Citations

Abstract Introduction: The programmed death-1 (PD-1) immune checkpoint pathway regulates T-cell-mediated antitumor immune responses in solid tumors and hematologic malignancies. Nivolumab (Bristol-Myers Squibb, Ono Pharmaceutical) is a fully human IgG4 PD-1-blocking monoclonal antibody with demonstrated efficacy in a range of tumors. Results from an independent cohort of 23 pts with R/R cHL in a phase 1 study (CA209-039) showed that nivolumab was well tolerated and yielded an overall response rate (ORR) of 87% (Ansell et al, N Engl J Med, 2015). This raises important questions including the necessary duration of treatment, the relevance of the depth of response (complete response [CR] vs partial response [PR]), the duration of response, and the feasibility of retreatment. Here, we present the clinical course and post-treatment outcomes from extended follow-up of these pts to shed some light on these questions. Methods: Pts with R/R cHL received nivolumab 3 mg/kg at weeks (wks) 1 and 4, and then every 2 wks for up to 2 years (yrs). Therapy was stopped earlier in pts with intolerance to treatment or progressive disease (PD) without evidence of clinical benefit. Pts who discontinued treatment due to toxicity were followed for up to 120 days after discontinuation; other pts were followed for 1 yr after discontinuation. Responding pts discontinued after confirmed CR or 16 wks after unconfirmed CR, or continued treatment for up to 2 yrs if they had PR or stable disease (SD). Pts who discontinued treatment with ongoing CR, PR, or SD could be retreated for confirmed PD occurring <1 yr after nivolumab discontinuation. Responses were evaluated using the Revised Response Criteria for Malignant Lymphoma (Cheson et al, J Clin Oncol, 2007). The primary endpoint was safety, and the key secondary endpoint was antitumor activity. Results: A total of 23 pts with R/R cHL were treated. The median follow-up observation time is now 86 wks (range: 32-107 wks). Of 20 responders (14 PR, 6 CR), 10 have had durable responses per protocol assessment; their treatment durations and response characteristics are shown in Table 1. Responses were maintained in 2 pts (#5 and #6) after discontinuing nivolumab for >40 wks and in 1 pt (#7) after stopping due to toxicity. Eight pts with durable responses have received nivolumab for >1 yr, including 7 pts who have been in response for >1.5 yrs. One pt (#2) with an initial CR experienced a relapse 43 wks after treatment was discontinued, and achieved a second response (CR) after retreatment with nivolumab. Of the 10 remaining responders, 4 eventually progressed (time to progression [TTP] range: 21.4-92 wks), 1 discontinued treatment due to toxicity with no PD within the 120-day follow-up period, and 5 discontinued nivolumab to undergo stem cell transplant (SCT; 4 allogeneic, 1 autologous) after achieving remission. Time to CR for all responders ranged from 3-88 wks after starting nivolumab, including 2 pts with initial PRs that converted to CRs with continued treatment. All 5 pts who proceeded to SCT had responded to nivolumab within 16 wks of starting treatment (4 PR, 1 CR). Three pts had a best overall response of SD (1 discontinued due to toxicity without documented PD within the 120-day follow-up period; 2 subsequently discontinued for PD [TTP: 15 and 15.3 wks, respectively]). Overall, 3 pts discontinued nivolumab due to adverse events (AEs; Grade 2 peripheral neuropathy, Grade 3 myelodysplastic syndrome, Grade 3 pancreatitis). Grade 1 or 2 immune-related AEs (IR-AEs) occurred in 4 of 10 pts and resolved without treatment in 2 pts. The incidence of IR-AEs did not increase with time on treatment. Conclusions: In pts with R/R cHL, nivolumab was well tolerated and produced a high ORR. Responses occurred within 16 wks of nivolumab initiation in 15 of 20 pts. Early responses to nivolumab allowed 5 pts to proceed to SCT and lasted ≥1 yr in 7 of 10 pts who did not pursue SCT. One pt achieved CR again after retreatment with nivolumab when relapse occurred within 1 yr of discontinuing treatment following an initial CR. Table 1. Treatment and Response Parameters for Pts with Durable Ongoing Responses Pt # Best Response Duration of Response, wks Time to First Response, wks Time on Treatment, wks 1 PR 90.7 3.6 96+ 2 CR 82.1 7.1 91+ 3 PR 73.1 7.6 82.4+ 4 PR 71.4 14.9 88+ 5 CR 71.1 3.1 24.9 6 CR 65.1 7.1 22.9 7 PR 55.9 15.3 70.9 8 CR 48.3 39 87 9 CR 45.3 55 82.9 10 PR 41.7 38.7 82.1+ +Still on treatment Disclosures Ansell: Bristol-Myers Squibb: Research Funding; Celldex: Research Funding. Armand:BMS: Research Funding; Infinity: Consultancy, Research Funding; Sequenta, Inc.: Research Funding; Merck: Consultancy, Research Funding. Timmerman:Valor Biotherapeutics: Research Funding; Janssen: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding. Shipp:BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy; Merck: Membership on an entity's Board of Directors or advisory committees. Bradley Garelik:Bristol-Myers Squibb: Employment. Zhu:Bristol-Myers Squibb: Employment. Lesokhin:Efranat: Consultancy; Genentech: Research Funding; Aduro: Consultancy; Janssen: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding.

