ALBERT

Description: Introduction. Cytokine release syndrome (CRS) and neurotoxicity (NT)(also known as immune effector cell-associated neurotoxicity syndrome or ICANS) are commonly observed after chimeric antigen receptor (CAR) T-cell therapy. While the clinical features of CRS have been extensively described, limited data exists for NT. Here, we report clinical and radiological features of NT after standard of care (SOC) axicabtagene ciloleucel (axi-cel) in patients (pts) with relapsed or refractory (r/r) large B-cell lymphoma (LBCL). Methods. Pts with r/r LBCL treated with SOC axi-cel at MD Anderson Cancer Center between 01/2018 and 04/2019 were included in the study. All pts received anti-seizure prophylaxis with levetiracetam starting on the day of axi-cel infusion for 30 days. CRS and NT were prospectively graded according to CARTOX criteria (Neelapu et al, Nat Rev Clin Oncol, 2018). Association between continuous variables were assessed using the bivariate Pearson correlation. Results. Ninety-five pts were included in the study, 72 (76%) with diffuse LBCL, 17 (18%) with transformed follicular lymphoma, and 6 (6%) with primary mediastinal LBCL. Median age was 60 (range, 18-85), 71 (75%) were male. Median number of previous therapies was 4 (range, 2-15), 26 (27%) had a previous autologous stem cell transplant (SCT), and 1 (1%) a previous allogeneic SCT. Eight (8%) pts had prior central nervous system lymphomatous involvement (parenchymal in 5), and 39 (41%) had prior neurological and/or psychiatric medical history. After axi-cel infusion, NT of any grade was observed in 65 (68%) pts, grade ³3 in 46 (48%)(Table). No significant association was observed between above outlined baseline characteristics and development of NT. Median time from axi-cel infusion to NT onset was 5 days (range, 0-25 days) and median duration was 6 days (range, 1-52 days); no new onset/recurrent NT was observed beyond day 30. Among the 65 pts who developed NT, a CT head without contrast was performed in 48, and was not evaluable in 2 because of motion artifacts. Among the 46 evaluable scans, 1 (4%) was abnormal as compared to baseline, and showed new onset cortical edema (non-diffuse but symmetrical). An MRI brain with contrast was performed in 36 pts, but was not evaluable in 10 because of lack of baseline, motion artifacts or differences in imaging sequences. Among the 26 evaluable scans, 15 (58%) showed abnormal findings, including autoimmune encephalitis-like, characterized by symmetric white matter changes of the pons and hippocampus (6; Fig. A), stroke-like (4; Fig. B), LMD-like (3; Fig. C) and PRES-like (2; Fig. D), with concomitant cortical edema in 5. EEGs were performed in 52 pts (〉1/pt, for a total of 116 EEGs) and were abnormal in 47 (90%). Focal and/or diffuse slowing was the most common abnormality (isolated finding in 35 [73%] pts), while epileptiform discharges and/or non-convulsive status epilepticus (NCSE) were observed 12 (27%) pts. A lumbar puncture was performed in 12 pts: median white blood cell count was 2 cells/µL (range, 0-6), median protein 47 mg/dL (range, 13-600), median glucose 69 mg/dL (range, 30-111), and cytology was positive for malignant cells in 2 (7%) pts. Convulsive seizure was observed in 4 (6%) pts and 10 (15%) received additional anti-seizure therapy for convulsive or non-convulsive seizures. Among the 65 pts with NT, dexamethasone up to 20 mg IV Q6H was given to 42 (65%) pts, methylprednisolone 1000 mg IV daily to 12 (18%), and tocilizumab to 64 (98%; during CRS or CRS with concurrent NT). Overall, 93 (98%) pts developed CRS, grade 〉3 in 27 (28%). A significantly higher rate of NT of any grade (96% vs 57%, p3 (81% vs 35%, p3 CRS. After a median follow-up of 4 months, 6-month progression-free (PFS) and overall survival (OS) rates were 60% and 65%, respectively. Significantly shorter 6-month PFS (46% vs 80%, p=0.02) and OS rates (56% vs 83%, p=0.01) were observed among pts developing NT of any grade. Conclusions. Our results suggest that multiple radiological