ALBERT

Description: Background: The phase II AIM trial (Tam et al, NEJM 2018; NCT02471391), using combination BTK inhibitor ibrutinib (IB) and BCL-2 inhibitor venetoclax (VEN) therapy achieved excellent 16 week complete remission rates (CRR) (primary endpoint; 62%) in patients (pts) with poor prognosis mantle cell lymphoma (MCL), higher than currently approved second line IB monotherapy. Additionally, overall response rate (ORR) by PET of 71%, with attainment of minimal residual disease (MRD) negativity was reported. At the time of primary endpoint analysis (median follow up 15.9 months), median progression free survival (PFS), duration of response (DOR), time to progression (TTP) and overall survival (OS) had not been reached. Herein, we update our results with an additional 21.6 months of follow-up and report the outcomes of pts who electively interrupted treatment. Methods: Pts with MCL who had relapsed or refractory disease (R/R; n=23) or were treatment naïve but inappropriate for chemotherapy (n=1) were enrolled. Pts commenced treatment with IB 560mg/d for 4 weeks, followed by weekly ramp-up of VEN to 400mg/d. Initially, pts were intended to continue IB and VEN until progressive disease or unacceptable toxicity; a later amendment allowed pts to electively interrupt both drugs if MRD-negative CR was reached. Pts who elected to interrupt therapy were closely monitored by peripheral blood flow MRD testing and regular CT scans, and were allowed to recommence both study drugs at MRD recrudescence or clinical progression. Results: Median age was 68 years (range, 47-81), median number of previous treatments was 2 (range, 0 to 6), and 50% had aberrations of TP53. As previously reported, the flow MRD-negative and ASO-PCR MRD-negative rates were 67% and 38%, respectively. For the current analysis, the median follow-up was 37.5 months (range, 1.4-45.3).The median DOR and TTP had not been reached and were estimated to be 74% and 60% at 30 months, respectively. The median PFS was 29 months (95% CI of 13-NE) (Figure 1), and the median OS was 32 months (95% CI of 27-NE) (Figure 2). For pts with TP53 aberrant MCL (n=12), the CRR was 50% (95% CI 21-79) with and without PET. In this group the ORR was 58% (95% CI 28-85) without PET and 50% (CI 21-79%) with PET. The DOR in 6 responders with TP53 aberrant MCL (excluding one pt with CRu) was 12+, 24+, 26+, 35+, 36+ and 38+ months from study commencement. In contrast, pts with ATM aberrant MCL (n=10) the CRR was 90% (95% CI 55-100) with and without PET, and the ORR was 90% (95% CI 55-100) with and without PET. Of the 9 responders with ATM aberrant MCL, the DOR was 9+, 9+, 12+, 24+, 31+, 35+, 36+, 37+ and 38+ months from study commencement. Of 13 deaths, 8 were due to PD. Of the other 5 deaths, 2 were due to infection, and 1 each to cardiac failure, glioblastoma, and graft versus host disease after an allograft that occurred after PD on trial. Five pts in MRD negative PET-confirmed CR electively interrupted treatment after a median 18.5 months (range 18-33) of therapy: one pt had radiological progression after 7 months, and the other 4 remained free of clinical or MRD progression after 6, 13, 17 and 18 months off therapy. Conclusions: The median PFS for the IB-VEN combination was 29 months. Treatment interruption was feasible for pts in MRD-negative complete remissions, raising the prospect of limited duration targeted-agent therapy in the management of R/R MCL. Disclosures Handunnetti: Gilead: Honoraria; Abbvie: Other: Travel Grant. Anderson:Walter and Eliza Hall Institute: Employment, Patents & Royalties: Institute receives royalties for venetoclax, and I receive a fraction of these.. Hicks:Clarity: Research Funding; Ipsen: Research Funding; Telix Pharmaceuticals: Equity Ownership. Bressel:Regeneron Pharmaceuticals: Consultancy. Koldej:NanoString Technologies: Other: Travel grant. Ritchie:Amgen: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; BMS: Research Funding; Takeda: Research Funding; Beigene: Research Funding; Imago: Research Funding; Novartis: Honoraria; Sanofi: Honoraria. Seymour:Roche: Consultancy, Research Funding, Speakers Bureau; Acerta: Consultancy; Takeda: Consultancy; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau. Roberts:Walter and Eliza Hall Institute: Patents & Royalties: Institute receives royalties for venetoclax, and I receive a fraction of these.; AbbVie: Other: Unremunerated speaker for AbbVie, Research Funding; Janssen: Research Funding; Australasian Leukaemia and Lymphoma Group: Membership on an entity's Board of Directors or advisory committees; BeiGene: Research Funding. Tam:AbbVie: Honoraria, Research Funding; Roche: Honoraria; BeiGene: Honoraria; Novartis: Honoraria; Pharmacyclics LLC, an AbbVie company: Honoraria; Janssen: Honoraria, Research Funding. OffLabel Disclosure: While ibrutinib is FDA approved for use in relapsed and refractory mantle cell lymphoma, venetoclax and combination venetoclax and ibrutinib are not licensed for use in mantle cell lymphoma. The use of venetoclax and ibrutinib for this indication is investigational.

