Citations

Abstract Backround: Dysregulation of the PI3K/Akt signal transduction pathway has been implicated in the development of a number of malignancies, including multiple myeloma (MM). This cellular signaling mechanism and its downstream targets (eg mTOR) regulate cell growth, proliferation and apoptosis. SF1126 (Semafore) is a water soluble prodrug of the pan-PI3K inhibitor, LY294002, whose anti-proliferative and pro-apoptotic activity has been well described in the literature. Preclinical studies using SF1126 in a variety of malignancies including glioma, prostate, non-small cell lung cancer, and breast cancer appear promising and have demonstrated profound antiangiogenic effects mediated through VEGF inhibition. Aim: To demonstrate in vitro anti-myeloma activity of SF1126, alone and in combination with dexamethasone, bortezomib, and melphalan and evaluate their effects on downstream targets of PI3K/Akt. Methods: MM cell lines (MM.1R, MM.1S, RPMI 8226) were treated with SF1126 (1–100uM), dexamethasone (5uM), bortezomib (5nM), melphalan (10uM) alone, and in combination. Growth inhibition following treatment was measured by MTT assay at 24 and 48 hours. Apoptosis was assessed by annexin-V binding assay using flow cytometry. Immunoblot analysis was performed to measure downstream targets of Akt including: p-PDK1 and mTOR (4E-BP1). Results: A clear dose response was established with an IC50 of 8.75uM in the MM.1R and 7.5uM in the MM.1S cell lines at 48 hours. At 24 and 48 hours, 5uM SF1126 alone resulted in 80% and 64% cell viability by MTT assay, respectively, in the MM.1R cell line. The combination of 5uM SF1126 with conventional agents was then tested in the MM.1R cell line. Combination with 5uM dexamethasone enhanced the efficacy of 5uM SF1126 by 26% at 48 hours. Combination with 10uM melphalan enhanced the efficacy of 5uM SF1126 by 20% at 24 hours. The combination with 5nM bortezomib enhanced the efficacy of 5uM SF1126 by 23% at 48 hours. Given prior experience demonstrating that short exposure to bortezomib activates Akt, we tested sequential administration of bortezomib and SF1126 in the MM.1R cell line. Optimal cell death was induced with bortezomib prior to SF1126, followed by concurrent administration. Immunoblot analysis of p-PDK1, downstream mTOR target (4E-BP1) were performed on the MM.1S cell line treated with 5, 10, 20, and 50uM SF1126 at 12 and 24 hours. At the 12 hour time point, p-PDK-1 appeared to increase, but was significantly reduced by 48 hours. A similar pattern of initial upregulation followed by reduction by 24 hours was seen with the mTOR protein 4E-BP1. Conclusion: SF1126 has dose dependent, in vitro activity in several multiple myeloma cell lines both as a single agent and in combination with dexamethasone, bortezomib, and melphalan. The addition of SF1126 to dexamethasone in a dexamethasone resistant cell line results in increased cell death, possibly by overcoming resistance mechanisms. The addition of SF1126 to bortezomib and melphalan also resulted in increased growth inhibition over either agent alone. These results warrant further study of this promising new pan-PI3K/Akt inhibitor.