patterns of NT after axi-cel are possible in r/r LBCL pts, MRI being more sensitive than CT scan for their detection. NCSE is a common event, supporting the use of seizure prophylaxis and EEGs for evaluation of these pts. Pts with NT experience a worse outcome, and additional clinical and biological predictors of NT will be analyzed and presented at the meeting. Figure Disclosures Nastoupil: Spectrum: Honoraria; Janssen: Honoraria, Research Funding; Bayer: Honoraria; Celgene: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding; Gilead: Honoraria; TG Therapeutics: Honoraria, Research Funding; Novartis: Honoraria. Westin:47 Inc: Research Funding; Novartis: Other: Advisory Board, Research Funding; Juno: Other: Advisory Board; MorphoSys: Other: Advisory Board; Unum: Research Funding; Curis: Other: Advisory Board, Research Funding; Genentech: Other: Advisory Board, Research Funding; Celgene: Other: Advisory Board, Research Funding; Kite: Other: Advisory Board, Research Funding; Janssen: Other: Advisory Board, Research Funding. Fowler:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding. Lee:Seattle Genetics, Inc.: Research Funding. Parmar:Cellenkos Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding. Wang:Guidepoint Global: Consultancy; BioInvent: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics: Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; MoreHealth: Consultancy, Equity Ownership; Acerta Pharma: Consultancy, Research Funding; Kite Pharma: Consultancy, Research Funding; VelosBio: Research Funding; Loxo Oncology: Research Funding; Celgene: Honoraria, Research Funding; Juno Therapeutics: Research Funding; Aviara: Research Funding; Dava Oncology: Honoraria. Pinnix:Merck: Research Funding. Hawkins:Novartis Pharmaceuticals: Other: advisory panels. Neelapu:Precision Biosciences: Consultancy; Novartis: Consultancy; Allogene: Consultancy; Incyte: Consultancy; BMS: Research Funding; Cellectis: Research Funding; Poseida: Research Funding; Karus: Research Funding; Acerta: Research Funding; Celgene: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Merck: Consultancy, Research Funding; Cell Medica: Consultancy; Unum Therapeutics: Consultancy, Research Funding; Pfizer: Consultancy. Chi:Kite, A Gilead Company: Consultancy, Honoraria, Other: Kite Patient Management Advisory Board.

Description: Introduction CAR-T cells targeting CD19 positive B-cells have improved outcomes and remission rates in relapsed/refractory non-Hodgkin lymphoma (NHL) and B-cell acute lymphoblastic leukemia (B-ALL). Although toxicities contributing to non-progression related mortality (NRM) have been reported in the pivotal trials, its incidence in the standard of care setting post-approval is unknown. The following data includes toxicity profiles implicated in events leading to NRM obtained from the FDA adverse event reporting system (FAERS) with comparison to MD Anderson (MDACC-L) CAR-T Lymphoma cohort and to the pivotal CAR-T trials. Methods We retrospectively queried FAERS for all adverse events (AE) associated with tisagenlecleucel (T) and axicabtagene ciloleucel (AC) reported from January 1, 2013-June 30, 2019. FAERS contains AEs from clinical trials and healthcare providers and is standardized according to the Medical Dictionary for Regulatory Activities (MedDRA), a clinically validated AE classification dictionary for pharmacovigilance monitoring. All cases with the outcome of death as reported by FAERS were queried. Cases in which the time to event with NRM was greater than 30 days or unknown were excluded. Total events recorded with NRM and disease progression were categorized according to the MedDRA coding system and compared using the chi-squared and a two-sided Fisher's exact test (statistical significance: p

Description: Key Points IRF4 deletion in Tcl-1 tg mice and IRF4low CLL patients enhances disease progression due to increased tumor immune evasion. This is caused by a downregulation of the antigen processing and presentation machinery and reduced T-cell costimulation.

