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Background: Progress in genome technology allows analysis of previously completed trials to identify subgroups potentially benefiting from therapy. Enzastaurin is a potent inhibitor of protein kinase C beta (PKC-β) and suppresses the phosphoinositide 3-kinase (PI3K)/AKT pathway. The safety and efficacy of Enzastaurin has been tested in more than 60 clinical trials including 2 major studies in DLBCL: (1) PRELUDE (A phase III maintenance trial of Enzastaurin vs Placebo, N=758) (Crump, 2016), and (2) S028 (A randomized phase II study of Enzastaurin/R-CHOP vs R-CHOP in frontline intermediate/high-risk DLBCL, N=101) (Hainsworth, 2016). DNA samples extracted from blood of patients from PRELUDE were retrospectively genotyped using whole genome SNP arrays. From the genome wide screening a novel genetic biomarker, DGM1, was identified showing high correlation with response to Enzastaurin treatment (Luo, ASH 2018). Importantly, these findings were replicated in the phase II S028 study. In the S028 study the hazard ratio (HR) for OS in high-risk (IPI ≥ 3) DGM1 positive (+) patients who received Enzastaurin/R-CHOP was 0.28 (0.1-0.81) when compared to subjects who received R-CHOP, a benefit favoring Enzastaurin (p=0.018). These data suggest that addition of Enzastaurin to R-CHOP may significantly improve outcome in frontline high-risk DGM1 (+) DLBCL. The ENGINE study was initiated to validate this finding in a prospective study. Study Design and Methods: Adult patients must have untreated CD20+ DLBCL, IPI ≥ 3. Patients are randomized 1:1 to Enzastaurin/R-CHOP or Placebo/R-CHOP for 6 cycles during combination phase. Each subject's treatment assignment will be unblinded after response assessment at the end of the combination phase. Subjects randomized to the investigational arm who have a complete or partial response will have the option to continue in the single agent phase to receive Enzastaurin for up to 2 additional years. The study intends to enroll approximately 235 patients with primary endpoint of OS in DGM1 (+) patients. The study is ongoing with 57 sites open in the US and China. As of 20 July 2019, 128 patients have been randomized. Clinical trial information: NCT03263026. Disclosures Nowakowski: Genentech, Inc.: Research Funding; Curis: Research Funding; Bayer: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; F. Hoffmann-La Roche Ltd: Research Funding; Selvita: Membership on an entity's Board of Directors or advisory committees; NanoString: Research Funding; MorphoSys: Consultancy, Research Funding. Brody:Acerta Pharma: Research Funding; Merck: Research Funding; Celldex Therapeutics: Research Funding; Genentech: Research Funding; Oncovir, Inc.: Research Funding; BMS: Research Funding; Kite Pharma: Research Funding. Lue:Kymera Therapeutics: Honoraria; Astex Pharmaceuticals: Honoraria. Luo:Denovo Biopharma LLC: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Zhang:Denovo Biopharma LLC: Employment. Han:Denovo Biopharma LLC: Employment. Jivani:TRACON Pharmaceuticals, Inc.: Other: Stock; Denovo Biopharma LLC: Employment. Liu:Denovo Biopharma LLC: Employment. Li:Denovo Biopharma LLC: Employment. Sun:Novartis: Other: Stock; Denovo Biopharma LLC: Employment.

