Citations

Abstract Background: It has been known for approximately 19 years that germline mutations in RUNX1, lead to familial platelet disorder with predisposition to myeloid malignancy (FPD-MM, OMIM 601399). Since that time researchers have identified a broad range of different RUNX1 mutations, in over 100 families. In large families, the diagnosis of malignancy shows variable penetrance among family members with the same mutation; some carriers of RUNX1 mutations do not develop malignancy. The causes of this heterogeneity are currently not known, complicating counselling and risk analysis for individual carriers. Recent advances in genetic sequencing technology applied by many FPD-MM research groups around the world have highlighted their value in understanding the somatic genetic changes that are associated with development of malignancies in germline RUNX1 mutation carriers. Collectively this information could lead to powerful insights essential for more precise risk assessment, monitoring, and therapeutic intervention. Specifically, a growing catalogue of somatic mutations associated with germline RUNX1 malignancy offers the opportunity for informed monitoring of asymptomatic RUNX1 carriers for additional high-risk somatic mutations, in turn providing the possibility for early therapeutic intervention to arrest the leukemic process. The challenge in advancing these goals for FPD-MM is the relative rarity of the disorder in individual populations. Global data sharing in a highly interactive FPD-MM research community offers a solution to this problem that benefits all patients world-wide. Aims: To create a global RUNX1 network through identifying and contacting researchers and clinicians with known and novel germline RUNX1 families, seeking their collaboration to share genomics data. To create a RUNX1.db portal to collectively house and analyse genomics data from germline RUNX1 carriers, with associated phenotype and clinical information, such that researchers have an ongoing means by which to combine their data with those generated by other groups around the world. Methods: RUNX1 network : Through existing collaborative networks, a systematic review of the literature, and referrals from initial contacts, we have identified a global network of researchers managing FPD-MM cases and families. RUNX1.db: We have adapted a custom-built variant analysis platform, VariantGrid, that is a visual web application and database designed to help scientists manage and analyse DNA variants that can be used to aggregate and analyse multiple datasets. Results: Preliminary analysis of aggregated data from the literature suggests there are features of germline RUNX1 syndrome that can be ascertained. These include frequent somatic mutation of RUNX1 in malignancy development, as well as mutations in genes associated with clonal hematopoiesis that may precede development of overt leukemia. This analysis also suggests that different types of germline RUNX1 mutations may be associated with different combinations of somatic mutations in the tumour. To further this analysis, we have identified over 70 groups internationally that either manage RUNX1 families or have identified potential germline carriers through genomics initiatives. This represents a large and growing resource for both scientific studies and clinical programs to benefit individuals with FPD-MM. Many of these groups have generated NGS data sets from patient samples which will be available for analysis through this portal. Further details and activities of the network, and results from the genomics aggregation database will be presented. Conclusion: We have created a global RUNX1 network, aggregated their data, and generated a RUNX1.db genomics portal for the continuous curation of genomics data from germline RUNX1 carriers. A preliminary analysis has already identified specific features of germline RUNX1 mutated malignancies that have clinical importance. Ongoing scientific and clinical studies through the RUNX1 network will enhance the power of aggregated data analysis, with RUNX1.db providing a central link, driving new insights that benefit patients. Disclosures Natsoulis: Imago BioSciences, Inc.: Consultancy, Equity Ownership. Guzman:Cellectis: Research Funding. DiNardo:Bayer: Honoraria; Karyopharm: Honoraria; Celgene: Honoraria; Agios: Consultancy; Medimmune: Honoraria; Abbvie: Honoraria. Borate:Novartis: Consultancy; Agios: Consultancy. Wei:Amgen: Honoraria, Other: