Crystal Structure Analysis Reveals That the Novel Type II Anti-CD20 Antibody GA101 Interacts with a Similar Epitope as Rituximab and Ocrelizumab but in a Fundamentally Different Way.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3726-3726 ◽  
Author(s):  
Gerhard J Niederfellner ◽  
Alfred Lammens ◽  
Manfred Schwaiger ◽  
Guy Georges ◽  
Kornelius Wiechmann ◽  
...  
Keyword(s):  
Research Funding ◽  
Type I ◽  
The Novel ◽  
Type Ii ◽  
Employment Equity ◽  
Equity Ownership ◽  
Cd20 Antibody ◽  
Anti Cd20 ◽  
Point Mutagenesis ◽  
Cd20 Antibodies

Abstract Abstract 3726 Poster Board III-662 CD20 is a specific cell surface marker found on normal as well as malignant B cells. Rituximab, a monoclonal antibody directed against CD20, has a major impact on treatment of malignant lymphomas. Although all therapeutic CD20 antibodies are directed against the two relatively small extracellular loops of CD20, such antibodies can be classified into Type I CD20 antibodies like Rituximab, Ofatumumab or Ocrelizumab or Type II CD20 antibodies like the novel glycoengineered humanized CD20 antibody GA101 or the murine antibody Tositumumab. Type I and Type II antibodies differ significantly in their mode of action and mechanisms of killing malignant B-cells. The molecular basis of this is not understood. We use data from epitope mapping, X-ray crystallography, isothermal titration calorimetry, and point mutagenesis i) to accurately map the epitopes of different anti-CD20 antibodies, in particular GA101, and ii) to compare the molecular interactions involved in their binding. Although the epitope regions of these antibodies largely overlap, the crystal structure shows that GA101 binds CD20 in a completely different orientation from Rituximab, Ocrelizumab and Ofatumumab and that its binding also involves a larger surface area. In agreement with predictions based on the crystallographic data, point mutagenesis of single amino acid residues confirmed that exchanges at certain positions in CD20 affect binding of Rituximab and GA101 differently. Our data suggest that engagement of CD20 by these antibodies favors different conformations of CD20, which could form the molecular basis for the observed differences in cellular signals triggered by the respective antibodies. Disclosures: Niederfellner: Roche: Employment. Schwaiger:Roche: Employment. Georges:Roche: Employment. Wiechmann:Roche: Research Funding. Franke:Roche: Research Funding. Schaefer:Roche: Employment. Jenewein:Roche: Employment. Slootstra:Pepscan: Employment, Patents & Royalties. Moessner:Glycart: Employment, Equity Ownership, Patents & Royalties. Umana:Glycart: Employment, Equity Ownership, Patents & Royalties. Hopfner:Roche: Research Funding. Klein:Roche: Employment, Equity Ownership, Patents & Royalties.

Protein Tomography Analysis Shows That CD20 Molecules Bound by Different Type I and Type II Anti-CD20 Antibodies Are Organized in Different Protein Complexes.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4782-4782
Author(s):  
Gerhard J Niederfellner ◽  
Annika Braennstroem ◽  
Frida Lindstrom ◽  
Magnus Jansson ◽  
Marika Lundin ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Large Fraction ◽  
Type I ◽  
Type Ii ◽  
Employment Equity ◽  
Downstream Signaling ◽  
Equity Ownership ◽  
Anti Cd20 ◽  
Tomography Analysis ◽  
Cd20 Antibodies

Abstract Abstract 4782 Ramos cells were labeled with Type I (Rituximab and Ocrelizumab) and Type II (B1/H299 and GA101) anti-CD20 antibodies and then fixed and stained with marker gold labeled 2ary antibodies. Protein complexes connected to marker gold were analyzed by Protein TomographyTM at SIDEC and the corresponding 3D-structures visualized (∼100 structures per antibody). Less than 5 % of the refined structures were dimeric. While most (60 – 90%) CD20 molecules were present in tetramers or even higher order defined complexes, a sizeable proportion was also engaged in large protein networks (11 -38%). For the multimeric complexes, we could clearly distinguish between extended (or open) and ring-like (or closed) conformations. Although cells had been labeled with an excess of antibody, as suggested by FACS binding curves, the antibodies bound CD20 monovalently in most refined structures. Bivalent binding was overall more prevalent with Rituximab and Ocrelizumab than with B1 and GA101 (1/3 vs 1/6 structures). The proportion of CD20 molecules present in ringlike complexes was higher for the Type II than for the Type I antibodies. In co-localization experiments, Rituximab-CD20 and GA101-CD20 complexes were also found to only partially colocalize, while a large fraction of the two antibodies were found in separate cell surface compartments. These findings suggest that the different antibodies favor different CD20 conformations that seem to be associated with different protein complexes and might form the basis for initiation of different downstream signaling processes. Disclosures: Niederfellner: Roche: Employment. Braennstroem:SIDEC: Employment. Lindstrom:SIDEC: Employment. Jansson:SIDEC: Employment. Lundin:SIDEC: Employment. Schaefer:Roche: Employment. Mundigl:Roche: Employment. Umana:Glycart: Employment, Equity Ownership, Patents & Royalties. Klein:Roche: Employment, Equity Ownership, Patents & Royalties.