Abstract Background: Synthetic lethality (SL) is characterized by the chemical inhibition of multiple aberrant genes to differentially kill malignant cells. We investigated small-molecule combinations for SL through in vitro and in vivo screening and optimization studies (as in the granted patents in USA and China) and demonstrated the synergistic potential of best-in-class combinations of targeted agents, drug repositioning, immune modulation and low-dose combinations. We hypothesize that BTK and mTOR inhibition coupled with an IMID will target multiple key signaling pathways, improve differential apoptosis and target acquired drug resistance. DTRM-555, an optimized mechanism-based combination, consists of the clinically differentiated BTK inhibitor DTRMWXHS-12 (or DTRM-12), everolimus (EV) and pomalidomide (POM). In xenograft tumor models, DTRM-555 administered orally has demonstrated superior efficacy over monotherapy at very low dose combinations of the three agents (1/18 of DTRM-12, 1/6 of EV, and 1/6 of POM). DTRM-12 monotherapy has been safe and well tolerated in simultaneous phase Ia trials (US and China) with preliminary efficacy across 50 mg through 400 mg once daily (QD). Here we report the US clinical results of the oral combination therapies DTRM-505 (DTRM-12 plus EV) and DTRM-555 (DTRM-12 plus EV plus POM) for the first time (NCT02900716). Methods: The safety and anti-tumor activity of the oral doublet therapy DTRM-505 and the oral triplet therapy DTRM-555 are evaluated using a "3+3" study design. Enrollment was conducted concurrently with a phase Ia study of DTRM-12 monotherapy; with DTRM-505 opened for accrual when monotherapy DTRM-12 cleared the 200-mg dose level. Eligible patients are at least 18 years old, having ECOG performance status less than 2 with relapsed/refractory chronic lymphocytic leukemia (CLL), diffuse large B cell lymphoma (DLBCL), mantle cell lymphoma (MCL), follicular lymphoma (FL) or classical Hodgkin lymphoma (cHL). Study treatment is administered daily for 21 consecutive days over a 28-day cycle. The dose-limiting toxicity (DLT) period was defined during the first cycle of therapy, and treatment was continued until disease progression or unacceptable toxicity. Patients underwent tumor evaluations every 2 months and response was recorded using revised response criteria (IWCLL and Cheson 2014). Results: Between 9/2016 and 7/2018, 19 patients have been treated with DTRM-12 monotherapy in the USA (6 pts, 50-300 mg) and China (13 pts, 50-400 mg). Patients have tolerated up to 23+ cycles of DTRM-12 monotherapy. Seven patients, including DLBCL, CLL, MCL, FL and cHL, have been treated with oral doublet therapy DTRM-505 for 2 to 12 cycles. Three patients (2 DLBCL, 1 FL) have been treated with oral triplet therapy DTRM-555, including one patient transitioned from the doublet DTRM-505 under an exploratory arm. No patient has discontinued due to an adverse event (AE) and no DLT has occurred. Recurring AEs are mostly grade 1 or 2 and responses have been seen with DTRM-505 and DTRM-555 across diverse lymphoma histologies (See Tables). All patients evaluable for response demonstrated partial response to DTRM-505 and DTRM-555, with 2/7 (doublet) and 3/3 (triplet) patients remaining on therapy. Conclusion: The maximum tolerated dose has not been reached for DTRM-12 monotherapy and for the current fixed dose doublet and triplet combinations. Toxicities have been mild and repeated cycles of study treatment have been well tolerated without delays of subsequent treatment cycles. Enrollment continues for refractory lymphoma patients to demonstrate the safety and efficacy for the first-in-class oral triplet therapy DTRM-555. Disclosures Huntington: Janssen: Consultancy; Bayer: Consultancy; Celgene: Consultancy. Schuster:Merck: Consultancy, Honoraria, Research Funding; Genentech: Honoraria, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; OncLive: Honoraria; Dava Oncology: Consultancy, Honoraria; Physician's Education Source, LLC: Honoraria; Nordic Nanovector: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Pharmaceuticals Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees. He:Zhejiang DTRM Biopharma Co. Ltd.: Other: Founder and CEO; Zhejiang DTRM Biopharma LLC: Other: Founder and CEO. Shen:Zhejiang DTRM Biopharma LLC: Other: Clinical Operations Director. Kennard:AbbVie, Gilead, Verastem: Consultancy. Dwivedy Nasta:Incyte: Research Funding; Takeda/Millenium: Research Funding; Debiopharm: Research Funding; Pharmacyclics: Research Funding; Rafael/WF: Research Funding; Aileron: Research Funding; Roche: Research Funding; Merck: Other: DSMC; Celgene: Membership on an entity's Board of Directors or advisory committees. Landsburg:Takeda: Consultancy; Curis: Consultancy, Research Funding. Porter:Novartis: Other: Advisory board, Patents & Royalties, Research Funding; Genentech: Other: Spouse employment; Kite Pharma: Other: Advisory board. Svoboda:Bristol-Myers Squibb: Consultancy, Research Funding; TG Therapeutics: Research Funding; Kyowa: Consultancy; Regeneron: Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; KITE: Consultancy. Song:Peking University Cancer Hospital (Beijing Cancer Hospital): Employment. Zhu:Beijing Cancer Hospital: Employment. Brander:Pharmacyclics, an AbbVie Company: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; TG Therapeutics: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Novartis: Consultancy, Other: DSMB; Genentech: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Teva: Consultancy, Honoraria; Acerta: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; DTRM: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; BeiGene: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding. Ding:Merck: Research Funding. Mato:Pharmacyclics, an AbbVie Company: Consultancy, Research Funding; AstraZeneca: Consultancy; Regeneron: Research Funding; Celgene: Consultancy; Acerta: Research Funding; TG Therapeutics: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Portola: Research Funding; Johnson & Johnson: Consultancy; Prime Oncology: Honoraria; Medscape: Honoraria.