Description: Key PointsCirculating tumor DNA can monitor disease and predict treatment failure by tracking driver mutations and karyotypic abnormalities in MDS.

Description: INTRODUCTION: Multiple myeloma (MM) is a biologically and clinically heterogeneous disease. Different recurrent driver genomic events have been reported, but to date no unifying feature has been identified in MM evolution. The recent interest in signatures of mutational processes through analysis of whole-exome sequencing data has led to initial insights into what generates MM mutational repertoire (Bolli et al, Nat Com 2014). Here, taking advantage of the increased power provided by whole genome sequencing (WGS), we analyzed 22 paired samples from 11 patients first at the smoldering (SMM)/MGUS stage and subsequently at the time of progression to symptomatic MM to gain a deeper understanding of the full landscape of mutational processes operative in MM, especially during their evolution over time. MATERIAL AND METHODS: DNA from bone marrow CD138+ cells underwent WGS along with a matched normal sample using HiSeq X Ten machines (Illumina, Inc.). Mutational signature extraction was performed running non-negative matrix factorization (NMF) as previously described (Alexandrov et al, Nature 2013). RESULTS: We have observed and utilized a median number of 5780 (range 2599-7760) substitutions per patient at the asymptomatic stage and 5954 (ranges 2824-8227) at progression to MM stage to extract mutational signatures. NMF extracted 5 main signatures (http://cancer.sanger.ac.uk/cosmic/signatures). Specifically, APOBEC- (signature #2) and age-related signatures (signatures #1 and #5) accounted for 13% (1-21%) and 23% (3.2-40%) of all substitutions, respectively. In addition, we found two known signatures that were not implicated in MM so far: non-canonical AID (Signature #9), contributing to 28% of all substitutions (17-55%); and signature #8, accounting for 28% of all substitutions (13-45%) and pertaining to a yet unknown mutational process. Finally, the fifth signature did not match any of the previously described ones, representing a potential novel process which we defined as MM-1 (7%, range (1-16%). Interestingly, we found a differential contribution of processes in non-coding and intronic regions where AID was more prevalent, while exonic regions where APOBEC and age signatures were more prevalent. In intronic regions we found widespread regions of kataegis (9/11 patients), reflective of localized hypermutation. In our patients, kataegis was associated with rearrangements in 60% of cases, and was present in both the SMM and MM sample in 84% of cases, suggestive of an early event during tumor development. Contrary to what is observed in solid cancers, APOBEC signature was only responsible for 25% of kataegis variants, vs 70% for AID, suggesting a causative role of aberrant AID activity in shaping the early mutational repertoire of neoplastic plasma cells. To confirm this, we looked at serial samples in our cohort. While the percent contribution of each signature varied in each patient, confirming genomic heterogeneity of MM, it did not change when paired SMM and MM samples from the same patient were compared. This shows that mutational processes required for the development of symptomatic MM act early, and have been already operative at the SMM stage. However, by clustering substitutions as clonal (early variants present at the time of tumor initiation) or subclonal (late variants arisen closer to the time of sampling) using a Bayesian hierarchical Dirichlet process (Bolli et al, Nature Comms 2014), we could analyze processes operative before SMM was diagnosed. NMF analysis of these clusters reported striking differences. Specifically, AID and age were the predominant mutational processes in early substitutions in all patients, contributing to a median of 35% (25-54%) and 30% (15-43%) of variants respectively. Conversely the contribution of AID was minimal among late substitutions (5%, 1-22%), where instead APOBEC, Signature #8 and MM-1 activity was prominent [19% (1-43), 38% (8-73%), 16% (2-50%) respectively]. CONCLUSION: WGS data allowed the identification of mutational processes operative well before MM becomes clinically evident. Our observation that all samples have signs of aberrant AID at the time of tumor initiation supports a unifying model where MM precursors are initially transformed with the contribution of AID, providing a fertile ground for other later processes (i.e APOBEC and signature #8) to act and shape the final genomic landscape of overt multiple myeloma. Disclosures No relevant conflicts of interest to declare.

