Sirulnik, Andres

BACKGROUND: Odronextamab (REGN1979) is a first-in-class, hinge-stabilized, fully human IgG4-based CD3 x CD20 bispecific antibody (bsAb) that has demonstrated encouraging safety, tolerability and preliminary efficacy in a first-in-human study of patients (pts) with relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (B-NHL). We report updated safety and efficacy data from the dose escalation and early dose expansion phase of the ongoing Phase (P)1 study (NCT02290951). METHODS: Odronextamab was administered using a step-up dose schedule consisting of an initial dose at Week (W)1, an intermediate dose at W2, and thereafter, a fixed weekly dose until W12 followed by maintenance Q2W dosing. Dexamethasone premedication was used to mitigate the risk for cytokine release syndrome (CRS). Key primary objectives were to assess safety and dose-limiting toxicities (DLTs), and to establish a maximum tolerated dose (MTD) and recommended P2 dosing regimen (RP2DR). Secondary objectives included a preliminary assessment of anti-tumor activity. RESULTS: As of Jun 25, 2020, 127 pts with R/R B-NHL have been treated at doses ranging from 0.03-320 mg. The study included pts with diffuse large B-cell lymphoma (DLBCL; n=71), follicular lymphoma (FL) Grade (Gr) 1-3a (n=37), mantle cell lymphoma (MCL; n=11), marginal zone lymphoma (n=6), and other B-NHLs (n=2). Pts were highly refractory (80.3%) and had received a median of 3 (range: 1‒11) prior lines of therapy; 29 pts (22.8%) received prior CAR T therapy (FL: 2; DLBCL: 25; MCL: 2) and 85 pts (66.9%) were double refractory to alkylator and anti-CD20 antibody, in any line of therapy. Median follow-up was 3.9 (0.4‒37.6) months (mo). No DLTs were reported during dose escalation and MTD was not reached with odronextamab doses up to 320 mg weekly. The most frequent treatment-related adverse events (AEs) of any grade were pyrexia (76.4%), CRS (62.2%), and chills (48.0%). Gr 3 CRS occurred in 8 pts (6.3%) and a Gr 4 CRS occurred in 1 pt (0.8%). Most of the CRS events occurred during the first 2 weeks of step-up dosing and resolved within a median of 2 days (range 1-41) with supportive care measures. No pts discontinued odronextamab treatment due to CRS. Gr 3 neurologic AEs were noted in 5 pts, of which only 3 (2.3%) were considered treatment-related: somnolence, syncope, and encephalopathy. None of these events required treatment discontinuation. There were no Gr 4 or higher neurologic AEs. Overall, 7 pts (5.5%) discontinued treatment due to treatment-related AEs. In pts with R/R FL Gr 1-3a, odronextamab demonstrated a broad window of therapeutic activity. In pts treated at doses of ≥5 mg (n=28), objective response rate (ORR) was 92.9%, and complete response (CR) rate was 75.0%; median duration of response (DoR) was 7.7 mo (range 0+-20.9+), with 13 of 21 CRs ongoing at last tumor assessment. The median duration of complete response (DoCR) was 8.1 mo (range 0+-19.9+) and follow-up is ongoing (Table). In pts with R/R DLBCL, encouraging activity was observed at higher odronextamab dose levels. In DLBCL pts who had not received prior CAR T therapy, treated at doses ≥80 mg (n=10), ORR and CR rate were 60%; median observed DoR was 10.3 mo (range 2.9-18.6+), with 4 of 6 CRs ongoing at last tumor assessment. The median DoCR was 9.5 mo (range 2.9-18.6+) and follow-up is ongoing. In DLBCL pts who were refractory to prior CAR T therapy, treated at doses ≥80 mg (n=21), ORR was 33.3%, and CR rate was 23.8%; median observed DoR was 2.8 mo (range 0+-18.9+), with 5 of 5 CRs ongoing at last tumor assessment. The median DoCR was 4.4 mo (range 0+-18.9+) and follow-up is ongoing. Based on an evaluation of preliminary antitumor activity and PK, RP2DR was identified for dose expansion cohorts. CONCLUSIONS: Odronextamab has demonstrated encouraging single agent antitumor activity in highly refractory pts with B-NHLs. Durable CRs have been observed in both indolent and aggressive B-NHL pts, including in pts refractory to CAR T therapy. Most CRs are ongoing at time of data cutoff, and updated data will be presented. Odronextamab has an acceptable safety and tolerability profile. Dexamethasone premedication and step-up dosing mitigates the risk for CRS and allows odronextamab administration up to 320 mg weekly without DLTs. A global P2 trial investigating odronextamab in R/R B-NHL is ongoing. Disclosures Bannerji: Regeneron Pharmaceuticals: Research Funding; AbbVie: Research Funding; Sanofi-Pasteur: Other: Spouse is employee; F. Hoffmann-La Roche Ltd/Genentech, Inc and Pharmacyclics LLC, an AbbVie Company: Research Funding. Allan:Acerta, Genentech, Abbvie, Sunesis, Ascentage, Pharmacyclics, Janssen, AstraZeneca, BeiGene: