Citations

Abstract Abstract 985 Introduction: CFZ is a novel and highly selective epoxyketone proteasome inhibitor currently in clinical development for the treatment of multiple myeloma (MM). Ph 1 and 2 studies with CFZ have demonstrated durable single-agent antitumor activity in pts with relapsed or refractory (R/R) MM. The present study, PX-171-003-A1, was an open-label, single-arm Ph 2b trial and enrolled patients with multiply relapsed MM whose disease was refractory (defined as <25% response on, or progression during or <60 days after completion of, therapy) to their last treatment regimen. Patients must have received ≥2 prior therapies including: 1) bortezomib (BTZ) and either thalidomide (THAL) or lenalidomide (LEN), and 2) an alkylating agent. Materials and Methods: Pts received CFZ at 20 mg/m2 on a QDx2 schedule (Days 1, 2, 8, 9, 15, and 16 every 28 days) in cycle (C) 1 and were dose escalated to 27 mg/m2 on the same schedule thereafter for up to 12 C. Pts completing 12 C were eligible to enter an extension study (PX-171-010). The primary endpoint was overall response rate (ORR) (≥ partial response [PR]). Secondary endpoints included: clinical benefit response (CBR) (ORR + Minimal response [MR]), duration of response for ≥PR (DOR), overall survival (OS), time to progression (TTP), progression free survival (PFS), and safety. Responses and progression were determined according to the International Myeloma Working Group (IMWG) criteria and were assessed and confirmed by an Independent Response Committee (IRC). Results: 266 pts were enrolled with a median duration of MM of 5.4 years including 83% whose disease had progressed on or within 60 d of last therapy and 17% whose disease had achieved <25 % response to the regimen immediately preceding study entry. Of the 266 pts enrolled pts, 257 were evaluable for response; 9 patients were considered not evaluable based on missing baseline or lacking at least one post-baseline M-protein. An ORR (≥PR) of 24% with a median DOR of 7.4 mo (range 6.2–10.3) was determined. Responses are detailed in the table. The CBR (ORR + MR) was 36%. Median DOR of pts with MRs was 6.3 months, indicating that long-term MRs were observed. An additional 32% (83 pts) achieved SD for at least 6 wks. To date, 79 pts (30%) completed ≥6 C and >11% of pts have completed all 12 C of protocol specified therapy and most have entered the extension protocol; 15 pts remain on study (all >10 C). OS and TTP data for the overall population will also be reported. The enrolled pts in this study were heavily pretreated having received a median of 5 prior lines of therapy (range 1–20, median of 13 anti-myeloma agents). 85% of pts had received at least 2 and 37% had received at least 3 drugs in the regimen just prior to entering the study. Prior anti-myeloma agents included 99.6% (265/266 pts) BTZ (median 2 prior regimens containing BTZ), 99.6% either THAL (74%) or LEN (94%), 98% corticosteroids, 91% alkylating agents, and 74% stem cell transplant; 65% of pts were refractory to BTZ at any point in time prior to study entry. The most common treatment-emergent adverse events ≥ Grade (G) 3 regardless of relationship to study drug were predominantly hematologic and included thrombocytopenia (22%), anemia (20%), lymphopenia (10%), pneumonia (8%), neutropenia (8%), fatigue (7%), hyponatremia (5%), and hypercalcemia (5%). Although 206 pts (77%) had G1/2 peripheral neuropathy (PN) at baseline, new onset PN was infrequent and G ≥3 PN occurred in <1%. Interestingly, in this subset of patients, efficacy response was nearly identical to that seen in the full study population with an ORR (≥PR) of 24%. Conclusions: Single-agent CFZ achieved durable responses in pts with R/R MM whose disease had relapsed after all available therapies including BTZ and immunomodulatory agents. The CBR and median DOR achieved with this steroid-sparing regimen establish that CFZ has the potential to offer substantial clinical benefit to patients with relapsed or refractory disease. CFZ was well-tolerated and side effects were clinically manageable with no new or unexpected toxicities observed. Importantly, exacerbation of pre-existing PN was uncommon. Cumulative side effects were not observed, allowing prolonged single-agent dosing for chronic disease control. Disclosures: Siegel: Millenium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Martin:Celgene: Honoraria; Onyx: Consultancy. Wang:Celgene: Research Funding; Onyx: Research Funding; Millenium: Research Funding; Novartis: Research Funding. Vij:Onyx: Honoraria. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria; Centocor Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Jagannath:Millenium, OrthoBiotec, Celgene, Merck, Onyx: Honoraria; Imedex, Medicom World Wide, Optum Health Education, PER Group: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Lonial:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Kukreti:Celgene: Honoraria; Roche: Honoraria; Ortho Biotech: Honoraria. Alsina:Millenium: Consultancy, Research Funding; Celgene: Research Funding; Novartis: Consultancy. Zonder:Millenium: Consultancy, Honoraria, Research Funding; Cephalon: Research Funding; Celgene: Honoraria. Wong:Onyx Pharmaceuticals: Employment. Vallone:Onyx Pharmaceuticals: Employment. Chang:Onyx Pharmaceuticals: Employment. Kauffman:Onyx Pharmaceuticals: Employment. Stewart:Millennium: Consultancy; Celgene: Honoraria. Singhal:Celgene: Speakers Bureau; Takeda/Millenium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Onyx : Research Funding.

