ALBERT

Description: Background: Lenalidomide (LEN) monotherapy has been effective in extending progression free survival (PFS) after myeloablative AuSCT in pts with MM. Elotuzumab (ELO), a humanized IgG1 immunostimulatory monoclonal antibody against signaling lymphocytic activation molecule F7 (SLAM F7), is FDA approved in combination with LEN and dexamethasone (DEX) for treatment of MM pts who have received 1-3 prior therapies. The objective of this phase 2 trial is to evaluate the efficacy and safety of adding ELO to LEN as maintenance therapy post-myeloablative AuSCT. We report updated results of the primary (PFS) and secondary (overall survival [OS] and toxicity) endpoints. Patients and Methods: Between 4/15/2015-1/27/2016, 27 evaluable pts were treated on 28 day cycles with ELO, 10 mg/kg iv weekly for cycles 1-2, q2weeks for cycles 3-6, then 20 mg/kg once monthly for cycles 7+. Pts enrolled after 1/28/2016 (n=57 pts) have received ELO, 10 mg/kg IV weekly for cycles 1-2, and 20 mg/kg on day 1 from cycle 3 until disease progression (PD). LEN has been dosed at 10 mg/day for cycles 1-3, with a dose increase to 15 mg/day at physician discretion starting with cycle 4, in the absence of non-hematologic toxicity 〉 grade 1 and significant cytopenias (ANC 〈 1000/mL, platelet count 〈 100,000/ml). For the 1st 8 weeks, pts

Description: Introduction: XmAb13676 is a humanized bispecific antibody that binds both CD20 and CD3 in order to recruit cytotoxic T cells to kill CD20 expressing malignant cells. Interim results of an ongoing first-in-human, dose-escalation study (XmAb13676-01; NCT02924402) in subjects with relapsed/refractory (R/R) non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL) are reported here. Methods: The study is a first-in-human, multi-center, open-label, phase 1, dose-escalation study in subjects with R/R NHL and R/R CLL with a standard 3 + 3 design. The primary objectives are to determine safety, tolerability, and the maximum tolerated dose (MTD) or recommended dose of XmAb13676. Secondary objectives include preliminary anti-tumor activity and PK/PD of XmAb13676. This study is designed in two parts: Part A, escalating dose cohorts that establish an initial priming dose as part of repeated weekly infusions at a fixed dose in a 28-day cycle; and Part B, with a dosing schedule consisting of a priming dose on C1D1 , established in Part A, followed by escalated dose(s) on subsequent weeks. Cytokine Release Syndrome (CRS) prophylaxis with dexamethasone was mandated prior to each administration of XmAb13676. Treatment was continued for 2 cycles or longer if there was evidence of therapeutic benefit. Results: At data cut-off, 44 subjects have been treated, 36 with NHL and 8 with CLL. NHL: Subjects with R/R NHL had a median age of 61.5 years (range 32-89), a median of 3.5 prior therapies (range 1-9) and had been diagnosed a median of 24.6 months (range 6.3-181.2) prior to treatment in the study. Treatment-emergent adverse events (TEAEs) related to treatment occurring in ˃ 3 subjects are shown in Table 1A. Nine treatment-related serious adverse events (SAE) occurred in 6 subjects. The most common treatment-related SAE was CRS, which occurred in 4 (11.1%) subjects with 1 of the events being Grade 4 and the other events being ≤ Grade 2. Treatment responses were assessed by the Lugano criteria or International Working Group criteria for Waldenström Macroglobulinemia (WM). There have been 7 objective responses: 2 complete responses (CR; DLBCL), 1 Very Good PR (VGPR; WM), and 4 partial responses (PR; 1FL, 3 DLBCL) at doses of 20-125 µg/kg. In the efficacy-evaluable population, at doses of 80-125 µg/kg, objective responses were observed in 6/18 patients. A priming dose of 45 µg/kg has been chosen for Part B. An MTD has not been reached and dose escalation is ongoing in Part B in NHL. CLL: Subjects with R/R CLL had a median age of 76 years (range 62-81), a median of 4.5 prior therapies (range 2-6) and had been diagnosed a median of 76.1 months (range 17.5-328.9) prior to treatment in the study. Treatment-related TEAEs occurring in ˃ 1 subject are shown in Table 1B. Three treatment-related serious adverse events (SAE) occurred in 2 subjects. The treatment related SAEs were CRS (Grade 3), hepatocellular injury (Grade 3), and jaundice cholestatic (Grade 2), each of which occurred in 1 (12.5%) subject. There has been 1 CR reported (Richter transformation) in 5 subjects at 20 µg/kg, the highest dose administered thus far. The treatment response was assessed by the Lugano criteria. An MTD has not been reached and dose escalation is ongoing in Part A in CLL. Conclusions: XmAb13676 demonstrated evidence of clinical activity in heavily pretreated subjects with R/R NHL and R/R CLL treated at doses between 20 and 125 µg/kg. CRS was generally manageable with premedication. The study is ongoing with further optimization of dose and schedule. Disclosures Patel: AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Genentech: Consultancy, Speakers Bureau; Pharmacyclics/Janssen: Consultancy, Speakers Bureau; Sunesis: Consultancy. Chanan-Khan:AbbVie: Research Funding; Xencor: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Jansen: Research Funding; Mayo Clinic: Employment; Ascentage: Research Funding; Millennium: Research Funding. Salles:Novartis, Servier, AbbVie, Karyopharm, Kite, MorphoSys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Epizyme: Consultancy, Honoraria; Roche, Janssen, Gilead, Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Other: Educational events; Merck: 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, Other: Educational events; BMS: Honoraria. Cartron:Gilead: Honoraria; Jansen: Honoraria; Celgene: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Sanofi: Honoraria. Thomas:Celgene: Research Funding; Amgen: Research Funding; Xencor: Research Funding; BMS: Research Funding. Wierda:KITE pharma: Research Funding; Sunesis: Research Funding; Miragen: Research Funding; Gilead Sciences: Research Funding; Acerta Pharma Inc: Research Funding; GSK/Novartis: Research Funding; Cyclcel: Research Funding; Loxo Oncology Inc.: Research Funding; AbbVie: Research Funding; Genentech: Research Funding; Juno Therapeutics: Research Funding; Oncternal Therapeutics Inc.: Research Funding; Pharmacyclics LLC: Research Funding; Xencor: Research Funding; Janssen: Research Funding. Liebowitz:Xencor: Employment, Equity Ownership. Pagel:AstraZeneca: Consultancy; Gilead Sciences: Consultancy; Pharmacyclics: Consultancy. Ribrag:MSD: Membership on an entity's Board of Directors or advisory committees; Roche: Other: Travel, accommodations, and expenses ; Nanostring: Membership on an entity's Board of Directors or advisory committees; Epizyme: Consultancy, Research Funding; Servier: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Infinity: Membership on an entity's Board of Directors or advisory committees; AZ: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses ; Incyte: Membership on an entity's Board of Directors or advisory committees; ArgenX: Research Funding. Saville:Xencor: Employment, Equity Ownership. Johnson:Xencor: Employment, Equity Ownership. Ly:Xencor: Employment, Equity Ownership. Phillips:Pharmacyclics: Consultancy, Research Funding; Bayer: Consultancy; Abbvie: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy; Seattle Genetics: Consultancy; Gilead: Consultancy; Incyte: Membership on an entity's Board of Directors or advisory committees.

Description: Introduction Plasmablastic lymphoma (PBL) is a rare, aggressive subtype of non-Hodgkin lymphoma. Published data are predominantly in the form of case reports and small retrospective case series. Initial reports of PBL were described in HIV positive patients (pts) with disease in the oral cavity, and in pts after organ transplantation on immunosuppressive therapy. The natural history may have evolved recently, with case reports of PBL in immunocompetent patients. There is no established standard of care therapy, though HIV positive pts benefit from initiation of anti-retroviral therapy, tend to respond to chemotherapy, have historically been associated with CD20 expression, and have increased overall survival rates compared with HIV negative pts with PBL. We now describe our experience in pts with PBL who received treatment at the University of Texas MD Anderson Cancer Center (UTMDACC). Methods We conducted a retrospective analysis of pts diagnosed with PBL between August 2000 and August 2012. We evaluated the baseline demographics, stage, therapy, response rate, progression-free survival (PFS) and overall survival (OS). Results 28 pts (males n=23) with PBL were identified, with a median age of 51 (range 26-81). 10 patients had a diagnosis of HIV, and 15 were EBV positive. 7 pts had stage I disease, 2 had stage II, 1 had stage III and 18 had stage IV disease. The primary site of disease in the 7 pts with stage I disease was: 2 in the maxillary sinus, 2 in the nasal cavity, and 1 each in the colon, testicle, and lower jaw. 2 pts with stage II disease had primary sites in bowel and tonsils. 7/17 (41%) of HIV negative pts and 2/10 (20%) of HIV positive pts had stage I/II disease. The median LDH was 492 IU/L (313-618), median Ki-67 proliferation index was 85%, and all pathological samples were CD20 negative. Median follow up was 16 months (1-120). 27 pts received systemic therapy (1 pt elected hospice care). PBL was an initial cancer diagnosis for 25 pts who received the following as first line therapy: Hyper-CVAD (cyclophosphamide, vincristine, Adriamycin, dexamethasone alternating with methotrexate and cytarabine) (n=10), CHOP (cyclophosphamide, Adriamycin, vincristine, prednisone) (n=7), modified CVAD, 2 with EPOCH (etoposide, vincristine, cyclophosphamide, Adriamycin, prednisone) (n=4), bortezomib/dexamethasone (n=1), and the DeAngelis protocol (methotrexate, vincristine, procarbazine, with intrathecal methotrexate) (n=1) for CNS involvement. 