Consultancy; Abbvie, Janssen, AstraZeneca, Pharmacyclics: Honoraria; Celgene, Genentech, Janssen, TG Therapeutics: Research Funding. Arnason:Regeneron: Consultancy; Juno: Consultancy. Brown:Catapult: Consultancy; Sun: Research Funding; Loxo: Consultancy, Research Funding; Verastem: Consultancy, Research Funding; TG Therapeutics: Consultancy; Sunesis: Consultancy; Rigel Pharmaceuticals: Consultancy; Pfizer: Consultancy; Octapharma: Consultancy; Novartis: Consultancy; Nextcea: Consultancy; MEI Pharma: Consultancy; Kite: Consultancy; Juno/Celgene: Consultancy; Eli Lilly and Company: Consultancy; Dynamo Therapeutics: Consultancy; BeiGene: Consultancy; Gilead: Consultancy, Research Funding; Invectys: Membership on an entity's Board of Directors or advisory committees, Other: DSMC; Acerta: Consultancy; Genentech: Consultancy; Pharmacyclics: Consultancy; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other; Astra-Zeneca: Consultancy; Janssen: Honoraria; AbbVie: Consultancy. Advani:Celgene, Forty Seven, Inc., Genentech/Roche, Janssen Pharmaceutical, Kura, Merck, Millenium, Pharmacyclics, Regeneron, Seattle Genetics: Research Funding; Astra Zeneca, Bayer Healthcare Pharmaceuticals, Cell Medica, Celgene, Genentech/Roche, Gilead, KitePharma, Kyowa, Portola Pharmaceuticals, Sanofi, Seattle Genetics, Takeda: Consultancy. Ansell:Bristol Myers Squibb: Research Funding; Takeda: Research Funding; Trillium: Research Funding; ADC Therapeutics: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; AI Therapeutics: Research Funding. O'Brien:Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Consultancy, Research Funding; Kite, Regeneron, Acerta: Research Funding; Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc. Vaniam Group, AbbVie, Alexion, Verastem, Eisai, Juno Therapeutics, Vida Ventures: Consultancy. Duell:Morphosys: Research Funding. Martin:Sandoz: Consultancy; Karyopharm: Consultancy, Research Funding; Celgene: Consultancy; Teneobio: Consultancy; I-MAB: Consultancy; Bayer: Consultancy; Beigene: Consultancy; Cellectar: Consultancy; Incyte: Consultancy; Kite: Consultancy; Morphosys: Consultancy; Regeneron: Consultancy; Janssen: Consultancy. Li:Regeneron Pharmaceuticals, Inc: Current Employment, Current equity holder in publicly-traded company. Flink:Regeneron Pharmaceuticals, Inc: Current Employment, Current equity holder in publicly-traded company. Zhu:Regeneron Pharmaceuticals, Inc: Current Employment, Current equity holder in publicly-traded company. Weinreich:Regeneron Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Yancopoulos:Regeneron Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Sirulnik:Regeneron Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Chaudhry:Regeneron Pharmaceuticals, Inc: Current Employment, Current equity holder in publicly-traded company. Ambati:Regeneron Pharmaceuticals, Inc: Current Employment, Current equity holder in publicly-traded company. Topp:Amgen, Boehringer Ingelheim, KITE, Regeneron, Roche: Research Funding; Amgen, KITE, Novartis, Regeneron, Roche: Consultancy. OffLabel Disclosure: The data described in the abstract will report on use of odronextamab in a Phase 1 clinical trial of patients with B-NHL

Abstract Over 40% of cases of multiple myeloma (MM) are associated with translocations of the immunoglobulin heavy (IgH) chain gene gene. The t(4;14) translocation, present in ca. 20% of myeloma cases, results in the overexpression of two potential oncogenes, MMSET and FGFR3, via juxtaposition of their endogenous promoters to regulatory elements of the IgH locus. The presence of t(4;14), and MMSET overexpression, is an adverse prognostic factor in MM irrespective of FGFR3 expression. MMSET contains several conserved motifs found in proteins involved in chromatin function (PWWP, HMG, PHD domains) and in the epigenetic control of transcription (SET domain). Accordingly, we found that the two main isoforms of the MMSET protein exhibit exclusive nuclear localization in both transfected fibroblasts and myeloma cells carrying t(4;14). Towards our goal of defining the ability of MMSET to affect gene regulation and contribute to the disease pathogenesis, we found that the SET domain of MMSET possesses in vitro methyltransferase activity specific for core histones H3 and H4. Using a computational approach and theoretical extrapolation from the solved NMR structure of vSET, we identified residues in the active site of MMSET essential for catalysis, whose mutation drastically reduces enzymatic activity. Reporter assays using Gal4 fusion constructs showed that both the amino terminus of MMSET, containing the PWWP and HMG domains, as well as the SET-containing carboxy terminus act as transcriptional repressors. MMSET interacts physically and