Abstract Abstract 3862 Somatic mutations in JAK2 and MPL are associated with the BCR-ABL negative myeloproliferative neoplasms (MPNs) including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). While oral JAK2 inhibitors improve peripheral blood counts and splenomegaly, these drugs show varying effects on JAK2 mutant allele burden and do not eliminate the malignant clone in humans or in animal models of MPN. Although much of the research to date has focused on JAK/STAT signaling, other pathways downstream of the class I cytokine receptors, including PI3K/AKT and ERK are also activated in MPNs. Our hypothesis is that persistent activation of these signaling pathways contributes to the progression of myeloproliferative neoplasms (MPNs). Multiple studies have shown that overexpression of activated JAK2 and MPL mutants (e.g. JAK2 V617F or MPL W515L) in primary murine bone marrow cells causes robust AKT, STAT3, and STAT5, JNK, ERK phosphorylation. To determine the extent to which these signaling pathways are involved in the disease, we cultured JAK2 V617F and MPL W515L expressing clones of the G1ME and 6133 megakaryocytic cell lines with a panel of small molecule kinase inhibitors. We discovered that inhibition of the PI3K/AKT and MAPK/JNK signaling pathways with triciribine and SP600125 respectively, potently suppressed growth of these cells by inducing G1 arrest and apoptosis. In contrast, inhibitors of Ras, ERK, Src family tyrosine kinase, and PKC failed to significantly inhibit proliferation of the JAK2 or MPL mutant expressing cells. Murine bone marrow cells transduced with MPL W515L show a dramatic expansion of megakaryocytes (CFU-MKs) and this expansion was abrogated in the presence of PI3K/AKT inhibitors suggesting a requirement for this pathway in aberrant megakaryocyte expansion. Since AKT inhibition showed the strongest effect, we assayed the activity of MK-2206, a potent and selective allosteric AKT inhibitor, on multiple models of MPNs. We discovered that MK-2206 induced proliferative arrest and apoptosis accompanied by suppression of PI3K/AKT signaling in G1ME and 6133 cells expressing MPLW515L. MK-2206 also potently inhibited liquid culture growth and colony formation of PMF patient CD34+ cells in vitro. Finally, in preliminary murine transplants experiments with MPLW515L expressing bone marrow progenitors, treatment with MK-2206 led to significant reductions in peripheral blood leukocytosis and extramedullary hematopoiesis. Together, these findings demonstrate that the PI3K/AKT axis represents a rational target for therapy in human myeloproliferative neoplasms. Disclosures: No relevant conflicts of interest to declare.

Abstract Background BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate, comprising the anti-CD138 chimerized MAb (nBT062) and the maytansinoid DM4 as cytotoxic agent. Once bound to CD138 on a target cell, the conjugate is internalized and releases DM4, leading to target cell death. CD138 (Syndecan-1) is highly overexpressed on various solid tumors and in hematological malignancies, and represents one of the most specific target antigens for identification of multiple myeloma (MM) cells. Data from two studies investigating BT062 as single agent demonstrated an acceptable tolerability profile and evidence of clinical activity in patients with heavily pretreated relapsed and/or refractory MM (1, 2). Preclinical studies showed enhanced anti-MM activity when BT062 was combined with lenalidomide and dexamethasone (Len/Dex). Based on these data, a Phase I/IIa study in MM was initiated to evaluate the safety and efficacy of BT062 in combination with Len/Dex. Objectives To determine the dose-limiting toxicities (DLTs), the maximum tolerated dose (MTD), the recommended phase II dose (RPTD), pharmacokinetics (PK), and anti-MM activity of increasing doses of BT062 (days 1, 8, and 15, every 4 weeks) in combination with Len (25 mg, daily on days 1-21) and low dose Dex (40 mg on days 1, 8, 15, and 22) in patients with relapsed and/or refractory MM. Methods This is a prospective, open label, dose-escalation, multicenter Phase I/IIa study. The Phase I part includes dose escalation, and the Phase IIa the expansion of the MTD or RPTD cohort. Patients aged ≥18 years with relapsed and/or refractory MM who have failed at least one prior therapy were eligible to participate. Prior treatment with Len and/or Dex was allowed. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for additional treatment cycles. Patients were enrolled in cohorts of at least 3 at each dose level; DLT in the first cycle triggered cohort expansion. Toxicities were assessed by CTCAE v4 and clinical response was assessed according to International Myeloma Working Group criteria. Results As of July 2013, a total of 15 patients have received BT062 at dose levels of 80 mg/m2 (N=3), 100 mg/m2 (N=6) or 120 mg/m2 (N=6). Two patients at the highest dose level discontinued study due to toxicity (DLT), another patient withdrew consent. The other 12 patients remain on treatment; median duration 144 days (range 8–385). The median number of prior therapies was 4 (range 1–11), 87% of patients had prior Len exposure, and 50% were Len/Dex refractory. The maximum administered dose (MAD) has been reached at 120 mg/m2, with mucosal inflammation (CTC grade 3) as DLT in one, and anemia (CTC grade 3) in a second of the 6 patients treated at this dose level. About 85% of reported Adverse Events (AE) were of CTC grade 1 or 2. The most common reported AEs were fatigue, hypokalemia, and