Abstract Abstract 1875 Recent experimental evidence suggests that acute myeloid leukemia (AML) originates from hematopoietic stem and progenitor cells (HSPC) following the acquisition of multiple genetic or epigenetic changes that initially give rise to pre-leukemic HSPC (pre-LSC) and then to fully transformed leukemia stem cells (LSC). Relapse continues to be the major cause of death in most subtypes of AML, suggesting that current therapies are largely ineffective in eliminating LSC and pre-LSC. Cellular heterogeneity and the recent observation that LSC are contained within different phenotypic cellular compartments are challenges for the identification of pathways contributing to the initiation and maintenance of AML. To address these challenges we employed a novel strategy of parallel transcriptional analysis of multiple phenotypic HSPC populations from individuals with AML with normal karyotype (N=5), -7/7q- (N=6) and complex karyotype (N=5), including long-term HSC, short-term HSC, and granulocyte-monocyte progenitors (GMP), and comparison to corresponding cell populations from age-matched healthy controls (HC) (N=6). Specifically, we sorted Lin−/CD34+/CD38−/CD90+ (LT-HSC), Lin−/CD34+/CD38−/CD90− (ST-HSC), and Lin−/CD34+/CD38+/CD123+/CD45RA+ (GMP), and hybridized RNA to Affymetrix GeneST 1.0 expression arrays. Differential gene expression was determined within each compartment by direct comparison of AML LT-HSC vs. HC LT-HSC, AML ST-HSC vs. HC ST-HSC, and AML GMP vs. HC GMP. Subsequent intersection of all differentially expressed genes revealed that only a relatively small number of 6 to 11 genes were consistently dysregulated in all examined leukemic stem and progenitor cell compartments. Interleukin 1 receptor accessory protein (IL1RAP) was one of the most significantly upregulated genes in LT-HSC, ST-HSC, and GMP in all examined subtypes of AML. IL1RAP is a transmembrane protein required for signaling through several receptors of the IL1 family, including IL-1R1 and ST2. We detected significant overexpression of IL1RAP protein on HSC and progenitor cells of AML patients. Interestingly, CD34+/Lin+ precursor cells showed only a marginal increase of IL1RAP at the protein level in AML, underscoring the importance of purifying HSPC with stringent lineage depletion. We performed fluorescence in situ hybridization in sorted IL1RAP+ and IL1RAP− cells from -7 AML. We observed that the -7 clone was restricted to IL1RAP+ cells, while IL1RAP- cells did not display monosomy 7, demonstrating that IL1RAP overexpression is a distinguishing feature of the cells of the -7 clone. Patients with normal karyotype AML showed a wider range of IL1RAP expression levels; some were as high as in -7 AML and others were as low as in HC. We asked whether IL1RAP expression levels were associated with known clinical or molecular parameters. We analyzed two published datasets of patients with normal karyotype AML (Metzeler, Blood. 2008;112:4193–4201; Tomasson, Blood. 2008;111:4797–4808). Patients with high IL1RAP levels showed inferior overall survival than patients with lower IL1RAP (p=2.2×10−7; median survival: 7.82 mo. for IL1RAP high, 20 mo. for IL1RAP low). Multivariate analysis using a Cox regression model showed that high IL1RAP status was an independent prognostic factor (p=0.002), and even stronger than FLT3 mutation status (p=0.006). In addition, we analyzed data from 183 patients with MDS and found IL1RAP expression to be specifically elevated in cases with RAEB-2, suggesting a role of IL1RAP in MDS and in the progression to AML. Downregulation of IL1RAP protein expression in 4 AML cell lines (THP1, OCI-AML3, HL60, HEL) led to a significant 45–98% decrease in clonogenic growth and increased apoptosis in vitro. To assess the effects of IL1RAP downregulation in vivo, we performed xenotransplants into immunodeficient NOD/SCID/IL2Rg-null mice. THP-1 AML cells showed a 92% reduced proliferation and infiltration of hematopoietic organs upon IL1RAP knockdown in comparison to a non-silencing control in vivo. Genetic studies to assess the role of IL1RAP in the initiation and maintenance of AML in an IL1RAP−/− mouse model are currently ongoing. In summary, our study provides a map of consistently dysregulated transcripts across multiple fractionated stem and progenitor cell types from patients with AML, and identifies IL1RAP as a putative new therapeutic and prognostic target in stem cells in AML and MDS. Disclosures: No relevant conflicts of interest to declare.

Objective To compare the effectiveness of rituximab (RTX) with cyclophosphamide (CYC) in patients who have central nervous system (CNS) involvement in antineutrophil cytoplasmic antibody–associated vasculitis (AAV). Methods A computer-assisted search was conducted to identify all adults who received a diagnosis of AAV with CNS involvement from January 1, 1997, through July 1, 2017, at our institution. Results Of the 17 patients identified, 11 had received RTX, and 6 had received CYC. Age at diagnosis of CNS involvement was similar in both groups. In the RTX group, 91% of the patients were women; in the CYC group, 33% were women (p = 0.03). At the time of CNS presentation, orbital involvement had occurred in 6 patients in the RTX group and in none of the patients in the CYC group. Initial remission of induction was achieved in all patients (100%) in the CYC group and in 10 patients (91%) in the RTX group. Two patients had no response to RTX: 1 patient when RTX was used for remission induction at the time of diagnosis and the second patient when RTX was used for remission induction after relapse. The median follow-up was 38 months (range, 9–127 months). Central nervous system relapse occurred in 4 patients in the RTX group and in 1 patient in the CYC group. Of the 4 patients in the RTX group with relapse, 3 had marked ocular involvement. Both nonresponder patients in the RTX group had ocular involvement. Conclusion Rituximab is as effective as CYC in remission induction in patients with CNS involvement in AAV.