Abstract Background: Mitochondrial activity is critical to maintain a high cellular proliferation especially in drug-resistant clones. Ibrutinib-resistance (IR) in CLL is associated with highly aggressive clinical behavior, carrying a median survival of ~3 months. While these outcomes are not yet reported in WM, resistance to ibrutinib is foreseeable considering no WM patients achieve a complete remission with BTK inhibitors (reported series). The transition to a highly proliferative drive in the IR clone remains a biological dilemma and understanding this will allow rationale development of therapeutic strategies. It is established that increased cell proliferation is highly dependent on the functional capabilities of the mitochondria. Yet the respiratory proficiencies and adaptation of mitochondrial machinery in the IR state remains unknown. Here we interrogated mitochondrial function and its relevance in IR cells using our WM models. Materials: WM cell lines (BCWM.1, non-IR) and its isogenic IR clone (BCWM.1/IR; 20-fold resistant, without BTK or CXCR4WHIM-like mutations) were used. Mitochondrial respirometry was measured by Seahorse XF96 flux analyzer (Fig. 1a). Drug sensitivity and cytotoxicity were determined by Cell-Titer Glo cell viability assay. Whole exome sequencing (WES) was performed on an Illumina HiSeq2000. Results: IR WM cells were noted to be in G1 arrest with altered morphologic features and growth kinetics. Despite growth arrest, IR cells showed increased basal oxygen consumption rate (OCR) (>30% increase) vs. parental (non-IR) cells. Consistent with this we observed enhanced mitochondrial ATP production suggesting increased mitochondrial utilization by the IR clones. We then measured maximal respiratory potential of WM cells with FCCP pre-treatment, which evaluates cellular potential to respond to increased ATP demand. We observed upregulation of mitochondrial spare respiratory capacity in BCWM.1/IR cells vs. parental BCWM.1 cell. In addition, a >50% increase in non-mitochondrial oxygen consumption/respiration was also noted (Fig.1b, c). To identify potential genomic changes that could explain mitochondrial overdrive, WES of the non-IR and IR cells was performed. Interestingly, this analysis did not uncover any mutational alterations in genes directing cellular oxidative phosphorylation (NDUF, COX1, COQ7, SURF1, etc.), glycolysis (PDK1, HK2, PKM2, ALDOA, etc.) or ATP production (ATP5, ND1, UCP1 and others). We then asked if mitochondrial function impacts therapeutic potential of a specific drug (or a class of drug), focusing specifically on proteasome disruption. First, we observed that proteasome inhibition- independent of the site (20S vs. 19S), retained high cytotoxic potential, wherein IR cells showed exquisite sensitivity to proteasome disruption. Interestingly, VLX1570 (targets 19S proteasome) had a 2-fold lower IC50 in IR clones than its non-IR counterpart. Cell respirometry demonstrated that compared to parental cells, VLX1570 (500nM) treatment significantly (p<0.002) and rapidly (2hr) attenuated basal respiration in IR clones at concentrations half of those needed to achieve similar effects in BCWM.1 cells. A concomitant decrease in ATP production as well as spare respiratory capacity was observed at these time points/drug concentrations (significantly more evident than in BCWM.1 cells). While our focus was mitochondrial bioenergetics and its therapeutic relevance in drug-resistant WM, unexpectedly we observed for the first time, evidence that VLX1570 induces changes in mitochondrial bioenergetics as early as 2hrs leading to increased mitochondrial membrane permeability and cell apoptosis in 6-12hrs. Comparable observations were made with bortezomib (targeting 20S). Conclusions: This is the first report identifying the role of mitochondrial hyper-drive in WM cells with resistance to ibrutinib. Of note, enhancedmitochondrial bioenergetics in the IR state increased sensitivity to proteasome inhibition and this was independent of the site of disruption in the proteasome pathway. Although, WES findings alone were not sufficient in explaining mitochondrial overdrive noted in our system, ongoing analysis of various mitochondrial functions (Fig. 1d) at the gene expression, copy number and epigenetic level may elucidate the underlying biomechanics of mitochondrial disposition in IR WM cells. Disclosures Ansell: BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Linder:Vivolux, Ab: Other: Shareholder. Ailawadhi:Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy.

