Citations

Abstract The human IGHV4-34 gene encodes antibodies which are intrinsically autoreactive when the VH domain is unmutated. Therefore, B cells expressing IGHV4-34 B-cell receptor immunoglobulins (BcR IG) are normally under close scrutiny in order to avoid unwanted autoreactivity, especially against DNA. The IGHV4-34 gene is frequently utilized in chronic lymphocytic leukemia (CLL), where, typically, it shows a high load of somatic hypermutation (SHM). We have previously reported distinctive SHM patterns amongst IGHV4-34 CLL, especially for subsets with stereotyped BcR IG. However, although a large number of cases (~2000) was previously studied, since even the largest subsets account for only ~3% of CLL, meaningful conclusions could not be reached for smaller subsets. Here we revisit this issue in a series of 16,528 CLL cases and focus on IGHV4-34 expressing subsets: #4 (IGHV4-34/IGHD5-18/IGHJ6 | 156 cases, 0.9%); #11 (IGHV4-34/IGHD3-10/IGHJ4 | 16 cases, 0.1%); #16 (IGHV4-34/IGHD2-15/IGHJ6 | 41 cases, 0.25%); #29 (IGHV4-34/IGHD: unassignable/IGHJ3 | 39 cases, 0.24%); and #201 (IGHV4-34/IGHD: unassignable/IGHJ3 | 43 cases 0.26%). Focusing on codons 27-104 within the VH domain (from CDR1-IMGT to FR3-IMGT), we calculated the sequence distance between subsets and the corresponding IGHV4-34 germline sequence based on a pairwise qualitative and quantitative comparison of the respective amino acid composition. The minimum distance calculated, and hence the greatest identity, was observed between subsets #4 and #16, both concerning IgG-switched cases (IgG-CLL), which is notable given the overall rarity of IgG-CLL. In contrast, the maximum distance, implying the least identity, was between subsets #16 and #201, the latter concerning IgM/D-CLL. Extreme variations between subsets were noted in codons spanning the entire VH domain. This result is consistent with our finding of a subset-biased distribution of mutations over the VH domain. More specifically, while subsets #11, #16, #29 and #201 had a lower frequency of mutations within VH CDR1 compared to VH CDR2, the exact opposite was seen in subset #4, with 40% of mutations in VH CDR1 versus 27% in VH CDR2. In addition, subsets #4, #11, #16 and #29 had a similar distribution of mutations in VH FR2 and VH FR3, in contrast to subset #201 that showed a preference for VH FR3 over VH FR2. Consequently, we noted that certain positions were targeted in a subset-specific manner e.g. codon 28 in VH CDR1 was heavily targeted in subsets #4 (68.6%) and #16 (87.8%), with most cases carrying an acidic amino acid (AA) introduced by SHM, glycine to glutamic acid, G>E: 51.3% for subset #4 and 78% for subset #16. The high prevalence of acidic AA introduced by SHM in these subsets is notable considering the electropositive nature of their VH CDR3 (especially of subset #4), strongly recalling edited anti-DNA antibodies. Interestingly, the G>E change was identified at a much lower frequency in other IGHV4-34 subsets: 18.75% for subset #11; 2.6% for subset #29; 7% for subset #201, all of which carried electronegative VH CDR3. Further, we noted that certain positions were heavily targeted in all subsets e.g. 56-86% targeting for SHM at codon 92 in VH FR3 where serine is encoded by the agc triplet, the ”hottest of hotspots”. This result could be viewed as sequence- rather than subset-dependent and linked to the molecular features of this codon, which is supported by the low targeting of codon 93 (0-6%), also encoding serine by the tct triplet. Other positions were targeted in all subsets but at vastly different frequencies e.g. codon 64 was targeted in 37.8% in subset #4 rising to 100% in subset #29. Finally, positions heavily targeted by SHM in certain subsets were unmutated in other subsets e.g. codon 36 in VH CDR1 remained unmutated in subset #16, in contrast 76.9% of subset #29 were mutated at this position resulting in an AA change. In conclusion, we document different spectra of SHM and AA changes between stereotyped IGHV4-34 CLL subsets. The finding of subset-biased, recurrent AA changes at certain codons indicates that the respective progenitor cells may have responded in a specific manner to the selecting antigen(s), despite expressing the same IGHV gene, indicating a functional purpose for these modifications. This is exemplified by the molecular characteristics of the recurrent AA changes in subset #4, thereby offering interesting pathogenetic hints. Disclosures No relevant conflicts of interest to declare.