Abstract Purpose: Predicting surgical outcome could improve individualizing treatment strategies for patients with advanced ovarian cancer. It has been suggested earlier that gene expression signatures (GES) might harbor the potential to predict surgical outcome. Experimental Design: Data derived from high-grade serous tumor tissue of FIGO stage IIIC/IV patients of AGO-OVAR11 trial were used to generate a transcriptome profiling. Previously identified molecular signatures were tested. A theoretical model was implemented to evaluate the impact of medically associated factors for residual disease (RD) on the performance of GES that predicts RD status. Results: A total of 266 patients met inclusion criteria, of those, 39.1% underwent complete resection. Previously reported GES did not predict RD in this cohort. Similarly, The Cancer Genome Atlas molecular subtypes, an independent de novo signature and the total gene expression dataset using all 21,000 genes were not able to predict RD status. Medical reasons for RD were identified as potential limiting factors that impact the ability to use GES to predict RD. In a center with high complete resection rates, a GES which would perfectly predict tumor biological RD would have a performance of only AUC 0.83, due to reasons other than tumor biology. Conclusions: Previously identified GES cannot be generalized. Medically associated factors for RD may be the main obstacle to predict surgical outcome in an all-comer population of patients with advanced ovarian cancer. If biomarkers derived from tumor tissue are used to predict outcome of patients with cancer, selection bias should be focused on to prevent overestimation of the power of such a biomarker. See related commentary by Handley and Sood, p. 9

Abstract BACKGROUND The impact of treatment on both the quality and the quantity of life, i.e. the ‘net clinical benefit’, should be considered to inform glioma patients and facilitate shared decision making. We applied two methods (i.e. Quality Adjusted Effect Sizes (QASES) and Joint Modelling (JM)) that combine survival and health-related quality of life (HRQoL) data into one outcome, to gain insight in the net clinical benefit of a treatment strategy. In addition, we assessed if both methods result in similar interpretations. MATERIAL AND METHODS We calculated the net clinical benefit in one randomized controlled trial, EORTC 26951 comparing radiotherapy (RT) + PCV chemotherapy versus RT alone, as a proof of concept for other trials. With the QASES method, effect sizes for differences in survival and HRQoL between treatment arms were calculated. Next, the combined effect size can be determined by weighing the emphasis put on survival or HRQoL (e.g. survival more important). JM allows simultaneous modeling of a longitudinal outcome (HRQoL), and a time-to event outcome (survival). HRQoL scales/items that were selected for primary analysis in the main study were also selected for this analysis: fatigue, global health, social functioning, communication deficit, seizures, physical functioning, and nausea/vomiting. RESULTS 288/386 patients completed baseline HRQoL forms and were included in the analysis. Overall survival (OS) was significantly longer with combined treatment (difference of 10.8 months). In contrast, the percentage of patients who experienced a clinically relevant deterioration (≥10 points) in nausea/vomiting, fatigue, social functioning and global health up to one year after treatment compared to baseline was larger in the RT+PCV arm. The QASES corresponded to a reduction in the median OS difference from 10.8 months to 6.8 months when adjusted for the HRQoL scales/items, when given equal weights to OS and HRQoL. JM analyses resulted in a theoretical loss of treatment effect in OS of 2–6% when adjusting for HRQoL. CONCLUSION Both methods showed that adjusting for the impact of treatment on a relevant HRQoL parameter reduced the survival benefit in the experimental treatment arm compared to standard treatment arm. Applying these methods may facilitate communicating the impact of treatment to patients in clinical practice.

ObjectiveTo assess the frequency of venous thromboembolism (VTE) events in the Rituximab in Antineutrophil Cytoplasmic Antibody (ANCA)–Associated Vasculitis (RAVE) trial and identify novel potential risk factors.MethodsVTE events in 197 patients enrolled in the RAVE trial were analyzed. Baseline demographic and clinical characteristics were recorded, and univariate and multivariate analyses were performed to identify factors associated with VTE in ANCA‐associated vasculitis (AAV).ResultsVTE occurred in 16 patients (8.1%) with an overall average time to event of 1.5 months (range 1.0–2.75). In univariate analyses with calculation of hazard ratios (HRs) and 95% confidence intervals (95% CIs), heart involvement (HR 17.408 [95% CI 2.247–134.842]; P = 0.006), positive proteinase 3 (PR3)–ANCA (HR 7.731 [95% CI 1.021–58.545]; P = 0.048), pulmonary hemorrhage (HR 3.889 [95% CI 1.448–10.448]; P = 0.008), and the presence of red blood cell casts (HR 15.617 [95% CI 3.491–69.854]; P < 0.001) were associated with the onset of VTE. In multivariate models adjusted for age and sex, the significant associations between VTE events and heart involvement (HR 21.836 [95% CI 2.566–185.805]; P = 0.005), PR3‐ANCA (HR 9.12 [95% CI 1.158–71.839]; P = 0.036), pulmonary hemorrhage (HR 3.91 [95% CI 1.453–10.522]; P = 0.007), and urinary red blood cell casts (HR 16.455 [95% CI 3.607–75.075]; P < 0.001) remained.ConclusionPatients diagnosed as having AAV with pulmonary hemorrhage, positive PR3‐ANCA, heart involvement, and the presence of red blood cell casts are at an increased risk to develop VTE. Further studies are needed to confirm and expand these findings and to explore the mechanisms of hypercoagulability in these patients with the aim of informing potential targets for therapeutic intervention.