Abstract Background: Indolent non-Hodgkin lymphoma (iNHL), including follicular lymphoma (FL) and marginal zone lymphoma (MZL), is typically responsive to initial chemoimmunotherapy, but relapse is expected. Single-agent rituximab is FDA approved and frequently administered for patients with relapsed/refractory (R/R) low-grade or follicular CD20-positive B-cell NHL. Lenalidomide is an immunomodulatory agent with preclinical and clinical antilymphoma activity alone and in combination with rituximab. We compared the efficacy and safety of lenalidomide plus rituximab (R2) to rituximab (plus placebo) in patients with R/R iNHL. Methods: AUGMENT (NCT01938001) is a multicenter, double-blind, randomized phase III study of R2 vs rituximab/placebo (control) in patients with FL grade 1-3a or MZL who were previously treated with ≥ 1 prior systemic therapy with documented relapsed or refractory disease but not refractory to rituximab (refractory was defined as < partial response to rituximab or rituximab-chemotherapy OR disease progression < 6 months after last rituximab dose). Patients were stratified by prior rituximab treatment (yes vs no), time since last antilymphoma therapy (≤ 2 vs > 2 years), and histology (FL vs MZL), and then randomized 1:1 to R2 or control for up to 1 year. R2 patients received oral lenalidomide 20 mg/day (d), d1-21/28 for 12 cycles plus rituximab IV 375 mg/m2 weekly in cycle 1 and d1 of cycles 2-5. Control patients received rituximab and placebo on the same schedule. Dose modifications were pre-specified in the protocol to manage toxicities. The primary endpoint was progression-free survival (PFS) per 2007 IWG criteria without PET as assessed by Independent Review Committee (IRC; central review). Secondary endpoints included overall response rate (ORR), complete response (CR), duration of response (DOR), time-to-next antilymphoma treatment (TTNLT), overall survival (OS), and safety. Results: A total of 358 patients were randomized (n = 178 R2; n = 180 control), median age was 63 years (range, 26 - 88), 34% FLIPI score ≥ 3, and histologies of 82% FL/18% MZL. Median number of prior systemic treatments was 1 (range, 1 - 12); 84% received prior rituximab and 51% had prior antilymphoma therapy within 2 years of enrollment. At median follow-up of 28.3 months, the study met its primary endpoint of PFS with HR = 0.46 (95% CI, 0.34 - 0.62; P < 0.0001) (Figure 1). Median PFS was 39.4 months for R2 vs 14.1 months for control. IRC-assessed ORR for R2 was 78% vs 53% for control (P < 0.0001). CR was 34% for R2 vs 18% for control (P = 0.001). Median DOR was 36.6 and 21.7 months for R2 and control arms, respectively. TTNLT was improved for R2 vs control with HR = 0.54 (95% CI, 0.38 - 0.78; P = 0.0007). OS data were not mature with 16 deaths reported in the R2 arm vs 26 deaths in control (HR = 0.61 [95% CI, 0.33 - 1.13]). Selected all-grade treatment-emergent adverse events (TEAEs) of interest more common in the R2 vs control arm (≥ 10% difference) were infections (63% vs 49%), cutaneous reactions (32% vs 12%), constipation (26% vs 14%), thrombocytopenia (15% vs 4%), and tumor flare reaction (11% vs 1%). Grade 3/4 TEAEs were reported in 69% R2 and 32% control patients. More frequent grade 3/4 TEAEs in the R2 vs control arm were primarily attributable to increased neutropenia (50% vs 13%) and leukopenia (7% vs 2%). Grade 5 TEAEs were reported in 2 patients in each arm. TEAEs leading to discontinuation of lenalidomide occurred in 9% of patients vs 5% for rituximab + placebo. Neutropenia was the only TEAE leading to discontinuation of lenalidomide in > 1 patient (n = 5). Seventy-one percent of R2 patients completed all 12 cycles of planned treatment vs 61% of control. Disease progression was the leading reason for discontinuation of lenalidomide/placebo (n = 21 R2, n = 54 control). Conclusions: R2 demonstrated superior efficacy over rituximab monotherapy (plus placebo) as measured by the primary endpoint of progression-free survival as well as secondary endpoints of ORR, CR, DOR, and