Description: CD74, also known as HLA-DR-associated invariant chain, is a type II transmembrane glycoprotein highly expressed in many B-cell malignancies. The limited expression of CD74 in normal tissues suggests it may be a suitable ADC target for these tumor types. Accordingly, we engineered an anti-CD74 human IgG1 antibody (SP7219) using novel Fab-based ribosome display methods. The selected Fabs were readily reformatted and directly screened as IgGs using Sutro's unique high-throughput, cell-free protein synthesis platform, Xpress CFTM. We then developed novel, potent ADCs, SP7676 and SP7675 (STRO-001), comprised of our lead antibody (SP7219) conjugated to non-cleavable DBCO-maytansinoid linker-warheads with an average drug-antibody ratios (DAR) of 2. We used site-specific conjugation technology which results in a high degree of homogeneity characterized by the drug linker covalently binding to a single defined site. The sites for conjugation were selected based on highest cell killing activity and stablity in vitro and in vivo. Both ADCs demonstrate potent cell killing activity across multiple B-cell tumor lines in vitro, and anti-tumor activity in preclinical multiple myeloma xenograft models. In vitro cytotoxicity assays show nanomolar potency of STRO-001 in four MM cell lines: Mc/CAR (IC50 0.8 nM), MM.1S (IC50 10-11 nM), U266B1 (IC50 8.5 -9.3 nM), and ARP-1 (IC50 4.3-22 nM). CD74 cell surface expression is required for ADC anti-proliferative effect but the expression level does not seem to correlate with in vitro potency. SP7676 elicited a robust anti-tumor response in the ANBL-6 multiple myeloma xenograft model. Durable regressions were observed in all mice at ≥ 3 mg/kg, with equivalent efficacy (regression) at 3 mg/kg (every 3 days x5) and 10 mg/kg (every 3 days x5 or weekly x3). SP7676 also elicited a clear survival benefit in a disseminated multiple myeloma CAG xenograft model starting at 1mg/kg every 3 days x 5 doses. Similarly, both SP7676 and STRO-001 inhibited the formation of internal visceral tumors in the ARP-1 xenograft model after 3 weekly doses of 3 mg/kg. Evaluation of our lead candidate, STRO-001 in additional MM cell lines and primary patient samples is planned. The tolerability of STRO-001 in non-human primates is under evaluation. STRO-001 was administered to cynomolgous monkeys in an exploratory dose-escalating study up to 30 mg/kg x 2 doses on Day 1 and 15. STRO-001 reduces normal B-cell populations at ≥1 mg/kg after a single dose, providing pharmacodynamic evidence of B-cell targeting while other hematopoietic lineages are mostly affected only at the highest dose studied. Anticipated hematologic toxicities were readily reversible at 1, 3 and 10 mg/kg and target organs of interest were identified. Based on these encouraging data, STRO-001 is advancing to IND-enabling studies for the treatment of CD74 expressing multiple myeloma and other B-cell malignancies. Disclosures Abrahams: Sutro Biopharma: Employment. Li:Sutro Biopharma: Employment. Yu:Sutro Biopharma: Employment. Krimm:Sutro Biopharma: Employment. Kahana:Celgene: Employment. Narla:Celgene: Employment. Schwartz:Celgene: Employment. Boylan:Celgene: Employment. Hoffmann:Sutro Biopharma: Employment. Steiner:Sutro Biopharma: Employment. Zawada:Sutro Biopharma: Employment. Stephenson:Sutro Biopharma: Employment. Bruhns:Sutro Biopharma: Employment. DeAlmeida:Sutro Biopharma: Employment. Matheny:Sutro Biopharma: Employment. Bussell:Sutro Biopharma: Employment. Galan:Sutro Biopharma: Employment. Kline:Sutro Biopharma: Employment. Vasquez:Sutro Biopharma: Employment. Yam:Sutro Biopharma: Employment. Stafford:Sutro Biopharma: Employment. Heinsohn:Sutro Biopharma: Employment. Sato:Sutro Biopharma: Employment. Molina:Sutro Biopharma: Employment. Hallam:Sutro Biopharma: Employment. Lupher:Sutro Biopharma: Employment.