Abstract Background: Diffuse large B-cell lymphoma (DLBCL) is curable for the majority of patients treated with anthracycline based immunochemotherapy (IC). However, up to 40% of patients will relapse or require retreatment of DLBCL and outcomes are poor in this setting. Here we examine the incidence, treatment patterns and outcomes of relapsed DLBCL in the R-CHOP era. Methods: Patients were prospectively enrolled in the University of Iowa / Mayo Clinic SPORE Molecular Epidemiology Resource (MER) within 9 months of diagnosis and followed for relapse, retreatment, and death. Clinical management at diagnosis and subsequent therapies were per treating physician. This analysis includes patients with DLBCL or primary mediastinal B-cell lymphoma (PMBCL) who underwent front-line anthracycline based IC; patients with primary CNS lymphoma or PTLD were excluded. All relapse and re-treatments were verified by medical record review. Response to front-line therapy was retrospectively classified per 2007 Revised Response Criteria for Malignant Lymphoma from available clinical and radiology records. Unplanned consolidative radiation (RT) without biopsy proven disease after achieving PR from IC (N=21) was not classified as a relapse. Results: 1039 patients with newly diagnosed DLBCL or PMBCL and treated with IC were enrolled in the MER from 2002-2012. Median age at diagnosis was 62 years (range 18-92) and 577 patients (56%) were male. 647 patients (63%) had stage III/IV disease and IPI at diagnosis was 0-1 in 350 patients (34%), 2 in 305 patients (29%), 3 in 250 patients (24%) and 4-5 in 134 patients (13%). At a median follow-up of 59 months (range 1-148), 258 patients had relapse or retreatment of DLBCL of which 184 (71%) died. Incidence of relapse was 21.7% (95% CI: 19.3%-24.4%) at 2 years and 25.5% (95% CI: 22.9%-28.5%) at 5 years. In addition, the incidence of lymphoma related death without documented relapse or retreatment was 4.7% (95% CI: 3.6%-6.2%) at 2 years. At first relapse, 174 patients (67% of relapsed) received platinum based salvage therapy with 90 (52%) subsequently proceeding to autologous stem cell transplant (ASCT). 22 patients received CNS directed systemic therapy at relapse with 9 (41%) proceeding to transplant, and 43 received non-platinum-based salvage systemic therapy with 7 proceeding to transplant (17%), 15 patients received RT only as 2nd line therapy, and 4 were untreated. At a median follow-up of 56 months (range 6-121) post-transplant, 39 of 107 patients who underwent transplant remain in remission with a 2-year post-transplant progression-free survival of 45% (95% CI 37%-56%). Response to front-line IC was predictive of post-relapse outcome. Survival post-relapse was superior in the 162 patients with responsive disease (CR or PR) at the end of front-line IC (median OS 21.0 months) compared to the 88 patients who had stable or progressive disease (median OS 6.8 months, HR = 2.33, 95% CI: 1.73-3.14 p<0.0001). Transient response in midst of front-line IC was similar to no response. Patients achieving a CR or PR to front-line IC were more likely to proceed to ASCT at relapse (55%) compared to patients with either SD or PD at the end of front-line IC (25% and 17% respectively, p<0.0001). Other factors associated with poor survival at first relapse were relapse within 12 months of diagnosis (HR = 2.24, 95% CI: 1.57-3.18, p<0.0001), IPI at diagnosis of 3-5 (HR=1.51, 95% CI: 1.13-2.03, p=0.0058), and age > 60 (HR =1.51, 95% CI: 1.12-2.03, p=0.0064). There was no difference in survival at first relapse by cell of origin (HR = 1.13, 95% CI: 0.74-1.72, p=0.59). Conclusions: Most patients undergo therapy after relapsed/refractory DLBCL but only one-third receive ASCT. Outcomes following all treatments for relapsed/refractory DLBCL remain poor. Factors associated with adverse outcomes include refractory to front-line therapy, early relapse, baseline IPI and advanced age. These outcomes provide relevant historical control for the many novel agents being tested in this unmet need. Figure 1. Figure 1. Disclosures Farooq: Kite Pharma: Research Funding. Maurer:Kite Pharma: Research Funding. Cerhan:Kite Pharma: Research Funding. Link:Genentech: Consultancy, Research Funding; Kite Pharma: Research Funding. Thompson:Kite Pharma: Research Funding.