2 pts had prior therapy for diagnosis of diffuse large B-cell lymphoma (DLBCL) and chronic lymphocytic leukemia (CLL) prior to diagnosis of PBL. The first pt with DLBCL was treated with Rituximab-hyper-CVAD 6 years earlier, and gemcitabine/oxaliplatin for the diagnosis of PBL. The second pt had CLL which underwent Richter's transformation to PBL, and was treated with hyper-CVXD (cyclophosphamide, vincristine, liposomal daunorubicin and dexamethasone). 1 pt underwent auto-stem cell transplant, while 8 pts received localized radiation (5 for consolidation and 3 for palliative therapy); 5/7 pts with stage I disease received consolidation with involved field radiation. After first line therapy, 20/27 patients (74%) achieved complete response, 5/27 (19%) partial response, and 2/27 (7%) stable disease. Median PFS and OS were 24.1 and 28.8 months, respectively. 5 year PFS and OS were 40% and 38%, respectively. Early stage disease (stage I or II) and younger age at diagnosis (less than 40 years old) were associated with improved survival. 5 year PFS for stage I/II pts was 90%. Conclusion 41% of HIV negative pts had stage I/II disease. Early stage PBL pts who received combined chemotherapy followed by radiotherapy achieved a good PFS of 90% at 5 years. PBL consistently lacked CD20 expression irrespective of HIV status. PBL can be seen in both HIV+ and HIV– patients with overall 40% long term survival. Disclosures: Qazilbash: Otsuka Pharmaceuticals: Research Funding. Fanale:Seattle Genetics, Inc.: Advisory/scientific board membership and travel expenses Other, Consultancy, Honoraria, Research Funding. Orlowski:Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene Corporation: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millenium Pharmaceuticals: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx Pharmaceuticals: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees.

Description: Abstract 1860 Background: ARRY-520 is a potent, selective inhibitor of kinesin spindle protein (KSP, eg5) which is required for cell cycle progression through mitosis. Treatment with ARRY-520 arrests cells in mitosis with subsequent induction of apoptosis due to degradation of survival signals during mitotic arrest. Cancers, such as multiple myeloma (MM), that depend on the short-lived survival protein Myeloid cell leukemia (MCL)-1 are highly sensitive to treatment with ARRY-520 in preclinical MM models, providing a strong rationale for its clinical investigation in this disease. Methods: This Phase 1 study was designed to evaluate the safety, pharmacokinetics (PK), preliminary efficacy and biological activity of ARRY-520 administered intravenously on Days 1 and 2 every 2 weeks without/with granulocyte colony-stimulating factor (G-CSF) support. Eligible patients (pts) had relapsed or refractory MM with ≥ 2 prior lines of therapy (including both bortezomib [BTZ] and an immunomodulatory [IMiD] agent), unless refusing or ineligible for this therapy. Cohorts were enrolled in a classical 3+3 dose escalation design. Results: Enrollment in this Phase 1 study is complete. Thirty-one pts have been treated, with a median age of 60 years (range 43–79) and a median of 6 prior regimens (range 2–16). All pts received a prior proteasome inhibitor (30 pts BTZ, 4 pts carfilzomib) and an IMiD-based agent (28 pts lenalidomide, 23 pts thalidomide). Twenty-four pts had an autologous stem cell transplant. The maximum tolerated dose (MTD) was determined to be 1.25 mg/m2/day without G-CSF. As neutropenia was the dose-limiting toxicity (DLT), dose escalation with G-CSF support was conducted and the MTD for ARRY-520 with G-CSF was determined to be 1.5 mg/m2/day. At the MTD, 1 of 7 pts had a DLT of febrile neutropenia. At doses above the MTD, additional DLTs of Grade 3 mucositis and Grade 3 corneal disorder were observed. ARRY-520 demonstrated an acceptable safety profile. The most commonly reported treatment-related adverse events (AEs) included hematologic events (anemia, leukopenia, neutropenia, thrombocytopenia), as well as anorexia, blurred vision, diarrhea, dizziness, fatigue, febrile neutropenia, mucositis, nausea and rash. No treatment-related AEs of neuropathy or alopecia were reported at the MTD. ARRY-520 has been dosed over extended periods of time (to date, median 7 cycles [range 1–44]), with no evidence of cumulative toxicity. The plasma concentrations of ARRY-520 were determined over a 7-day period during Cycle 1 following the Day 1 and 2 infusions of ARRY-520. The preliminary noncompartmental PK parameter estimates in this population were similar to those observed in prior oncology studies. The PK was characterized by low clearance (CL = 2.2 L/hr/m2) and a large volume of distribution (Vss = 232 L/m2). The t1/2 of elimination was very long (67 hrs). Concentrations were typically maintained above the in vitro IC50 for KSP inhibition for ≥ 7 days suggesting therapeutically active concentrations of drug were maintained in pts for sustained periods. Further analyses of PK relative to safety and activity are on-going. ARRY-520 showed activity as a single agent across a range of doses in this heavily