Citations

Abstract Background: Synthetic lethality (SL) is characterized by the chemical inhibition of multiple aberrant genes to differentially kill malignant cells. We investigated small-molecule combinations for SL through in vitro and in vivo screening and optimization studies (as in the granted patents in USA and China) and demonstrated the synergistic potential of best-in-class combinations of targeted agents, drug repositioning, immune modulation and low-dose combinations. We hypothesize that BTK and mTOR inhibition coupled with an IMID will target multiple key signaling pathways, improve differential apoptosis and target acquired drug resistance. DTRM-555, an optimized mechanism-based combination, consists of the clinically differentiated BTK inhibitor DTRMWXHS-12 (or DTRM-12), everolimus (EV) and pomalidomide (POM). In xenograft tumor models, DTRM-555 administered orally has demonstrated superior efficacy over monotherapy at very low dose combinations of the three agents (1/18 of DTRM-12, 1/6 of EV, and 1/6 of POM). DTRM-12 monotherapy has been safe and well tolerated in simultaneous phase Ia trials (US and China) with preliminary efficacy across 50 mg through 400 mg once daily (QD). Here we report the US clinical results of the oral combination therapies DTRM-505 (DTRM-12 plus EV) and DTRM-555 (DTRM-12 plus EV plus POM) for the first time (NCT02900716). Methods: The safety and anti-tumor activity of the oral doublet therapy DTRM-505 and the oral triplet therapy DTRM-555 are evaluated using a "3+3" study design. Enrollment was conducted concurrently with a phase Ia study of DTRM-12 monotherapy; with DTRM-505 opened for accrual when monotherapy DTRM-12 cleared the 200-mg dose level. Eligible patients are at least 18 years old, having ECOG performance status less than 2 with relapsed/refractory chronic lymphocytic leukemia (CLL), diffuse large B cell lymphoma (DLBCL), mantle cell lymphoma (MCL), follicular lymphoma (FL) or classical Hodgkin lymphoma (cHL). Study treatment is administered daily for 21 consecutive days over a 28-day cycle. The dose-limiting toxicity (DLT) period was defined during the first cycle of therapy, and treatment was continued until disease progression or unacceptable toxicity. Patients underwent tumor evaluations every 2 months and response was recorded using revised response criteria (IWCLL and Cheson 2014). Results: Between 9/2016 and 7/2018, 19 patients have been treated with DTRM-12 monotherapy in the USA (6 pts, 50-300 mg) and China (13 pts, 50-400 mg). Patients have tolerated up to 23+ cycles of DTRM-12 monotherapy. Seven patients, including DLBCL, CLL, MCL, FL and cHL, have been treated with oral doublet therapy DTRM-505 for 2 to 12 cycles. Three patients (2 DLBCL, 1 FL) have been treated with oral triplet therapy DTRM-555, including one patient transitioned from the doublet DTRM-505 under an exploratory arm. No patient has discontinued due to an adverse event (AE) and no DLT has occurred. Recurring AEs are mostly grade 1 or 2 and responses have been seen with DTRM-505 and DTRM-555 across diverse lymphoma histologies (See Tables). All patients evaluable for response demonstrated partial response to DTRM-505 and DTRM-555, with 2/7 (doublet) and 3/3 (triplet) patients remaining on therapy. Conclusion: The maximum tolerated dose has not been reached for DTRM-12 monotherapy and for the current fixed dose doublet and triplet combinations. Toxicities have been mild and repeated cycles of study treatment have been well tolerated without delays of subsequent treatment cycles. Enrollment continues for refractory lymphoma patients to demonstrate the safety and efficacy for the first-in-class oral triplet therapy DTRM-555. Disclosures Huntington: Janssen: Consultancy; Bayer: Consultancy; Celgene: Consultancy. Schuster:Merck: Consultancy, Honoraria, Research Funding; Genentech: Honoraria, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; OncLive: Honoraria; Dava Oncology: Consultancy, Honoraria; Physician's Education Source, LLC: Honoraria; Nordic Nanovector: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Pharmaceuticals Corporation: Honoraria, 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. He:Zhejiang DTRM Biopharma Co. Ltd.: Other: Founder and CEO; Zhejiang DTRM Biopharma LLC: Other: Founder and CEO. Shen:Zhejiang DTRM Biopharma LLC: Other: Clinical Operations Director. Kennard:AbbVie, Gilead, Verastem: Consultancy. Dwivedy Nasta:Incyte: Research Funding; Takeda/Millenium: Research Funding; Debiopharm: Research Funding; Pharmacyclics: Research Funding; Rafael/WF: Research Funding; Aileron: Research Funding; Roche: Research Funding; Merck: Other: DSMC; Celgene: Membership on an entity's Board of Directors or advisory committees. Landsburg:Takeda: Consultancy; Curis: Consultancy, Research Funding. Porter:Novartis: Other: Advisory board, Patents & Royalties, Research Funding; Genentech: Other: Spouse employment; Kite Pharma: Other: Advisory board. Svoboda:Bristol-Myers Squibb: Consultancy, Research Funding; TG Therapeutics: Research Funding; Kyowa: Consultancy; Regeneron: Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; KITE: Consultancy. Song:Peking University Cancer Hospital (Beijing Cancer Hospital): Employment. Zhu:Beijing Cancer Hospital: Employment. Brander:Pharmacyclics, an AbbVie Company: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; TG Therapeutics: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Novartis: Consultancy, Other: DSMB; Genentech: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Teva: Consultancy, Honoraria; Acerta: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; DTRM: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; BeiGene: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding. Ding:Merck: Research Funding. Mato:Pharmacyclics, an AbbVie Company: Consultancy, Research Funding; AstraZeneca: Consultancy; Regeneron: Research Funding; Celgene: Consultancy; Acerta: Research Funding; TG Therapeutics: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Portola: Research Funding; Johnson & Johnson: Consultancy; Prime Oncology: Honoraria; Medscape: Honoraria.