Superior Efficacy of the Novel Type II, Glycoengineered CD20 Antibody GA101vs. the Type I CD20 Antibodies Rituximab and Ofatumumab

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3925-3925 ◽  
Author(s):  
Sylvia Herter ◽  
Inja Waldhauer ◽  
Tina Otz ◽  
Frank Herting ◽  
Sabine Lang ◽  
...  
Keyword(s):  
Cell Death ◽  
Type I ◽  
Type Ii ◽  
B Cell Depletion ◽  
Employment Equity ◽  
Direct Cell ◽  
Equity Ownership ◽  
Cd20 Antibody ◽  
Dose Dependent ◽  
Cd20 Antibodies

Abstract Abstract 3925 GA101 is Type II, glycoengineered CD20 monoclonal antibody currently in PhII/III clinical trials. We have previously shown that GA101 mediates superior in vitro and in vivo activity compared to the Type I CD20 antibody rituximab. By epitope mapping and crystallography we have shown that GA101 recognizes CD20 in a unique way that is different from Type I CD20 antibodies and have proposed that this may be the basis for the Type II character of GA101. Here we compare for the first time GA101 with rituximab, the standard of care in various clinical settings in NHL and B-CLL in combination with chemotherapy, as well as with the Type I CD20 antibody ofatumumab, which was recently approved for treatment of B-CLL patients refractory to fludarabine and alemtuzumab. The following assays were used to compare the three anti-CD20 antibodies: i) Binding to NHL cell lines Z138 (MCL, ca. 60.000 CD20 binding sites per cell) and SU-DHL4 (DLBCL, ca. 1 Mio CD20 binding sites per cell) assessed by FACS, ii) Cell death induction, detected by AxV/PI staining and FACS, on a panel of NHL cell lines, iii) Antibody dependent cellular cytotoxicity mediated by PBMNCs as effector and Z138, SU-DHL4 as target cells (ADCC, LDH release assay); iv) Complement dependent cytotoxicity with Z138, SU-DHL4 as target cells (CDC, LDH release assay) and v) B-cell depletion (assessed by FACS) in whole blood from healthy donors. Dose-dependent anti-tumoral activity was assessed in a s.c. SU-DHL4 NHL xenograft model in Scid beige mice. Survival experiments in a disseminated Z138 MCL model are ongoing and an update on the results will be included as part of the poster presentation. Ofatumumab (“Arzerra”) was purchased from a local pharmacy, GA101 and rituximab were obtained from Hoffmann La Roche AG, Basel. First, binding studies confirmed that GA101 shows half-maximal binding to NHL cells relative to rituximab and ofatumumab, a known property of Type II CD20 antibodies. EC50 values of binding were comparable indicating that GA101, rituximab and ofatumumab have apparent binding affinities in the low nanomolar range on NHL cells independent of the level of CD20 expression. Second, the three CD20 antibodies were compared for their induction of direct cell death as measured by AxV/PI staining. Overall, GA101 mediated superior direct cell death induction compared to rituximab and ofatumumab utilizing a panel of NHL cell lines of different origins. Immune effector-related mechanisms of action were subsequently compared by ADCC and CDC assays. GA101, a glycoengineered antibody with enhanced affinity for FcgRIIIa, was found to exhibit up to 100-fold higher ADCC potency than rituximab and ofatumumab on Z138 and SU-DHL4 cells. CDC, as expected for a Type II CD20 antibody was ca. 10 to 1,000 less potent compared to the Type I antibodies rituximab and ofatumumab. In order to integrate the different mechanisms of action (direct cell death, ADCC, CDC), autologous ex vivo B-cell depletion assays with whole blood from healthy donors containing natural immune effector cells, human complement and physiological concentrations of human immunoglobulins were performed. These studies showed that GA101 was more potent in terms of EC50 values and more efficacious in terms of absolute B-cell depletion when compared to rituximab and ofatumumab. Finally, the dose-dependent effects of the three CD20 antibodies was studied on the growth of s.c. SU-DHL4 DLBCL xenografts in SCID beige mice. GA101 induced a dose-dependent anti-tumoral effect including complete tumor remission and was superior to the Type I antibodies rituximab and ofatumumab at saturating antibody doses. In summary, the preclinical data presented herein demonstrate that the Type II, glycoengineered CD20 antibody GA101 is differentiated from the Type I CD20 antibodies rituximab and ofatumumab by its superior overall activity supporting its further clinical investigation. Of note, in contrast to previous publications, in this series of assays no superior preclinical activity of ofatumumab was observed when compared to rituximab. Disclosures: Herter: Roche: Employment, Patents & Royalties. Waldhauer:Roche: Employment. Otz:Roche: Employment. Herting:Roche: Employment, Patents & Royalties. Lang:Roche: Employment. Nicolini:Roche: Employment. Römmele:Roche: Employment. Friess:Roche: Employment, Patents & Royalties. Van Puijenbroek:Roche: Employment. Bacac:Roche: Employment. Weidner:Roche: Employment, Equity Ownership. Gerdes:Roche: Employment, Equity Ownership, Patents & Royalties. Umana:Roche: Employment, Equity Ownership, Patents & Royalties. Klein:Roche: Employment, Equity Ownership, Patents & Royalties.

scholarly journals Long-Term Follow-up of a Phase 1 Study of Idelalisib (ZYDELIG®) in Combination with Anti-CD20 Antibodies (Rituximab [R] or Ofatumumab [O]) in Patients with Relapsed or Refractory Chronic Lymphocytic Leukemia (CLL)

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5653-5653 ◽  
Author(s):  
Richard R. Furman ◽  
Sven de Vos ◽  
Jacqueline C. Barrientos ◽  
Marshall T. Schreeder ◽  
Ian W. Flinn ◽  
...  
Keyword(s):  
Research Funding ◽  
Phase 1 ◽  
Lymphocytic Leukemia ◽  
Extension Study ◽  
Employment Equity ◽  
Tp53 Mutations ◽  
Long Term Follow Up ◽  
Equity Ownership ◽  
Anti Cd20 ◽  
Cd20 Antibodies