TTNLT in patients with R/R FL grade 1-3a and MZL. At this early analysis, fewer deaths have been observed in the R2 arm. Despite additional hematologic toxicity, greater efficacy of the R2 regimen (and fewer early progressions) allowed more patients to complete the planned therapy and delayed the need for subsequent treatment. R2 represents an important new treatment option in patients with previously treated FL/MZL, with meaningful advantages over single-agent rituximab. Disclosures Leonard: Celgene: Consultancy; Karyopharm: Consultancy; ADC Therapeutics: Consultancy; MEI Pharma: Consultancy; Juno: Consultancy; Bayer: Consultancy; AstraZeneca: Consultancy; Sutro: Consultancy; Biotest: Consultancy; United Therapeutics: Consultancy; Pfizer: Consultancy; Novartis: Consultancy; Genentech/Roche: Consultancy; Gilead: Consultancy; BMS: Consultancy. Trněný:F. Hoffman-La Roche Ltd: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory board, Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Other: Advisory board; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory board; Abbvie: Honoraria, Research Funding; Gilead: Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Advisory board; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory board; Morphosys: Membership on an entity's Board of Directors or advisory committees, Other: Advisory board; Sandoz: Honoraria. Izutsu:Otsuka: Honoraria; Bristol- Myers Squibb: Honoraria; Nihon Medi-Physics: Honoraria; Novartis: Honoraria; Mundhi: Honoraria; HUYA Bioscience International: Research Funding; Kyowa Hakko Kirin: Honoraria; Takeda: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Amgen: Research Funding; Bayer: Consultancy, Honoraria, Research Funding; Gilead Sciences: Honoraria; Eisai: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Astellas: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Zenyaku: Research Funding; Celltrion: Research Funding; MSD: Honoraria; Ono: Honoraria, Research Funding; Symbio: Research Funding; Celgene: Consultancy, Research Funding; Solasia: Research Funding; Sanofi: Research Funding; Meiji Seika: Honoraria; Shionogi: Honoraria; Asahi Kasei: Honoraria. Fowler:Janssen: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding. Zhu:Beijing Cancer Hospital (Peking University Cancer Hospital): Employment. Scheliga:INCA - Instituto Nacional Do Cancer, Brazil: Employment. Pinto:Servier: Consultancy; BMS: Honoraria, Research Funding; MSD: Honoraria; Roche: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Gilead: Honoraria. Scheinberg:Novartis: Consultancy, Speakers Bureau; Janssen: Honoraria, Research Funding; Pfizer: Speakers Bureau. Flinn:Trillium: Research Funding; Takeda: Research Funding; Calithera: Research Funding; Incyte: Research Funding; Verastem: Research Funding; ArQule: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding; Forty Seven: Research Funding; Agios: Research Funding; BeiGene: Research Funding; Kite: Research Funding; Portola: Research Funding; Verastem: Consultancy, Research Funding; Celgene: Research Funding; Pfizer: Research Funding; Forma: Research Funding; Merck: Research Funding; Novartis: Research Funding; Constellation: Research Funding; Curis: Research Funding; Infinity: Research Funding; TG Therapeutics: Research Funding; Genentech: Research Funding; Gilead: Research Funding. Moreira:Instituto Português de Oncologia do Porto FG, EPE, Porto, Portugal: Employment. Liu:Celgene: Employment, Equity Ownership. Kalambakas:Celgene: Employment, Equity Ownership. Fustier:Celgene: Employment, Equity Ownership. Wu:Celgene: Employment, Equity Ownership. Gribben:Cancer Research UK: Research Funding; Unum: Equity Ownership; Novartis: Honoraria; Abbvie: Honoraria; Wellcome Trust: Research Funding; Acerta Pharma: Honoraria, Research Funding; Kite: Honoraria; NIH: Research Funding; Roche: Honoraria; Janssen: Honoraria, Research Funding; Medical Research Council: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; TG Therapeutics: Honoraria; Pharmacyclics: Honoraria.