Advisory committee, Research Funding; Pfizer: Honoraria, Other: Advisory committee; Celgene: Honoraria, Other: Advisory committee, Research Funding; Abbvie: Honoraria, Other: Advisory board, Research Funding, Speakers Bureau; Servier: Consultancy, Honoraria, Other: Advisory committee, Research Funding; Novartis: Honoraria, Other: Advisory committee, Research Funding, Speakers Bureau. Dokal:MRC, Bloodwise, Telomerase Activator Sciences: Research Funding; The Gary Woodward Dyskeratosis Congenita Trust: Membership on an entity's Board of Directors or advisory committees; Action Medical Research, European School of Haematology: Membership on an entity's Board of Directors or advisory committees; Barts and The London School of Medicine and Dentistry, Queen Mary University of London,: Employment, Research Funding; Telomerase Activator Sciences: Research Funding; Barts and The London, Queen Mary University of London: Employment; Gary Woodward Dyskeratois Congenita Trust: Membership on an entity's Board of Directors or advisory committees. Hiwase:Novartis: Research Funding; Celgene: Research Funding. Branford:Cepheid: Honoraria; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Qiagen: 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, Research Funding, Speakers Bureau. Kramer:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Research Funding; Daiichi Sankyo: Consultancy. Owen:Merck: Honoraria; Teva: Honoraria; AbbVie: Research Funding; Pharmacyclics: Research Funding; Janssen: Honoraria, Research Funding; Celgene: Research Funding; AstraZeneca: Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Honoraria, Research Funding. Fitzgibbon:Epizyme: Consultancy, Research Funding; Gilead: Consultancy. Rienhoff:Imago BioSciences, Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Kurokawa:Astellas Pharma: Research Funding; Sumitomo Dainippon Pharma: Research Funding; Nippon Sinyaku: Honoraria, Research Funding; Kyowa Hakko Kirin: Honoraria, Research Funding; Eizai: Research Funding; MSD: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Pfizer: Research Funding; Takeda Pharmaceutical: Research Funding; Otsuka Pharmaceutical: Research Funding; Teijin Pharma: Research Funding; Chugai Pharmaceutical: Research Funding.

Abstract The current view is that treatment failures of AML patients are due to persistence of leukemia stem cells (LSCs). The presence of FMS-like tyrosine kinase-3 (FLT3) Internal tandem duplication (ITD) is associated with poor prognosis. But, FLT3 tyrosine kinase inhibitors (TKI) demonstrate transient clinical activity in FLT3-ITD+ AML patients. Persistent FLT3-ITD+ AML LSC represent a source of relapse. There is a pressing need to target LSC and improve outcomes for FLT3-ITD+ AML patients. PRMT1, the predominant arginine methyltransferase, has been implicated in pathogenesis of AML rare subtype (i.e., acute megakaryoblastic leukemia). Herein, we show that PRMT1 protein expression is significantly increased in LSC-enriched AML CD34+CD38- cells relative to the counterparts of normal peripheral blood stem cells (PBSC) (AML n=9, normal n=8, p=0.0004,). Following PRMT1-knockdown (KD), AML CD34+ cells (n=15) demonstrated varying degrees of apoptosis while the survival of normal cells were not affected. Interestingly, we observed significant apoptosis-induction in a subset of samples bearing FLT3-ITD mutation (6 out of total 15) upon PRMT1-KD (ShCtrl 13.9±3.6%, ShPRMT1 32.5±4.6%, p<0.001). PRMT1-KD induced apoptosis was also more evident in cord blood (CB) CD34+ cells expressing FLT3-ITD (ShCtrl 19.4±1.3%, ShPRMT1 45.2±2.5%, p<0.001) relative to that of FLT3-WT (ShCtrl 27.47±1.8%, ShPRMT1 36.9±1.6%, p=0.0167). In 293T cells ectopically overexpressing FLT3-WT or FLT3-ITD, co-immunoprecipitation (co-IP) indicated greater interaction between PRMT1 and FLT3-ITD. Through RNA-Seq profiling two AML lines (MV4-11, OCI-AML3) plus one FLT3-ITD transduced CB CD34+ cells with PRMT1-KD, we obtained a differentially-regulated gene set as a "PRMT1 signature". This signature was enriched in FLT3-ITD+ AML relative to FLT3-WT AML according to ssGSEA analysis using two AML datasets (GSE14468, GSE10358), indicating PRMT1 may cooperate with FLT3-ITD regulating AML maintenance. Given that PRMT1 directly interacts with FLT3-ITD, we next asked whether PRMT1 catalyzes FLT3-ITD protein methylation. Through mass-spectrometry analysis of a FLT3-ITD+ AML specimen and in vitro methylation assay, we identified that PRMT1 catalyzes FLT3-ITD