Background:There are limited treatment options for red blood cell (RBC) transfusion dependent (TD) LR (IPSS Low/Int‐1) MDS patients who are relapsed/refractory to ESAs. Imetelstat is a first‐in‐class telomerase inhibitor that targets cells with short telomeres and active telomerase, characteristics observed in some MDS patients across all disease stages. Preliminary results show that imetelstat is effective treatment in LR‐MDS patients inducing durable TI (Steensma et al ASH 2018 Abstr463).Aims:We report updated efficacy data with a median follow‐up of 12.1 months in 38 LR non‐del(5q) MDS patients, R/R to ESA and LEN/HMA naive from the open‐label, single‐arm Part 1 of IMerge, an ongoing phase 2/3 study (NCT02598661).Methods:Part 1 of the IMerge study included patients with LR MDS, who were heavily transfused (≥4U/8wks), were R/R to ESA or had sEPO >500 mU/mL. Imetelstat 7.5 mg/kg was administered IV every 4 weeks. The primary endpoint was 8‐week TI rate; key secondary endpoints included 24‐week TI rate, safety, duration of TI, and hematologic improvement (HI) rate. Among the initially enrolled patients, higher 8‐week TI rate was observed in the non‐del5q, LEN/HMA naive patients. Therefore, the study was amended to subsequently enroll only these patients. From a total of 57 patients enrolled in Part 1, 38 were non‐del(5q), LEN/HMA naïve patients (13 in the initial and 25 in the expansion cohort). Here we report long‐term efficacy, safety and biomarker data from these 38 patients.Results:Median baseline RBC transfusion burden was 8U/8weeks (range 4–14), 37% of the patients had IPSS Int‐1; 71% had WHO 2001 RARS or RCMD‐RS subtype and 32% with evaluable sEPO levels had baseline level >500 mU/mL.As of 23 January 2019, median follow‐up was 12.1 months for the 38 patients, representing 30.4 and 11.6 months for the initial 13 and additional 25 patients, respectively. The 8‐week TI rate was 45% (17/38) and median TI duration was 8.5 months (range 1.8–32.4). Of the 17 responding patients, 10 (59%) remained transfusion free for over 24 weeks. The 8‐week TI rate did not differ based on the presence of ring sideroblasts or baseline sEPO levels. The 24‐week TI rate was 26% (10/38). Erythroid HI, defined as transfusion reduction by at least 4 units /8 weeks (IWG2006), was achieved in 68% (26/38) of the patients. The most frequently reported adverse events were manageable and reversible grade ≥3 cytopenias. 6/38 patients had IPSS‐R intermediate/poor cytogenetic risk. All 6 patents achieved 8‐week TI; 2/6 patients achieved partial cytogenetic response. Post treatment decrease in telomerase hTERT RNA level was observed in 25/34 (73.5%) patients with available sample. Among 7 patients with pre‐ and post‐treatment mutation analyses, six had SF3B1 mutations at baseline, and a decrease in the mutation VAF was observed in 2 patients that had longest TI duration on study.Summary/Conclusion:In high RBC transfusion burden patients with non‐del(5q) LR‐MDS R/R to ESA and naive to LEN/HMA, single‐agent imetelstat yielded 8‐week TI rate of 45%, with a median duration of 8.5 months (range 1.8–32.4). The 24‐week TI rate was 26%. HI‐E rate was 68%. All patients with IPSS‐R intermediate and poor cytogenetic risk responded. Biomarker analyses of telomerase activity and mutation allele burden indicate an effect on the malignant mutant clone. These data support Part 2 of IMerge, Phase 3 placebo‐controlled, randomized portion of the study, expected to open mid‐2019.