Abstract Background Diffuse large B cell lymphoma (DLBCL) with high-risk features carries a poor prognosis despite treatment with immunochemotherapy regimen incorporating rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP). Hence, dose adjusted rituximab, etoposide, prednisone, vincristine, cyclophosphamide and doxorubicin (DA.R-EPOCH), a higher intensity regimen, is suggested as an upfront treatment of high-risk DLBCL. In our study, we analyzed the outcomes in a prospectively followed cohort of patients with de novo high-risk DLBCL who received DA.R-EPOCH, and compared them to the patients who received R-CHOP. Furthermore, we conducted a cost analysis to determine which of the two treatments produces a larger financial burden. Method Patients diagnosed with DLBCL who received chemo-immunotherapy at our center between January 2011 to December 2016 were included in the analysis. High-risk DLBCL was defined by the presence of any of the following features at diagnosis: NCCN- IPI score ≥4, tumor measuring ≥5 cm, MYC ± BCL2 or BCL6 rearrangement by FISH or MYC overexpression (>40% by immunohistochemistry [IHC]), Ki-67 index ≥80% and non-GCB immunophenotype by Hans algorithm. Responses were evaluated at middle and end of chemotherapy. Overall (OS) and progression free survival (PFS) were calculated. For the cost analysis, standardized costs were obtained from Mayo Clinic Florida cost data warehouse based upon patient encounters and treatments. Report cost-to-charge ratios were multiplied by the charges for all hospital billed services, and all resulting costs were adjusted to 2016 dollars with the Gross Domestic Product (GDP) Implicit Price Deflator. Patients who did not receive their complete planned treatment at our facility were excluded from the cost analysis. Results Of 80 patients with high-risk DLBCL, 52 (65%) patients were treated with R-CHOP and 28 (35%) with DA.R-EPOCH. The median follow-up was 11.2 months (range: 0.7- 151.3 months). The planned treatment completion rate and complete remission rate at the end of treatment were similar in both groups. There was no significant difference in OS and PFS among the patients treated with DA.R-EPOCH compared to R-CHOP. The hazard ratio (HR) for PFS was 0.79 (95% CI- 0.28-2.29, P=0.67) and OS was 0.86 (95% CI- 0.26-2.78, P=0.80) (Figure 1). In Cox-regression analysis, low baseline albumin, ECOG performance status ≥2, above-normal LDH, high NCCN- IPI and low cumulative chemotherapy doses were associated with poor OS and PFS. Overall incidence of grade ≥ 3 neutropenia, neuropathy, and unplanned hospitalizations were similar between the two treatment groups. Patients treated with DA.R-EPOCH required more red cell transfusions during the treatment (P=0.004). The total mean cost associated with DA.R-EPOCH and R-CHOP regimens was $106,940 ± $39,351 and $58,509 ± 24,588, respectively (P<0.001). The cost associated with hospital services, laboratory testing and evaluation and management were higher in DA.R-EPCOH group compared to R-CHOP group (P<0.001) (Table 2). Conclusion Our study showed that there was no significant difference in PFS and OS of patients with DLBCL with high-risk features when treated with R-CHOP compared to DA.R-EPOCH. DA.R-EPOCH was associated with higher red cell transfusion requirement and treatment related expenses. A prospective randomized comparison is warranted between these two regimens specifically for patients with high-risk DLBCL. Disclosures No relevant conflicts of interest to declare.