Abstract Background: Peripheral T-Cell lymphomas (PTCLs) constitute approximately 10% of lymphoid malignancies and consist of several distinct entities based on pathologic and clinical characteristics. With the exception of a few subtypes (e.g., ALK-positive anaplastic large cell lymphoma (ALCL) and some primary cutaneous or leukemic forms of PTCL), a majority of PTCLs are aggressive as characterized by poor treatment response, rapid disease progression and poor overall survival. We have shown that landmark timepoints of event-free survival after diagnosis can stratify subsequent overall survival (OS) in diffuse large B-cell and follicular lymphoma. Here we evaluate this approach in newly diagnosed aggressive PTCLs treated with anthracyline-based or related chemotherapy. Methods. Newly diagnosed PTCL patients were prospectively enrolled in the University of Iowa/Mayo Clinic Lymphoma SPORE Molecular Epidemiology Resource (MER) from 2002-2012. Clinical data were abstracted from medical records using a standard protocol. For this analysis, we included patients receiving anthracycline-based or other multiagent chemotherapy for the following PTCL subtypes: ALK-negative ALCL (N=24); angioimmunoblastic T-cell lymphoma (AITL, N=34); PTCL, not otherwise specified (NOS; N=60); enteropathy-associated T-cell lymphoma (EATL, N=8); extranodal NK/T-cell lymphoma, nasal type (ENKTL, N=11); and hepatosplenic T-cell lymphoma (HSTCL, N=1). Patients were prospectively followed, and event-free survival (EFS) was defined as time from diagnosis to progression, re-treatment, or death due to any cause. Landmark EFS timepoints were assessed at 12 (EFS12) and 24 (EFS24) months after the date of diagnosis. Subsequent OS was defined as time from a specific endpoint (diagnosis, event or EFS landmark). Replication was performed in a population-based cohort of T-cell lymphomas diagnosed from 2000-2009 from the Swedish Lymphoma Registry. Results. 138 eligible patients were enrolled in the MER from 2002-2012, the median age at diagnosis was 58 years (range, 19-88), 66% were male, 73% had Stage III-IV disease, and 33% had IPI 0-1. At a median follow-up of 47 months (range 11-120), 87 patients (63%) had an event and 70 patients (51%) had died. From diagnosis, only 60 patients were event-free at 12 months (EFS12 45%). Patients who failed to achieve EFS12 had a poor subsequent OS from event (median OS = 6.8 months, 95% CI: 5.3-14.0, figure 1). In contrast, patients who achieved EFS12 had a favorable subsequent OS (median unreached, figure 2). Of the 427 eligible patients in the Swedish registry, the median age at diagnosis was 66 years (range, 18-88), 63% were male, 68% had Stage III-IV disease, and 25% had IPI 0-1. PTCL subtypes were: ALK-negative ALCL (N=89); AITL (N=80); PTCL, NOS (N=183); EATL (N=44); ENKTL (N=24); and HSTCL (N=7). At a median follow-up of 86 months (range 40-158), 333 patients (79%) had an event and 316 patients (74%) had died. From diagnosis, 183 patients were event-free at 12 months (EFS12 44%). Similar to the MER cohort, Swedish patients failing EFS12 had poor subsequent survival (median OS = 3.7 months, 95% CI: 2.9-5.3, figure 1). Swedish patients achieving EFS12 had a favorable subsequent OS (median OS = 89 months, figure 2). Similar results were obtained when conducting landmark analysis at 24 months after diagnosis (EFS24). Conclusion. Relapse and re-treatment events within the first 12 months of diagnosis are associated with very poor OS in PTCL treated with anthracyclines or related chemotherapy, while patients achieving EFS12 have encouraging subsequent OS. Stratifying patients into prognostically distinct subsets using EFS12 may help focus biologic and biomarker studies. EFS12 has potential as an early endpoint for studies of newly diagnosed PTCL. Further investigation of determinants related to post-EFS12 survival is needed. Disclosures Maurer: Kite Pharma: Research Funding. Cerhan:Kite Pharma: Research Funding. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding. Link:Genentech: Consultancy, Research Funding; Kite Pharma: Research Funding. Thompson:Kite Pharma: Research Funding. Relander:Respiratorius: Patents & Royalties: valproate for DLBCL.