arginine (R) methylation (Me) at two conserved residues, 972 and 973. Using in-house R972/973 Me antibody, we validated the expression of FLT3 R-Me in FLT3-ITD AML speciemens (7 out of 7). To test R-Me function, we transduced MLL-AF9 (MA9) overexpressing murine c-Kit+ cells with methylation-deficient FLT3-ITD (R972/973K, arginine [R] to lysine [K]) construct, and found that MA9 cells expressing R972/973K underwent more apoptosis than that of WT FLT3-ITD (WT FLT3-ITD 9.7±1.1%, R972/973K 23.7±2.1%, p=0.003). The double transformed cells were further transplanted into recipients for leukemia development. Mice receiving MA9 cells expressing R972/973K exhibited longer survival (median survival: WT FLT3-ITD 36 days, R972/973K 50 days, p=0.002, n=6). Mechanistically, expression of R972/973K did not affect the total tyrosine phosphorylation level of FLT3-ITD. Additionally, FLT3-ITD R-Me expression persisted after a TKI (AC220) treatment. These facts indicated that FLT3-ITD R-Me function is independent of FLT3-ITD kinase activity. We then used a FLT3-ITD+ patient derived xenograft (PDX) model to assess the effects of TKI and PRMT1 inhibition. Following engraftment >1% in peripheral blood, we divided mice (n=24) into 4 groups and treated each with vehicle, MS023 (a type I PRMT inhibitor, ACS Chem Biol. 2016;11:772-781) (160 mg/kg/i.p), AC220 (10 mg/kg/i.g) or combination for 4 weeks. MS023 treatment downregulating FLT3 R-Me levels enhanced elimination of FLT3-ITD AML cells by AC220 treatment (AC220 24.6±13.4% vs combination 7.6±6.5%, p=0.02, n=6). At 16 weeks post-secondary BMT, significant AML burden in single drug treated transplants was observed, but less AML cells were detected in combination-treated transplants (AC220 52.3%, vs combination 25.4%, p<0.001, n=6). MS023 had little effect on long-term in vivo engraftment of CD34+ from a human CB specimen (vehicle 76.3±5.9%, MS023 72.2±3.4%, p=0.21, n=5). In summary, our study demonstrated PRMT1 overexpression contributes to AML stem/progenitor cell survival possibly through FLT3-ITD methylation, supporting further exploration into how PRMT1-mediated FLT3 methylation governs LSC survival. Disclosures Khaled: Alexion: Consultancy, Speakers Bureau; Daiichi: Consultancy; Juno: Other: Travel Funding.

PurposeTo clinically implement and comprehensively evaluate two independent methods for beam monitor calibration of scanning proton beam.MethodsSeven proton energies that represent the lowest to highest energy proton beams were selected. Single energy layer circular fields of diameter 15 cm with 2.5 mm spot spacing and 10 times of repainting (FS15cm) were designed for all energies. The effective measurement points of Bragg peak chamber (BPC), advanced Markus chamber (AMC) and farmer chamber (FC) were all aligned to 2 cm depth in water using SSD setup. The BPC and AMC were cross‐calibrated with farmer chamber (FC) using the field FS15cm. In order to evaluate BPC's lateral response uniformity, a collimated narrow proton beam (5.8 mm diameter) was delivered to the active area and edge of the BPC. The dose area product (DAP) was measured using two methods by two BPCs, one AMC and one FC. For method 1, a single spot proton beam was delivered to the geometric center of the BPC. For method 2, the fields FS15cm were delivered to FC and AMC, respectively. Accumulated charges by these chambers were converted to DAPs, and the quantitative difference of DAPs between both methods was calculated. The causes of the uncertainties were discussed, and the advantages of the two methods were compared.ResultsThe two BPCs showed different lateral response uniformity. BPC1 has a uniform response from the center up to a radius of 3.5 cm. BPC2 has a uniform response only to 2 cm and the response dropped 1% to 2% at 3.5 cm from center. BPC2 also has significant over‐response compared to BPC1. A 2.2% systematic error would be transferred to DAP if the over‐response from BPC2 was not considered. The DAPs measured by method 1 with two BPCs and by method 2 with FC and AMC were consistent to 0.5%. The major uncertainty component of method 1 is from the cross‐calibration of the BPC.ConclusionsThe two independent methods for DAP were shown to give consistent results, given the sources of uncertainties were carefully addressed in the measurements. Direct measurement of DAP with BPC is very efficient, but it may be subject to more than 2% systematic error if the BPC lateral response is not carefully evaluated.