Description: The maturation of a committed erythroid progenitor to a functional erythrocyte is characterized by a global decline in transcription and progressive nuclear condensation that ultimately culminates in enucleation. At the molecular level, erythroid maturation is driven by erythroid transcription factors and chromatin modifying enzymes that work in a coordinated manner to drive the expression of erythroid-specific genes, while silencing most other genes during the process of chromatin condensation and enucleation. Setd8 is the sole histone methyltransferase in mammals capable of mono-methylating histone H4 Lysine 20 (H4K20me1). In vitro studies suggest that Setd8 and H4K20me1 play critical roles in cell cycle progression, nuclear condensation, and DNA damage response (Reviewed in Beck et al, Genes and Development, 2012). In vivo studies on the function of Setd8 and H4K20me1 have been limited by the early embryonic lethality of constitutive Setd8 deletion (Oda et al, MCB, 2009). Although Setd8 is broadly expressed in tissues, there is a striking increase in Setd8 expression in CD71+ erythroid cells (Wu et al, Genome Biology, 2009), suggesting that Setd8 may have erythroid specific functions. Initial studies from our lab and others suggest that Setd8 regulates erythroid maturation and represses Gata2 expression (Malik et al MCB 2015; DeVilbiss et al MCB 2015). To delineate the function of Setd8 in vivo, we generated an erythroid-specific Setd8 deletion by crossing mice with flox sites flanking exon 7 of Setd8 (Setd8 fl/fl; Oda et al, MCB, 2009) with mice expressing a Cre-Recombinase GFP fusion protein under the control of the endogenous erythropoietin receptor promoter (ErGFPCre; Heinrich et al, Blood, 2004). Setd8Δ/Δ;ErGFPCre embryos demonstrated visible anemia starting at E9.5, with death occurring at E12.5 due to severe anemia. The early onset of anemia is consistent with a defect in primitive erythropoiesis. Cytospins and imaging flow cytometric analyses demonstrated a block in primitive erythroblast maturation and a profound impairment in nuclear condensation, with a nuclear area of 96 um2 in the Setd8 null erythroblasts and 56um2 in the littermate control erythroblasts at E10.5. Setd8 null erythroblasts also had abnormalities in cell cycle progression as well as increased staining for γH2AX, suggesting accumulation of DNA damage. There were similar numbers of Erythro-myeloid progenitors, (EMP; defined as defined as Ter119-negative, kit-hi,CD41-hi cells) in both the Setd8Δ/Δ;ErGFPCre and littermate control embryos, however the Setd8 null progenitors failed to differentiate into definitive erythroblasts. The role of Setd8 in transcriptional regulation is controversial, with some studies suggesting it is an activator and others suggesting it is a repressor. Global transcriptome analyses on sorted populations of Setd8 null and littermate control erythroblasts suggest that Setd8 acts primarily as a repressor in erythroid cells, with the majority of transcripts upregulated following Setd8 deletion. RNA-seq analyses further demonstrated a profound increase in the expression of cell cycle checkpoint enzymes such as P21 (fold change 73, p〈 e-53) and a significant increase in Gata2 expression (fold change 16, P

Description: Introduction Musculoskeletal ultrasound (MSKUS) is being used increasingly for point-of-care (POC) assessment of painful hemophilic joints and has proven to be a critical tool in the evaluation of the presence of hemarthrosis. To date, MSKUS examinations are exclusively performed in the clinic, which often results in delays to definitive diagnosis since patients and caregivers are not always able to undergo or perform a clinical assessment at the time of the event. The use of pocket handheld ultrasound devices, which have primarily been applied for cardiopulmonary and abdominal POC bedside assessments, offers a promising solution to this problem by enabling patients and remote clinics to acquire images for off-site real-time evaluations via tele-transmission. In this study, we evaluated the extent to which the quality of images generated by the handheld ultrasound devices compared to stationary MSKUS and if the image interpretation was similar between various health care providers. The aim is to establish the dynamic potential of this pocket sized device as a cost effective and comparable alternative to the stationary MSKUS. Methods A total of 72 typical joint views (36 of the knee, 20 of the elbow and 16 of the ankle) were acquired from healthy volunteers and hemophilia patients at the same session with the stationary GE LogiqS8 and the handheld GE V2scan. Ten different health care providers (7 physicians, 2 physical therapists and 1 nurse), all trained at least in the CME-accredited MSKUS course at the University of California, San Diego, (UCSD), reviewed these images side by side. Information about view, probe placement and tissue compressibility to identify effusions was provided. Each subject was asked to evaluate the following characteristics on a graded scale: (1) similarity of the handheld image to the GE LogiqS8 image, (2) their confidence in identification of major landmarks on the handheld image compared to the GE LogiqS8 image and if an effusion was present, (3) their ability to identify the effusion on both images. The adjudicators were a board-certified radiologist and a senior hematologist trained and experienced in MSKUS. Study procedures complied with rules set forth by the UCSD Human Research Protection Program. Results A total of 