pretreated population (31 evaluable pts) with 3 confirmed partial responses (PR) and 1 confirmed minimal response (MR) per International Melanoma Working Group (IMWG) and European Group for Blood and Marrow Transplantation (EMBT) criteria. PRs had a median of 7 prior therapies (range 2–8). Responses were durable; to date, the durations of responses for PRs were 3.4+ months (mos), 11.9+ mos and 12.0 mos, respectively. Of interest, the time to response with ARRY-520 was prolonged, with a median time to PR of 3.7 mos (range 3.7–8.1). Notably, responses were observed in pts refractory to multiple standard-of-care agents. In addition, 4 pts experienced a best response of stable disease (SD) lasting ≥ 10 mos. To date, 5 pts remain on study, including 2 of 3 PRs. Conclusions: In this Phase 1 study, ARRY-520 shows promising evidence of clinical activity, with a long duration of response and an acceptable safety profile in heavily pretreated MM Patients. A Phase 2 portion of the study is ongoing to obtain additional information on the efficacy, safety and biological effects of ARRY-520 at 1.5 mg/m2/day with G-CSF support. Disclosures: Shah: Array BioPharma: Consultancy, Research Funding; Celgene: Consultancy; Onyx: Consultancy, Research Funding. Off Label Use: ARRY-520. Zonder:Millenium: Consultancy, Research Funding, Speakers Bureau; Celgene: Speakers Bureau; Medtronics: Honoraria; Amgen: Consultancy. Cohen:Celgene: Consultancy, Honoraria; Millenium: Consultancy, Honoraria; Onyx: Consultancy, Honoraria. Orlowski:Array BioPharma: Honoraria, Membership on an entity's Board of Directors or advisory committees. Alexanian:Array BioPharma: Research Funding. Thomas:Array BioPharma: Research Funding; Centecor: Research Funding; Novartis: Research Funding; Immunomedics: Research Funding; Celgene: Research Funding; Millenium: Research Funding. Weber:Array BioPharma: Research Funding. Kaufman:Keryx: Consultancy; Celgene: Research Funding; Merck: Research Funding. Walker:Array BioPharma: Employment, Equity Ownership. Litwiler:Array BioPharma: Employment. Karan:Array BioPharma: Employment. Hilder:a: Employment. Ptaszynski:Array BioPharma Inc.: Consultancy. Lonial:Millenium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Bristol Myers Squibb: Consultancy; Onyx: Consultancy; Merck: Consultancy.

Description: Background: Allogeneic transplantation is a potentially curative approach in patients with myeloma. The potential benefit is offset by a higher risk of transplant-related mortality (TRM), graft-vs.host disease (GVHD) and opportunistic infections. The success of reduced intensity conditioning approaches has renewed interest in allogeneic transplantation. In this randomized phase II trial we evaluated whether lowering the dose of melphalan in a nonablative preparative regimen can lower the toxicity and TRM. Two reduced intensity regimens: fludarabine + melphalan 140 mg/m2 (FM 140) and fludarabine + melphalan 100 mg/m2 (FM 100) were compared in patients undergoing allogeneic stem cell transplantation. Methods: We enrolled 22 patients, 11 in each arm, who were 70 years of age or younger and had an HLA-identical sibling donor. Patients underwent allogeneic transplantation between April 2002 and January 2007. Median age was 52.5 years (Range: 32–63). GVHD prophylaxis consisted of tacrolimus and methotrexate 5mg/m2 on days 1, 3, 6 and 11. Median interval between diagnosis and transplant was 28 months (9–232). Only 6 patients (27%) received transplant for the consolidation of first remission, the rest had relapsed or refractory disease (73%). Twenty-one patients had a prior autotransplant; 3 of these had 2 prior autotransplants. Median number of prior treatment regimens was 5 (1–10). Cytogenetic abnormalities were observed in 8/22 patients (36%). Results: The 2 groups were comparable in terms of age, disease status, prior therapy and other prognostic factors. Median time to neutrophil engraftment in both arms was 12 days. TRM in the first 100 days was zero in both arms. Response rate (CR 18% + PR 64%) was 82%, with no significant difference between the 2 arms. After a median follow up of 25 months (26 months in FM 100, 21 months in FM 140), Kaplan-Meier estimates of 2-year PFS in FM 100 vs. FM 140 were 41% vs. 42%, respectively. Kaplan-Meier estimates of 2-year OS in FM 100 vs. FM 140 were 60 vs. 36%, (p=0.4), respectively. There was no significant difference in the incidence of grade II-IV acute GVHD (27 vs. 36%) or chronic GVHD (50 vs. 43%) between the 2 arms. There was a decrease in overall grade II-IV toxicity in the FM 100 arm (45% vs. 73%) that did not reach statistical significance (p=0.2) Patients transplanted in relapse had shorter PFS (0.09). Conclusions: The dose of melphalan in preparative regimen can be safely reduced without adversely impacting the engraftment in this heavily pretreated patient population. There was a trend towards lower grade II-IV toxicity and prolonged OS in the FM 100 arm. This approach may be more beneficial when used early in the course of treatment.