Abstract Introduction: PI3Kδ signaling is critical for the proliferation, survival and homing/tissue retention of malignant B cells. Idelalisib is a first-in-class, highly selective, oral inhibitor of PI3Kδ recently approved for the treatment of relapsed CLL in combination with R. This report summarizes the long-term follow-up of the Phase 1 combination experience of idelalisib with anti-CD20 antibodies. Methods: This Phase 1 study evaluated idelalisib for relapsed/refractory CLL continuously given at 100 mg BID (4 of the pts receiving R) or 150 mg BID (all other pts) in combination with a total of 8 infusions of rituximab (R, 375 mg/m2 weekly x 8), or a total of 12 infusions of ofatumumab (O, 300mg initial dose either on Day 1 or Day 2 relative to the first dose of idelalisib, then 1,000 mg weekly x 7, then 1,000 mg every 4 wks x 4). Pts on treatment after 48 weeks were eligible to continue idelalisib on an extension study. Clinical response was evaluated according to published criteria (Hallek 2008; Cheson 2012). Results: 40 pts (12F/28M) with a median (range) age of 66 (43-87) years and a WHO performance status of 0 (24, 60%) or 1 (16, 40%) were enrolled. 19 pts received idelalisib in combination with R and 21 with O. Adverse disease characteristics (n, %) included Rai Stage III/IV (20, 50%), bulky lymphadenopathy (23, 58%), refractory disease (15, 38%), multiple prior therapies (median 2, range: 1-9). Almost all pts (39, 98%) had at least 1 prior therapy containing R, and 3 of the 21 pts (14%) receiving idelalisib + O had received prior O. 63% of the pts receiving idelalisib + R, and 48% of the pts receiving idelalisib + O were refractory to R. Prior therapies also included alkylating agents (31, 78%, [bendamustine: 20, 50%]) and purine analogs (31, 78%, [fludarabine: 28, 70%]). Data available from 39 pts showed that 11 (28%) pts had evidence of del(17p) and/or TP53 mutations and 30 (75%) had unmutated IGHV. As of 7/15/2014, the median (range) treatment duration was 18 (0-44) months. 23 (58%) pts have completed the primary study and enrolled into the extension study. Primary reasons for study discontinuation (as reported by investigators) included disease progression (14, 35%), adverse events (AEs) (12, 30%), investigator request (3, 8%), withdrawal of consent (n=1), BMT (n=1). There were a total of 8 deaths on study: 2 deaths occurred after disease progression, and 6 pts died because of AEs (all assessed as unrelated/unlikely related to idelalisib by investigators). A total of 4 pts (10%) were continuing idelalisib treatment on the extension study at time of analysis. Selected treatment-emergent AEs (any Grade/≥Gr 3, regardless of causality) included diarrhea/colitis (55%/23%), cough (40%/3%), pyrexia (40%/3%), dyspnea (30%/3%), fatigue (25%/0%) nausea (25%/0%), rash (20%/0%), pneumonia (20%/18%), and pneumonitis (8%/5%). Elevation of liver transaminases (TA, any Grade/≥Gr 3) was seen in 30%/10%. Re-exposure to idelalisib after resolution of TA elevation generally was successful; only 1 patient discontinued the study because of (recurrent) TA elevation. Other AEs leading to study discontinuation and reported as possibly/probably related to idelalisib included diarrhea/colitis (4, 10%), pyrexia (n=1), interstitial lung disease (n=1), pneumonia (n=1), rash (n=1), psoriasis (n=1). Secondary malignancies leading to discontinuation (all reported as unrelated) were breast cancer (n=1), recurrent colon cancer (n=1), AML (n=1). There was no obvious overall difference in the toxicity reported for pts receiving idelalisib with rituximab compared to those with ofatumumab. The ORR (N=40) was 83% (33/40), with 2 CRs (5%) reported. Median PFS (N=40) and duration of response (DOR) (n=33) were 24 months. Median (range) time to response was 1.9 (range 1.7-16.9) months. Median overall survival (OS) has not been reached with a KM estimate for OS of 80% at 24 months. For the 11 pts with del(17p) and/or TP53 mutations, the response rate was 73%, and the median PFS and DOR were 20 and 24 months, respectively. Conclusions: Combinations of idelalisib with anti-CD20 antibodies such as R or O represent non-cytotoxic regimens with acceptable safety profiles and considerable activity resulting in durable tumor control in pts with relapsed/refractory CLL, including those with high risk factors such as del(17p) or TP53 mutations. A Phase 3 trial evaluating the efficacy of idelalisib in combination with ofatumumab is ongoing (NCT01659021). Disclosures Furman: Gilead Sciences: Research Funding. Off Label Use: Zydelig is a kinase inhibitor indicated for the treatment of patients with: 1) Relapsed chronic lymphocytic leukemia (CLL), in combination with rituximab, in patients for whom rituximab alone would be considered appropriate therapy due to other co-morbidities; 2) Relapsed follicular B-cell non-Hodgkin lymphoma (FL) in patients who have received at least two prior systemic therapies; and 3) Relapsed small lymphocytic lymphoma (SLL) in patients who have received at least two prior systemic therapies.. de Vos:Gilead Sciences: Research Funding. Barrientos:Gilead Sciences: Research Funding. Schreeder:Gilead Sciences: Research Funding. Flinn:Gilead Sciences: Research Funding. Sharman:Gilead Sciences: Research Funding. Boyd:Gilead Sciences: Research Funding. Fowler:Gilead Sciences: Research Funding. Leonard:Gilead Sciences: Research Funding. Rai:Gilead Sciences: Research Funding. Kim:Gilead Sciences: Employment, Equity Ownership. Viggiano:Gilead Sciences: Employment, Equity Ownership. Jahn:Gilead Sciences: Employment, Equity Ownership. Coutre:Gilead Sciences: Research Funding.

