karyopharm Therapeutics: Employment. Norori:Karyopharm Therpeutics: Consultancy. Savona:Karyopharm Therpeutics: Membership on an entity's Board of Directors or advisory committees. Rashal:Karyopharm Therapeutics: Employment. Mirza:Karyopharm Therpeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kauffman:Karyopharm Therapeutics: Employment, Equity Ownership. Shacham:Karyopharm Therpeutics: Employment, Equity Ownership.

Abstract: Despite advances in the field, chronic graft-versus-host-disease (cGVHD) remains a leading cause of morbidity and mortality following allogenic hematopoietic stem cell transplant. Because treatment options remain limited, we tested efficacy of anticancer, chromatin-modifying enzyme inhibitors in a clinically relevant murine model of cGVHD with bronchiolitis obliterans (BO). We observed that the novel enhancer of zeste homolog 2 (EZH2) inhibitor JQ5 and the BET-bromodomain inhibitor JQ1 each improved pulmonary function; impaired the germinal center (GC) reaction, a prerequisite in cGVHD/BO pathogenesis; and JQ5 reduced EZH2-mediated H3K27me3 in donor T cells. Using conditional EZH2 knockout donor cells, we demonstrated that EZH2 is obligatory for the initiation of cGVHD/BO. In a sclerodermatous cGVHD model, JQ5 reduced the severity of cutaneous lesions. To determine how the 2 drugs could lead to the same physiological improvements while targeting unique epigenetic processes, we analyzed the transcriptomes of splenic GCB cells (GCBs) from transplanted mice treated with either drug. Multiple inflammatory and signaling pathways enriched in cGVHD/BO GCBs were reduced by each drug. GCBs from JQ5- but not JQ1-treated mice were enriched for proproliferative pathways also seen in GCBs from bone marrow-only transplanted mice, likely reflecting their underlying biology in the unperturbed state. In conjunction with in vivo data, these insights led us to conclude that epigenetic targeting of the GC is a viable clinical approach for the treatment of cGVHD, and that the EZH2 inhibitor JQ5 and the BET-bromodomain inhibitor JQ1 demonstrated clinical potential for EZH2i and BETi in patients with cGVHD/BO.

Abstract: To study transcriptional pathways and develop targeted therapeutics for cGVHD, we studied the effects of emerging therapeutic agents targeting GCs. BCL6 is a master regulatory transcription factor, which facilitates GC development in a cooperative manner with emerging chromatin-associated factors, namely the EZH2 lysine methyltransferase and the BRD4 epigenetic reader protein. Using a murine multi-organ system cGVHD model induced by low T cell numbers, we have shown that cGVHD is dependent on pathogenic antibodies and the GC reaction. To determine whether strategies that disrupt GC integrity could be used to treat cGVHD we targeted Bcl6 using a direct-acting ligand (79-6), EZH2 using three structurally-distinct inhibitors (JQ-E, UNC1999 and DZNep), and a first-in-class BRD4 inhibitor (JQ1). In T cells, Bcl6 is selectively expressed in T follicular helper and regulatory cells. Using donor T cells from a Bcl6-mCherry reporter, we observed a 10-fold increase in % of CD4+/mCherry+ splenic T cells in cGVHD vs bone marrow (BM) only controls on d56. The small-molecule Bcl6 inhibitor 79-6 was synthesized and used to treat mice with active cGVHD from d28-56. Treatment reversed cGVHD-induced bronchiolitis obliterans (BO) measured by d56 pulmonary function tests (PFTs). This correlated with a 2-fold decrease in GC B cells and decrease in lung collagen (Fig 1 C). EZH2 catalyzes the methylation of lysine 27 on histone 3 (H3K4me3) silencing genes to a transcriptionally repressive state. EZH2 is massively upregulated during the GC reaction, and prevents GC B cell terminal differentiation, allowing affinity maturation to occur. Furthermore, naive T cells express low EZH2 levels, EZH2 is rapidly upregulated upon allostimulation.To determine whether EZH2 expression in donor BM or splenic T cells was critical for cGVHD, recipients were given wild type (WT) vs EZH2 floxed, Cg1-Cre (for B cell specific EZH2 deletion) BM + WT T cells, WT BM + EZH2 floxed, CD4-Cre vs WT T cells or WT BM + WT T cells. EZH2 deletion in either BM-derived B cells or splenic T cells completely prevented cGVHD (Fig 1 A) with a decrease in d56 splenic GC frequency (Fig 1 B). We compared 3 drugs that reduce H3K4me3: two pyridinone inhibitors, which inhibit SAM-dependent methylation (JQ-E and UNC1999) and DZNep, which destabilizes EZH2 complexes. At established doses given d28-56, DZNep and UNC1999 were ineffective or toxic, respectively. In contrast, JQ-E fully reversed cGVHD lung dysfunction and fibrosis around the bronchioles was significantly decreased (Fig 1 C). JQ1 is a first in class epigenetic reader that recognizes histone modifications and has been shown to reduce B cell lymphomas via inhibiting super-enhancer-associated transcripts and to treat cardiac failure-induced fibrosis. JQ1 given to cGVHD mice d28-56 significantly inhibited BO as assessed by PFTs and collagen deposition (Fig 1 D). Taken together, these data demonstrate for the first time the critical role of Bcl6 and targeting of histones that affect the transcriptional repressive states via EZH2 and a BET bromodomain epigenetic reader. These data provide a strong foundation for clinical trials of inhibitors that directly or epigenetic modifiers and readers that indirectly target Bcl6. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract: Circulating levels of murine CCL9 and human homolog CCL15 are increased during cGVHD. Targeting CCL9 in vivo reverses murine cGVHD.