diarrhea. Amongst the 9 patients currently evaluable for efficacy, responses were observed across all dose levels with a overall response rate (ORR) of 78%; including 1 patient with complete response (120 mg/m2), 1 patient with very good partial response (80 mg/m2), and 5 patients with partial response (80 and 100 mg/m2). Two other patients achieved disease stabilization, resulting in a clinical benefit in 100% of the evaluated patients. Interestingly, partial response was observed in 3 patients refractory to prior treatment with Len/Dex. The MTD has been defined as 100 mg/m2 and is currently expanded to further evaluate the safety and efficacy of BT062 at the RPTD. Conclusion Preliminary data from this ongoing study indicate that BT062 is well tolerated in combination with Len/Dex at dose levels that induce responses in patients with relapsed and/or refractory multiple myeloma, including Len/Dex-refractory patients. Updated results on safety and efficacy will be presented. References 1. Jagannath et al, BT062, an Antibody-Drug Conjugate Directed Against CD138, Shows Clinical Activity in Patients with Relapsed or Relapsed/Refractory Multiple Myeloma. Blood. 2011; 118: Abstract 305. 2. Heffner et al, BT062, an Antibody-Drug Conjugate Directed Against CD138, Given Weekly for 3 Weeks in Each 4 Week Cycle: Safety and Further Evidence of Clinical Activity. Blood. 2012; 120: Abstract 4042. Disclosures: Somlo: Celgene: Research Funding, Speakers Bureau; NIH: Research Funding; Millennium: Speakers Bureau. Heffner:Genentech: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Biotest: Honoraria, Research Funding; Onyx: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding. Siegel:Millennium: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau. Zimmerman:Celgene: Honoraria; Millennium: Honoraria; Onyx: Honoraria. Jagannath:Millennium: Honoraria; Celgene: Honoraria. Munshi:Celgene: Consultancy; Novartis: Consultancy; Millennium: Consultancy. Lonial:Millennium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Sanofi: Consultancy; Onyx: Consultancy. Ruehle:Biotest AG: Employment. Chavan:Biotest Pharmaceuticals: Employment. Patel:Biotest Pharmaceuticals: Employment. Rothenburger:Biotest AG: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Gilead: Consultancy; Sanofi Aventis: Consultancy; Onyx: Consultancy; Celgene: Consultancy; Acetylon: Equity Ownership; Oncopep: Equity Ownership.

Abstract Introduction: With approval of Daratumumab (Dara), targeting CD38 has become an attractive therapeutic option for various B cell cancers including WM. Using preclinical models of WM we investigated CD38 expression patterns, the impact of drug-resistance and the anti-WM effects of Dara, in vitro. An important aspect of our evaluation was the identification of optimal CD38 expression that correlates with maximal cytotoxic effects of Dara; such an approach has not been attempted previously in WM. Methods: WM cell lines (BCWM.1, MWCL.1 and RPCI.WM1) with isogenic proteasome inhibitor-resistant (CR, resistant to carfilzomib, bortezomib and ixazomib) and ibrutinib-resistant subclones (IR) were used. CD38 expression was measured by flow cytometry and a grading system was developed based on increasing CD38 MFI values with 1+= <50,000, 2+ = >50,000 and 3+ = >100,000. Daratumumab-induced specific lysis due to antibody dependent cell cytotoxicity (ADCC) or complement dependent cytotoxicity (CDC) was measured using the Calcein AM assay at an effector to target ratio (E:T) of 100:1. Peripheral blood mononuclear cells (PBMCs) and complement-containing serum were obtained from healthy human donors. Daratumumab, carfilzomib and ibrutinib were obtained from commercial sources. Results: Expression of CD38 (MFI) was highest in RPCI-WM1 (91295.6) > BCWM.1 (13865.3) > MWCL-1 (9804.19) (Figure 1A.). Intriguingly we observed an interesting change in CD38 expression with induction of drug resistance; all CR clones showed a decrease in MFI (RPCI-WM1/CR; øMFI 55960.5 > MWCL-1/CR; øMFI 3890.0 > BCWM.1/CR; øMFI 1381), while decreased expression was noted in all IR clones except one (MWCL-1/IR; øMFI 6272.96, BCWM.1/IR; øMFI 3076 vs. RPCI-WM1/IR; _MFI 461784.6) (Figure 1B). When we applied our CD38 expression grading system, RPCI-WM1/IR cells classified as Grade 3+, RPCI-WM1 and its CR clones as Grade 2+, while all other WM cells were Grade 1+. We noted that utilization of this grading system was helpful in correlating the extent of cytotoxicity to the level of CD38 expression (Table 1). We next treated WM cells with Dara and observed direct lysis in only RPCI-WM1/CR (43%) > BCWM.1/CR (19%) and RPCI-WM1 (11%) cells. However, when Dara-treated WM cells were cocultured with PBMCs, significantly increased ADCC was noted in RPCI-WM1 (90.3%), RPCI-WM1/IR (88.3%) and RPCI-WM1/CR (68.0%) cells (Figure 1C). Although CDC has been reported as a mechanism of mAb-mediated cell death in WM our evaluation of CDC as a potential effector mechanism in daratumumab-treated WM was negative as expected, highlighting ADCC rather than CDC as the primary cytotoxic mechanism. Conclusion: Our analysis of CD38 in WM preclinical models highlights several important findings: 1.) Expression of CD38 changes as WM tumor clones evolve with induction of drug-resistance; an effect that may also be cell-type specific as evidenced by increased CD38 expression in RPCI-WM1/IR cells, 2.) Daratumumab can exert a direct lethal effect in WM cells but this effect is variable and cell line dependent, 3.) Expression of CD38 is an important factor directing cytotoxicity of Dara however antigen density appears to be an important factor and a grading system can be beneficial for future preclinical and/or clinical studies, 4.) ADCC and not CDC appear to be the prominent mechanism of action and 5.) ADCC-mediated cytolytic activity of Dara is contingent on CD38 expression as evidenced by the most specific lysis being noted in CD38 Grade 2+ and 3+ expressing WM cells (Table 1.). These observations can help direct optimal design of clinical studies with Dara in WM where drug resistance and CD38 expression should be further explored as factors contributing to the clinical efficacy of this new agent. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding.