scholarly journals Reduction of Mitochondrial Membrane Potential Leads to Enhancement of Type-II CD20-Antibody Cytotoxicity in Diffuse Large B-Cell Lymphoma

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1763-1763 ◽  
Author(s):  
Emma Vilventhraraja ◽  
Tetyana Klymenko ◽  
Jennifer Edelmann ◽  
John Gribben ◽  
Andrejs Ivanov
Keyword(s):  
Oxidative Phosphorylation ◽  
Cell Lines ◽  
Mitochondrial Function ◽  
Type I ◽  
Type Ii ◽  
Antibody Treatment ◽  
Respiratory Capacity ◽  
Cd20 Antibody ◽  
Anti Cd20 ◽  
Cd20 Antibodies

Abstract Diffuse Large B Cell Lymphoma (DLBCL) is the most prevalent non-Hodgkin lymphoma (NHL) in adults. Since the addition of the Type I anti-CD20 antibody Rituximab to chemotherapy, the overall survival of NHL patients has improved dramatically compared to the pre-Rituximab era. DLBCL however, has the worst survival rates out of all NHLs with an average 5-year survival of 55%. Unfortunately 40% of all DLBCL patients relapse within 2 years, and those that relapse or have refractory disease tend not to respond well to antibody-based salvage therapies. Since the discovery and utilisation of Rituximab, many have tried to enhance the efficacy of anti-CD20 antibodies in order to improve first-line treatment of DLBCL, leading to the evolution of Type II humanised anti-CD20 antibodies. The complete biological role of CD20 remains unclear, however it has been shown to act as part of an ion channel complex that is a component of the store operated calcium (Ca2+) system. This complex has the ability to facilitate mitochondrial membrane permeabilisation, resulting in reduced mitochondrial function. In order to investigate the effect of Type I- and Type II- anti-CD20 antibodies on mitochondrial function, we established a panel of 4 DLBCL cell lines. We used the XF Seahorse Mito Stress Test to reveal bioenergetic profiles of the cell lines before and after treatment with a panel of Type I and Type II anti-CD20 antibodies (2 Type-I and 2 Type-II anti-CD20 antibodies for each cell line). Basal oxidative phosphorylation (OxPhos), ATP production, and maximal and spare respiratory capacity of each sample were calculated as a measure of mitochondrial function. Next we used Metformin, a well-established inhibitor of oxidative phosphorylation to reduce the mitochondrial membrane potential (MMP) across our panel of cell lines. We confirmed MMP reduction by staining cells with JC-1, a chameleon dye used as an indicator of MMP and analysed samples using flow cytometry. We then used the XF Seahorse Mito Stress Test, this time to assess how combining each CD20-antibody with an OxPhos inhibitor effects mitochondrial function (10 conditions for each cell line). Finally, we used the same conditions to conduct clonogenic survival assays to see whether cytotoxicity of Type-I or Type-II anti-CD20 antibodies could be enhanced. We have observed that treatment with anti-CD20 antibodies results in a significant increase in the maximal respiratory capacity of our panel of cell lines. Conversely, pharmacological inhibition of oxidative phosphorylation causes a significant reduction in basal oxidative phosphorylation as well as a reduction in the maximal respiratory capacity of the cell lines in our panel. We also show that treatment combining an OxPhos inhibitor with either Type-I or Type-II CD20-antibodies prevents the increase in maximal respiratory capacity observed with CD20-antibody treatment alone. When analysing the clonogenic survival of cell lines we have found that only the cytotoxicity of Type-II anti-CD20 antibodies is enhanced by simultaneously treating cell lines with Metformin. We also used Annexin V/PI staining to assess cell death and show that inhibiting oxidative phosphorylation in conjunction with CD20-antibody treatment does not result in a significant increase in cell death across our panel of cell lines. Our data indicate for the first time that when cells are treated with CD20-antibodies they increase their maximal mitochondrial respiratory capacity to compensate for reduced basal mitochondrial function. We also show that inhibition of oxidative phosphorylation disables the cells from being able to compensate for the reduced mitochondrial function that is caused by CD20-antibody treatment. Importantly our data show that the reduction of mitochondrial function caused by combining Metformin with Type-II CD20 antibodies leads to a significant reduction in clonogenicity. We believe that understanding the mechanism of the inhibition of mitochondrial function will allow us to establish effective treatment combinations to significantly improve the efficacy of anti-CD20 antibody therapy in DLBCL. Disclosures No relevant conflicts of interest to declare.

A Retrospective Analysis of Pneumocystis Jirovecii Pneumonia Infection in Patients Receiving Idelalisib in Clinical Trials

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3705-3705 ◽  
Author(s):  
Laurie H Sehn ◽  
Michael Hallek ◽  
Wojciech Jurczak ◽  
Jennifer R. Brown ◽  
Paul M. Barr ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Pneumocystis Jirovecii Pneumonia ◽  
Employment Equity ◽  
Advisory Committees ◽  
Increased Risk ◽  
Equity Ownership ◽  
Cd20 Antibody ◽  
Anti Cd20 ◽  
Support Research