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. Many children and adults with acute myeloid leukemia (AML) relapse or are incurable with current treatment modalities, highlighting a need for alternative therapies. Chimeric antigen receptor (CAR) T cells targeting CD123 have demonstrated potent anti-leukemia activity in murine xenograft models of human AML. However, CD123-redirected T cell treatment of mice engrafted with normal human hematopoietic cells resulted in profound myeloablation, raising concerns for hematologic toxicity in patients with AML who may be treated with such therapies. We hypothesized that T cell deletion after CD123-redirected T cell-induced eradication of AML could minimize this bystander toxicity without impairing leukemia control, thereby increasing the therapeutic window of anti-AML CAR T cell immunotherapy. Methods. To test this hypothesis, we compared three termination strategies in human AML xenograft models: (1) T cell ablation with the anti-CD52 antibody alemtuzumab after treatment with T cells lentivirally-transduced with anti-CD123-41BB-CD3ζ (CART123), (2) T cell ablation with the anti-CD20 antibody rituximab after treatment with CART123 engineered to co-express CD20 (CART123/CD20), and (3) treatment with "biodegradable" anti-CD123 mRNA-electroporated CAR T cells (RNA-CART123). Mice engrafted with luciferase-expressing human AML cell lines (MOLM14, MOLM13, U937) or primary AML specimens (n=3) were treated with CD123-redirected CAR T cells as above. For T cell depletion studies, alemtuzumab 1 or 5 mg/kg was injected intraperitoneally (IP) at 1-4 weeks after 1x105-106 CART123 to determine optimal dosing and timing of T cell ablation. In subsequent studies, rituximab 10 mg/kg was injected IP 4 weeks after 1x105 -106 CART123/CD20, or 1x107 RNA-CART123 were injected intravenously at 5, 9, and 16 days after AML engraftment. Mice were followed by weekly bioluminescent imaging and/or quantitative flow cytometry analyses of blood, spleen, and/or bone marrow. Results. CART123 treatment of CD123+ AML xenografts induced marked T cell expansion and leukemia eradication in vivo, resulting in long-term animal survival (p<0.0001 vs untransduced T cell-treated controls). Minimal xenogeneic graft-versus-host effects were observed. One dose of alemtuzumab rapidly eliminated T cells in all tested models with best efficacy of 5 mg/kg dosing at 4 weeks post-CART123. CART123/CD20 inhibited AML proliferation with similar kinetics to those of CART123, and 1 dose of rituximab at 4 weeks post-CART123/CD20 infusion rapidly eliminated T cells while preserving leukemia remission. Alemtuzumab or rituximab alone did not inhibit AML proliferation in non-CART123-treated xenograft models vs AML-only controls (p=1.00). Mice with CART123- or CART123/CD20-induced AML remission at time of T cell ablation remained leukemia-free for ≥12 weeks, and animal survival did not differ from that of CD123-redirected CAR T cell-treated mice that did not undergo T cell depletion (p=1.00). In contrast, early depletion of T cells with alemtuzumab at 1, 2, or 3 weeks post-CART123 resulted in failure to eliminate AML with subsequent leukemia progression and animal death. Furthermore, AML rechallenge of animals with alemtuzumab- or rituximab-ablated T cells resulted in rapid leukemia proliferation without T cell re-expansion, confirming completeness of T cell depletion. Non-ablated mice demonstrated CAR T cell re-expansion with rejection of CD123+ leukemia rechallenge (p<0.0001). RNA-CART123 rapidly eliminated AML and facilitated long-term animal survival, although RNA-CART123 had expectedly shorter persistence in vivo than did CART123 or CART123/CD20. Conclusions. Alemtuzumab and rituximab completely eliminated CD123-redirected CAR T cells in human AML xenograft models. Sustained leukemia remission required CART123 or CART123/CD20 persistence for 4 weeks prior to T cell termination via alemtuzumab or rituximab post-CART123 or CART123/CD20, respectively. Ongoing studies are investigating efficacy of T cell elimination in additional xenograft models and against other anti-AML CAR T cell immunotherapies. Results from these studies may help to identify promising T cell termination strategies that will augment efficacy of CAR T cell therapy in patients with AML, particularly prior to stem cell transplantation. RNA-CART123 trials in patients with relapsed/refractory AML will open soon. Disclosures Off Label Use: depletion of CAR T cells with alemtuzumab or rituximab. Kenderian:Novartis: Patents & Royalties, Research Funding. Ruella:Novartis: Patents & Royalties, Research Funding. Aplenc:Sigma Tau: Consultancy. June:Novartis: Patents & Royalties, Research Funding. Grupp:Novartis: Consultancy, Research Funding. Gill:Novartis: Patents & Royalties, Research Funding.