Abstract Background: The phosphatidylinositol 3-kinase/mammalian target of rapamycin (mTOR) signal transduction pathway integrates signals from multiple receptor tyrosine kinases to control cell proliferation and survival. Everolimus (RAD001, Novartis Pharmaceuticals) is an oral investigational antineoplastic agent that targets mTOR. Objectives: To learn the anti-tumor activity and toxicity of single-agent RAD001 in pts with relapsed/refractory aggressive NHL. Patients and Methods: Patients were eligible if they had measurable disease, a platelet count >75,000, an absolute neutrophil count >1,000, and a creatinine and bilirubin <2x laboratory upper limit of normal. Patients received RAD001 10 mg PO daily and were evaluated monthly. Dose reductions to 5 mg daily and 5 mg every other day were allowed. Response was assessed after 2 cycles and periodically thereafter. Patients could remain on drug until progression or toxicity. Results: Thirty-seven pts were treated - 20 (54%) with relapsed diffuse large cell (DLC), 14 (38%) with relapsed mantle cell (MCL), 2 high grade, and 1 follicular grade III. The median age was 72 years (range, 45–92). Patients had received a median of 4 prior therapies (range, 1–15). The overall response rate was 32% (12/37; 95% CI:20–49%) with 1 complete response and 11 partial responses. The ORR was 35% (7/20) in the DLC group and 29% (4/14) in the MCL patients. Patients have received a median of 2 cycles (range, 1–16+) of therapy. The median time to progression for all 37 patients is 3.1 months (95%CI; 2.0 – 4.7). The median duration of response for the 12 responders is 5.5 months (95% CI; 2.3 – 9.2) and 5 pts remained progression free at 6 months. Three patients are currently maintaining a response with a median time of 10.5 months (range, 2.9–15.6+months). RAD001 was well tolerated. The incidence of grade 3 anemia, neutropenia, and thrombocytopenia in this heavily pretreated pt population was 11%, 16%, and 30%. Two pts developed grade 4 neutropenia. Grade 2 hypercholesterolemia occurred in 11%; grade 2 hyperglycemia in 16%; grade 3 hyperglycemia in 11% and 1 pt had grade 4 hypertriglyceridemia. Summary: RAD001 has single-agent activity in relapsed aggressive NHL and provides proof-of-concept that targeting the mTOR pathway in NHL is clinically relevant.

Abstract Abstract 3898 Background: Although chemoimmunotherapy (CIT) has substantially improved response rates, treatment free survival, and overall survival in patients with chronic lymphocytic leukemia (CLL), only 4050 of patients achieve a complete remission and the majority have residual disease when evaluated using sensitive assays. There remains interest in identifying new approaches to improve the effectiveness of CIT. Ofatumumab is a humanized anti-CD20 monoclonal antibody that is approved for patients with relapsed CLL refractory to fludarabine and alemtuzumab. The single agent activity of ofatumumab in patients with refractory CLL suggests it may have greater efficacy than rituximab in patients with CLL. To explore the efficacy of ofatumumab based CIT, we initiated a clinical trial studying the effect of ofatumumab in combination with pentostatin and cyclophosphamide (PCO) for patients with previously untreated CLL. METHODS: Eligible patients were previously untreated and had CLL in need of treatment according to the NCI-WG criteria (Blood 111:5446). The treatment schema included 6 cycles of ofatumuamb (300 mg on day 1 of cycle 1;1000 mg on day 2 of cycle 1 and day 1 of cycles 26) followed by pentostatin (2 mg/m2) and cyclophosphamide (600 mg/m2) administered every 21 days. All patients underwent complete response evaluation including evaluation for MRD using sensitive flow cytometry (Leukemia 21:956) at the completion of treatment. RESULTS: 33 patients were enrolled at Mayo Clinic and Duke University between 3/2010 and 9/2010. All patients were eligible for treatment and have completed active treatment. Clinical characteristics included: 76 male, median age 63 (range: 5083); intermediate Rai risk 27; and high Rai risk 73. On prognostic testing 33 were CD38, 48 Zap-70 , 58 IGHV unmutated, and 6 had high risk FISH (del 17p13; del 11q22). 26 of 33 eligible patients (79) completed all 6 cycles of PCO induction. Seven patients went off treatment early (toxicity: n5; refusal: n1; progression: n1). Adverse events deemed at least possibly related to PCO induction included 8 (24) patients with grade 3 hematologic toxicity and 5 (15) with grade 3 non-hematologic toxicity. The overall response rate to PCO induction was 94 (31/33) with 15 (45) CR/CRi, 5 (15) CCR, 9 (27) nPR, and 2 (6) PR. 2/10 (20) patients with CR's tested for MRD were also MRD negative by 6 color flow cytometry analysis. Finally, we compared this cohort of patients treated with ofatumuamb-based CIT to our prior 108 patient cohort of patients treated with rituximab-based CIT both of which used an identical chemotherapy backbone (pentostatin and cyclophosphamide). Although the age, gender, ALC, and prognostic profile (CD38, ZAP-70, and IGHV mutation status) of treated patients were similar (all p0.3), the ofatumumab cohort included more advanced stage patients (Rai stage III/IV: 73 vs. 41 p0.002). Ofatumumab-based CIT appeared to be better tolerated than our previous experience with rituximab-based CIT (grade 3 hematologic toxicity ofatumumab-CIT 24 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\scriptstyle \raisebox{1ex}{8$}\!\left/ \!\raisebox{-1ex}{$33$}\right.}\]\) \end{document} vs. rituximab-CIT51 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\scriptstyle \raisebox{1ex}{55$}\!\left/ \!\raisebox{-1ex}{$108$}\right.}\]\) \end{document}, p0.009; grade 3 non-hematologic toxicity ofatumumab-CIT 15 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\scriptstyle \raisebox{1ex}{5$}\!\left/ \!\raisebox{-1ex}{$33$}\right.}\]\) \end{document} vs. rituximab-CIT 24 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\scriptstyle \raisebox{1ex}{26$}\!\left/ \!\raisebox{-1ex}{$108$}\right.}\]\) \end{document}, p0.34). Despite a higher proportion of Rai Stage III/IV patients in the ofatumumab cohort, the efficacy of ofatumumab-based CIT also compared favorably to our previous experience with rituximab based CIT (Table). CONCLUSION: Front-line ofatumumab-based CIT appears to be well-tolerated in patients with CLL. Compared to our historic experience with rituximab based CIT, ofatumumab-based CIT appeared to have less hematologic toxicity and improved efficacy. This trial has been expanded to provide a larger experience with ofatumumab-based CIT. Disclosures: Shanafelt: Hospira: Research Funding; Glaxo-Smith-Kine: Research Funding; Genentech: Research Funding. Off Label Use: Off label use of pentostatin and Ofatumumab. Lanasa:GlaxoSmithKline: Consultancy, Speakers Bureau. Zent:GlaxoSmithKline: Research Funding; Genentech: Research Funding; Genzyme: Research Funding. Tun:Celgene: Research Funding. Kay:Biothera: Research Funding; Clegene: Research Funding; Cephalon: Research Funding; Genentech: Research Funding; Glaxo Smith Kline: Research Funding; Hospira: Research Funding; Novartis: Research Funding; Supergen: Research Funding; Calistoga: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Emergent Biosolutions (Formerly Trubion): Membership on an entity's Board of Directors or advisory committees.