Abstract Introduction: Opportunistic infections such as Pneumocystis jirovecii pneumonia (PJP) occur commonly in immunocompromised hosts such as patients (pts) with cancer (especially hematological malignancies such as chronic lymphocytic leukemia [CLL] and indolent non-Hodgkin lymphoma [iNHL]) or those receiving immunosuppressive therapies (such as steroids, chemotherapy). Recently, an increased risk of PJP infection was identified in 3 ongoing phase 3 studies evaluating idelalisib, administered in combination with the standard regimens rituximab (R) or bendamustine and rituximab (BR), in front-line CLL and early-line iNHL. Subsequently, a comprehensive analysis evaluating PJP infection across the clinical development program was performed to identify possible risk factors for developing PJP infection, including age, concomitant therapy (co-therapy) administered, geographic distribution of PJP infection, and regional use of prophylaxis. Methods: A retrospective analysis of 2198 pts receiving study treatment with idelalisib alone or in combination with co-therapy (anti-CD20 antibody or BR) and pts receiving only co-therapy (anti-CD20 ± bendamustine) (n = 1391 and 807, respectively) across 8 studies (frontline/relapsed CLL and relapsed iNHL) between 2010 and 2016 was performed. PJP infection was defined based on MedDRA high-level term of pneumocystis infections. In this analysis, other parameters were included for evaluation of risk of developing PJP infection-prophylaxis for PJP, geographic region, age, and CD4 count. Results: The overall incidence of PJP infection was 2.5% in pts on idelalisib ± co-therapy vs 0.2% in pts receiving only anti-CD20 antibody alone or BR alone (relative risk = 12.5). The median time to PJP event was 141 days since initiation of IDELA or co-therapy. The incidence of PJP infection was similar, irrespective of pt age. In the pt population receiving IDELA ± co-therapy - prophylaxis for PJP reduced the incidence of infection to 1.3% (from 3.4% in pts not receiving prophylaxis). Additionally, analysis by type of co-therapy received - the incidence of PJP infection was 2.2% vs 3.1% with IDELA + BR and IDELA + anti-CD20 alone respectively. A correlation between CD4 count (<200 cells/mcL) and an increased risk of PJP infection was not observed. Additional data are provided in Table 1. Conclusion: There is a small but increased risk of PJP infection during treatment with idelalisib within the clinical trial program. These data suggest that prophylaxis for PJP may reduce the risk of infection by as much as 60%. Administration of PJP prophylaxis is now recommended in all pts receiving treatment with idelalisib. Disclosures Sehn: roche/genentech: Consultancy, Honoraria; amgen: Consultancy, Honoraria; seattle genetics: Consultancy, Honoraria; abbvie: Consultancy, Honoraria; TG therapeutics: Consultancy, Honoraria; celgene: Consultancy, Honoraria; lundbeck: Consultancy, Honoraria; janssen: Consultancy, Honoraria. Hallek:Mundipharma: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau; Gilead: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau; Janssen-Cilag: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau; F. Hoffmann-LaRoche: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau. Jurczak:Gilead Sciences: Research Funding; Celltrion, Inc: Research Funding; Janssen: Research Funding; Bayer: Research Funding; Acerta: Research Funding. Brown:Infinity: Consultancy; Gilead Sciences: Consultancy; Janssen: Consultancy; Pfizer: Consultancy; Sun BioPharma: Consultancy; Celgene: Consultancy; Roche/Genentech: Consultancy; Abbvie: Consultancy. Barr:Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Consultancy. Catalano:Roche: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Membership on an entity's Board of Directors or advisory committees. Coutre:Gilead Sciences: Consultancy, Research Funding. Furman:Gilead Sciences: Consultancy; Pharmacyclics: Consultancy, Speakers Bureau; Janssen: Consultancy; Genentech: Consultancy; Abbvie: Consultancy, Honoraria. Lamanna:Gilead Sciences: Membership on an entity's Board of Directors or advisory committees, Research Funding. Zelenetz:Gilead Sciences: Research Funding. Sharman:Gilead Sciences, Inc.: Honoraria, Research Funding. Adewoye:Gilead Sciences: Employment, Equity Ownership. Kim:Gilead Sciences: Employment, Equity Ownership. Flinn:Janssen: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Gilead Sciences: Research Funding; ARIAD: Research Funding; RainTree Oncology Services: Equity Ownership. Salles:Gilead: Honoraria, Research Funding; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Roche/Genentech: Consultancy, Honoraria, Research Funding; Mundipharma: Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria.

Differential Patterns of Gene Expression and CD20 Localisation by the Type II Anti-CD20 Antibody Obinutuzumab (GA101) Compared with the Type I Antibody Rituximab Suggests Binding to Functionally Distinct CD20 Subpopulations on B-Cell Lymphoma Cell Lines,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3721-3721
Author(s):  
Gerhard Niederfellner ◽  
Olaf Mundigl ◽  
Alexander Lifke ◽  
Andreas Franke ◽  
Ute Baer ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cell ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Mechanisms Of Action ◽  
Type I ◽  
Type Ii ◽  
Cd20 Antibody ◽  
Anti Cd20