Description: Introduction: Follicular lymphoma (FL) is the most common indolent non-Hodgkin lymphoma in the world and has a median age at diagnosis in the seventh decade. FL in young adults (YA; 40 years old or younger) is extremely rare. Currently, there are no standard approaches guiding treatment of YA patients with FL, and very little is known about disease characteristics and outcomes of YA patients with FL given limited research conducted in this vulnerable population. To gain further insight into FL in YA, we analyzed the National LymphoCare Study (NLCS) to describe disease and patient characteristics, as well as features of treatment in YA patients with FL. We previously reported that 2-year progression-free survival (PFS) is an important survival endpoint in patients with FL undergoing chemo-immunotherapy. Hence, we also sought to characterize 2-year PFS in this age group and compare it to older cohorts. Methods: Evaluablepatients were identified in the NLCS, and those between 18–40 years of age with newly diagnosed FL at any stage were classified as YA patients. Patients with mixed histology or transformed disease were excluded, as were patients with progression of disease prior to beginning first-line treatment. Survival probability was estimated by the Kaplan-Meier method. We estimated the association of age group with PFS using hazard ratios (HR) and 95% confidence intervals (CI) from multivariable Cox models. Results: A total of164 YA patients with FL were analyzed, representing 6.2% of the NLCS population, similar to the observed frequency in the Surveillance, Epidemiology, and End Results (SEER) Program data (4.8% of all FL). Sixty nine percent of YA patients had advanced stage disease. The majority of patients (80%) had low-grade histology, and 50% had good risk disease according to the Follicular Lymphoma International Prognostic Index (FLIPI). Nineteen percent of patients (31/164) underwent watchful waiting, 12% received rituximab monotherapy, and 47% received chemo-immunotherapy (61% of whom received R-CHOP [rituximab, doxorubicin, vincristine, prednisone]). There was no significant difference in FLIPI score or other baseline disease characteristics compared to adult patients aged 41–60 years. Eleven deaths occurred among YA with FL; only 5 of these were lymphoma related. Overall survival (OS) at 2 years was 97.4% (95% CI 93.3%, 99.0%), and at 5 years, 93.7% (88.3%, 96.7%), which was similar to patients aged 41–60 (97.2% [96.0%, 98.0%] at 2 years, and 92.0% [90.1%, 93.5%] at 5 years). After a median follow-up of 7.1 years, OS in YA FL was 92%. Through follow-up, there were 64 PFS events. The estimated 2-year PFS (95% CI) for YA and adults 41–60 was 75.9% (67.1%, 82.6%) and 80.9% (78.1%, 83.4%), respectively. After adjusting for FLIPI score, there was no difference in PFS for YA with FL requiring first-line treatment (excluding watchful waiting) compared to adults aged 41–60 years (HR=0.93; 95% CI 0.69, 1.25), and no difference in OS compared to adults aged 41–60 years (HR=1.19; 95% CI 0.64, 2.23). Conclusions: In the largest cohort of YA patients with FL to date, we found few differences in outcomes compared to patients aged 41–60. FLIPI and other disease characteristics were similar to adults aged 41–60 years. There were no differences between YA FL and adults aged 41–60 in PFS for all treated patients. OS in the YA group of patients with FL was outstanding. YA patients with FL have reassuringly similar outcomes to patients aged 41–60. Fertility preservation and survivorship issues should be taken into consideration when defining management strategies, but otherwise these data support that YA patients with FL should not be approached differently from older adults with the same disease. Disclosures Byrtek: Genentech, Inc.: Employment, Equity Ownership. Dawson:Genentech, Inc.: Employment, Equity Ownership. Zhou:RTI-HS: Employee of RTI-HS, which has research contracts with Genentech Other. Flowers:Seattle Genetics: Consultancy; Spectrum: Consultancy, Research Funding; Sanofi: Research Funding; Abbott: Research Funding; Novartis: Research Funding; OptumRx: Consultancy; Millennium/Takeda: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Allos: Consultancy. Farber:Gilead: Speakers Bureau; Janssen/Pharmacyclics: Speakers Bureau; Seattle Genetics: Speakers Bureau; Leukemia Lymphoma Society NJ Chapter: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Speakers Bureau, Stock ownership Other. Cerhan:Genentech, Inc.: LymphoCare Scientific Advisory Board Other. Link:Genentech, Inc.: Consultancy, Scientific Advisory Board for Genentech Other.