Abstract Abstract 3899 BACKGROUND: Although chemoimmunotherapy (CIT) has substantially improved response rates, treatment free survival, and overall survival in patients with chronic lymphocytic leukemia (CLL), only 40–50% of patients achieve a complete remission and the majority have residual disease when evaluated using sensitive assays for minimal residual disease (MRD). While these facts generated interest in consolidation strategies for patients with residual disease, previous trials of alemtuzumab-based consolidation found excess morbidity/mortality. In 2008 we began a trial of lenalidomide-based consolidation for patients with previously untreated CLL who had received 6 cycles of CIT induction. Preliminary analysis suggested that lenalidomide consolidation may improve the quality of response and prolong time to retreatment (Shanafelt; ASH 2010), although follow-up was short (median 16 months). METHODS: Eligible patients were previously untreated and had CLL in need of treatment according to the NCI-WG criteria (Blood 111:5446). Treatment schema consisted of 6 cycles of pentostatin (2 mg/m2), cyclophosphamide (600 mg/m2) and rituximab (375 mg/m2) given every 21 days (Blood 109:405). All patients completing 6 cycles of PCR induction, underwent complete restaging including evaluation for MRD using sensitive flow cytometry. Patients subsequently received 6 months of lenalidomide consolidation by daily administration with a starting lenalidomide dose of 5 mg/day and escalation to 10 mg/day after the first cycle as tolerated. Patients again underwent complete restaging including MRD evaluation after 6 months of lenalidomide. At the time of restaging, MRD negative patients entered observation. Those with residual disease continued on lenalidomide and underwent repeat MRD assessment every 3 months until an MRD negative state was achieved. RESULTS: 45 patients were enrolled at Mayo Clinic between 3/2008 and 12/2009 of whom 44 were eligible. Median age was 65 (range: 44–78) and 71% of patients were male. 61% of patients had intermediate Rai risk and 39% high Rai risk. On prognostic testing 32% were CD38+, 52% Zap-70+, 52% IGHV unmutated, and 16% had high risk FISH (del 17p13; del 11q22). Of the 38 eligible patients who completed 6 cycles of PCR induction, 34 (89%) initiated lenalidomide consolidation. Thus by intent to treat analysis, 34/44 (77%) patients starting CIT with PCR were able to receive consolidation therapy. Among the 34 patients who initiated consolidation, the median number of cycles of lenalidomide received was 6 (range: 1–29). Nine of 34 (26%) patients had the lenalidomide dose increased to 10 mg daily while 18 (53%) required a reduction to 5 mg every other day. Five patients are still on lenalidomide at the time of this report. No cases of tumor lysis syndrome or tumor flare reaction were observed. Adverse events deemed at least possibly related to lenalidomide consolidation included 23 (68%) patients with grade 3+ hematologic toxicity and 5 (15%) with grade 3+ non-hematologic toxicity. Among the 34 patients who received at least 1 cycle of lendalidomide, 6 patients have improved the quality of their response including 3 patients who converted from having residual disease to a MRD- state. After a median follow-up of 29 months, 39/44 patients are alive and the median duration of response has not been reached. To date 8/44 (18%) patients have progressed to require additional treatment. Finally, since the eligibility criteria were nearly identical to our historic trial of PCR without lenalidomide consolidation, we conducted an intent to treat analysis that compared all 44 patients in the present trial (i.e. regardless of whether they received lenalidomide consolidation) to the 64 patients previously treated on our PCR trial (Blood 109:405). The demographic and prognostic characteristics of patients in the two studies were similar. With the caveat it represents a comparison across phase II trials, the proportion of patients free of retreatment at 30 months was 79% (95% CI:67–93) for PCR followed by lenalidomide consolidation vs 66% (95% CI: 54–80) for PCR alone (Figure 1). CONCLUSION: Lenalidomide-based consolidation for CLL patients receiving first-line CIT induction appears to improve the quality of response and prolong time to retreatment. Randomized clinical testing of lenalidomide-based consolidation appears warranted. Disclosures: Shanafelt: Celgene: Research Funding; Hospira: Research Funding; Genentech: Research Funding. Off Label Use: PCR-Lenalidomide (off label use of pentostatin and lenalidomide). Tun:Celgene: Research Funding. Kay:Biothera: Research Funding; Clegene: Research Funding; Cephalon: Research Funding; Genentech: Research Funding; Glaxo Smith Kline: Research Funding; Hospira: Research Funding; Novartis: Research Funding; Supergen: Research Funding; Calistoga: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Emergent Biosolutions (Formerly Trubion): Membership on an entity's Board of Directors or advisory committees.