Description: Abstract 2976 Background: c-Met receptor tyrosine kinase (RTK) activity has been implicated in establishing the oncogenic phenotype across several human cancers with high levels of the activating c-Met ligand, hepatocyte growth factor (HGF). Malignant plasma cells secrete HGF-activator (HGFA), which converts HGF to its active form, and high HGF levels are correlated with a poor prognosis in multiple myeloma (MM). Syndecan 1 (CD138) on malignant plasma cells binds HGF and potentiates interleukin-6-induced growth and migration. HGF stimulation of myeloma cells also activates autophosphorylation of c-Met and other critical downstream signaling pathways promoting oncogenesis. Finally, pre-clinical studies have shown that suppression of c-Met signaling with a number of small molecules, including ARQ 197, induced myeloma cell apoptosis. Tevantinib-mediated cytotoxic response was observed at concentrations of less than 5 μM, which are achievable in the clinic. These findings supported the hypothesis that suppression of the HGF/c-Met signaling axis could be a rational strategy against relapsed multiple myeloma. Methods: In this phase II study, the efficacy and safety of ARQ 197, a non-competitive and highly selective inhibitor of the c-Met RTK, is being studied in patients with relapsed multiple myeloma. Primary objectives were to determine the overall response rate (ORR) to single-agent tivantinib in patients with relapsed multiple myeloma who had received one to four prior lines of therapy, and to define the toxicities in this population. ARQ 197 was administered at a starting oral dose of 360 mg twice daily with meals for each day of every 4-week treatment cycle. This dose was selected from prior phase I investigations in solid tumors, and at this dose level, steady-state plasma level sof ARQ-197 were 7 μM. Treatment could continue providing that patients did not experience undue toxicities, or disease progression. Tivantinib is provided through the Cancer Therapy Evaluation Program (CTEP), and this study is supported by CTEP, as well as the M. D. Anderson Cancer Center SPORE in Multiple Myeloma. Results: A total of 10 patients have been enrolled and treated to date, all of whom were evaluable for toxicity, with 8 evaluable for response based on having completed two treatment cycles. Patients had received from 1–3 prior lines of therapy for their disease, and 7/10 (70%) had presented with International Staging System stage I disease at diagnosis. All patients on study had an ECOG performance status of 1 or better, and received a median of 3.5 cycles of tivantinib (range 1–7). The most common adverse events (AEs) of any grade seen in at least 30% of patients included diarrhea (30%), dizziness (30%), dry eyes (30%), shortness of breath (30%), memory change (30%), myalgias (40%), fatigue (60%), and neutropenia (60%). Serious AEs (SAEs) occurred in 2 patients, including one patient with grade 3 syncope, and another with grade 4 neutropenia and a grade 3 anal fissure. Stable disease (SD) has been seen as the best response in 5/7 (71%) evaluable patients, which was maintained for up to 7 cycles, while the remaining patients showed evidence of disease progression. Conclusion: Enrollment is continuing to this first study of any c-Met inhibitor in patients with relapsed multiple myeloma to better define the role of single-agent tivantinib in this setting. To date, tivantinib has been tolerated well, and some evidence of activity has been seen, with stable disease in 63% of patients, all of whom were progressing at the time of enrollment. Updated toxicity and efficacy data will be presented at the time of the Annual Meeting. Correlative studies are also underway with the goal of identifying potential predictive biomarkers. Disclosures: Off Label Use: Tivantinib is being evaluated for patients with relapsed myeloma, but is not yet approved in this setting.