Description: BACKGROUND: Patients with relapsed and/or refractory non-Hodgkin's lymphoma (NHL), especially those with aggressive lymphomas, have overall poor prognosis. Novel targets and therapies are under investigation. Molibresib (GSK525762) is a potent and specific inhibitor of the bromodomain and extraterminal domain (BET) family of proteins, the inhibition of which prevents transcriptional complex assembly and the subsequent expression of oncogenic drivers. Molibresib inhibits growth in NHL cell lines, both in vitro and in vivo. Study BET116183 was designed to evaluate the safety, tolerability, and preliminary efficacy of molibresib in relapsed and refractory hematologic malignancies. Here we report the results from the NHL dose escalation cohort. METHODS: Eligible subjects were adults with relapsed or refractory NHL. An accelerated dose titration was employed with one subject per dose level until the occurrence of a ≥Grade 2 drug-related toxicity; thereafter, subjects were enrolled in a standard 3+3 design. A Neuenschwander continual reassessment method (N-CRM) model was used to provide guidance for the next dose level. Dose escalation continued until the maximum tolerated dose (MTD) was identified. All data, including safety, tolerability, pharmacokinetics (PK), and efficacy, were used to identify the recommended part 2 dose (RP2D). RESULTS: From 14 May 2014 to the data cutoff date of 24 June 2018, 27 NHL subjects were enrolled and received at least one dose of study drug. Of these, 19 (70%) had B-cell lymphomas (diffuse large B-cell lymphoma [DLBCL], mantle cell lymphoma, marginal zone lymphoma, follicular lymphoma , and Burkitt's lymphoma); eight subjects (30%) had T-cell lymphomas (cutaneous T-cell lymphoma [CTCL], anaplastic T-cell lymphoma [ATCL], peripheral T-cell lymphoma, and adult T-cell leukemia/lymphoma). The median age was 64 years (range 24 to 76); 20 subjects (76%) were male and 7 subjects (24%) were female. The median number of prior treatments was 3 (range 1 to 〉 4). From the starting dose of 10 mg molibresib orally once daily (QD), the dose was escalated to 80 mg QD. The median time on study was 1.4 months (range 0.2 to 20 months). Two dose-limiting toxicities (DLTs) were identified in subjects treated at 60 mg QD, though one was subsequently determined not to be a DLT. One subject experienced Grade 4 thrombocytopenia related to study drug. A second subject experienced a Grade 2 mechanical fall; this event was later revised to unrelated to study drug. Across all dose levels, all subjects experienced an adverse event (AE); 25 subjects (93%) experienced at least one AE that was deemed to be related to molibresib treatment. The most common related AEs across all dose levels were thrombocytopenia (n = 21 [78%]), fatigue (n = 6 [22%]), nausea (n = 6 [22%]), diarrhea (n = 4 [15%]), and rash (n = 4 [15%]). Blood bilirubin was increased in 3 subjects (11%), and prothrombin time and activated partial thromboplastin time were prolonged in 2 subjects each (7%). Common Grade 3 and Grade 4 related events included thrombocytopenia (n = 19 [70%]), as well as anemia, asthenia, and increased blood bilirubin (n = 2 [7%] each). No Grade 5 related AEs were reported. Among all subjects, 11 (41%) required dose reduction for toxicity: 7 subjects at the 60 mg dose level (39% treated at that dose) and 4 at the 80 mg dose level (57% treated at that dose). PK analyses showed dose-proportionality after single and repeat dosing, with large variability between subjects. One subject with DLBCL achieved a complete remission that was durable through week 54 on study. Four additional subjects (one DLBCL and 3 CTCL) achieved partial remission, for an objective response rate (ORR) of 5/27 (18.5%). Five more subjects had stable disease as best response. Of six CTCL/ATCL