Abstract Introduction Primary CNS lymphoma (PCNSL) is a diffuse large B-cell lymphoma (DLBCL), predominantly of non-germinal center (non-GC) subtype. Currently available treatments remain disappointed with a non-optimal complete remission rate and a high relapse rate. As such, novel therapeutic agents are urgently needed. Constitutive activation of the NF-kB pathway via mutations in B cell receptor (BCR) (CD79B) and mutation of MYD 88 and TBL1XR1 pathways plays an important role in PCNSL. Ibrutinib, an inhibitor of BCR signaling, has been found to have significant therapeutic activity in relapsed or refractory non-CNS non-GC DLBCL that display similar NFKB mutational patterns. We have performed a CNS pharmacokinetic (PK) study of Ibrutinib and evaluated its therapeutic activity against CNS lymphoma (CNSL) in murine models. Methods CNS PK study in mice - The first study was done in a CNSL model created by intracerebral implantation of luciferase-transfected lymphoma cells (MC116) in nude mice in comparison to healthy nude mice without lymphoma cell implantation (N=5 per group). Once the tumor activity was confirmed by bioluminescence imaging in CNSL group, all the mice were treated with ibrutinib 12 or 30 mg/kg/day by oral gavage (OG) for 5 days. Blood and brain were collected 2 hours after the last dose. Ibrutinib was measured by ultra performance liquid chromatography with tandem mass spectrometry. Cerebro-spinal fluid (CSF) PK study in Sprague-Dawley (SD) rats - Ibrutinib 50 mg/kg single dose was given by OG (N=6). Microdialysates of CSF were collected from a ventricle of the brain and a carotid artery via microdialysis catheters every hour for 13 hours post-treatment. Drug concentrations were determined by capillary electrophoresis with laser detection. Preclinical therapeutic evaluation - A murine CNS lymphoma model was created by intracerebral injection of the OCI-Ly10 non-GC DLBCL cells, which were confirmed to have CD79 A and MYD 88 mutations and show high sensitivity to Ibrutinib in vitro. Animals were sacrificed if they showed severe clinical signs or symptoms or >20% weight loss. Ibrutinib 30 mg/kg was administered by OG daily starting at day 7 post-implantation and until the last sacrifice in the control group treated with vehicle. Therapeutic efficacy was determined by Kaplan-Meier survival analysis using date of sacrifice as endpoint. Results CNS PK study in mice - 1) Ibrutinib levels in plasma, normal brain tissue and brain-tumor were analyzed. Ibrutinib was not detected in healthy control mice treated with vehicle. In healthy mice treated with ibrutinib (12 mg/kg and 30 mg/kg), Ibrutinib mean plasmatic levels were 9.31 (±3.56) ng/mL and 42.2 (±20.9) ng/mL respectively. At 12 mg/kg dose level, ibrutinib was detectable but not quantifiable in brain tissue. After treatment with 30 mg/kg,iIbrutinib mean levels were 0.0077 (±0.0053) and 0.0071 (±0.00483) ng/g tissue in right and left cerebral hemispheres respectively. In CNSL mice treated with ibrutinib (12 mg/kg and 30 mg/kg), Ibrutinib mean plasmatic levels were 12.03 (±9.04) ng/mL and 42.64 (±42.04) ng/mL respectively, brain ibrutinib levels were 0.008 (±0.005) and 0.007 (±0.003) ng/g tissue for tumor-bearing right hemisphere and non-tumor bearing left hemisphere respectively for 30 mg/kg, while brain ibrutinib level was detectable but not quantifiable at 12mg/kg. CSF PK study in SD rats - CSF penetration of ibrutinib was determined to be ~5.2 % as calculated by area under the curve (AUC) ratio of CSF and blood samples. Cmax in CSF is ~0.35 uM, which is significantly higher than published EC50 concentrations for DLBCL cell lines. Preclinical therapeutic evaluation -Ibrutinib showed an excellent therapeutic activity with significant prolongation of survival (p=0.0137) (fig 1). At a median follow-up of 112 days, the median survival in treated CNSL group is 56 days compared to 33 days in the control group. At the end of the follow-up 33% of animals in treated CNSL group are still alive without treatment. Conclusion Ibrutinib achieves high concentrations in brain and CSF in murine CNS PK models with promising single-agent preclinical therapeutic activity against CNS lymphoma in a murine model. Further studies to develop combination regimen are ongoing. Figure Figure. Disclosures Soussain: Roche: Research Funding; Celgene: Research Funding; Pharmacyclics: Research Funding.