Description: Introduction: Waldenström's macroglobulinemia (WM) is a rare, indolent B-cell lymphoma characterized by lymphoplasmacytic cell infiltration of bone marrow and elevated serum levels of immunoglobulin M (IgM) protein. Despite recent advances in treatment the disease relapses in most patients. About 90% of WM patients harbor the MYD88 L265P oncogenic mutation. MYD88 is an adapter protein in the Toll-like receptor (TLR) pathway. The MYD88 L265P oncoprotein has been shown to amplify TLR 7 and 9 signaling, leading to downstream activation of NF-κB and cytokine signaling pathways that promote tumor cell survival and proliferation (Lim, AACR 2013). IMO-8400 is an investigational oligonucleotide antagonist of endosomal TLRs 7, 8 and 9. In preclinical studies in a human cell line and animal models of WM, IMO-8400 inhibited key cell signaling pathways, including NF-κB, BTK, STAT-3 and IRAK-4, and inhibited tumor growth and tumor IgM production. In Phase 1 and 2 clinical trials in healthy subjects (N=30) and in patients with autoimmune disease (N=35), IMO-8400 was generally well tolerated and demonstrated evidence of clinical activity. Based on these data, we initiated a Phase 1/2 clinical trial of IMO-8400 in WM, the first study of a drug candidate specifically targeting the MYD88 L265P mutation. Methods: This Phase 1/2 multicenter, open-label, dose-escalation clinical trial continues to recruit adult patients with relapsed or refractory WM (NCT Identifier: NCT02092909). In a classic 3x3 dose escalation scheme, patients are enrolled in one of three sequential escalating dose cohorts and receive subcutaneous IMO-8400 at dosages of 0.6, 1.2 or 2.4 mg/kg per week, respectively, for 24 weeks. The presence of the MYD88 L265P mutation is assessed by PCR-based genetic screening following enrollment. Patients who complete the 24-week treatment period are eligible to enroll in an extension trial. The primary study objective is to evaluate the safety and tolerability of escalating IMO-8400 dosages. Secondary objectives include preliminary evaluation of clinical response based on international guidelines and identification of an optimal dose for further evaluation (Kimby, Clin Lymphoma Myeloma 2006). Results: Overall, 17 patients (6 female, 11 male) have been enrolled in three dose cohorts to date. Median baseline characteristics include: age 66 years, prior therapies 4 (range 1-13), serum IgM 2,225 mg/dL, serum M protein 0.96 g/dL, and B2-microglobulin 3.42 mg/L. IMO-8400 has been generally well tolerated across all dose cohorts to date, with patient exposure ranging from 2-46 weeks in the Phase 1/2 and extension trials. The most common adverse events reported to date include transient flu-like symptoms and injection site reactions. One serious adverse event of worsening grade 3 arthritis, deemed possibly related to study drug, was reported in a patient with a pre-existing history of arthritis in the 2.4 mg/kg dose cohort. This patient discontinued study treatment. To date, no other patients have discontinued treatment due to treatment-related adverse events. Preliminary evidence of clinical activity for IMO-8400 has been observed in all dose cohorts. In June 2015, an independent Data Review Committee reviewed 4-week safety data from the highest dose cohort and agreed that 2.4 mg/kg was safe for further evaluation. Safety, pharmacokinetics and preliminary activity for all three dose cohorts will be presented. Conclusions: IMO-8400 is a mutation-targeted therapy in development for the treatment of patients with relapsed or refractory WM. In an ongoing Phase 1/2 clinical trial in WM, IMO-8400 has been generally well tolerated and has demonstrated preliminary evidence of clinical activity. Safety results support continued evaluation of IMO-8400 at 2.4 mg/kg/week in this patient population. Disclosures Thomas: Novartis, Celgene, Acerta Pharmaceuticals, Idera Pharmaceuticals: Research Funding. Harb:Astex Pharmaceuticals, Inc.: Research Funding; Idera Pharmaceuticals: Research Funding. Beck:Idera Pharmaceuticals: Research Funding. Nashat:Idera Pharmaceuticals: Research Funding. Ansell:Idera Pharmaceuticals: Research Funding. Eradat:Idera Pharmaceuticals: Research Funding. Libby:Idera Pharmaceuticals: Research Funding. Hajdenberg:Celgene: Speakers Bureau; Novartis: Speakers Bureau; Incyte: Speakers Bureau; AbbVie: Speakers Bureau; Gilead: Speakers Bureau; Janssen: Speakers Bureau; Idera Pharmaceuticals: Research Funding. Heffner:Idera Pharmaceuticals: Research Funding. Hoffman:Idera Pharmaceuticals: Research Funding. Vesole:Celgene Corporation: Speakers Bureau; Idera Pharmaceuticals: Research Funding. Simov:Idera Pharmaceuticals: Employment. Wyant:Idera Pharmaceuticals: Employment. Brevard:Idera Pharmaceuticals: Employment. O'Leary:Idera Pharmaceuticals: Employment. Agrawal:Idera Pharmaceuticals: Employment.