Abstract Introduction The phagocytic activity of macrophages is regulated by activating ("eat") and inhibitory ("do not eat") signals. Under normal physiologic conditions, the ubiquitously expressed cell surface antigen CD47 suppresses phagocytosis by binding to signal regulatory protein alpha (SIRPα) on macrophages. It is hypothesized that overexpression of CD47 by cancer cells enables immune evasion. Blockade of CD47 results in phagocytosis of cells bearing "eat" signals and primes effective anti-tumor T cell responses. TTI-621(SIRPαFc)is a soluble recombinant fusion proteinconsisting of the CD47 binding domain of human SIRPα linked to the Fc region of human IgG1designed to both: 1) block the CD47 "do not eat" signal, and 2) engagemacrophage Fcγ receptors with IgG1 Fc to enhance phagocytosis and antitumor activity.In vitro, TTI-621 binds to normal human cells, platelets, a wide range of human primary tumor cells and cell lines, but only minimally to human erythrocytes. TTI-621 selectively promotes macrophage-mediated phagocytosis of hematologic and solid tumors over that observed with normal monocytes, and exhibits antitumor activity in xenograft mouse models. Methods A first-in-human, phase 1, open label, multicenter study (NCT02663518) is ongoing to evaluate the safety and tolerability, and to identify the maximum tolerated dose of TTI-621 in patients (pts) with relapsed/refractory lymphomas using a 3+3 dose-escalation design. Once the optimal dose has been determined in the dose-escalation phase, multiple expansion cohorts will be enrolled comprising pts with various relapsed/refractory hematologic malignancies. Assessments include peripheral receptor occupancy, serum cytokine levels, pharmacokinetics, and immunogenicity. Eligible pts are adults with advanced, measurable, hematologic malignancies, who have progressed on standard anticancer therapy or for whom no other approved therapy exists. Pts are required to have baseline hemoglobin ≥10 g/dL, platelets ≥75 x 109/L, and be transfusion- and growth factor-independent. Pts with cutaneous T-cell lymphoma, high-grade lymphoma, and acute promyelocytic leukemia are excluded. TTI-621 is administered IV once weekly at protocol-defined doses. Treatment may continue until disease progression or unacceptable toxicity. Results Eleven pts (6M/5F, age 21-72 years) have been enrolled as of the data cut-off date of 28 July 2016. Lymphoma diagnoses included Hodgkin (N=4), diffuse large B cell (DLBCL) (N=4), follicular (N=2), and mantle cell (N=1). Treatment has been reasonably well tolerated by pts in the 0.05 mg/kg (N=3), 0.1 mg/kg (N=3), and 0.3 mg/kg (N=5) dose cohorts. The majority of pts experienced mild to moderate infusion-related events. Hemoglobin levels have remained stable or improved with treatment. Transient, dose-dependent decreases in platelets and leukocytes occurred in the hours following infusion in all pts without clinical sequelae. The 0.3 mg/kg dose was associated with reversible, dose-limiting toxicity (DLT) in 2 of 5 pts: one pt with G3 elevated ALT/AST and G4 platelet count, and a second pt with G4 platelet count who was transfused. Dosing at 0.2 mg/kg is now being explored. Aside from the DLTs and 2 non-DLT G3 platelet count (all in 0.3 mg/kg cohort), treatment-related adverse events have been ≤G2. CD47 receptor occupancy increased with each cohort, peaking at the end of infusion and remaining detectable 24 hrs after the 1st infusion in Cohort 3. Macrophage-associated cytokines, including MIP-1α and MIP-1β, increased during the 4 hrs after infusion. Six pts continue to receive weekly infusions of TTI-621; one pt with DLBCL and another with FL have experienced progression-free intervals of 161 and 70 days, respectively. Conclusions TTI-621 has been reasonably well tolerated. Pts retained stable hemoglobin levels consistent with minimal drug binding to erythrocytes. Manageable, dose-dependent thrombocytopenia was likely due to increased phagocytic clearance of platelets. TTI-621 binds to CD47+ cells in a dose-dependent manner, potently yielding increases in cytokines associated with augmented phagocytic activity. Enrollment continues at the 0.2 mg/kg dose level; updated data will be provided at the meeting. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures Ansell: BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Chen:Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Millenium: Consultancy, Research Funding, Speakers Bureau; Genentech: Consultancy, Speakers Bureau; Merck: Consultancy, Research Funding. Flinn:Janssen: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Gilead Sciences: Research Funding; ARIAD: Research Funding; RainTree Oncology Services: Equity Ownership. O'Connor:Bristol Myers Squibb: Research Funding; Spectrum: Research Funding; TG Therapeutics: Research Funding; Mundipharma: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Seattle Genetics: Research Funding; Bristol Myers Squibb: Research Funding; Mundipharma: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; TG Therapeutics: Research Funding. Johnson:Trillium Therapeutics: Employment. Irwin:Hoffmann La Roche: Employment, Equity Ownership; Trillium Therapeutics: Employment, Equity Ownership. Petrova:Trillium Therapeutics Inc: Employment, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Uger:Trillium Therapeutics: Employment, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Sievers:Seattle Genetics: Employment, Equity Ownership; Trillium Therapeutics: Employment, Equity Ownership; MEI Pharma: Consultancy.