subjects enrolled, three subjects had partial response for an ORR of 50% in this sub-population. CONCLUSIONS: This is the first study evaluating the safety and efficacy of the BET inhibitor molibresib in NHL subjects. Overall, thrombocytopenia and other AEs were monitorable, manageable and reversible. The RP2D was identified as 60 mg QD. Single-agent activity was observed across multiple NHL subtypes at both 60 mg and 80 mg doses; most notable was a 50% response rate in subjects with CTCL. Because of the promising data, Part 2 of the BET116183 study is currently open and enrolling subjects with CTCL to better define the clinical activity of BET bromodomain inhibition in this histology. Disclosures Dickinson: GSK: Consultancy. Kamdar:Genentech: Consultancy; Seattle Genetics: Speakers Bureau. Mateos:Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: 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; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees. Alegre:Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Kim:Roche: Research Funding; Mundipharma: Research Funding; J&J: Research Funding; Novartis: Research Funding; Kyowa-Kirin: Research Funding; Celltrion: Research Funding; Takeda: Research Funding. Martín:Janssen: Honoraria, Other: Travel expenses; Celgene: Consultancy, Honoraria, Other: Travel expenses; Roche: Consultancy, Honoraria, Other: Travel expenses; Servier: Honoraria, Other: Travel expenses. Horner:GSK: Employment. Winnberg:GSK: Employment. Mathew:GSK: Employment. Botbyl:GSK: Employment. Karpinich:GSK: Employment. Kremer:GSK: Employment. Dhar:GSK: Employment. Karadimitris:GSK: Research Funding; Gilead: Honoraria; Celgene: Research Funding.

Description: Introduction: Evaluation of patients' psychosocial burden related to their cancer and its treatment is important for shared decision making by patients and their healthcare team. We aimed to better understand the impact of age on this burden as reported by patients with chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL), and follicular lymphoma (FL) using data from a large US patient advocacy survey. Methods: We developed a survey to understand patients' perceptions of disease burden and impact on physical and emotional health. The survey was designed through consultation with medical experts, patient advocacy organizations and research team members. Concept elicitation and cognitive pretesting were conducted with patients to inform the survey content. The survey was administered electronically to patients with CLL, DLBCL, or FL who had received either initial or subsequent treatment within the past year. The survey consisted of categorical Likert options that quantified the impact of disease on physical function, sleep, cognition, work, emotional health and quality of life (QoL). The survey data were analyzed descriptively by patients' reported age: 60 years or older versus less than 60 years. Results: The survey was completed by 424 patients who were associated with The Leukemia & Lymphoma Society and/or the Lymphoma Research Foundation (309 patients with CLL, 59 patients with DLBCL and 69 patients with FL). Respondents had a mean age of 66 years (range: 22-95 with five patients electing not to report their age), 79% were 60 years or older, and 51% were female. A greater proportion of younger patients (