Abstract Abstract 3721 The anti-CD20 antibody rituximab has become central to the treatment of B-cell malignancies over the last decade. Recently, it has been shown that anti-CD20 antibodies can be divided into two types based on their mechanisms of action on B cells. Rituximab is a type I antibody that redistributes CD20 into lipid rafts and promotes complement-dependent cytotoxicity (CDC), while the type II, glycoengineered antibody GA101 has lower CDC activity but higher antibody-dependent cellular cytotoxicity and direct cell death activity. In preclinical studies GA101 was superior to rituximab in B-cell killing in vitro, depletion of B cells from whole blood, and inhibition of tumour cell growth in lymphoma xenograft models. GA101 is currently being evaluated in Phase II/III trials, including comparative studies with rituximab. To investigate the differences in direct effects of GA101 and rituximab on B-cell lymphoma signaling, we have analysed the effects of antibody binding on gene expression in different B-cell lines using a GeneChip Human Genome U133 Plus 2.0 Array (Affymetrix). Rituximab and GA101 rapidly induced gene expression changes in SUDHL4 and Z138 cells, including regulation of genes associated with B-cell-receptor activation such as EGR2, BCL2A1, RGS1 and NAB2. The effects on gene expression differed markedly between different cell lines and between the two antibodies. SUDHL4 cells showed pronounced changes in the gene expression pattern to rituximab treatment, while Z138 cells, which represent a different B-cell stage, showed less pronounced changes in gene expression. The reverse was true for GA101, suggesting not only that the signaling mediated by CD20 differs in different cell lines, but also that in a given cell line the two types of antibodies bind CD20 molecules with different signaling capacity. For each cell line, gene expression induced by other type I antibodies (LT20, 2H7, MEM97) was more like rituximab and that induced by other type II antibodies (H299/B1, BH20) was more like GA101 in terms of the number of genes regulated and the magnitude of changes in expression. Unbiased hierarchical clustering analysis of gene expression in SUDHL4 could discriminate type I from type II antibodies, confirming that the two classes of antibody recognised CD20 complexes with inherently different signalling capacities. By confocal and time-lapse microscopy using different fluorophores, rituximab and GA101 localised to different compartments on the membrane of lymphoma cells. GA101/CD20 complexes were relatively static and predominantly associated with sites of cell–cell contact, while rituximab/CD20 complexes were highly dynamic and predominantly outside areas of contact. These findings suggest that type II antibodies such as GA101 bind distinct subpopulations of CD20 compared with type I antibodies such as rituximab, accounting for the differences in mechanisms of action and anti-tumour activity between these antibodies. Disclosures: Niederfellner: Roche: Employment. Mundigl:Roche: Employment. Lifke:Roche: Employment. Franke:Roche: Employment. Baer:Roche: Employment. Burtscher:Roche: Employment. Maisel:Roche: Employment. Belousov:Roche: Employment. Weidner:Roche: Employment. Umana:Roche: Employment, Patents & Royalties. Klein:Roche: Employment, Equity Ownership, Patents & Royalties.

Safety and Immunogenicity Of Inactivated Varicella-Zoster Virus Vaccine In Adults With Hematologic Malignancies Receiving Treatment With Anti-CD20 Monoclonal Antibodies

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2290-2290
Author(s):  
Shelly McNeil ◽  
Robert Betts ◽  
Steven Lawrence ◽  
Andrea Velardi ◽  
Eva Kimby ◽  
...  
Keyword(s):  
Immune Response ◽  
Monoclonal Antibodies ◽  
Research Funding ◽  
Hematologic Malignancies ◽  
Employment Equity ◽  
Varicella Zoster ◽  
Cell Responses ◽  
Equity Ownership ◽  
Ifn Γ ◽  
Anti Cd20

Abstract Background Herpes zoster (HZ) incidence is higher in patients with hematologic malignancies (HM) (25-100 cases/1000 person-years) than in the general population (3-5 cases/1000 person-years). This immunocompromised population can experience significant morbidity and occasional mortality from complications associated with reactivation of the varicella-zoster virus (VZV). In general, there is limited data in the literature regarding the effect of anti-CD20 monoclonal antibodies, used in treatment of HM patients, on vaccine-related cell-mediated immune response. Due to the potential negative impact of anti-CD20 monoclonal antibodies on vaccine immunogenicity and efficacy, HM patients receiving anti-CD20 monoclonal antibodies have been excluded from prior inactivated VZV vaccine (inactivated-ZV) studies. This study evaluated the safety and immunogenicity of inactivated-ZV in HM patients receiving anti-CD20 monoclonal antibody therapy. Methods This was an open label, single arm, multicenter Phase I study of a 4-dose inactivated-ZV regimen (∼30 days between each dose) in patients ≥18 years old with HM receiving anti-CD20 monoclonal antibodies either as a single agent or in a combination chemotherapy regimen and not likely to undergo HCT (n=80). Blood samples were collected at baseline prior to dose 1 and 28 days postdose 4 to measure VZV-specific T-cell responses using interferon-gamma enzyme-linked immunospot (IFN-γ ELISPOT). The primary hypothesis was that inactivated-ZV would elicit significant VZV-specific immune responses at ∼28 days postdose 4, with the statistical criterion being that the lower bound of the two-sided 90% confidence interval (CI) on the geometric fold rise (GMFR) be >1.0. All vaccinated patients were evaluated for adverse events (AE), including VZV-like rashes, through 28 days postdose 4. Results The 4-dose inactivated-ZV regimen elicited a statistically significant VZV-specific immune response measured by IFN-γ ELISPOT at 28 days postdose 4 in the per-protocol population (GMFR = 4.34 [90% CI: 3.01, 6.24], p-value <0.001). As the lower bound of the 2-sided 90% CI for GMFR was >1.0, the pre-specified primary immunogenicity success criterion was met. Overall, 85% (68/80) of patients reported ≥1 AEs, 44% (35/80) reported ≥1 injection-site AEs, and 74% (59/80) reported ≥1 systemic AEs. The most common injection-site AEs were pain (32%), erythema (31%), and swelling (26%). The most common systemic AEs were pyrexia (25%) and diarrhea (14%). Twelve patients (15%) experienced serious AEs, including one event determined by the investigator to be vaccine-related (convulsion: day 8 postdose 1). One patient experienced a fatal serious AE (Richter’s transformation to Hodgkin’s disease; day 34 postdose 1) assessed as not vaccine-related by the investigator. In general, the frequencies of AEs did not increase with subsequent doses of vaccine. No inactivated-ZV recipient had a rash that was PCR positive for VZV vaccine strain. Conclusions In adults with HM receiving anti-CD20 monoclonal antibodies, inactivated-ZV was well tolerated and elicited statistically significant VZV-specific T-cell responses ∼28 days postdose 4. Disclosures: McNeil: Merck: investigator Other, Research Funding. Betts:Merck: investigator Other, Research Funding. Lawrence:Merck: investigator Other, Research Funding. Velardi:Merck: investigator Other, Research Funding. Kimby:Merck: investigator Other, Research Funding. Pagnoni:Merck: Employment, Equity Ownership. Stek:Merck: Employment, Equity Ownership. Zhao:Merck: Employment, Equity Ownership. Chan:Merck: Employment, Equity Ownership. Lee:Merck: Employment, Equity Ownership. Parrino:Merck: Employment, Equity Ownership.