Abstract Abstract 1926 Background: Follicular lymphoma (FL) is the second most common non Hodgkin lymphoma in the United States, comprising up to 30% of all non Hodgkin lymphomas. Typically an indolent disease, relapses are common. High dose therapy followed by autologous stem cell transplant is an option that has shown to produce prolonged progression-free and relapse-free survival in patients who relapse. Adequate bone marrow reserve for peripheral stem cell mobilization has been shown to be adversely effected by prior regimens such as fludarabine and radioimmunotherapy. Concerns regarding stem cell mobilization at the point of relapse have led some to collect stem cells early in the course of disease to allow for potential subsequent transplant after relapse. Recent advances in stem cell mobilization have resulted in a 3% collection failure rate for lymphoma patients at the point of planned transplant at our institution versus a historical rate of up to 30%. We studied the utilization of stem cells collected for potential future use in FL patients in remission or prior to therapy at the point of relapse or progression in order to determine the utility of this approach. Methods: Record review of patients diagnosed with FL through the Mayo Clinic Tumor Registry and the Mayo Clinic Lymphoma Data Base who had cryopreserved stem cells for potential future transplant at relapse. Cost of stem cell storage at our institution was reviewed as was the subsequent use of the collected cells. Results: 73 patients with FL had stem cells collected and stored. 37 (51%) were collected prior to a double dose yttrium-90 (90Y) ibritumomab tiuxetan trial for relapsed lymphoma as required by the study. The median age at collection of this group was 56 years (range 28–70). Stem cells remain in storage for a median of 44 months (range 8–119). The median cost of cryopreservation and storage is $4,094 based on the median storage time of 44 months (range $3,628 to 5,065) with a collection cost of $3,524.20 and an annual storage fee of $155.39. This does not include the cost of filgrastim for mobilization, nor line placement. At 5 years, 60% of the cells were not utilized, and at 10 years, 56% of the cells were not utilized. 36 (49%) of the total number of patients were not part of the double dose 90Y ibritumomab tiuxetan trial, but were collected in remission for possible future use or in the setting of relapsed, progressed or transformed disease for potential future transplant. Five of these patients required the use of plerixafor for adequate mobilization. The median age at collection of this group was 47 years (range 24–76). Stem cells remain in storage for a median of 39 months (range 2–128). The median cost of cryopreservation and storage is $4,029 based on the median storage time of 39 months (range $3,550 to 5,182) with a collection cost of $3,524.20 and an annual storage fee of $155.39. This does not include the cost of filgrastim or plerixafor for mobilization, nor line placement. At 5 years, 89% of these cells were not used, and at 10 years, 71% of cells were not used. Conclusion: The utilization of stem cells collected early in the course of FL patients is low, with the majority of cells not being utilized at 10 years. Given improved mobilization techniques resulting in 97% efficacy of stem cell collection at relapse, routine collection and storage of stem cells early in the course FL is not recommended. Disclosures: Micallef: Genzyme: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Abstract 4125 Background: With the exception of angioimmunoblastic T-cell lymphomas, which are thought to derive from follicular helper T cells, little is known about the cell of origin for the most common peripheral T-cell lymphoma (PTCL), PTCL-unspecified (PTCL-U). Following appropriate antigenic stimulation, naïve CD4+ T helper (TH) cells differentiate into effector cells that secrete TH cytokines under the transcriptional regulation of subset-specific transcription factors. Methods: PTCL-U patients (n=53) from a single institution were retrospectively identified and immunohistochemical analysis of Foxp3, T-bet and GATA-3 expression performed on diagnostic biopsy specimens. Immunohistochemical staining was reviewed in a blinded fashion by a hematopathologist and all specimens with greater than 10% staining were scored as positive. Transcription factor expression was correlated with patient characteristics and clinical outcomes. Results: GATA-3 expression was observed in 22 (42%) patients, T-bet expression in 17 (32%) patients and Foxp3 expression in 4 (7%) patients. In order to determine the prognostic significance of GATA-3 or T-bet expression, overall survival was compared between patients with GATA-3 (or T-bet) positive or negative tumors. The median overall