Description: Purpose: Drug resistance is the greatest obstacle to the successful treatment of multiple myeloma (MM). We investigated whether the clinical XPO1 inhibitor selinexor (KPT-330), when combined with bortezomib or carfilzomib, could overcome proteasome inhibitor (PI) resistance in myeloma. Experimental Design: PI-resistant human MM cell lines 8226-B25 and U266-PSR were treated with the XPO1 inhibitors selinexor or KOS-2464 in combination with bortezomib or carfilzomib and assayed for apoptosis and viability. Mice challenged with PI-resistant human MM cells (U266-PSR) were treated with selinexor +/- bortezomib. CD138+/light-chain+ MM cells from PI-refractory MM patients were treated with selinexor +/- bortezomib or selinexor +/- carfilzomib and assayed for apoptosis. All experiments were compared to the standard of care, bortezomib therapy. IkBα-protein was assayed by Western blot and immunofluorescence microscopy and IkBα-NFkB-complex formation by proximity ligation assay. IkBα protein knockdown in human MM cells by siRNA was performed to determine the mechanism of selinexor inhibitor action. Further analysis of selinexor/bortezomib treatment on intra-cellular protein levels and intra-cellular localization was performed by lysine and N-terminal labeling with six-plex tandem mass tags (heavy isotope) and assayed by LC-MS/MS discovery proteomics. Results: Selinexor in combination with bortezomib or carfilzomib decreased viability and induced apoptosis in PI-resistant MM cells. Resistant MM cell lines were up to 10-fold resistant to single agent bortezomib or carfilzomib when compared to parental cells. The combination of the XPO1 inhibitors selinexor or KOS-2464 sensitized drug resistant cells to bortezomib (P 〈 0.02) and carfilzomib (P 〈 0.005) when compared to single agents. Selinexor and bortezomib inhibited PI-resistant MM tumor growth and increased survival with minimal toxicity in NOD/SCID-g mice. Bone marrow mononuclear cells isolated and treated with selinexor or KOS-2464 and bortezomib or carfilzomib from newly diagnosed (n=8), relapsed (n=5), and bortezomib (n=8) and carfilzomib (n=6) refractory MM patient samples were all sensitized by selinexor and KOS-2464 to bortezomib (P 〈 0.043) and carfilzomib (P 〈 0.044) as shown by increased apoptosis. Normal, non-myeloma CD138/light-chain double-negative patient cells were not sensitized to apoptosis by XPO1 inhibitors. Immunofluorescence microscopy of IkBα in 8226-B25 PI-resistant cells showed an increase in IkBα after treatment with selinexor/bortezomib as compared with vehicle control or single agent bortezomib or selinexor. Nuclear IκBα was also increased by selinexor treatment. IkBα protein expression was increased by bortezomib (70%) and selinexor (50%) versus control. The selinexor/bortezomib combination increased IkBα protein (212%) as compared to vehicle control or single agent bortezomib or selinexor. Similar results were found in drug-naïve 8226 and U226 cells, as well as PI-resistant 8226-B25 and U225-PSR cells. The increase in nuclear IkBα after selinexor treatment was confirmed by ImageStream flow cytometry. Selinexor/bortezomib therapy significantly increased IkBα-NFkB-complexes in PI-resistant MM cells. Selinexor in combination with bortezomib increased proximity co-localization of NFkB and IkBα without affecting XPO1 protein expression after 4 hours of drug treatment. Analysis of the number of NFkB-IkBα foci/binding showed that selinexor/bortezomib increased the number of foci in the nucleus versus untreated control or single agent selinexor or bortezomib (P ≤ 0.00077). IkBα knockdown reduced selinexor-induced cytotoxicity in both IM-9 (9.5-fold) and 8226 (12.3 to 25.4-fold) human MM cells. Intracellular protein analysis by heavy isotope labeling and LC-MS/MS showed changes in several signaling pathways including p53, MAPK, VEGF and angiopoietin, IL-1, HMGB1/TLR and APRIL and BAFF as well as those related to NFkB signaling. Conclusion: Selinexor, when used in combination with bortezomib or carfilzomib has the potential to overcome PI drug resistance in MM. Disclosures Kashyap: Pharma: Employment. Landesman:Karyopharm Therapeutics: Employment. Kauffman:Karyopharm: Employment, Equity Ownership. Shacham:Karyopharm: Employment, Equity Ownership.