Abstract Background Despite improvements in outcome following the addition of rituximab (R) to CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) (R-CHOP), patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) and International Prognostic Index (IPI) scores of 3-5 at diagnosis have a poor outcome. Enzastaurin is a potent inhibitor of PKCβ, a component of the B-cell receptor signaling complex, with preclinical activity and clinical activity in a phase II trial in patients with relapsed DLBCL, providing the rationale for this study in the primary therapy setting. Methods PRELUDE was a multi-national, randomized, double-blinded, placebo-controlled study. Patients were required to have a histologic diagnosis of DLBCL, pre-treatment IPI score ≥3, and a complete response (CR) or CRu by International Working Group Criteria, or a negative FDG-PET scan after 6–8 cycles of R-CHOP. Patients were randomly assigned in a 2:1 ratio to receive either enzastaurin 500 mg daily or an identical placebo as maintenance therapy, for a planned treatment duration of 3 years. The primary endpoint was DFS, defined as lack of disease progression or death. Assuming a 2-year DFS rate in the control group of 70%, the primary analysis had 80% power to detect a HR of 0.67, eg, a 2-year DFS rate of 79% in the enzastaurin group. Secondary endpoints included overall survival (OS) and event-free survival (EFS). Data were analyzed 3 years after the last enrolled patient initiated treatment. Results From May 2006–April 2010, 758 patients were enrolled (enzastaurin, n=504; placebo, n=254). Median age at enrollment was 64 years (range 21-89); at diagnosis, 65% of patients had stage IV disease, 48% had B symptoms, and 25% had a mass >10 cm; baseline disease and patient characteristics were well balanced between treatment arms. Fifty-seven percent had a negative PET scan following completion of R-CHOP. Median follow-up time for all patients was 48 months (range 0.03–80). At the time of analysis, 209 events had occurred. The DFS HR for enzastaurin vs. placebo was 0.92 (95% CI: 0.69, 1.22; 2-sided log-rank p=0.54). DFS at 24 and 48 months were 79% and 70% for the enzastaurin arm, and 75% and 71% for placebo, respectively. OS at 24 and 48 months was 87% and 81% for enzastaurin, and 89% and 82% for placebo; HR for enzastaurin vs. placebo was 1.04 (95% CI: 0.74, 1.47; 2-sided log-rank p=0.81). Percent of ITT population patients on therapy at 12, 24, and 36 months was 70.6%, 60.6%, and 20.1% for enzastaurin; 72.3%, 60.6%, and 22.1% for placebo. Biomarker subgroup analysis was performed and will be available at time of presentation. Treatment emergent AEs (all grades) that were possibly study drug-related and significantly different between enzastaurin and placebo included chromaturia (18.5% vs. 0.4%), QTc prolongation (10.8% vs. 3.6%), and diarrhea (10.3% vs. 2.8%). There were no significant differences in number of patients with at least 1 grade 3 or higher AE between treatment arms. No significant differences were observed in the frequency of deaths while on therapy. Conclusion Enzastaurin did not improve DFS, EFS, or OS in patients with high-risk DLBCL and CR following R-CHOP treatment. Disclosures: Crump: Roche: Honoraria; Jansen-Ortho: Honoraria; Celgene: Honoraria; Lundbeck: Honoraria; Novartis: Research Funding; Seattle Genetics: Honoraria. Off Label Use: rituximab for maintenance therapy post autolgous transplant for lymphoma. Leppä:Eli Lilly: Research Funding. Ogura:Eli Lilly: Research Funding. Rifkin:Millenium, Celgene, ONYX: Membership on an entity’s Board of Directors or advisory committees. Mackensen:Eli Lilly: Consultancy. Offner:Eli Lilly: Membership on an entity’s Board of Directors or advisory committees. Smith:Genentech, Celgene, Spectrum, Seattle Genetics, Gilead, Amgen/Micronet: Consultancy. Tobinai:Eli Lilly: Research Funding. Hahka-Kemppinen:Eli Lilly: Employment. Thornton:Eli Lilly: Employment. Shi:Eli Lilly: Employment. Lin:Eli Lilly: Employment. Kahl:Genentech: Consultancy. Savage:Eli Lilly: Consultancy.