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.

Abstract Abstract LBA-6 Background: Multiple myeloma (MM) patients who have become refractory to bortezomib (BORT) and refractory or otherwise ineligible for thalidomide or lenalidomide (LEN) have a poor prognosis, with a median overall survival (OS) of 9 months (Kumar. Leukemia. 2012). There is no standard treatment available for these patients. Pomalidomide (POM) is a novel immunomodulatory drug that has shown activity in LEN- and BORT-refractory patients (Vij. ASCO 2012). MM-003 is an open-label, multicenter, phase 3 trial designed to compare the efficacy and safety of POM + low-dose dexamethasone (LoDEX) vs high-dose dexamethasone (HiDEX) in a population of patients who are refractory to both LEN and BORT. Here we present the final progression-free survival (PFS) and interim OS analysis of MM-003. Methods: Eligible patients with primary refractory or relapsed and refractory disease were enrolled. All patients with documented disease progression during treatment or within 60 days of completing their last myeloma therapy (including ≥ 2 consecutive cycles of LEN and BORT either alone or in combination), were randomized 2:1 to receive either POM + LoDEX (arm A) or HiDEX alone (arm B). Patients progressing on HiDEX had the opportunity to receive POM in the companion trial, MM-003C. Patients in arm A received POM 4 mg on days 1–21 and DEX 40 mg (20 mg for patients > 75 years of age) on days 1, 8, 15, and 22 in a 28-day cycle. Patients in arm B received DEX 40 mg (20 mg for patients > 75 years of age) on days 1–4, 9–12, and 17–20 in a 28-day cycle. Treatment was continued until progressive disease or unacceptable toxicity. Patients were stratified by age (≤ 75 vs > 75 years), disease population (refractory vs refractory and relapsed vs refractory and intolerant [intolerant to BORT only]), and number of prior therapies (2 vs > 2). The primary endpoint was PFS; secondary endpoints included safety, OS, overall response rate (ORR; ≥ partial response) by IMWG and EBMT criteria, duration of response, time to progression, and quality of life. OS was to be tested only if PFS would be statistically significant; therefore, alpha was controlled at 0.05 2-sided for both PFS and OS. Results: The Data and Safety Monitoring Board (DSMB) reviewed the protocol-specified final analysis results. 455 patients were randomized from March 2011 to Sept 2012. 302 patients received POM + LoDEX, and 153 patients received HiDEX. At the time of analysis, 45% of patients in arm A and 25% of patients in arm B remained on study. The median number of prior therapies was 5 (range, 1–17). 72% of patients were refractory to both LEN and BORT. At the PFS final analysis, with a median follow-up of 18 weeks, PFS was significantly longer with POM + LoDEX vs HiDEX alone (median 15.7 vs 8.0 weeks; 267 total events; hazard ratio [HR], 0.45; P <.001). OS interim analysis was performed as planned; OS also was significantly longer with POM + LoDEX vs HiDEX alone (median not reached vs 34 weeks; 134 events; HR, 0.53; P<.001), crossing the prespecified O’brien-Fleming superiority boundary. This includes 45 pts who received POM after progressing on HiDEX. Median duration of treatment was 12.4 weeks in arm A and 8 weeks in arm B. Following DSMB review of the data, immediate crossover of arm B patients to arm A was recommended. Overall, 25% of patients in arm A and 38% in arm B died, with progressive disease and infections as the primary reasons. Frequent grade 3/4 hematologic toxicities included neutropenia (42% in arm A vs 15% in arm B), thrombocytopenia (21% vs 24%), and febrile neutropenia (7% vs 0%). Other toxicities (grade 3/4) were predominantly infections (24% vs 23%), hemorrhage (3% vs 5%), glucose intolerance (3% vs 7%), neuropathy (1% vs 1%), and venous thromboembolism (1% vs 0%). The primary reason for discontinuation was progressive disease: 35% arm A and 49% arm B. Complete results will be presented at the meeting. Conclusions: POM + LoDEX significantly increased PFS and OS compared with HiDEX in patients who are refractory to LEN and BORT, a population with limited treatment options. The OS superiority boundary was crossed. Based on these data, POM + LoDEX should become the new standard of care in patients who have exhausted the novel agents, LEN and BORT. Disclosures: Dimopoulos: Celgene: Honoraria. Off Label Use: Pomalidomide is an investigational drug and is not approved for the treatment of patients with any condition. Lacy:Celgene: Research Funding. Moreau:Celgene: Honoraria, Speakers Bureau. Weisel:Celgene: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Song:Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees. Delforge:Celgene: Consultancy, Honoraria, Speakers Bureau; Janssen-Cilag: Consultancy, Honoraria; OrthoBiotech: Consultancy, Honoraria, Speakers Bureau. Karlin:Celgene: Consultancy. Goldschmidt:Novartis: Honoraria, Speakers Bureau; Janssen: Honoraria, Research Funding, Speakers Bureau; Celgene: Honoraria, Research Funding, Speakers Bureau. Yu:Celgene: Employment. Sternas:Celgene: Employment, Equity Ownership. Jacques:Celgene: Employment, Equity Ownership. Zaki:Celgene: Employment, Equity Ownership. San Miguel:Onyx: Membership on an entity’s Board of Directors or advisory committees; Janssen: Membership on an entity’s Board of Directors or advisory committees; Millennium: Membership on an entity’s Board of Directors or advisory committees; Celgene: Membership on an entity’s Board of Directors or advisory committees; Novartis: Membership on an entity’s Board of Directors or advisory committees.