Abstract Background: High risk CLL patients treated with novel targeted therapies continue to experience disease progression (PD), and more than 50% of these PD patients evolve into Richter's syndrome (RS), (Maddocks, Jama Oncol 2015). Standard chemotherapy for large cell lymphoma has limited efficacy (median overall survival <12 months) in RS. Novel immunotherapy using a PD-1 antibody to block immune checkpoint signals to activate the cytotoxic T -cell has significant efficacy in relapsed Hodgkin lymphoma (Ansell, NEJM 2015). We conducted a phase 2 trial to test the safety and clinical efficacy of the anti-PD-1 antibody pembrolizumab in patients with relapsed/refractory CLL and relapsed low grade B non-Hodgkin lymphoma (B-NHL) (MC1485 trial). Methods: MC1485includes two arms: patients with relapsed/refractory CLL (including RS) and patients with relapsed B-NHL. The main end points of this study are safety and overall response rate. The first 6 patients enrolled in either arm were included in a designed safety interim analysis. Here we report the initial interim analysis from the CLL arm. Relapsed/refractory CLL including RS who had ECOG performance 0-2 and normal organ function were included. Patients with active autoimmune disease or interstitial lung disease were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks until progression, excessive toxicity, or completion of 2 years of therapy. Soluble plasma PD-L1 levels were measured in these 6 patients using an established ELISA assay (Frigola, Clin Cancer Res, 2011). CD8+ T cell subsets were assessed for their functional status using an established analysis (Liu, Oncoimmunology. 2013) at baseline and after 2 cycles of therapies. Results: As of July 27th, 2015, 16 relapsed/refractory CLL patients including 5 RS patients were enrolled. The median age was 71 years (58-81). The median number of prior therapies was 3 (1-6). All CLL patients had received chemoimmunotherapy (FCR/PCR). 4 out of 5 RS patients had received anthracycline-containing chemotherapy. 5 out of 8 patients who had received prior ibrutinib therapy progressed on ibrutinib. 8 patients had 17p-/TP53 mutation. Herein, we report preliminary results from the interim analysis of CLL arm including 4 RS and 2 CLL as well as the 5th RS who had response evaluation by PET. The median cycles of therapy administered was 4 (3-7). One patient experienced grade 2 cytokine release syndrome with transient febrile neutropenia, grade 3 headache and skin rashes. These symptoms resolved with steroid therapy. One patient experienced grade 3 myalgia and was also treated with steroids. The other patients in this safety cohort tolerated pembrolizumab well. The most common drug-related adverse events were grade 1 dyspnea (33%, 2/6) and grade 1 anemia (33%, 2/6). Based on investigator assessment using the Cheson 2007 International Working Group Criteria, 4 out of 5 RS patients had responded to therapy. One patient had a complete remission after 2 cycles and remains in remission. One patient had almost complete PET response after two cycles and is classified as PR as her bone marrow have not been re-evaluated yet. Two patients had notable responses with nodal and skin lymphoma improvements before they showed potential evidence of progressive diseases. The remaining 1 RS and 2 CLL had stable disease and continued on therapy at the last follow-up. Soluble PD-L1 levels (sPD-L1, n=6) were measured at baseline and after 2 cycles of therapies. 3 RS patients who had responded to therapy had decreased or stable sPD-L1 levels. The 4th RS and two CLL had increased sPD-L1 levels and had not demonstrated clinical response. CD8 T-cell subset analyses performed blindly (n=4) showed increased CD8 T cell function in one of the 4 patients tested. This patient who demonstrated CD8 T cell functional enhancement is the only patient in the 4 tested patients who had notable response to pembrolizumab. Conclusion: Pembrolizumab is tolerated in relapsed CLL and RS patients. Early efficacy observed in heavily pretreated RS patients including patients progressed on both anthracycline-based treatment and ibrutinib indicate PD-1 inhibition is a promising novel approach in patients with RS. Our CD8 T cell subset analysis may be used as a biomarker assay to predict clinical response in the era of novel immunotherapy. This trial and further correlative analysis is ongoing and will be presented at the ASH meeting. Disclosures Ding: Merek: Research Funding. Shanafelt:Cephalon: Research Funding; Pharmactckucs: Research Funding; Janssen: Research Funding; Hospira: Research Funding; Polyphenon E Int'l: Research Funding; Celgene: Research Funding; Glaxo-Smith_Kline: Research Funding; Genentech: Research Funding. Kay:Tolero Pharma: Research Funding; Hospira: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding.