Description: Methods: As reported previously, PVX-410 Multi-Peptide Vaccine (OncoPep, Inc.) is being developed for the treatment of SMM. PVX-410 consists of 4 human leukocyte antigen-A2 (HLA-A2), synthetic 9-mer peptides from unique regions of 3 multiple myeloma (MM)-associated antigens (XBP1 US184-192; XBP1 SP367-375; CD138260-268; and CS1239-247) emulsified in Montanide® ISA-720 VG (Seppic). Adults with SMM at high risk of progression to active MM and were HLA-A2-positive were eligible. The primary objective of this study was to determine the tolerability of PVX-410, initially as monotherapy. Immune response and change in M protein and free light chain ratio (FLC) were also assessed. PVX-410 alone was safe and immunogenic in the initial 12 patients treated, with all 12 having positive immune response to at least 1peptide, as determined by interferon-gamma enzyme-linked immunosorbent spot (Elispot) and tetramer assays. Given its immunomodulatory properties, it was hypothesized that co-administration of lenalidomide (len; Celgene Corporation) would enhance the T cell-mediated immune response induced by PVX-410. Accordingly, the tolerability, immunogenicity, and anti-MM activity of PVX-410+len was then investigated. Results in the PVX-410 alone cohort were previously reported. In the PVX-410+len cohort, patients received a dose of PVX-410, 0.8mg (0.2mg/peptide / 0.8mg total dose) subcutaneously plus 0.5 mL (1mg) Hiltonol® (poly-ICLC; Oncovir, Inc.) intramuscularly every 2 weeks for a total of 6 doses with 3 standard cycles of len (25 mg orally) on Days 1-21 every 28 days, without dexamethasone. Patients are followed for 12months post-treatment. Blood samples for immune response evaluation are collected at Week 0 (Baseline; pre-dose), 2, 4, and 8 during treatment and at Months 1, 3, 6, 9, and 12 post-treatment. Disease response is assessed at the same time points, except Weeks 0 and 2, using International Myeloma Working Group and modified European Group for Blood and Bone Marrow Transplant criteria. Results: Overall, 22 patients have been enrolled, with ages ranging from 39 to 82 years. Ten patients were enrolled in the PVX-410+len cohort, with 9 evaluable for response. All 10 patients received at least 1 cycle of len; 8 received all 3 cycles; 1 received 1 cycle before discontinuing due to a deviation; and 1 completed 2 cycles as of the cutoff date. One patient had 7 of 21 planned doses held due to neutropenia related to lenalidomide, but resumed the next cycle at a reduced dose (from 25 mg to 20 mg). Immunogenicity data with PVX-410+len and PVX-410 alone, as determined via intracellular cytokine staining and tetramer analysis, will be presented. With PVX-410 alone, 5 patients, 2 of 3 with the low-dose of 0.4 mg (0.1mg/peptide) and 3 of 9 at the target-dose (0.2 mg/peptide), experienced progression to active disease within 9 months post-treatment, and 7 had stable disease (SD) at the last follow up visit in the 12 month follow up period. With PVX-410+len, 5 patients have experienced partial or minimal responses and 3 have experienced SD. Durability of response is assessed through the 12-month study period; 1 patient has progressed to active myeloma during this time. PVX-410 was well-tolerated alone and with len. Most adverse events (AEs) have been ≤Grade 2 and non-serious. AEs seen more frequently with PVX-410+len versus PVX-410 alone are expected with len and include hematologic abnormalities (neutropenia, anemia, thrombocytopenia), gastrointestinal disorders (nausea, diarrhea, constipation), skin and cutaneous disorders (rash, pruritus), and myalgia. There was 1serious AE in the combination cohort (pneumonia), considered possibly related to len and unrelated to PVX-410. Conclusions: Six doses of PVX-410 were well tolerated in 22 patients with SMM. Additional AEs seen with PVX-410+len versus PVX-410 alone were expected with the addition of len to the treatment regimen. An immune response to the vaccine was seen in all patients treated with PVX-410 alone and is expected to be enhanced with PVX-410+len; these data will be presented. Based on the promising findings to date, an evaluation of PVX-410 in combination with an antibody to the programmed cell-death-1-ligand complex (PD1/PDL1) is planned to begin in 2015. Disclosures Nooka: Spectrum Pharmaceuticals: Consultancy; Onyx Pharmaceuticals: Consultancy. Off Label Use: Off label use of lenalidomide. Wang:Janssen: Honoraria; Pharmacyclics, Janssen, Celgene, Oncopep, Kite, Juno: Research Funding. Thomas:Novartis, Celgene, Acerta Pharmaceuticals, Idera Pharmaceuticals: Research Funding. O'Donnell:Millennium: Consultancy. Shah:Millenium: Research Funding; Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Array: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees. Kaufman:Milleniumm, Celgene, Novartis, Onyx, Spectrum: Consultancy. Lonial:Onyx: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding. Richardson:Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium Takeda: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees. Raje:Takeda: Consultancy; BMS: Consultancy; Celgene Corporation: Consultancy; Amgen: Consultancy; Onyx: Consultancy; AstraZeneca: Research Funding; Millenium: Consultancy; Novartis: Consultancy; Acetylon: Research Funding; Eli Lilly: Research Funding.