Abstract Background Ixazomib, the first oral proteasome inhibitor, is approved by the US FDA, in combination with Rd, for the treatment of MM patients (pts) who have received at least 1 prior therapy. Approval was based on the double-blind, placebo-controlled phase 3 TOURMALINE-MM1 study (NCT01564537) in 722 pts with RRMM (Moreau et al, N Engl J Med 2016), in which IRd showed superior PFS versus placebo-Rd (HR 0.74) at the final prespecified analysis, with limited additional toxicity. Prespecified subgroup analyses showed a consistent PFS benefit with IRd, but with a differential treatment effect according to prior therapy exposure. An exploratory study objective was to evaluate potential relationships between treatment outcomes and tumor gene expression patterns. c-MYC is a proto-oncogene that encodes a transcription factor regulating cell proliferation, growth, protein translation, metabolism, and apoptosis, and increased c-MYC expression is involved in MM pathogenesis/progression. We analyzed the impact of c-MYC expression on PFS in RRMM pts treated with IRd or placebo-Rd. Methods Pts with RRMM after 1-3 prior lines of therapy were randomized 1:1 to receive oral ixazomib or placebo, plus lenalidomide and dexamethasone, until disease progression or unacceptable toxicity. Randomization was stratified by number of prior therapies (1 vs 2-3), proteasome inhibitor exposure, and ISS disease stage. The primary endpoint was PFS by independent review committee assessment. Data reported here are from the final prespecified statistical analysis of PFS (median follow-up ~15 months). Bone marrow aspirate samples were collected at screening for tumor gene expression analysis. Whole transcriptome sequencing (RNAseq) of bone marrow-sorted CD138+ cells was performed using the Illumina Truseq protocol on the Illumina HiSeq platform; this generated a median of 50 million paired-end reads (100 bp length) per sample. c-MYC expression was evaluated by treatment arm and according to number of prior therapies (1 vs 2-3). PFS was analyzed in subgroups dichotomized according to median c-MYC expression (c-MYC-high/c-MYC-low). Results RNAseq data were available for 59% (427/722) of enrolled pts; 213 (50%) had high and 219 (50%) had low c-MYC expression (dichotomized according to the median). Impact of c-MYC expression (high vs low) on PFS, irrespective of treatment arm, was not significant (p=0.98). However, a significant treatment effect of IRd vs placebo-Rd was only seen in pts with high c-MYC expression (interaction p=0.024); in these pts (IRd: n=109; placebo-Rd: n=104) a significant PFS benefit was seen with IRd (HR 0.41; 95% CI: 0.26-0.65, p=0.00011). Impact of c-MYC expression was then analyzed by number of prior therapies. In the overall TOURMALINE-MM1 population, per stratification, 212/213 pts in the IRd/placebo-Rd arms had 1 prior therapy, and 148/149 had 2-3 prior therapies. After median follow-up of ~15 months, median PFS in pts with 1 prior therapy was 20.6 vs 16.6 months with IRd vs placebo-Rd (HR 0.88; 95% CI: 0.65-1.20), and in pts with 2-3 prior therapies was not reached vs 12.9 months (HR 0.58; 95% CI: 0.40-0.84, p=0.0033). The level of c-MYC expression was shown to be significantly higher in pts with 2-3 prior therapies vs 1 prior therapy, with median expression of 6.94 (SD=1.71, n=177) vs 6.52 (SD=1.74, n=250) (log2 scale), t-test p-value 0.0153. In pts with 1 prior therapy, no differences in PFS were observed between pts with low c-MYC expression (HR 1; 95% CI: 0.59-1.8, p=0.934), while a prolonged PFS benefit was observed in pts with high c-MYC expression (HR 0.48; 95% CI: 0.26-0.88, p=0.0146) (Figure, A and B). In pts with 2-3 prior therapies, both the c-MYC-high and c-MYC-low pts showed improved PFS with IRd vs placebo-Rd; the difference in PFS was statistically significant only in c-MYC-high pts (HR 0.36; 95% CI: 0.18-0.72, p=0.00269) (Figure, C and D). Conclusions In TOURMALINE-MM1, c-MYC expression was higher in MM tumor samples from pts with 2-3 vs 1 prior