720 responses were analyzed from the images of normal and hemophilic joints. Among the responses, 87% of images were rated as at least moderately similar to very similar between the handheld device and the stationary ultrasound. In terms of identification, 88% of the responses were rated as at least moderately confident to very confident in the identification of major landmarks on the handheld image. Among a total of 170 responses for effusions, 87% of effusions were identified with both the handheld device and the stationary MSKUS (Table). These percentages were consistent between the different joints with slightly higher rates of correct identification on the handheld device noted in the knee where 100% of effusions were recognized correctly. Representative images depicting an effusion in the lateral recess of the knee acquired simultaneously with the handheld GE V2scan and stationary MSKUS is provided (Figure). There was no significant discrepancy of answers between the types of providers. Conclusion The image quality of the handheld pocket device (GE V2 scan) was sufficient to determine major landmarks in joints and to diagnose effusions, with image interpretation comparable between the various health care providers encompassing physicians, nurses, and physical therapists. These findings highlight the potential in the application of this device as a novel POC modality for both patient-performed tele-ultrasound or tele-ultrasound use in remote, resource limited regions for real-time assessments of hemarthrosis. While encouraging, these observations need to be further validated and extended more broadly in future studies. Table Table. Disclosures Kruse-Jarres: Baxalta: Consultancy, Honoraria; Grifols: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; CSL Behring: Consultancy, Honoraria; Bayer: Consultancy, Honoraria. Quon:Bayer: Consultancy; Biogen: Consultancy, Speakers Bureau; Grifols: Speakers Bureau; Novo Nordisk: Consultancy, Speakers Bureau. von Drygalski:Pfizer: Consultancy, Honoraria, Speakers Bureau; Hematherix LLC: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Consultancy, Honoraria, Speakers Bureau; CSL-Behring: Consultancy, Honoraria, Speakers Bureau; Biogen: Consultancy, Honoraria, Speakers Bureau; Bayer: Consultancy, Honoraria, Speakers Bureau; Baxalta/Shire: Consultancy, Honoraria, Speakers Bureau.

Description: Introduction: Both inter- and intra-tumoral heterogeneity are obstacles to improving oncology clinical outcomes. Mantle cell lymphoma (MCL) is an extremely heterogeneous disease in clinical, pathological, genetic, and transcriptomic profiling. Furthermore, MCL patients frequently develop therapeutic resistance after frontline therapies. In this study, we performed longitudinal transcriptomic analysis on primary patient MCL specimens at single-cell resolution, aiming to understand the dynamic and complex cellular and molecular changes underlying therapeutic resistance and identify potential targets to overcome dual resistance to ibrutinib and venetoclax. Methods: Sequential single-cell transcriptome sequencing (scRNA-seq) was performed on patient specimens collected during the course of treatment(s) from 5 MCL patients (3 ibrutinib responders and 2 ibrutinib-venetoclax non-responders). Integrative computational approaches were employed to characterize the cellular and molecular basis of therapeutic resistance and clonal evolution. An orthotopic PDX model derived from one of the non-responders was established and used to validate the novel findings and to investigate the in vivo efficacies of multiple novel potential targets. Results: The 3 ibrutinib responders and 2 ibrutinib-venetoclax non-responders were highly heterogeneous in clinical and pathological profiling. To dissect the inter- and intra-tumor heterogeneity underlying the therapeutic resistance, we performed sequential scRNA-seq analysis of 21 specimens collected at baseline, during treatment, and/or at disease remission/progression. The scRNA-seq analysis revealed a high degree of inter- and intra-tumor heterogeneity with distinct cellular and transcriptomic profiling within and across ibrutinib-responders and ibrutinib-venetoclax non-responders. Unsupervised pathway enrichment analysis identified more than 15 cancer hallmarks significantly upregulated in ibrutinib-venetoclax non-responders. We tracked the clinical ibrutinib-induced lymphocytosis at a single-cell transcriptomic level in ibrutinib responders and disease-progression-associated clonal evolution in non-responders. Multiple actionable targets were identified, and targeting these showed effective anti-MCL activity in the orthotopic PDX model derived from one of the ibrutinib-venetoclax non-responders. Conclusions: This study demonstrates the potential of longitudinal single-cell transcriptomic analysis to reveal the molecular mechanisms underlying tumor heterogeneity, clonal evolution, disease progress, and therapeutic resistance, and to identify potential novel targets to circumvent therapeutic resistance in mantle cell lymphoma and other diseases. Disclosures Wang: Pharmacyclics: Honoraria, Research Funding; Juno Therapeutics: Research Funding; Celgene: Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Guidepoint Global: Consultancy; Kite Pharma: Consultancy, Research Funding; Acerta Pharma: Consultancy, Research Funding; MoreHealth: Consultancy, Equity Ownership; Loxo Oncology: Research Funding; VelosBio: Research Funding; BioInvent: Consultancy, Research Funding; Dava Oncology: Honoraria; Aviara: Research Funding.