Description: Introduction Carfilzomib (Car) is a proteasome inhibitor (PI) that was recently approved for the treatment of relapsed or refractory multiple myeloma. It is indicated for patients (pts) who previously received the proteasome inhibitor bortezomib (Bz) and an immunomodulatory drug (thalidomide or lenalidomide (len)) and had disease refractory to the last line of therapy. With the increasing number of therapeutic options, the optimal sequencing strategy of PIs to maximize clinical benefit and patient outcomes is unclear. The objective of our study was to therefore evaluate the activity of Bz after Car exposure. Methods Pts who enrolled and received Carfilzomib-based therapy on clinical trials at The University of Texas M. D. Anderson Cancer Center were screened for subsequent Bz therapy. Carfilzomib was administered as a single agent, or with len/dexamethasone (dex). We evaluated the overall response and tolerability of Bz pre- and post-Car, and to Car-based therapy. Results 16 pts were identified with a mean age of 67 (range 48-85), including 11 women and 5 men. ISS stage was I in 10 pts, stage II in 1, and stage III in 5. Median lines of therapy prior to Car were 3 (1-9), and 11 pts had prior stem cell transplant. Prior to Car-based therapy, 5 pts were Bz naïve, 7 were Bz sensitive, and 4 were Bz intolerant. Among the 16 patients treated with Car as a single agent, or Car in combination with dex (n=1), len/dex (n=12), panobinostat (n=2) and pomalidomide/dex (n=1) the overall response rate (ORR) to Car-based therapy on protocol (≥MR) was 75% (12/16). Among the 16 pts who subsequently received Bz after Car, 4 patients remained sensitive to Car (2/4 were Bz naïve), 5 were intolerant to Car, and 7 were Car refractory (3/7 were Bz naïve). Patients received Bz in combination with various other therapeutics, including cyclophosphamide/dex (n=5), melphalan/dex (n=2), modified-CVAD (n=3), len/dex (n=5), pegylated doxorubicin/dex (n=7) and bendamustine (n=3). The ORR to Bz-based therapy after Car was 81% (13/16). Among the 7 patients who were refractory to Car, 5/7 patients had ≥MR to Bz based therapy, while 2 patients were Bz intolerant due to rash and neutropenia. Among the 13 pts who responded to Bz after Car, 10 patients had received prior Bz. 3/5 pts who were Bz naïve had ≥MR. 4/4 patients who were intolerant to prior Bz had ≥MR, and 6/7 Bz sensitive patients had ≥MR. Discussion Bortezomib-based therapy is feasible after carfilzomib exposure in patients including those who were previously intolerant to bortezomib. The ORR(≥MR) in this patient population to Bz-based therapy was 81%. Disclosures: Thomas: Millenium: Research Funding; Novartis Pharmaceuticals: Research Funding; Celgene: Research Funding; Immunomedics: Research Funding; Pharmacyclics: Membership on an entity’s Board of Directors or advisory committees; Onyx: Membership on an entity’s Board of Directors or advisory committees. Orlowski:Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees. Shah:Celgene: Consultancy, Research Funding; Array: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Millenium: Consultancy, Research Funding; Onyx: Consultancy, Research Funding.

Description: Abstract 2734 Background: Rituximab was first approved by the FDA for use in relapsed and/or refractory low grade or follicular B cell non-Hodgkin's lymphoma in 11/1997. Since that time it has been widely used in WM, and is the backbone of drug combinations developed for treatment of this disease. Methods: To evaluate the impact of rituximab on overall survival (OS), we retrospectively evaluated patients (pts) treated at our center who received primary therapy for symptomatic WM with combinations of either alkylating agents (AA), nucleoside analogs (NA) +/− AA, or bortezomib (B), each with or without rituximab (R). The effect of primary therapy on OS was compared between patients receiving primary therapy before and after rituximab use for WM began at our center (11/11/1998). OS was calculated from the date of initial treatment until date of death or last follow-up. Due to small patient numbers, those who received vincristine-doxorubicin-dexamethasone (2 pts), single agent rituximab (3 pts), or rituximab-alkylating agent combinations (11 pts) as primary therapy, were excluded from the analysis. Results: Among 315 patients with previously untreated symptomatic WM treated since 3/1966, 118 received AA alone; 137 received NA +/− AA alone (85 pts) or with R (52 pts), and 44 received B + R. Median age, hemoglobin, platelet count and β2 microglobulin were comparable between all treatment groups (AA alone, NA +/− AA alone, NA +/− AA + R, B + R). Only median albumin differed significantly, with levels of 3.7 g/dL (AA alone), 4.1 g/dL (NA+/− AA alone), 4.3 g/dL (NA+/− AA + R) and 4.4 g/dL (B + R), respectively (p 〈 0.01). The median OS of pts treated with AA was 4.5 years, and 6.5 years with NA +/− AA, while the median OS of pts treated with NA+/− AA + R (median follow-up: 8 years) and B + R (median follow-up: 2.6 years) has not been reached. Comparing all patients treated with vs. without R, median OS is 〉13 years vs. 5.6 years (p