PURPOSEPatients with indolent non-Hodgkin lymphoma typically respond well to first-line immunochemotherapy. At relapse, single-agent rituximab is commonly administered. Data suggest the immunomodulatory agent lenalidomide could increase the activity of rituximab.METHODSA phase III, multicenter, randomized trial of lenalidomide plus rituximab versus placebo plus rituximab was conducted in patients with relapsed and/or refractory follicular or marginal zone lymphoma. Patients received lenalidomide or placebo for 12 cycles plus rituximab once per week for 4 weeks in cycle 1 and day 1 of cycles 2 through 5. The primary end point was progression-free survival per independent radiology review.RESULTSA total of 358 patients were randomly assigned to lenalidomide plus rituximab (n = 178) or placebo plus rituximab (n = 180). Infections (63% v 49%), neutropenia (58% v 23%), and cutaneous reactions (32% v 12%) were more common with lenalidomide plus rituximab. Grade 3 or 4 neutropenia (50% v 13%) and leukopenia (7% v 2%) were higher with lenalidomide plus rituximab; no other grade 3 or 4 adverse event differed by 5% or more between groups. Progression-free survival was significantly improved for lenalidomide plus rituximab versus placebo plus rituximab, with a hazard ratio of 0.46 (95% CI, 0.34 to 0.62; P < .001) and median duration of 39.4 months (95% CI, 22.9 months to not reached) versus 14.1 months (95% CI, 11.4 to 16.7 months), respectively.CONCLUSIONLenalidomide improved efficacy of rituximab in patients with recurrent indolent lymphoma, with an acceptable safety profile.

Background— Apixaban is approved for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. However, the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial included a substantial number of patients with valvular heart disease and only excluded patients with clinically significant mitral stenosis or mechanical prosthetic heart valves. Methods and Results— We compared the effect of apixaban and warfarin on rates of stroke or systemic embolism, major bleeding, and death in patients with and without moderate or severe valvular heart disease using Cox proportional hazards modeling. Of the 18 201 patients enrolled in ARISTOTLE, 4808 (26.4%) had a history of moderate or severe valvular heart disease or previous valve surgery. Patients with valvular heart disease had higher rates of stroke or systemic embolism and bleeding than patients without valvular heart disease. There was no evidence of a differential effect of apixaban over warfarin in patients with and without valvular heart disease in reducing stroke and systemic embolism (hazard ratio [HR], 0.70; 95% confidence interval [CI], 0.51–0.97 and HR, 0.84; 95%, CI 0.67–1.04; interaction P =0.38), causing less major bleeding (HR, 0.79; 95% CI, 0.61–1.04 and HR, 0.65; 95% CI, 0.55–0.77; interaction P =0.23), and reducing mortality (HR, 1.01; 95% CI, 0.84–1.22 and HR, 0.84; 95% CI, 0.73–0.96; interaction P =0.10). Conclusions— More than a quarter of the patients in ARISTOTLE with nonvalvular atrial fibrillation had moderate or severe valvular heart disease. There was no evidence of a differential effect of apixaban over warfarin in reducing stroke or systemic embolism, causing less bleeding, and reducing death in patients with and without valvular heart disease. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00412984.