Abstract Background In the U.S. over 14,000 new cancer cases occur annually in people under 21 years of age; approximately 21% of cases are acute lymphoblastic leukemia (ALL) and ∼ 30% classify as Burkitt lymphoma (BL). Most cases of ALL and BL are due to malignant B-cells that have acquired disease-defining oncogenic lesions that facilitate their rapid proliferation. To maintain a state of homeostasis, the malignant cells rely heavily on the ability of the internal degradation and recycling systems to match the high rate of protein turnover. As such, the ubiquitin proteasome system (UPS) is central in this operation where it prevents buildup of misfolded proteins while also regulating the availability of anti-apoptotic proteins such as BCL2 and MCL1. These observations coupled with the observation that UPS disruption leads to cellular demise have resulted in the development of several proteasome inhibitors (PI). These PI have primarily been examined in adult B-cell malignancies. The feasibility of a bortezomib-containing regimen for use in pediatric malignancies has been examined by the TACL consortium and demonstrated a 73% response rate in relapsed/refractory ALL patients. However, a major limitation of bortezomib-based therapy is an increased incidence of peripheral neuropathy (PN), which was also noted in the TACL study. As such, more potent and reportedly less toxic PI have been developed that seem to carry considerably lower risk for development of PN. Such agents that maintain a high response rate and carry reduced long-term adverse effects are highly desirable in pediatric age patients. Aim Investigation of the novel proteasome inhibitors carfilzomib and MLN9708 (Millennium Pharmaceuticals) in preclinical models of pediatric B-lymphocytic cancer. Methods Representative preclinical models of BL (Raji cell line) and B-ALL (ALL-1 cells) were used in this study. Proteasomal activity was measured using synthetic fluorogenic peptide substrates. Cell viability was measured by MTS assay. Apoptosis was determined by annexin-v/PI staining and mitochondrial membrane permeability (MOMP) was assessed using TMRM followed by flow cytometry. Protein profiling was performed via immunoblot. Results In an effort to understand the effect of carfilzomib and MLN9708 in our pediatric cancer models, we first assessed their ability to inhibit proteasomal activity. While chymotrypsin-like activity, which is the target of both PIs, is inhibited by more than 90% in both cell lines, inhibition (∼ 35%) of caspase-like function conferred by the b1 subunit was more significantly pronounced in MLN9708 treated Raji and ALL-1 cells. Next we performed an MTS assay to determine the growth inhibitory effects of these PI in vitro. Both PI inhibited the growth of the Raji and ALL-1 cells in a dose dependent manner. Carfilzomib showed a more potent effect (IC50 ∼1nM in both cell lines) as compared to MLN9708 (IC50 ∼30nM in ALL-1 cells and ∼50nM in Raji cells). To further understand mechanisms of growth inhibition we examined both tumor cell lines for induction of apoptosis along with corresponding markers. As compared to Raji cells, we observed ALL-1 cells to be more sensitive to the effects of both PI, albeit with MLN9708 (50nM) inducing more cell death (65%) as compared to carfilzomib (10nM, 50% cell death). Further, we observed altered MOMP, cleavage of caspases 9, 3 and PARP-1 were found to occur in both cell lines in presence of carfilzomib or MLN9708. These changes indicate the apoptotic effects of novel PI in ALL-1 and Raji cells are via mitochondrial destabilization and caspase activation. As inhibition of the UPS aids NOXA and BIM (pro-apoptotic BCL2 proteins) mediated cell death, we examined the expression of BCL2 family proteins changes in Raji and ALL-1 cells in response to novel PI. Indeed protein levels of both BCL2 and MCL1 were reduced in carfilzomib and MLN9708 treated cells. Reduced BCL2 expression was more pronounced in ALL-1 cells as compared to Raji cells and downregulation was noted to be dose-dependent. Summary Our data show that both carfilzomib and MLN9708 potently inhibit the viability of malignant ALL and BL cells in vitro. We conclude that PI are promising anti-neoplastic therapeutics that target not only the UPS but also modulate the expression of critical anti-apoptotic proteins. Data from mechanistic studies conducted herein underscore the need for further research in in vivo models of these diseases. Disclosures: Foran: Celgene: Research Funding.