Description: Background: Central Nervous System (CNS) lymphoma is a rare and distinct subtype of diffuse large B-cell lymphoma (DLBCL). CNS lymphoma has a unique genomic profile which has similarities to the activated B-cell (ABC) subtype of DLBCL, which may speak to potential targets for therapy. These aberrancies include near uniform reliance on Toll-Like Receptor signaling, mutations of MYD88, and frequent translocation or copy number alterations of 9p24 which codes for programmed death receptor ligand 1 (PD-L1). Mutations of MYD88 may predict for response to Bruton's tyrosine kinase (BTK) inhibitors in patients with systemic DLBCL. Expression of PD1 or PD-L1, which corresponds to response with PD-targeted therapy in solid tumors, has been found on up to 90% of CNS lymphoma cases, and 60% of specimens had tumor infiltrating lymphocytes which were PD1+ (Berghoff, Clin Neuropath 2014). In addition, the majority of CNS lymphoma cases have a copy gain of 9p24.1, associated with increased expression of PD-L1 (Chapuy, Blood 2016). This suggests a potential ongoing immune reaction against CNS lymphoma, but the microenvironment and tumor conspire to render the immune response ineffective. Ibrutinib is a BTK inhibitor which is FDA approved for multiple B-cell malignancies and is known to achieve therapeutic concentration in the cerebral spinal fluid (CSF), with activity in CNS lymphoma as a single agent and in combination with other agents. Nivolumab is a PD1 inhibitor which is FDA approved for multiple malignancies, with impressive anecdotal evidence of single agent activity in CNS lymphoma. Ibrutinib and nivolumab have been combined in other studies with modest toxicities. Study Design and Methods: We are conducting a phase II, open label, single center clinical trial combining ibrutinib with nivolumab to treat patients with relapsed CNS lymphoma (NCT03770416). Patients are eligible if they have CNS lymphoma relapsed after or were refractory to at least 1 prior line of therapy with adequate organ and bone marrow function, are aged 18y or greater, have not received prior ibrutinib or PD1 inhibitor, and do not require persistent high dose steroids. The trial has two cohorts which will be sequentially enrolled. Cohort A begins with ibrutinib 560mg oral daily for a single 28-day cycle, followed by ibrutinib combined with nivolumab 240mg IV every 14 days. Cohort B begins with the ibrutinib and nivolumab combination during the first cycle. Patients who have at least a partial response at the conclusion of the planned 6 cycles of combined ibrutinib and nivolumab may continue therapy for up to 2 years total or until progression of disease or unacceptable toxicity occurs. Neurocognitive assays and patient reported outcome instruments are being utilized. The primary objective is to determine the best overall response rate during the first 24 weeks of therapy. Secondary objectives will include the response rate of ibrutinib as a lead in prior to the combination, the complete response rate, landmark survival outcomes, and the safety of the combination. Exploratory analyses include assays of the blood and CSF for ctDNA and immune profiling. The first patient was treated in February 2019, with a planned total of 40 patients to be enrolled. Disclosures Westin: MorphoSys: Other: Advisory Board; Juno: Other: Advisory Board; Novartis: Other: Advisory Board, Research Funding; Kite: Other: Advisory Board, Research Funding; Janssen: Other: Advisory Board, Research Funding; 47 Inc: Research Funding; Genentech: Other: Advisory Board, Research Funding; Curis: Other: Advisory Board, Research Funding; Celgene: Other: Advisory Board, Research Funding; Unum: Research Funding. Fowler:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding. Nastoupil:TG Therapeutics: Honoraria, Research Funding; Novartis: Honoraria; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Celgene: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding; Spectrum: Honoraria; Bayer: Honoraria. Neelapu:Allogene: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Novartis: Consultancy; Karus: Research Funding; Celgene: Consultancy, Research Funding; Precision Biosciences: Consultancy; Cell Medica: Consultancy; Incyte: Consultancy; Acerta: Research Funding; Unum Therapeutics: Consultancy, Research Funding; Pfizer: Consultancy; BMS: Research Funding; Poseida: Research Funding; Merck: Consultancy, Research Funding; Cellectis: Research Funding. Parmar:Cellenkos Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: ibrutinib and nivolumab are not yet indicated for CNS lymphoma