Description: Retinoids such as all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid (9-cis-RA) have an important role in many aspects of proliferation and differentiation of hematopoietic cells. They exert their effects by binding to retinoic acid receptors (RARs) and/or retinoid X receptors (RXRs). We studied the effects of novel retinoids on proliferation and differentiation of HL-60 and NB4 myeloid leukemic cells, as well as acute promyelocytic leukemia (APL) cells from patients. RXR-selective SR11345 (Retinoid C) had little ability to inhibit the clonal growth and to induce the differentiation of either HL-60 or NB4 cells. However, SR11276 (Retinoid E), which activated both the RAR and RXR classes, and SR11278 (Retinoid D), which activated the RAR subtypes , β, and γ, could inhibit clonal growth of both cell types, as well as leukemic cells from APL patients. The combination of ATRA and either SR11276 or SR11278 additively inhibited APL cell proliferation. SR11302 (Retinoid A), with reported anti-AP–1 activity and no activation of RARs and RXR and SR11363 (Retinoid B), which selectively activated RARβ and γ, were inactive. The clonal proliferation of both HL-60 and NB4 cells that were pulse-exposed to 10-9 mol/L ATRA, SR11276, SR11278, or SR11345 for 3 days, washed, and plated in methylcellulose culture were inhibited by 0%, 51%, 21%, and 1% for HL-60 cells and 43%, 41%, 35%, and 1% for NB4, respectively, compared with nontreated control cells. When the HL-60 cells were pulse-exposed to 10-9 mol/L of either SR11278 or SR11276, plus 10-9 mol/L ATRA for 3 days, colony numbers were reduced by 46% and 64%, respectively. Induction of leukemic cell differentiation as determined by the nitroblue tetrazolium (NBT) assay showed that the combination of 10-7 mol/L of either SR11278 or SR11276 with 10-7 mol/L ATRA had additive effects on HL-60 cells, NB4 cells, and fresh APL cells. Induction of CD11b expression on both HL-60 and NB4 cells occurs during their differentiation. Expression of this antigen was synergistically augmented by the combination of either 10-7 to 10-8 mol/L SR11278 or 10-7to 10-9 mol/L SR11276 with 10-9 mol/L ATRA compared with either analog alone in HL-60 cells. Expression of the novel myeloid specific transcription factor C/EBPɛ was increased by SR11278 and SR11276 in both the HL-60 and NB4 cell lines. We conclude that retinoids or combination of retinoids with specificities for both RAR and RXR may markedly enhance the ability of ATRA to inhibit clonal growth and induce differentiation of HL-60 and NB4 leukemic cells. This occurs in the absence of continuous contact with retinoids.

Description: Background Disease characteristics, treatment patterns, and outcomes of follicular lymphoma (FL) patients (pts) aged 〉80 years (yrs) are infrequently reported. Further, the original Follicular Lymphoma International Prognostic Index (FLIPI) has not been formally studied in pts aged 〉80 yrs. Also, whether FLIPI is associated with overall survival (OS) in pts aged 〉80 yrs is unknown. Patients/Methods We used the National LymphoCare Study—a Genentech-sponsored, prospective, multicenter registry of FL pts across the United States without study-specific treatment—to comprehensively analyze FL pts aged 〉80 yrs. Using Pearson chi-squared tests, associations of age groups with disease characteristics and overall response rate (ORR) were examined. Median progression-free survival (PFS) and OS by treatment regimen were estimated using the Kaplan-Meier method. Cox proportional hazards regression that were adjusted for baseline disease factors were used to assess treatment differences in PFS, lymphoma-related mortality (LRM, which includes both disease and treatment-related deaths), and OS, as well as the significance of age by treatment interactions. FLIPI and a prognostic model that was constructed based on the findings were used to predict outcomes. Results Of 2649 evaluable pts, 209 (8%) were aged 〉80 yrs. Compared with pts aged ≤60, pts aged 〉80 yrs were more likely to be Caucasian, to have worse performance status, to have lower hemoglobin (Hgb) value (80 yrs had lower ORR compared with younger pts and were less likely to receive rituximab + chemotherapy (P 80 yrs when rituximab + chemotherapy induction was administered (44% for pts aged ≤60, 59% for pts aged 〉80, P=.04). After adjusting for maintenance use, sex, and baseline factors, age significantly differentiated PFS impact of observation, rituximab monotherapy, and rituximab + chemotherapy (P=.01). No treatment regimen provided superior