INTRODUCTION: Histologic remission is associated with superior long-term clinical outcomes in ulcerative colitis (UC). VARSITY, the first head-to-head comparison of biologic agents in UC (NCT02497469; EudraCT 2015-000939-33), showed superior clinical remission and endoscopic improvement at Week 52 with vedolizumab (VDZ), a gut-selective, humanized, α 4 β 7 integrin monoclonal antibody, vs adalimumab (ADA), a systemic, human, anti-tumor necrosis factor (anti-TNF) monoclonal antibody. 1 Both VDZ and ADA were generally safe and well-tolerated. 1 This analysis compared histologic improvements with VDZ vs ADA in VARSITY. METHODS: Patients with moderately to severely active UC were randomized 1:1 to active VDZ intravenous (IV) infusions (300 mg)/placebo subcutaneous (SC) injections or placebo IV/active ADA SC (160/80/40 mg). Prespecified histologic exploratory endpoints included histologic remission (Geboes score < 2 or Robarts Histopathology Index [RHI] score < 3) and minimal histologic disease activity (Geboes score < 3.2 or RHI score < 5) at Week 14 and Week 52. Histologic remission was also assessed based on previous anti-TNF use. RESULTS: A total of 769 patients received ≥1 dose of VDZ (n = 383) or ADA (n = 386). Median (range) duration of exposure was 477 (127, 630) days for VDZ and 420 (71, 454) days for ADA. Mean (standard deviation) baseline histologic disease activity was similar between groups (Geboes: VDZ, 15.0 [4.92]; ADA, 15.1 [5.03]; RHI: VDZ, 19.5 [8.74]; ADA, 19.6 [8.89]). Histologic remission induced by VDZ at Week 52 was greater than with ADA in the overall (Geboes or RHI), anti-TNF naïve (Geboes or RHI), and anti-TNF failure (RHI only) groups (Table 1). Histologic remission at Week 14 favored VDZ over ADA, with larger differentiation when using RHI (Table 1). VDZ also outperformed ADA in achieving minimal histologic disease activity at Weeks 14 and 52 (Table 1). CONCLUSION: VARSITY showed that use of VDZ, compared with ADA, achieved higher rates of histologic remission and minimal histologic disease activity at Weeks 14 and 52 in patients with moderately to severely active UC. These data support the use of VDZ over ADA in UC.