Abstract: Allogeneic hematopoietic stem cell transplantation (aHSCT) is hampered by chronic graft-versus-host disease (cGVHD), which results in multi-organ fibrosis and loss of function. In particular, bronchiolitis obliterans (BO) and scleroderma resulting from fibrotic bronchiolar and cutaneous response, respectively, are two devastating outcomes for cGVHD patients. Fibrotic manifestations often are considered irreversible and progressive. Therefore, new therapies targeting fibrosis are urgently needed. Pirfenidone (5-methyl-1-phenyl-2- (1H)-pyridone) exhibits a well-documented anti-inflammatory and anti-fibrosis function in multiple pre-clinical models and is the first and only FDA-approved drug for idiopathic pulmonary fibrosis. For this study, Pirfenidone was synthesized as a crystalline solid and found to be pure both by melting point and NMR spectroscopy. We evaluated Pirfenidone's anti-fibrosis function in 2 pathophysiologically distinct cGVHD murine models: 1. a major mismatched multi-organ system model (C57BL/6 to B10.BR) that induces BO as a result of a cGVHD-induced germinal center (GC) reaction, antibody deposition and fibrosis in the lung; and 2. a minor antigen mismatched model (B10.D2 to BALB/c) in which severe scleroderma is the major disease manifestation. In the BO model, pulmonary function loss in cGVHD mice (as reflected by increased resistance, elastance and decreased compliance of the lung) was restored by Pirfenidone treatment (400mg/kg) during both the early (day28-56) (Fig A, representative of 3 experiments with 5-8 mice per group) and late stages (day56-84) of the disease. Pathologic changes in the lung, such as collagen deposition and narrowing of bronchioles, were significantly reduced by Pirfenidone. The size and frequency of GCs in the spleen, and the frequency of GC B cells (Fig B, representative of 2 experiments with 5-8 mice per group) and T follicular helper cells were all significantly reduced in Pirfenidone- treated groups. To determine whether GCs were directly affected by Pirfenidone, we evaluated Pirfenidone in C57BL/6 mice immunized with sheep red blood cells (SRBC) to induce GCs. Interestingly, Pirfenidone did not reduce the SRBC-induced GC reaction (Fig C) (comparable frequencies of splenic GC B cells, T follicular helper cells and serum IgG levels were seen between Pirfenidone and vehicle-treated groups). These results suggested that Pirfenidone suppresses the GC reaction through a cGVHD-specific mechanism, rather than through immune regulation. Mechanistically, Pirfenidone administration attenuated the sequestration of pro-fibrogenic F4/80+ macrophages (Fig D, representative of 2 experiments) and TGF-β (Fig E, representative of 2 experiments) production within the lung. These results have led us to elucidate a potential mechanism of cGVHD: antibody deposition in the lung results in the activation of macrophages and TGF-β that drive fibrotic change and tissue damage, resulting in the exposure of auto- and allo- antigens to the immune system that support and sustain pathologic GC reactions. In the B10.D2 to BALB/c sclerodermatous cGVHD model, Pirfenidone treatment (400mg/kg, day21-55) improved clinical signs of scleroderma and reduced macrophage infiltration in the skin (Fig F). In summary, this is the first study evaluating a commercially available anti-fibrosis drug on pathologically distinct pre-clinical cGVHD models. Our data suggests Prifenidone reversed cGVHD in the BO model and, to a lesser extent, in the scleroderma model. Thus, Pirfenidone is a novel therapeutic agent for treating cGVHD patients with fibrosis that have been typically refractory to therapies. A. Resistance of lungs was measured on day56 of transplantation; Elastance and compliance correlated with resistance but were not shown here. B. Flow cytometry analysis of GC B cells of no cGVHD vs cGVHD mice treated with Pirfenidone or vehicle; C. Flow cytometry analysis of GC B cells from SRBC-immunized mice treated with Pirfenidone or vehicle; D and E. Macrophage F4/80 and TGF-β quantification of day56 lungs of no cGVHD vs cGVHD mice treated as indicated; F. Skin GVHD scores were recorded on indicated dates of irradiated BALB/c mice transplanted with B10.D2 donor BM alone or with T cells and treated as indicated. Unpaired student T test was used for statistical analysis. ****:P 〈 0.0001; ***: P 〈 0.001; **: P 〈 0.01; *: P 〈 0.05; ns: not significant. Figure Figure. Disclosures No relevant conflicts of interest to declare.

Abstract: Pirfenidone ameliorates cGVHD in murine models with distinct pathophysiology. The efficacy of pirfenidone is associated with inhibition of macrophage infiltration and TGF-β production.