PFS or OS in pts aged 〉80 yrs. With a median follow-up of 6.5 yrs for all pts (4.3 yrs for pts aged 〉80 yrs), 5-year OS was 59% and 92%for patients aged 〉80 and ≤60 yrs, respectively. OS in pts aged 〉80 yrs varied based on FLIPI score (log-rank test, P=.01; Figure 1). Interestingly, the percentage of deaths that were disease-related was 40% in pts aged 〉80 yrs, which was comparable to the percentage in pts aged ≤60 yrs of 48%. Cox modeling showed that lower Hgb, B symptoms, and male sex predicted worse OS (P80 yrs. Recognizing that males have inferior OS compared with females in the general population, we constructed a prognostic model composed only of B symptoms and Hgb level 80 yrs and so was a proposed prognostic model comprising lower Hgb and B symptoms. Independent validation of this model is required, and additional prospective studies that are designed for the oldest old are warranted. Disclosures: Nabhan: Genentech Inc.: Advisory Board Other, Honoraria. Byrtek:Genentech, a member of the Roche group: Employment, Equity Ownership; Roche: Equity Ownership, stock options, stock options Other. Dawson:Genentech: Employment; Roche: Equity Ownership. Link:Genentech: Consultancy; Millenium: Consultancy; Pharmacyclics: Consultancy; Spectrum: Consultancy; Genentech: Research Funding; Millenium: Research Funding; Pharacyclics: Research Funding. Zelenetz:GSK: Consultancy; Celgene: Consultancy; Cephalon: Consultancy; Gilead: Consultancy; Seattle Genetics: Consultancy; Sanofi-Aventis: Consultancy; Genentech: Research Funding; GSK: Research Funding; Roche: Research Funding; Cancer Genetics: Scientific Advisor Other. Cerhan:Genentech: Scientific Advisory Board of the National LymphoCare Study Other. Flowers:Abbott, Celgene, Millennium/Takeda, Sanofi, Spectrum, Janssen: Research Funding; Celgene, Genentech Bio-oncology: Consultancy.

Description: Multi-functional enzymes such as thrombin acquire specificity from exosite-dependent interactions. Peptide inhibition studies of protein-protein interactions are useful to identify exosite functions. We developed a novel general approach for exosite analysis using photocrosslinking of exosite inhibitory peptides that also carry a fluorescent tag and reporter. Here we demonstrate the method’s feasibility in studying the thrombin-hirugen (enzyme-peptide) complex. Thrombin contains two positively-charged exosites, named exosites I and II. Hirugen, the C-terminal residues 54 to 65 of hirudin, binds exosite I of thrombin. A series of desulfo-hirugen analogs were synthesized with either an additional fluorescein-(benzoyl) phenylalanine-(abbreviated Fl-bF-), or Fl-bF-mercaptopropionic acid or Fl-bF-lactic acid moiety conjugated to the N-terminal end of the peptide; i.e. a fluorescent label followed by a photocrosslinker and a cleavable linker in succession were conjugated to the N-terminus of hirugen analogs. Each hirugen analog was bound and photocrosslinked to thrombin, and the resulting covalent complex was purified from the reactants to homogeneity. These thrombin-hirugen adducts hydrolyzed small oligopeptide substrates (CBS 34-47 or S2366) with an efficiency similar to that of native thrombin, showing that the active site was unaffected by labeling. However, these adducts were significantly inhibited in assays of fibrinogen clotting and of thrombomodulin-mediated protein C activation, implying that exosite I was blocked, causing reduced accessibility for the substrate, fibrinogen, or for the cofactor, thrombomodulin. Exosite II mediates thrombin binding to heparin. The thrombin-hirugen adduct bound to and eluted from heparin-Sepharose like native thrombin, suggesting that exosite II was unaffected by the photocrosslinked hirugen analog. Treatment of the thrombin-(Fl-bF-mercaptopropionic acid) hirugen adduct that contains a thioester bond with the mild nucleophile hydroxylamine released the amino acids C-terminal to the thioester bond from the adduct, effectively releasing hirugen residues 54–65 from the complex while retaining the fluorescein reporter near exosite I (Fl-thrombin). This treatment did not affect the amidolytic activity of Fl-thrombin. Additionally, Fl-thrombin could be inhibited by unlabeled hirugen suggesting that exosite I was uncovered by release of the peptide by hydroxylamine treatment. In summary, our results show that exosites of clotting factors, e.g., thrombin, can be specifically targeted and labeled with fluorescent reporters. This novel technology may have broad applicability for studies of protein-protein interactions that regulate coagulation.