INTRODUCTION: VARSITY is the first head-to-head trial comparing the efficacy and safety of 2 biologic therapies, vedolizumab (VDZ) and adalimumab (ADA), in patients with moderately to severely active ulcerative colitis (UC). We previously reported significantly higher rates of clinical remission (31.3% vs 22.5%; P = 0.0061) and endoscopic improvement (39.7% vs 27.7%; P = 0.0005) at Week (Wk) 52 with VDZ vs ADA. 1 METHODS: VARSITY was a phase 3b, randomized, double-blind, double-dummy, active-controlled study (NCT02497469; EudraCT 2015-000939-33). Here we report the predefined, exploratory endpoints of early clinical response and clinical remission (defined in the Table 1) within the first 14 wks, as well as durable clinical remission (patients in clinical remission at Wk 14 and Wk 52). RESULTS: A total of 769 patients received ≥1 dose of VDZ (n = 383) or ADA (n = 386). Baseline characteristics were comparable between the 2 groups. A trend for separation in clinical response started to emerge at Wk 6 favoring VDZ vs ADA. Clinical response at Wk 14 favored VDZ vs ADA (257 [67.1%] vs 177 [45.9%]; treatment difference 21.2%). More patients achieved clinical remission at Wk 14 on VDZ vs ADA (102 [26.6%] vs 82 [21.2%]; treatment difference 5.3%). Patients on VDZ achieved higher rates of durable clinical remission (70 [18.3%] vs 46 [11.9%]); laboratory results correlated with these findings. Post hoc analyses showed a larger mean (standard deviation) change of C-reactive protein (CRP) from baseline to Wk 14 (−32.88 [155.77] nmol/L VDZ vs −3.35 [260.81] nmol/L ADA) and to Wk 52 (−50.87 [174.76] nmol/L VDZ vs −37.21 [169.17] nmol/L ADA) in favor of VDZ. Greater mean declines in fecal calprotectin (FCP) levels were seen in patients on VDZ compared with ADA (Wk 14: −1,551.3 [6,236.70] mg/kg VDZ vs −1,167.6 [4,647.67] mg/kg ADA; Wk 52: −2,187.3 [7,440.42] mg/kg VDZ vs −1,846.6 [4,560.55] mg/kg ADA). CONCLUSION: Patients on VDZ had numerically higher rates of both clinical response and clinical remission by Wk 14 compared with ADA. Patients on VDZ also achieved higher rates of durable clinical remission compared with ADA. CRP and FCP results correlated with these findings. These data on early clinical response and clinical remission, as well as durable remission, further support the use of VDZ over ADA in patients with moderately to severely active UC.

Abstract Pericardial involvement in the setting of inflammatory bowel disease can occur not only as an adverse event related to medical therapy but also as an extraintestinal manifestation of the disease itself. In the following case series, we describe 2 cases of pericarditis in patients diagnosed with Crohn disease. Our first case reviews the clinical presentation of acute pericarditis as an adverse event associated with anti-tumor necrosis factor therapy. In contrast, our second patient is a case of acute pericarditis as a precursor of the clinical recurrence of Crohn disease following operative resection. Pericardial disease should be considered in the differential diagnosis of acute and subacute presentations of chest discomfort and shortness of breath in patients with inflammatory bowel disease.

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