therapies. The IRd regimen was active in c-MYC-high and c-MYC-low pts, but its impact on PFS vs placebo-Rd was greater in c-MYC-high pts, thus providing a potential explanation for the enhanced PFS benefit with IRd vs placebo-Rd in pts with 2-3 prior therapies. The PFS benefit with IRd in c-MYC-low pts with 2-3 prior lines suggests that, in advanced MM, further genomic alterations may also be contributing to ixazomib sensitivity. Disclosures Di Bacco: Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Bahlis:BMS: Honoraria; Onyx: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau. Avet-Loiseau:Takeda: Speakers Bureau; Janssen: Speakers Bureau; Celgene: Speakers Bureau; Sanofi: Speakers Bureau. Masszi:Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Ganly:Medipics: Equity Ownership; Novartis: Honoraria; Roche: Honoraria. Cavo:Bristol-Myers Squibb: Consultancy, Honoraria; Millennium: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Langer:Celgene: Consultancy; Takeda: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Novartis: Consultancy. Kumar:Array BioPharma: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; AbbVie: Research Funding; Onyx: Consultancy, Research Funding; Noxxon Pharma: Consultancy, Research Funding; Glycomimetics: Consultancy; Kesios: Consultancy; BMS: Consultancy; Millennium: Consultancy, Research Funding; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding. Berg:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Lin:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Li:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Badola:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Shen:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Zhang:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Wang:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Esseltine:Takeda: Equity Ownership; Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment; Johnson and Johnson: Equity Ownership. Luptakova:Takeda Oncology: Employment. van de Velde:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Richardson:Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees. Moreau:Bristol-Myers Squibb: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Janssen: Honoraria, Speakers Bureau; Novartis: Honoraria; Amgen: Honoraria.

AbstractIntroductionMyocardial infarction (MI) is associated with an increase in subsequent heart failure (HF), recurrent ischemic events, sudden cardiac arrest, and ventricular arrhythmias (SCA‐VA). The primary objective of the study to determine the role of intercurrent HF and ischemic events on the development of SCA‐VA following first type I MI.Methods and resultsA retrospective cohort study of patients experiencing first type 1 MI in Olmsted County, Minnesota (2002‐2012) was conducted by identifying patients using the medical records linkage system (Rochester epidemiology project). Patients aged ≥18 years were followed from the time of MI till death or 31 July, 2017. Intercurrent HF and ischemic events were the primary exposures following MI and their association with outcome SCA‐VA was assessed. Eight hundred and sixty‐seven patients (mean age was 63 ± 14.5 years; 69% male; 49.8% ST‐elevation myocardial infarction) who had their first type I MI during the study period were included. Majority of acute MI patients were revascularized using percutaneous coronary intervention and bypass surgery (628 [72.43%] and 87 [10.03%] respectively). During a mean follow‐up of 7.69 ± 4.17 years, HF, recurrent ischemic events and SCA‐VA occurred in 155 (17.9%), 245 (28.3%), and 40 (4.61%) patients respectively. Low ejection fraction (adjusted hazard ratio [HR] 0.95; 95% confidence interval [CI], 0.93‐0.98; P < .001), intercurrent HF (adjusted HR 3.11; 95% CI, 1.39‐6.95; P = .006) and recurrent ischemic events (adjusted HR 3.47; 95% CI, 1.68‐7.18; P < .001) were associated with subsequent SCA‐VA.ConclusionSCA‐VA occurred in a small proportion of patients after MI and is associated with intercurrent HF and recurrent ischemic events.