Description: The generation of a functional erythrocyte from a committed progenitor requires significant changes in gene expression during a time of hemoglobin accumulation, rapid cell division, and nuclear condensation. Disruption of this process is associated with myelodysplastic syndromes and congenital anemias. Congenital Dyserythropoietic Anemia type I (CDA-I), is an autosomal recessive disease that presents with severe macrocytic anemia early in infancy or early childhood. Patients with CDA-I have erythroid hyperplasia in the bone marrow. The erythroblasts in CDA-I are frequently binucleate, have chromatin bridging, and defective chromatin condensation (Renella 2011). CDA-I is most commonly caused by mutations in the protein codanin 1 (CDAN1). The function of CDAN1 is poorly understood, but it is thought to regulate histone incorporation into nascent DNA during cellular replication (Ask 2012). The study of CDA-1 has been limited by lack of in vitro models that recapitulate key features of the disease, and to date, the majority of studies on CDAN1 function have been done in non-erythroid cells. To model CDA-I we introduced a point mutation (PM) commonly observed in CDA-1 patients (R1042W) into HUDEP2 cells. In addition, we generated two HUDEP2 cell lines with heterozygous deletion of CDAN1 (del-R1042). All CDAN1 mutant cell lines had decreased viability in during both expansion and terminal maturation compared to control lines. Chromatin bridges and multinucleate cells were observed in all three mutant CDAN1 lines but were most prominent in the PM line. Intriguingly, global gene analysis demonstrated that all mutated lines had significantly elevated gamma-globin expression compared to controls, consistent with reports of elevated fetal globin expression in CDA-1 patients. Interestingly, the PM cell line had faster cell divisions than the del-R1042 or control lines, characterized by decreased doubling time and verified by quantifying dilution of a fluorescent dye. In contrast, the del-R1042 lines had slower cell doubling times than both the controls and the PM line. The PM line also had an increased median intensity of BrdU compared to controls and del-R1042 lines, suggesting an accelerated S-phase. KI67 staining of the PM line showed an increase percentage of mitotic cells. These data are consistent with the finding that multinucleate cells and chromatin bridges are more common in the PM line. Furthermore, electron microscopy suggests the PM cell line may have defects in heterochromatin formation. Together, these data imply a specific functional role for residue R1042, and suggest that within the context of R1042W, loss of the arginine residue and replacement thereof with a tryptophan may have different mechanistic consequences. Collectively, our preliminary data suggests that CDAN1 is important in the regulation of DNA replication and organization in maturing erythroblasts. Specific mutations may confer a change of function which results in dysplastic erythroid cells that are sensitive to dysregulated cell cycle mechanics due to the high rate of cell division. We hypothesize R1042W substitution may accelerate cell division at the expense of appropriate checkpoints and result in dysplastic erythroid cells and mimic the clinical presentation of increased multinuclearity, decreased cell viability, and increased gamma globin expression. Most importantly, generation of models with specific patient mutations will provide further mechanistic insight into CDA-I pathology. Disclosures No relevant conflicts of interest to declare.

Description: Introduction Based on improvement of overall survival (OS), lenalidomide (R) maintenance after up-front autologous stem cell transplantation has recently been approved for multiple myeloma (MM) patients (pts). Conversely, in transplant non-eligible (TNE) pts R maintenance after R-based induction improved progression free survival (PFS) but had no impact on OS. First-line treatment with VMP is considered a standard of care for newly diagnosed (ND) TNE pts, but whether maintenance therapy with R after VMP induction can further improve PFS and OS is currently unknown. Aims The prospective phase IIb GERMAIN trial (EudraCT-No: 2012-003023-38) aimed to evaluate the role of R maintenance after VMP induction in ND TNE MM pts. The trial, which planned to include 286 ND TNE MM pts, closed early in December 2017 due to insufficient accrual and high discontinuation rate. The present analysis focuses on the reasons for the high drop out rate. Methods After induction with 6 courses of VMP (Mateos et al., Lancet Oncology 2010), pts achieving at least a partial response (PR) were randomized 1:1 to R 10 mg or placebo (PCB) daily until progression (PD) or unacceptable toxicity. Pts with