survival (OS) was 2 years (95% confidence interval 0.7–12.8 years) for patients with GATA-3 negative tumors, compared with a median OS of 0.9 years (95% confidence interval 0.5–1.2 years, p=0.02) for GATA-3 positive cases. The median overall survival was 1.6 years (95% confidence interval 1.0–6.8 years) for patients with T-bet negative tumors, compared with a median overall survival of 0.7 years (95% confidence interval 0.3–0.9 years, p=0.005) for T-bet positive cases. As a subset of tumors coexpressed GATA-3 and T-bet, both of which are adverse prognostic factors, we examined survival outcomes between those patients with tumors expressing either GATA-3 or T-bet (n=29) and those with tumors which do not express either transcription factor (n=24). The median OS and PFS observed for patients with positive tumors was 0.7 years (95% confidence interval 0.6–1.1 years) and 0.7 years (95% confidence interval 0.5–0.9 years), respectively. In contrast, patients with GATA-3/T-bet negative tumors experienced markedly superior survival, with a median OS and PFS of 3.8 years (95% confidence interval 1.6–12.9 years, p<0.0001) and 2.0 years (95% confidence interval 1.5–12.8 years, p<0.0001), respectively. Four-year estimates of overall and progression-free survival were less than 10% for patients with GATA-3/T-bet positive tumors, whereas 4-year OS and PFS were 49% and 32%, respectively, for those with negative tumors. Both GATA-3 and T-bet expression were associated with advanced age and tumor stage. Therefore, we analyzed GATA-3/T-bet expression as a prognostic factor for survival on both univariate and multivariate analyses, adjusting for pertinent risk factors, including patient age and tumor stage. On univariate analysis, GATA-3/T-bet expression was associated with inferior overall survival (hazard ratio 4.4, 95% confidence interval 2.1–10.4, p<0.0001). Patient age (>60 years), poor performance status (ECOG performance status >1), and stage III/IV disease were also associated with inferior overall survival on univariate analysis. However, when adjusting for these latter adverse prognostic factors on multivariate analysis, GATA-3/T-bet expression remained an independent predictor of poor overall survival in PTCL-U (adjusted hazard ratio 3.2, 95% confidence interval 1.4–8.5, p=0.008). Similarly, when adjusting only for high-risk features (>2 adverse prognostic factors), as defined by the Prognostic Index in PTCL-U (PIT), GATA-3/T-bet expression remained an independent predictor of inferior overall survival on multivariate analysis (adjusted hazard ratio 4.9, 95% confidence interval 2.2–11.5, p<0.0001). Conclusions: GATA-3 and T-bet expression identify subsets of high-risk PTCL-U patients who may benefit from alternative treatment strategies. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 4168 Background: Primary Pulmonary MALT lymphoma represents 15–20% of Extranodal Marginal Zone Lymphomas of Mucosa Associated Lymphoid Tissue (MALT). In contrast to the more common gastric MALT lymphoma, natural history, prognosis and treatment outcomes for primary pulmonary MALT lymphoma are not well defined. Herein, we report a single institution experience. Methods: Consecutive patients with primary pulmonary MALT lymphoma registered in the Mayo Clinic Lymphoma Database, which includes all consenting patients with lymphoma seen at Mayo Clinic Rochester, were reviewed for clinical features, treatment outcome progression free survival (PFS) and overall survival (OS). The pathology for all patients was centrally reviewed by hematopathologist and the diagnoses were based on WHO lymphoma classification criteria. PFS and OS were assessed using the Kaplan–Meier method and the Cox proportional hazard model was used to assess the impact of variables on PFS and OS. Results: Between December 1986 and June of 2009, ninety-seven patients with primary pulmonary MALT lymphoma were enrolled. The median age at diagnosis was 63 years (range 31–87). There were 43 (44%) males. The initial presentation was a unilateral pulmonary lesion (n=47, 48%), bilateral pulmonary lesions (n=41, 42%), and pulmonary lesion with intrathoracic lymphadenopathy (n= 4, 4%). Bone marrow involvement and presence of B symptoms were 4, 4% and 5, 5%, respectively. International Prognostic Index (IPI) was 0–1, 2–3 and 4–5 in 69, 25 and 1 patient(s) respectively. The median follow-up was 10.4 years. The estimated median OS was 13. 