functionally with a number of known co-repressor molecules, such as HDAC1, HDAC2, Sin3a, and SIRT1, but not HDAC4 or HDAC6. As such, MMSET co-expression enhances HDAC1 and HDAC2-mediated repression in transcriptional reporter assays, and MMSET repression is partially relieved by the addition of an HDAC inhibitor. A yeast two hybrid screen identified a number of other functional partners of MMSET, including ZNF331/RITA (Rearranged in Thyroid Adenoma), a KRAB domain/zinc finger protein previously implicated in malignancy. MMSET and ZNF331 co-localize in the nuclei of transfected fibroblasts, co-immunoprecipitate, and display cooperative repression in reporter assays. Collectively, these data support the idea that MMSET is a biologically active, bifunctional transcriptional mediator acting as a HMT enzyme in chromatin remodeling and as a complex adaptor in the recruitment of repressor species. Presently we are modeling the biological effects of MMSET through a conditional overexpression system in a B cell line. While low levels of MMSET are ubiquitiously expressed, induction of high levels of MMSET expression in the B cell line is associated with growth suppression and G1 arrest. While paradoxical for a presumed oncoprotein, such actions have been observed for other disease-associated proteins such as Runx1/MTG8. In contrast, a myeloma cell line harboring t(4;14) proliferates in the presence of high level MMSET expression. RNAi-mediated knockdown of MMSET in these cells induces apoptotic cell death. This suggests that MMSET may be critical for growth and survival of myeloma cells. Profiling of gene expression changes in these systems should link the transcriptional and biological activities of MMSET.

Abstract Abstract 2847 Background and Purpose: Myelofibrosis (MF) is a progressive Philadelphia-negative myeloproliferative neoplasm characterized by debilitating symptoms, massive splenomegaly, and anemia, which severely impairs quality of life. When medical therapy is not effective or tolerated, splenectomy may be required to ease symptoms in patients with symptomatic portal hypertension, massive splenomegaly, and/or frequent red blood cell transfusions (Barbui et al. J Clin Oncol. 2011;29:761–770). In a recent study (Tefferi et al. Mayo Clin Proc. 2012;87:25–33) up to 27% of patients diagnosed with MF eventually underwent splenectomy. However, splenectomy is associated with limited duration of symptom response, high rates of perioperative morbidity and mortality, and acceleration of hepatomegaly. Clinical studies in patients with MF have demonstrated that ruxolitinib, an oral JAK1/JAK2 inhibitor, provides significant and durable reductions in splenomegaly, the burden of MF-associated symptoms, and also improved quality of life. In this post hoc analysis of pooled data from these studies, we determined the incidence of splenectomy in patients treated with ruxolitinib and those who received placebo or best available therapy (BAT) to evaluate whether ruxolitinib therapy may affect the need for splenectomy. Methods: This analysis included patients who participated in the ruxolitinib phase I/II trial (N=153; Verstovsek et al. N Engl J Med. 2010;363:1117–1127); COMFORT-I, a phase III, 24-month placebo-controlled trial of ruxolitinib (N=309; Verstovsek et al. N Engl J Med. 2012;366:799–807); and COMFORT-II, a phase III, 48-month randomized trial comparing the effects of ruxolitinib and BAT (N=219; Harrison et al. N Engl J Med. 2012;366:787–798). Incidence of splenectomy while on treatment or during the protocol-specified follow-up period, adjusted for differences in the duration of follow up, was calculated for patients on ruxolitinib, placebo, or BAT. Results: As a result of the crossover rules and a higher discontinuation rate on the comparator arms in the phase III studies, mean follow-up duration for placebo (0.67 years) or BAT (0.95 years) overall was substantially shorter than mean follow-up duration for ruxolitinib (1.78 years). Baseline characteristics of the 14 patients who underwent splenectomy were as follows: median age=63 years; median time since initial diagnosis=7.8 years; median spleen length (n=13): 17.0 cm (range: 0–28.0 cm); median spleen volume (in those with measurement, n=11)=2924 cm3 (range: 1203–6807 cm3); IPSS high risk=50%, intermediate-2 risk=43%, intermediate-1=7%. Among patients originally randomized and treated with ruxolitinib, the incidence of splenectomy was 1.1 events per 100 patient years (Table). For patients treated with placebo or BAT in the phase III studies, the incidence of splenectomy was approximately three times higher at 2.9 events per 100 patient years, despite the fact that patients on placebo or BAT were allowed to crossover