Ublituximab (TG-1101), a Novel Glycoengineered Anti-CD20 Monoclonal Antibody, in Combination with Ibrutinib Is Highly Active in Patients with Relapsed and/or Refractory CLL and MCL; Results of a Phase II Trial

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4679-4679 ◽  
Author(s):  
Jeff P. Sharman ◽  
Charles M. Farber ◽  
Daruka Mahadevan ◽  
Marshall T. Schreeder ◽  
Heather D. Brooks ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Alkylating Agent ◽  
Single Agent ◽  
Employment Equity ◽  
Advisory Committees ◽  
Highly Active ◽  
Efficacy Assessment ◽  
Equity Ownership ◽  
Anti Cd20

Abstract Introduction: Ublituximab (UTX) is a novel, chimeric monoclonal antibody (mAb) which targets a unique epitope on the CD20 antigen and has been glycoengineered to enhance affinity for all variants of FcγRIIIa receptors, demonstrating greater antibody-dependent cellular cytotoxicity (ADCC) activity than rituximab and ofatumumab, particularly against cells that express low CD20 levels. Two Phase I trials of single agent UTX in relapsed/refractory CLL reported significant response rates with rapid and sustained lymphocyte depletion and a manageable safety profile. Ibrutinib, a novel oral BTK inhibitor approved for patients with previously treated CLL and MCL, displays high single agent activity and has reported increased activity in combination with non-glycoengineered anti-CD20 mAbs. Herein we report safety and efficacy data on the first combination of ibrutinib with a glycoengineered anti-CD20 mAb, UTX, from an ongoing Phase 2 trial. Methods: Eligible patients have relapsed or refractory CLL/SLL or MCL with an ECOG PS ≤ 2. The study was designed to assess safety, tolerability, and early overall response rate, with an initial safety run-in period consisting of 6 patients followed by open enrollment. UTX (Cohorts of 600 and 900 mg for CLL and at 900 mg for MCL patients) is administered on Days 1, 8, and 15 in Cycle 1 followed by Day 1 of Cycles 2 - 6. Ibrutinib is started on Day 1 and continues daily at 420 mg and 560 mg for CLL and MCL patients respectively. Following Cycle 6, patients come off study but remain on ibrutinib. Primary endpoint for safety: Adverse Events and Dose Limiting Toxicities (DLT) during safety run-in. Phase II primary efficacy endpoint: ORR with an emphasis on early activity with response assessments by CT scan scheduled prior to cycles 3 and 6 only. Results: 40 patients (33 CLL/ 7 MCL) have been enrolled to date with enrollment continuing. 23 M/17 F, median age 72 yr (range 52-86), ECOG 0/1/2: 20/19/1, median prior Tx = 2 (range 1-6), 38% with ≥ 2 prior anti-CD20 therapies; prior purine analog = 43%; prior alkylating agent = 68%; and prior purine and alkylating agent = 43%. No DLTs were observed during the safety run-in. Gr 3/4 AE’s occurring in at least 5% of patients and at least possibly related to UTX and/or ibrutinib included: neutropenia, thrombocytopenia, diarrhea, rash, leukocytosis, and infusion related reaction. There were no Grade 3/4 adverse events reported in ≥ 10% of patients. Ibrutinib was dose reduced due to an AE in 2 patients (1 diarrhea, 1 rash) and discontinued in 2 patients due to ibrutinib related AE’s (diarrhea and rash). IRR’s were managed with infusion interruptions with no patient requiring an ublituximab dose reduction. As of July 2014, 24/40 patients are evaluable for response. Best response to treatment is as follows: TableTypePts (n)CR (n)PR (n)SD (n)ORR (%)CLL non 17p/11q10-9190%17p/11q817-100%Total CLL18116194%MCL632183% The one CLL patient who achieved stable disease had a 46% nodal reduction. UTX appears to control ibrutinib related lymphocytosis with more than half of the patients within normal range for ALC by first efficacy assessment. Conclusions: Data suggests ublituximab, a glycoengineered anti-CD20 mAb, in combination with ibrutinib is both well-tolerated and highly active in patients with relapsed or refractory CLL and MCL. ORR was 94% in patients with CLL (100% in patients with high risk CLL: 17p, 11q del with 1 CR), with responses attained rapidly (median TTR: 8 weeks). In MCL, 83% of patients achieved a response at first efficacy assessment, with 50% of patients achieving a CR by week 20. For most patients, responses improved by the second efficacy assessment. The addition of ublituximab appears to mitigate ibrutinib related lymphocytosis producing earlier clinical responses than historically seen with ibrutinib monotherapy. Efficacy and safety will be updated on all enrolled patients. Disclosures Sharman: TG Therapeutics: Research Funding; Gilead: Consultancy, Research Funding; Roche: Research Funding; Pharmacyclics: Research Funding; Celgene: Consultancy, Research Funding. Farber:Leukemia Lymphoma Society NJ Chapter: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Alexion: Stock ownership Other. Schreeder:TG Therapeutics, Inc.: Research Funding. Kolibaba:TG Therapeutics: Research Funding; Gilead: Research Funding; Glaxo Smithkline: Research Funding. Sportelli:TG Therapeutics: Employment, Equity Ownership. Miskin:TG Therapeutics, Inc.: Employment, Equity Ownership. Weiss:TG Therapeutics, Inc.: Employment, Equity Ownership. Greenwald:TG Therapeutics: Research Funding.