6 years and the median PFS was 5.5 years (Figure). In a multivariate analysis, age >60 (p=0.02) and ECOG PS>2 (p=0.01) were associated with shortened survival. The IPI and age adjusted IPI were not predictive of overall survival. The treatment outcomes for the most common treatment modalities are summarized in the Table below. The median PFS of the 38% of patients who had a complete surgical resection was excellent at 11.2 years; whereas for observed patients with residual disease after biopsy was 3.2 years. Only 8 patients received single agent rituximan with relatively low response rate. Summary: The prognosis of primary pulmonary MALT lymphoma is favorable, with a median survival of over 13 years. In patients with resectable disease, surgery alone is associated with excellent disease control. Further prospective studies are needed to define the optimal treatment of primary pulmonary MALT lymphoma. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2702 Background: CXCR5 [chemokine (C-X-C motif) receptor 5; also known as Burkitt lymphoma receptor 1 (BCR1)] is expressed on mature B-cells, subsets of CD4+ and CD8+ T-cells, and skin-derived migratory dendritic cells. CXCL13 is the ligand for CXCR5, and together they are involved in guiding B-cells into the B-cell zones of secondary lymphoid organs as well as T-cell migration. CXCR5 is also expressed in malignant cells in NHL patients. Single nucleotide polymorphisms (SNPs) in CXCR5 have not been extensively studied, although two studies reported that SNPs from this chromosome 11 gene were associated with risk of primary biliary cirrhosis in a European population and with risk of NHL in an Asian population. This study evaluated the role of common germline genetic variation in the risk and prognosis of the common NHL subtypes of diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), mantle cell lymphoma (MCL), marginal zone lymphoma (MZL) and peripheral T-cell lymphoma (PTCL). Methods: Ten SNPs in CXCR5 were genotyped using a clinic-based study of 2694 NHL cases (including 586 DLBCL, 588 FL, 137 MCL, 230 MZL, and 158 PTCL) and 1521 controls enrolled from 2002–2009 in the Molecular Epidemiology Resource of the University of Iowa/Mayo Clinic Lymphoma SPORE. Clinical data were abstracted for all NHL patients and all were prospectively followed for disease progression, retreatment, transformation and death. SNPs were selected from HapMap using a standard tagging approach (r2≥0.80 and minor allele frequency (MAF) ≥0.05) and included SNPs 5kb upstream and downstream from the gene. Genotyping was conducted using a custom Illumina iSelect panel. All SNPs were in Hardy-Weinberg equilibrium in the control group. The most prevalent homozygous genotype was used as the reference group, and each SNP was modeled as having a log-additive effect in the regression model. For risk of NHL, odds ratios (ORs) and 95% confidence intervals were calculated using unconditional logistic regression, adjusted for age and gender. For prognosis, hazard ratios (HR) were calculated for both event-free (EFS) and overall (OS) survival using Cox proportional hazards regression, adjusting for age, treatment type, and IPI (DLBCL, PTCL), FLIPI (FL), or MIPI (MCL). To determine risk of FL transformation to DLBCL, a competing risk Cox model was used. A p<0.05 was declared as statistically significant. Results: Of the 10 CXCR5 tag SNPs in our study, 5 were associated with risk of NHL, with rs1790192 (MAF=0.39 among controls) having the strongest association (OR=1.19, 95%CI 1.08–1.30; p=0.0003). This SNP was strongly associated with FL (OR=1.44, 95%CI 1.25–1.66; p=3.1×10−7), and was also associated with DLBCL (OR=1.16, 95%CI 1.01–1.33; p=0.038) and PTCL (OR=1.29, 95%CI 1.02–1.64; p=0.037) but not MCL or MZL. For FL, none of the SNPs were associated with EFS or OS, although rs1790192 was associated with better outcome among FL patients that were observed (HR=0.64; 95%CI 0.47–0.87; p=0.0039). For DLBCL, none of the SNPs were associated with EFS, while three SNPs were associated with OS: rs523604 (HR=0.79; 95%CI 0.64–0.97; p=0.028), rs12363277 (HR=0.57; 95%CI 0.33–0.99; p=0.046), and rs3922 (HR=0.79; 95%CI 0.65–0.97; p=0.027). The latter SNP was also associated with risk of transformation from FL to DLBCL (HR=0.61; 95%CI 0.40–0.91; p=0.016). For MCL, MZL and PTCL, none of the SNPs were associated with either EFS or OS. Conclusions: Several germline CXCR5 polymorphisms were associated with NHL risk, particularly rs1790192 with risk of FL as well as DLBCL and PTCL. CXCR5 SNPs did not appear to be important in prognosis for most NHL subtypes, although rs1790192 was associated with a better outcome in untreated FL and rs3922 was associated with OS in DLBCL patients and with risk of FL transformation. These results provide additional evidence for a role of host genetic variation in CXCR5 in lymphomagenesis, mainly in risk of disease development, although there may also be a role for CXCR5 in FL and DLBCL prognosis. Replications of these findings in additional studies are needed. Disclosures: Ansell: Seattle Genetics, Inc.: Research Funding.

Abstract 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.