to ruxolitinib if they had worsening symptomatic splenomegaly. Conclusions: Although limited by small numbers, results of this analysis suggest that ruxolitinib reduces the need for splenectomy in patients with MF. Because of crossover to ruxolitinib and higher discontinuation rates in placebo and BAT, follow-up duration was shorter in these treatment arms compared with ruxolitinib. Further, ruxolitinib treatment in crossover patients may have prevented progression of symptomatic splenomegaly in some patients who may have otherwise become candidates for splenectomy. Our analysis may underestimate the true incidence of splenectomy among patients not receiving ruxolitinib therapy and therefore, the relative reduction in splenectomy rate in patients receiving this therapy. Longer-term follow up will better define the splenectomy rate in ruxolitinib-treated patients. Disclosures: Verstovsek: Incyte Corporation: Research Funding. Kiladjian:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Shire: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding. Mesa:Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding. Vannucchi:Novartis: Membership on an entity's Board of Directors or advisory committees. Gotlib:Incyte Corporation: Consultancy, Honoraria, Support for travel to meeting for the study or other purposes from Incyte Other. Kantarjian:Incyte: grant support Other. Sirulnik:Novartis: Employment, Equity Ownership. Peng:Incyte Corporation: Employment, Equity Ownership. Sandor:Incyte Corporation: An employee of Incyte and receiving stock options as part of his compensation Other, Employment. Harrison:Novartis: Honoraria, Research Funding, Speakers Bureau; YM Bioscience: Consultancy, Honoraria; Sanofi Aventis: Honoraria; Shire: Honoraria, Research Funding.

SummaryPatients with myelofibrosis (MF) have significant debilitating symptoms, physical disabilities, and poor health‐related quality of life (HRQoL). Here, we report post‐hoc analyses of the impact of ruxolitinib, a potent and selective JAK1 and JAK2 inhibitor, on disease‐related symptoms and HRQoL in MF patients from the large phase 3 COMFORT‐II study (N = 219). During the follow‐up period of 48 weeks, HRQoL and MF‐associated symptoms improved from baseline for ruxolitinib‐treated patients but remained the same or worsened for best available therapy (BAT)‐treated patients. Based on the European Organization for Research and Treatment of Cancer QoL Questionnaire core 30 items (EORTC QLQ‐C30), treatment‐induced differences in physical and role functioning, fatigue, and appetite loss significantly favoured ruxolitinib versus BAT from week 8 (P < 0·05) up to week 48 (P < 0·05). Ruxolitinib resulted in significantly higher response rates in global health status/QoL and Functional Assessment of Cancer Therapy‐Lymphoma (FACT‐Lym) summary scores versus BAT at most time points (P < 0·05). Significant improvements in the Lymphoma subscale (including symptoms of pain, fever, itching, fatigue, weight loss, loss of appetite, and other patient concerns), FACT‐General, FACT‐Lym trial outcome index, and FACT‐Lym total were also observed with ruxolitinib versus BAT starting at week 8 and continuing thereafter. Overall, these data demonstrated that ruxolitinib improved HRQoL in MF patients and further support the use of ruxolitinib for the treatment of symptomatic MF.

Abstract MMSET, identified by its fusion to the IgH locus in t(4;14)-associated multiple myeloma, possesses domains found within chromatin regulators, including the SET domain. MMSET protein is overexpressed and highly associated with chromatin in myeloma cell lines carrying t(4;14). MMSET possesses methyltransferase activity for core histone H3 lysine 4 and histone 4 lysine 20, whereas MMSET made in cells only modified H4. Segments of MMSET fused to the Gal4 DNA binding domain repressed transcription of a chromatin-embedded Gal4 reporter gene. MMSET-mediated repression was associated with increased H4K20 methylation gene and loss of histone acetylation. Consistent with this repressive activity, MMSET could form a complex with HDAC1 and HDAC2, mSin3a, and the histone demethylase LSD1, suggesting that it is a component of corepressor complexes. Furthermore, MMSET coexpression enhances HDAC1- and HDAC2-mediated repression in transcriptional reporter assays. Finally, shRNA-mediated knockdown of MMSET compromised viability of a myeloma cell line, suggesting a biologic role for the protein in malignant cell growth. Collectively, these data suggest that, by acting directly as a modifier of chromatin as well as through binding of other chromatin-modifying enzymes, MMSET influences gene expression and potentially acts as a pathogenic agent in multiple myeloma.