Abstract Background: The 2016 revision to the World Health Organization (WHO) classification of myeloid neoplasms has specifically categorized germline mutations that are associated with myeloid clonal evolution (Arber et al. Blood 2016). This group consists of myeloid neoplasms with an isolated germline predisposition (CEBPA, DDX41), myeloid neoplasms associated with congenital thrombocytopenia (ETV6, RUNX1, ANKRD26) and germline myeloid neoplasms with multi-organ dysfunction (GATA2, chromosomal breakage disorders, telomere biology disorders etc). We carried out this study to describe the clinical spectrum of germline disorders with predisposition to myeloid neoplasms as categorized by the 2016 WHO classification revision. Methods: After Institutional Review Board (IRB) approval, the adult and pediatric bone marrow failure syndrome database (1990-2016) and the electronic medical record were queried for germline disorders involving GATA2, CEBPA, DDX41, ETV6, RUNX1, ANKRD26, Down syndrome and Noonan syndrome. Chromosomal breakage assays (Diepoxybutane/Mitomycin-C), flow-fluorescent in-situ hybridization (FISH) for telomere length assessment, Fanconi anemia complementation assays and Sanger/Next Generation sequencing (NGS) for the aforementioned germline disorders with myeloid predisposition were carried out in Clinical Laboratory Improvement Amendments (CLIA)-certified laboratories. These disorders were then classified based on the 2016 WHO classification revision. Results : 54 individuals (37 families) were included in the study. Eleven (20%) patients belonging to 5 families were identified as having germline mutations with a preexisting platelet disorder: ETV6 (n=1), ANKRD26 (n=5), RUNX1 (n=5). Forty-three (79%) patients (32 families) had inherited syndromes with multi-organ dysfunction: GATA2 (n=11, 26%), bone marrow failure syndromes (n=14, 33%) and telomere biology disorder (n=14, 33%). There was one patient with neurofibromatosis with a germline PTPN11 mutation who developed juvenile myelomonocytic leukemia, while there were three patients with Down syndrome; 2 with transient abnormal myelopoiesis and one who developed acute megakaryocytic leukemia. The clinical phenotype, prevalence and characteristics of myeloid clonal evolution and outcomes are presented in Table 1. No patients with germline CEBPA or DDX41 mutations were identified. Patients with germline platelet disorders did not have any prominent non-hematological manifestations. Erythrocytosis (20%) with long-standing thrombocytopenia (100%) was a unique feature associated with ANKRD26 mutations. Non-hematologic clues such as human papillomavirus (HPV)-driven warts, primary lymphedema (Emberger syndrome) and frequent atypical infections with monocytopenia were seen in patients with germline GATA2 mutations, and preceded myeloid clonal evolution (morphologic, cytogenetic and molecular). Notably, the age at presentation and penetrance of myeloid transformation was variable, with individuals from the same family developing symptoms during the first decade of life and others remaining asymptomatic to date (fifth decade). Somatic ASXL1 mutations were detected in all 3 (100%) patients with GATA2 mutations and in one patient with ANKRD26 mutation that developed myeloid clonal evolution. In our study myeloid clonal evolution was seen in 40% with RUNX1 mutations, 27% with GATA2 mutations, and 20% with ANKRD26 mutations. We could not calculate the same for bone marrow failure syndromes as the total number of cases seen are still being assessed. Outcomes with allogeneic stem cell transplantation were favorable in appropriately selected patients (Table 1). Conclusion : The 2016 WHO revision to the classification of myeloid neoplasms highlights the importance of recognition and molecular characterization of germline mutations (syndromic and non-syndromic) with risk for myeloid clonal evolution. While some of these disorders (GATA2, Fanconi anemia, telomere biology disorders) may have important non-hematological clues, many present with isolated thrombocytopenia (RUNX1, ETV6). The age and frequency of myeloid evolution is highly variable. Acquisition of somatic ASXL1 mutations at the time of clonal myeloid transformation highlights the role of epigenetic dysregulation in disease evolution. Disclosures Kenderian: Novartis: Patents & Royalties, Research Funding.