Abstract Abstract 1268 Poster Board I-290 Purpose There are reports of an increased risk of skin cancers in patients with B-Chronic Lymphocytic Leukemia (CLL). These skin cancers include basal cell and squamous cell carcinoma. This analysis was performed to more completely define the prevalence of skin cancers in patients in the Mayo Clinic Rochester CLL database and to look for contributing factors. Methods The Mayo Clinic Rochester CLL Database includes all patients with a diagnosis of CLL since January 1995 seen in the Division of Hematology and who have signed institutional review board approved consents for research. For this study, 2240 patients were analyzed to compare differences in characteristics between CLL patients with and without skin cancer. Chi-square statistics were used to compare qualitative variables (age categories, gender, referral status, ALC categories, CD38, ZAP-70, IgVH gene mutation status, FISH categories, Rai stage), and t-tests were used for quantitative variables (age at diagnosis, ALC values). Overall survival (OS) and time to first treatment (TFT) analyses were performed with results being displayed using Kaplan-Meier curves and p-values calculated using a log-rank test. Prevalence of melanoma among CLL patients was compared to the age-adjusted prevalence of melanoma in individuals in the Iowa SEER registry. Results Median follow-up for the 2240 patients diagnosed between 1/1/1995 and 8/11/2009 was 4.6 years. In aggregate, 293 (13.1%) patients were found to have non-melanoma skin cancer (squamous cell carcinoma or basal cell carcinoma) cancer. The diagnosis of non-melanoma skin cancer occurred before the CLL diagnosis in 39% and at or after the diagnosis of CLL in 61%. There were 57 (2.5%) cases of melanoma in association with CLL. The diagnosis of melanoma occurred before the CLL diagnosis in 38% and at or after the diagnosis of CLL in 62%.The prevalence of non-melanoma skin cancer and melanoma skin cancer were both higher in non-referred (geographically regional) CLL patients than referred CLL patients (16.6% vs. 11.4%, p<0.001 for non melanoma; 2.0% vs. 3.6%, p=0.03 for melanoma). The prevalence of melanoma in CLL patients was higher than that of age-adjusted prevalence for individuals in the Iowa SEER registry (2.5% vs. 0.03%; p<0.001). We next evaluated the relationship between CLL patients with skin cancer and demographic characteristics, prognostic parameters, and CLL related treatment. The risk of non-melanoma skin cancer in CLL was found to be associated with age (median age at diagnosis with skin cancer 67.6 vs. without skin cancer 63.3, p<0.001) and with sex (males 15.1% vs females 8.9%, p <0.001). There was no statistical significant difference in frequency of non-melanoma skin cancer associated with absolute lymphocyte count (ALC), Rai stage, CD 38, Zap 70, IgVH gene mutation status, FISH, or treatment history. The risk of melanoma in CLL was found to be associated with age at diagnosis (median age with melanoma 69.9 vs. without melanoma 63.8, p=0.002) and CD38 (positive 1.3% vs negative 3.1%, p=0.03). There was no statistically significant difference associated with gender, ALC, Rai stage, Zap 70, IgVH gene mutation status, FISH, or treatment history. Since the presence of skin cancer could be a marker of immune dysregulation we hypothesized skin cancer may be associated with clinical outcome of CLL. Accordingly, we evaluated the relationship between non-melanoma skin cancer and melanoma skin cancer and TFT and OS. Contrary to our hypothesis, TFT (median 6.0 years vs. 4.9; p=0.04) and OS (median 10.8 years vs. 9.7; p=0.02) of patients with non-melanoma skin cancer were both longer than those without non-melanoma skin cancer. No differences in TFT (p=0.06) or OS (p=0.66) were observed among patients with melanoma compared to those without melanoma. Conclusions We find in our cohort of CLL patients a higher prevalence of melanoma than the general population. Risk of melanoma and non-melanoma skin cancer among patients with CLL does not appear to be related to CLL characteristics, with the exception of CD 38, or CLL outcome. The diagnosis of melanoma and non-melanoma skin cancer in patients with CLL does not appear to be a risk factor for either CLL specific outcomes (TFT) or shorter survival. Disclosures Kay: Biogenc-Idec, Celgene, Genentech, genmab: Membership on an entity's Board of Directors or advisory committees; Genentech, Celgene, Hospira, Polyphenon Pharma, Sanofi-Aventis: Research Funding. Zent:Genentech, Bayer, Genzyme, Novartis: Research Funding. Shanafelt:Genentech: Research Funding; Hospira: Membership on an entity's Board of Directors or advisory committees, Research Funding; Polyphenon E International: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Bayer Health Care Pharmaceuticals: Research Funding.