AbstractObjectiveTo characterize the molecular and phenotypic basis of a severe slow‐channel congenital myasthenic syndrome (SCCMS).MethodsIntracellular and single‐channel recordings from patient endplates; alpha‐bungarotoxin binding studies; direct sequencing of AChR genes; microsatellite analysis; kinetic analysis of AChR activation; homology modeling of adult human AChR structure.ResultsAmong 24 variants reported to cause SCCMS only two appear in the AChR δ‐subunit. We here report a 16‐year‐old patient harboring a novel δL273F mutation (δL294F in HGVS nomenclature) in the second transmembrane domain (M2) of the AChR δ subunit. Kinetic analyses with ACh and the weak agonist choline indicate that δL273F prolongs the channel opening bursts 9.4‐fold due to a 75‐fold increase in channel gating efficiency, whereas a previously identified εL269F mutation (εL289F in HGVS nomenclature) at an equivalent location in the AChR ε‐subunit prolongs channel opening bursts 4.4‐fold due to a 30‐fold increase in gating efficiency. Structural modeling of AChR predicts that inter‐helical hydrophobic interactions between the mutant residue in the δ and ε subunit and nearby M2 domain residues in neighboring α subunits contribute to structural stability of the open relative to the closed channel states.InterpretationThe greater increase in gating efficiency by δL273F than by εL269F explains why δL273F has more severe clinical effects. Both δL273F and εL269F impair channel gating by disrupting hydrophobic interactions with neighboring α‐subunits. Differences in the extent of impairment of channel gating in δ and ε mutant receptors suggest unequal contributions of ε/α and δ/α subunit pairs to gating efficiency.

Abstract Dysregulation of ErbB-mediated signaling is observed in up to 90% of solid tumors. ErbB family cross-talk is implicated in the development of resistance and metastasis, including CNS metastases. Inhibition of multiple ErbB receptors may result in improved patient outcomes. EO1001 is a novel, patented, oral, brain-penetrating, irreversible pan-ErbB inhibitor targeting EGFR (ErbB1), HER2 (ErbB2) and HER4 (ErbB4). METHODS: (1) In vitro testing. EO1001 demonstrates high specificity for the ErbB family of receptors with excellent, balanced equipotent activity against EGFR, HER2 and HER4 (0.4 to 7.4 nM). EO1001 inhibits signaling downstream of wild type EGFR, mutant EGFR (T790M, L858R and d746-750) and HER2. (2) PK and toxicity. In rodent studies in vivo, EO1001 exhibited a half-life of 16–20 hours. EO1001 rapidly enters the CNS and penetrates tumor tissue at higher concentrations relative to plasma. Safety of EO1001 was evaluated by repeat-dosing studies in SD rats and beagle dogs. Toxicities typical of the ErbB inhibitor class, including gastro-intestinal effects, weight loss and decreased activity were observed at higher dose groups in both species. Mortality was observed in SD rats at higher dose groups. (3) In vivo efficacy studies. EO1001 was studied following oral administration in several erbB-positive mouse xenograft models including N87 (Her2+), H1975 (EGFR/T790M), GBM12 (EGFR+), GBM39 (EGVRvIII+). Following oral administration, treatment with EO1001 resulted in a statistically significant improvement in outcomes compared to positive and negative controls in both CNS and systemic tumor models. EO1001 was well-tolerated with no gastrointestinal side effects observed at efficacious doses in these models. CONCLUSION: Based on research to date, EO1001 has the potential to be a best-in-class CNS-penetrating pan-ErbB inhibitor with a safety and pharmacokinetic profile amenable for use as a single agent and in combination with other agents. EO1001 is poised to enter phase 1-2a clinical testing in the second-half of 2019.

Background: To assess the differential effect of robotic assisted radical cystectomy (RARC) versus open radical cystectomy (ORC) on survival outcomes in matched analyses performed on a large multicentric cohort. Methods: The study included 9757 patients with urothelial bladder cancer (BCa) treated in a consecutive manner at each of 25 institutions. All patients underwent radical cystectomy with bilateral pelvic lymphadenectomy. To adjust for potential selection bias, propensity score matching 2:1 was performed with two ORC patients matched to one RARC patient. The propensity-matched cohort included 1374 patients. Multivariable competing risk analyses accounting for death of other causes, tested association of surgical technique with recurrence and cancer specific mortality (CSM), before and after propensity score matching. Results: Overall, 767 (7.8%) patients underwent RARC and 8990 (92.2%) ORC. The median follow-up before and after propensity matching was 81 and 102 months, respectively. In the overall population, the 3-year recurrence rates and CSM were 37% vs. 26% and 34% vs. 24% for ORC vs. RARC (all p values > 0.1), respectively. On multivariable Cox regression analyses, RARC and ORC had similar recurrence and CSM rates before and after matching (all p values > 0.1). Conclusions: Patients treated with RARC and ORC have similar survival outcomes. This data is helpful in consulting patients until long term survival outcomes of level one evidence is available.