Abstract Background Lemierre's syndrome, sometimes referred to as postanginal septicemia or human necrobacillosis, is a multisystemic infection beginning in the oropharynx and leading to thrombosis of the internal jugular vein (IJV) with septic emboli and potential thrombotic extension to the central nervous system. This disorder occurs in the setting of oropharynx infection, leading to peritonsillar abscess. Within the abscess, anaerobic organisms penetrate the neighboring IJV resulting in an infected thrombus. Often polymicrobial, the infection is associated with the gram-negative bacillus Fusobacterium necrophorum, and if left untreated, may lead to fatal sepsis. With the advancement of antimicrobial therapies and earlier diagnosis of the disease, patient outcomes have improved. There is no clear consensus regarding the role of anticoagulation in this disorder. Some reports are in favor of anticoagulation therapy in conjunction with systemic antibiotic therapy while others support the use of antibiotic therapy alone. The purpose of this study is to better define the role of anticoagulation in this disorder and if thromboses outcomes are improved with anticoagulation therapy. Methods Pediatric and adult patients diagnosed with Lemierre's syndrome at the Mayo Clinic (Rochester, MN) between the years 1964 and 2014 were identified. Study inclusion criteria required radiologic confirmation of jugular vein thrombosis (JVT) in the setting of oropharynx infection, clinically diagnosed blood stream or local bacterial infection and intraoperative or radiological confirmation of head and neck loculated infection, and at least 3 months follow up. Patient demographics, clinical, microbiological and radiographic features, management and thromboses outcomes were reviewed. Thrombosis outcome was defined based on radiological findings defined as: CR (complete response-resolution of thrombus), PR (partial response-improvement with decrease in size of thrombus) and NR (no response). Progression/recurrence of thrombosis and bleeding complications data were also reviewed. Results Twenty-four patients were identified with the diagnosis of Lemierre's syndrome. Six patients were excluded due to lack of at least 3 months of follow up. Of the remaining 18 (8 females; 10 males) patients included in this analyses, 7 patients received anticoagulation therapy. Six patients were of the pediatric age group (<18 years). Median age of patients who received anticoagulation was 18.6 years [age range: 14-46.4 years]. Median age for the non-anticoagulated group was 19.2 years [age range: 16-71.8 years]. Microbiologically documented infective organisms were: Fusobacterium necrophorum (n=10), Fusobacterium necrophorum and Arcanobacterium heamolyticum (n=1), Staphylococcus aureus (n=2), Mycoplasma pneumoniae (n=1), Streptococcus pyogenes (n=1), others (n=3). Laterality of thrombosis presentation at diagnosis: right IJV (n=7), left IJV (n=6), bilateral IJV (n=2), left external jugular vein (n=3). Other site involvement/extension included pulmonary (n=2), cavernous sinus thrombosis (n=1), and sigmoid sinus thrombosis (n=1). All patients received broad-spectrum antibiotics. Seven patients received ≥4 weeks anticoagulation (median: 20.6 weeks; range 4-32.9 weeks]. Choice of anticoagulants and duration of anticoagulation practices were at the discretion of the treating physicians. Anticoagulation therapy consisted of unfractionated heparin (UFH) (n=1), UFH with transition to Coumadin (n=1), low molecular weight heparin (LMH) with transition to Coumadin (n=4), LMH (n=1). All patients had an improvement in their thrombus by 3 months (non-anticoagulated patient group: CR=9 and PR=2; anticoagulated patient group: CR=2 and PR=5). None of the patients developed recurrent thrombosis or progression during the follow up period regardless of their anticoagulation status. None of the patients who were anticoagulated developed bleeding complications. Conclusions This retrospective study suggests that anticoagulation in Lemierre's syndrome does not affect thrombosis outcomes. All patients achieved partial or complete thrombus resolution and no progression/recurrence of thrombus was noted in any patient regardless of whether anticoagulation status. Aggressive and prompt antimicrobial therapy remains the standard of care for this life-threatening disorder. Disclosures No relevant conflicts of interest to declare.