Abstract Background: In 2006 Lenalidomide received FDA approval for myelodysplasia (MDS) with interstitial deletion 5q [del(5q)] based on conventional cytogenetic (CC) results before and after treatment. In clinical practice, FISH studies of interphase nuclei with probes for EGR1 are widely used to detect del(5q), but it is not known whether this method has similar efficacy as CC. Thus, we compared CC and FISH results for various forms of del(5q). Methods: We selected 145 patients (pts) in our cytogenetic database with del(5q). These pts had various forms of del(5q) and were representative of our clinical practice. This series included 9 pts with MDS that were studied before and after treatment with Lenalidomide. CC studies were done using standard procedures to analyze 20 metaphases from bone marrow. FISH studies were done on the same specimens using stored left-over cells and standard procedures for EGR1 (5q31.2) and D5S23/D5S721 (5p15.2). The cutoff for del(5q) for FISH was <6.0% based on 200 nuclei. Results: Among 145 pts, 104 were referred for MDS, 9 acute myeloid leukemia, 9 lymphoproliferative disorders, 7 myeloproliferative disorders and 16 without clinical information. A total of 116 pts had breakpoints at del(5)(q13q33), 17 del(5)(q15q33), 8 del(5)(q11.2~q31q31~q35), 3 del(5)(q22q33) and 1 del(5)(q13q22). Del(5q) was detected in 144 pts by both CC and FISH. One pt had del(5)(q13q22) in 20/20 metaphases but was normal by FISH. Percent abnormal cells by FISH was lower in 135/145 pts compared to CC (mean difference 22.5 ± 19.6, range −42 to 98). For 9 pts with MDS, 29 specimens were collected before and after treatment with Lenalidomide: 7 achieved complete cytogenetic remission (four relapsed) and 2 showed a decrease in percent abnormal metaphases. Results of CC and FISH for these 9 pts were concordant for detection of del(5q) and trend of tumor burden due to treatment for 28/29 specimens. The discordant specimen was collected 222 days after treatment; results of CC were normal but FISH was abnormal in 19% of nuclei. Among the 29 specimens, percent abnormal cells by FISH was lower than CC in 27 (mean difference 13.9% ± 22.5, range −19.0 to 73.5). Each of the 9 treated pts had only del(5q) prior to treatment, and was detected by both FISH and CC. After treatment, FISH did not detect a separate cytogenetic clone involving deletion 20q without del(5q) in 2 pts nor did it identify development of other anomalies in 3 pts. Conclusions: Results of CC and FISH were mostly concordant, but differed in 4 respects. First, 1/145 pts was normal by FISH but had del(5q) by CC. This pt had unusual breakpoints that did not result in loss of EGR1. Second, percentage of cells with del(5q) was usually lower by FISH than CC. This observation is likely related to a different mitotic rate of cells with del(5q) versus normal cells. Third, 1 specimen was abnormal by FISH but normal by CC after treatment, but 2 subsequent specimens were concordant. This discrepancy was likely due to interference of mitosis of del(5q) cells and residual non-proliferating disease. Fourth, 2 treated pts developed a separate cytogenetic clone without del(5q) and 3 developed other anomalies that could not be detected by FISH. We believe FISH for EGR1 is useful in clinical practice, but not a substitute for CC.

Abstract Introduction: Ibritumomab tiuxetan (Zevalin¨) is a radioimmunoconjugate agent that targets CD20-expressing B cell lymphomas. Currently, it is the only radioimmunoconjugate agent available on the market and is FDA approved for relapsed/refractory follicular lymphoma (FL). A retrospective study of patients with low grade FL (WHO grade 1 and 2) treated with ibritumomab tiuxetan at Mayo Clinic Florida from 2000 to 2016 was performed. Methods: The patient population consisted of previously untreated as well as relapsed low grade FL. We evaluated patient characteristics, response rate, duration of response, progression free survival, overall survival and time to next treatment. Previously untreated patients were treated with ibritumomab tiuxetan due to ineligibility for standard chemotherapy and prolonged immunotherapy, or their preference. Comparison between previously untreated FL patients treated with ibritumomab tiuxetan as the first line of treatment versus patients with relapsed FL treated with ibritumomab tiuxetan as second, third or fourth line therapy was made. Results: Low grade FL patients (n=41) that received ibritumomab tiuxetan were identified; 13 patients (32%) with previously untreated FL and 28 patients (68%) with relapsed FL. The data on response to treatment is presented in Table 1. Ibritumomab tiuxetan use in previously untreated FL was associated with more complete responses than in the relapse setting (92% vs 50% at 6 months, p=0.036). Previously untreated FL patients that received ibritumomab tiuxetan as first line therapy had better progression free survival (80% vs 35% at 3 years). Ibritumomab tiuxetan use in relapsed FL was associated with significant shorter time to relapse compared to previously untreated FL (median 1.3 years vs 4.8 years, p=0.017, figure 1) and shorter time to next treatment (65% at 4 years compared to 0% in previously untreated, p=0.007). 15% of newly diagnosed FL treated with ibritumomab tiuxetan relapsed compared to 64% of relapsed FL patient. There was no significant difference in overall survival between the two groups. The incidence of grades 3-4 neutropenia (Absolute Neutrophil Count <1000 x109/L), Anemia (Hb <8 g/dL) and Thrombocytopenia (Platelets <25 x109/L) were 47%, 7.7% and 48.7% respectively. Only 6/41 patients (15%) had cytopenias that required transfusion of blood products. More significant cytopenias were seen in relapsed group compared to previously untreated group. Conclusions: Ibritumomab tiuxetan as first line treatment in previously untreated FL patients at our institution was associated with improved response rate, better progression free survival and shorter time to next treatment when compared to its use in relapsed FL. Ibritumomab tiuxetan has significant therapeutic efficacy for both previously untreated as well as relapsed low grade FL. It was well tolerated without significant treatment-related morbidity or mortality. Moreover, treatment schedule was very convenient for the patients. Our results suggest that treatment with ibritumomab tiuxetan is an effective option for those previously untreated low grade FL patients who cannot take standard chemoimmunotherapy. Disclosures No relevant conflicts of interest to declare.