Abstract Higher bone marrow cell dose has been associated with improved survival after allogeneic BMT. Although PBSC provides higher cell dose, it also provides a higher number of T cells which increases the risk of GVHD and may negatively impact the outcome in pediatric patients. A prospective multi-center trial was conducted to evaluate the safety and feasibility of G-CSF primed bone marrow in children receiving HLA-identical sibling bone marrow transplantation (BMT). Thirty eight children at 9 different centers, 17 female and 21 male with a median age of 9.8 years (range 0.8–17) were enrolled between May 2003 and May 2005. Fifteen patients had high risk diseases (ALL ≥CR2=4, AML≥ CR2/refractory=5, Advanced MDS=3, JMML=1, NHL=2) and 23 had standard risk disease (SAA=6, Red Cell Aplasia=1, Sickle cell disease=1, CML-CP=2, AML CR1=9, ALL CR1=2, MDS-RA=2). Five patients had undergone a prior allogeneic transplant. All patients received myeloablative preparative regimens (Cy/TBI±VP-16=12, BU/Cy±other=20 and Cy/ATG=6) and 32 (84%) received CSP/FK506 with MTX as GVHD prophylaxis. Donors were HLA identical siblings except for one who was syngeneic. Donors with median age of 9.2 y (range 1.1–22) received 5 mcg/kg/day of GCSF SQ for 5 consecutive days. Bone marrow was collected on the fifth day with a median volume of 14.5 cc/kg (range 5.2–25). No donor experienced any complications related to G-CSF administration or harvest, up to the time of last follow-up at one month after the harvest. The absolute CD34 cell count at the day of the harvest was measured in 28 patients and it was significantly higher in bone marrow compared to peripheral blood, median of 50/μl (8–247) vs 513/μl (116–156) respectively (p <0.0001). Median nucleated and CD 34 cells infused was 8.4x108/kg (range 2.4–60.9) and 8.7x106/kg (range 2–27.6) respectively. No G-CSF was administered post transplant. All patients had neutrophil engraftment at a median of 19 days (13–28), and all but one patient with early post-transplant relapse had platelet engraftment at a median of 20 days (9–44). Thirteen patients (35%) developed grade 2 GVHD and 4 of 34 evaluable patients (12%) developed chronic GVHD (3 limited and 1 extensive). There was no transplant related mortality. Among 30 patients with malignant disorders 9 (30%) relapsed (6 with high risk and 3 with standard risk disease). The EFS and OS of patients with standard disease at 1 year is 84% (95% CI 68–100%) and 95% (95% CI 87–100) respectively. With a median follow up of 1 year the estimated EFS and OS of all patients at one year is 76% (CI 62–93) and 92% (95% CI 83–100) respectively. We conclude that G-CSF primed bone marrow from pediatric donors is safe and can result in high NC and CD34 cell dose that facilitate engraftment after myeloablative BMT without a discernable increase in the risk of GVHD. A prospective randomized trial comparing G-CSF primed bone marrow to unstimulated marrow is planned.

Abstract Background: Aberrant B-cell receptor (BCR) and MYD88 signaling cooperatively drive Waldenstrom macroglobulinemia (WM) tumor cell survival. To sustain BCR-driven growth and maintain optimal cellular homeostasis, WM cells upregulate proteasome function. We have recently described the role of two distinct 19S proteasome-associated deubiquitinating enzymes (DUBs), USP14 and UCHL5, in maintaining WM-cell viability. Pharmacologic inhibition with b-AP15 (commercial compound) results in WM-cell death and accumulation of high molecular weight ubiquitinated protein conjugates; an event that is phenocopied by siRNA knockdown of USP14 and UCHL5. VLX1570 is a lead-optimized clinical grade analog of b-AP15 with enhanced solubility, stability and target residence time. We investigated the effect of VLX1570 on BCR components, WM cell survival proteins and its in vivo activity in a human xenograft model of WM. Materials: VLX1570 was obtained from Vivolux AB and bortezomib from Sellekchem. Human WM cell lines (BCWM.1, MWCL-1 and RPCI-WM1) and their drug-resistant derivatives were used (total n=12). Bone marrow aspirates from WM-patients and from healthy donors were obtained from the Mayo Clinic biospecimens core. PBMCs from healthy donors were used as comparators where needed. NOD/SCID mice were obtained from Taconic Labs and used for profiling the in vivo properties of VLX1570. Results: We first examined for USP14/UCHL5 protein expression by immunohistochemical analysis in primary tumor tissue from WM patients and compared it to healthy donor cells. WM patient-derived cells exhibited greater staining intensity of both DUBs. Preferential binding of VLX1570 to USP14 and UCHL5 in WM cells was probed in a WM cell using an enzyme-based competition assay (HA-Ub-Vs), which demonstrated time-dependent decrease in labeled USP14 and UCHL5 after treatment with VLX1570. In drug-resistant (bortezomib or ibrutinib-resistant) WM cells, VLX1570 induced >50% tumor-specific apoptosis and displayed synergistic activity with ibrutinib (median CI: 0.5). In addition to ER stress markers, we had previously observed that gene expression of BCR-signalosome components were reduced in VLX1570-treated WM cells (NanoString platform) and this was substantiated at the protein level where p-SYK, SYK and BTK decreased in a time-dependent manner. BCR end-effectors were probed in response to VLX1570 and a decrease in nuclear translocation of NFkB (p65) was noted. USP14 has been shown to control the availability of the chemokine receptor CXCR4, which regulates homing of WM cells to bone marrow. After VLX1570 treatment, we noted a significant decrease in CXCR4 surface receptor expression in all WM cell lines tested and primary WM cells. Lastly, to determine the in vivo anti-WM effects of VLX1570, we injected NOD/SCID mice (xenotransplanted with RPCI-WM1-Luc cells) with VLX1570 (I.P. route, 4.4mg/kg every other day) and measured tumor burden along with pharmacodynamic indicators. VLX1570-treated mice (n=7) demonstrated significantly lower tumor volumes by caliper measurement and bioluminescent signal (p=0.01 - 0.003) as well as reduced serum human-IgM, compared to vehicle-treated mice (n=7). Importantly, mice treated with VLX1570 survived longer vs. vehicle-treated mice (median survival, 62 vs. 44 days, respectively, p=0.0008). No unforeseen toxicities were noted and weight of the mice in vehicle vs. VLX1570-treated mice did not significantly change. IHC analysis in mice tumor tissues demonstrated reduced CXCR4, human-IgM, Ki67 and increased cleaved caspase-3 and ubiquitinated (k48-linked) protein level, the latter serving as a more specific indicator of USP14/UCHL5 inhibition. Conclusions: We provide substantial in vitro and in vivo evidence on the anti-WM effects of a novel first-in-class clinical grade USP14/UCHL5 inhibitor, VLX1570. In addition to anticipated induction of ER stress machinery, we describe for the first time VLX1570-mediated modulation of BCR components and WM cell survival proteins as well as demonstrate its robust activity in an aggressive human xenograft model of WM. These data provide the rationale for a clinical trial of single agent VLX1570 in patients with symptomatic WM. Disclosures Martin: Janssen: Consultancy, Honoraria; Acerta: Consultancy; Gilead: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Bayer: Consultancy. Gullbo:Vivolux AB: Other: Shareholder. Linder:Vivolux AB: Other: Shareholder.

Abstract BMT CTN 0201 was a randomized study of unrelated donor bone marrow (BM) vs. peripheral blood (PB) (N=551) in hematopoietic cell transplantation (HCT) for hematologic malignancies. The primary analysis after 2 years of follow up showed similar survival, disease-free survival and treatment-related mortality between the graft types. There was a higher rate of graft failure with bone marrow (9% vs. 3%, p=0.002) and a higher rate of chronic GVHD with peripheral blood (53% vs. 41%, p=0.01). (Anasetti et al, NEJM 2012) Patient reported outcomes (PROs) were collected from patients > 16 years old at enrollment and 0.5, 1, 2 and 5 years after transplantation with the Functional Assessment of Cancer Therapies - Bone Marrow Transplant (FACT-BMT), Mental Health Inventory (MHI), and Lee chronic graft-versus-host disease (cGVHD) symptom scale. At 5 years, 102 BM and 93 PB participants were alive and eligible for the quality of life (QOL) study. Clinically meaningful differences (changes in scores that are noticeable to patients) were considered 0.5 x standard deviation of the total population based on the distribution method. Results: Data as of 5/25/15 were analyzed. 70% completed the pre-randomization assessment, and 74-78% of adult survivors completed the 5 year assessment. Age < 30 at transplant and high risk disease were associated with missing 5 year data, but not graft source. Response rates at 0.5, 1 and 2 years were 28-43% of survivors. There are no differences in any of the primary QOL scores in the first two years after HCT using univariate comparisons, although missing data severely limit conclusions during this period. At 5 years, the FACT-Trial Outcome Index (TOI), the MHI Psychological Well-Being, and the cGVHD symptom scale scores are all significantly better for BM patients, although only the latter two are still significant after adjustment for multiple testing (p<0.0125 because of 4 primary QOL variables). Results were similar when tested in multivariate models adjusting for baseline patient-reported scores and also imputing missing values based on patient characteristics (Table). Of the 7 chronic GVHD subscales, symptoms in the eye, lung, and energy were significantly better with BM (p<0.01). A diagnosis of cGVHD was highly associated with patient-reported cGVHD symptoms but not with QOL or psychological status. Inclusion of extensive cGVHD in the multivariate models did not change the significance of PRO differences suggesting that differences in cGVHD incidence do not explain the PRO findings. With a median follow up of 73 months for survivors, no difference in survival between PB and BM is observed (p=0.84, Figure). Conclusion: At 5 years after transplant, recipients of unrelated donor BM have better psychological well-being and less burdensome chronic GVHD symptoms than recipients of PB. Survival rates are similar. Table. Comparisons of primary QOL variables at 5 years, adjusted for QOL values at baseline and missing data using inverse probability weighting using significant clinical characteristics. QOL scale Bone marrow (n=102) Peripheral blood (n=93) P value Clinically significant difference* Difference between BM and PB (95% CI) FACT-BMT TOI, mean +/- SE (higher scores better) 76.7 +/- 1.6 (n=79) 70.5 +/- 1.9 (n=69) 0.014 8.5 6.2 (1.3-11.1) MHI - Psychological well-being, mean +/- SE (higher scores better) 78.9 +/- 1.7 (n=80) 72.2 +/- 1.9 (n=72) 0.011 8.4 6.7 (1.6-11.8) MHI-Psychological Distress, mean +/- SE (lower scores better) 16.0 +/- 1.3 (n=80) 19.0 +/- 1.5 (n=71) 0.128 6.5 -3.0 (-6.8,0.9) Chronic GVHD symptoms, mean +/- SE (lower scores better) 13.1 +/- 1.5 (n=80) 19.3 +/- 1.6 (n=72) 0.004 7.1 -6.3 (-10.5, -2.0) SE, standard error *0.5 x STD Figure 1. Figure 1. Disclosures Lee: Bristol-Myers Squibb: Consultancy; Kadmon: Consultancy. Maziarz:Athersys: Consultancy, Patents & Royalties, Research Funding; Novartis: Consultancy.