Ublituximab, a Novel Glycoengineered Anti-CD20 Monoclonal Antibody (mAb), in Combination with TGR-1202, a Next Generation Once Daily PI3kδ Inhibitor, Demonstrates Activity in Heavily Pre-Treated and High-Risk Chronic Lymphocytic Leukemia (CLL) and B-Cell Lymphoma

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 801-801 ◽  
Author(s):  
Matthew A. Lunning ◽  
Julie M. Vose ◽  
Marshall T. Schreeder ◽  
Nathan Fowler ◽  
Loretta J. Nastoupil ◽  
...  
Keyword(s):  
High Risk ◽  
Research Funding ◽  
Next Generation ◽  
Employment Equity ◽  
Once Daily ◽  
Richter's Transformation ◽  
Equity Ownership ◽  
Anti Cd20 ◽  
Ecog Ps ◽  
11Q Deletion

Abstract Introduction: Ublituximab (UTX) is a novel chimeric mAb targeting a unique epitope on the CD20 antigen, glycoengineered to enhance affinity to FcγRIIIa receptors, thereby demonstrating significantly greater ADCC than rituximab. UTX monotherapy in patients (pts) with rituximab relapsed/refractory NHL and CLL has reported a 43% ORR (ASCO 2014). TGR-1202 is a next generation, once daily, oral PI3Kδ inhibitor which notably lacks the hepatotoxicity associated with other PI3Kδ inhibitors, and is active in pts with relapsed and refractory hematologic malignancies (EHA 2014). UTX and TGR-1202 have shown synergistic activity in-vitroin various lymphoid cell lines (Lugano 2013). This Phase 1 trial evaluates safety and efficacy of the combination of a glycoengineered anti-CD20 (UTX) and a PI3Kδ inhibitor (TGR-1202) in pts with heavily pre-treated relapsed or refractory CLL and NHL. Methods: Eligible pts have relapsed/refractory CLL or NHL with an ECOG PS ≤ 2. A 3+3 design evaluates cohorts of CLL and NHL pts independently with UTX dosed on Days 1, 8, 15 of Cycles 1 & 2 followed by maintenance therapy. UTX starts at 600 mg in Cohort 1 and increases to 900 mg for pts with CLL and is fixed at 900 mg for pts with NHL. TGR-1202 starts at 800 mg QD in Cohort 1 and is increased in subsequent cohorts. An amendment in July 2014 was introduced to include an improved micronized formulation of TGR-1202, starting at 400 mg once daily and increasing in subsequent cohorts. There are no limits on prior therapy, and patients with Richter’s Transformation or who are refractory to prior PI3Kδ inhibitors or BTK inhibitors are eligible. Primary endpoints: Safety and Dose Limiting Toxicities (DLT). Secondary endpoints: Efficacy (ORR, CR rate). Results: As of August 2014, 21 pts have been enrolled: 8 CLL/SLL, 7 DLBCL, 5 Follicular Lymphoma, and 1 patient with Richter’s Transformation. Median age is 64 years (range 35-82); 12 male/9 female. Median prior Tx = 3 (range 1-9); median ECOG PS = 1. All pts are evaluable for safety. Adverse events have been manageable with no safety concerns noted. Day 1 infusion related reactions (IRR) were the most common treatment related adverse event (48%), with all but one event Grade 1 or 2 in severity, followed by neutropenia (38%), diarrhea (29%), and nausea (29%). Notably, no events of TGR-1202 related hepatotoxicity have been reported to date. All IRR and neutropenia events have been manageable with dose delays. One neutropenia related dose delay in a CLL patient at UTX 600 mg + TGR 800 mg met the criteria for a DLT, necessitating enrollment of additional pts into this cohort. No other DLTs have been reported, including at higher dose levels. Fifteen pts were evaluable for efficacy with 6 pts too early for response assessment. Among evaluable pts, 80% displayed a reduction in tumor burden at first efficacy assessment, despite pts exhibiting a number of high-risk characteristics, including 3/5 CLL pts having 17p/11q deletion and a median of 6 prior lines of therapy amongst pts with FL. Objective responses are summarized below: Table TypePts (n)PRn (%)ORRn (%)PD(n)% pts ≥ SD for 12 wksMedian Prior Rx CLL/SLL54 (80%)4 (80%)-5 (100%)2 (1 – 3) Richter’s1---1 (100%)1 FL4---4 (100%)6 (3 – 8) DLBCL52 (40%)2 (40%)14 (80%)3 (1 – 6) Total156 (40%)6 (40%)114 (93%)3 (1 – 8) Amongst pts with CLL, 2/2 pts with normal cytogenetics achieved a PR including a patient with prior treatment with a BTK inhibitor, while 2/3 pts with presence of 17p/11q deletion achieved a PR, with the remaining patient having SD with a 44% nodal reduction at first assessment. Conclusions: Preliminary data suggests the combination of UTX + TGR-1202 is well tolerated with early signs of clinical activity in heavily pre-treated and high-risk patient subsets. Enrollment is ongoing with at least 30 patients anticipated. Disclosures Lunning: Onyx: Consultancy; Alexion: Consultancy; Gilead: Consultancy; Spectrum Pharmaceuticals: Consultancy. Schreeder:TG Therapeutics, Inc.: Research Funding. Pauli:TG Therapeutics, Inc.: Consultancy. Miskin:TG Therapeutics, Inc.: Employment, Equity Ownership. Sportelli:TG Therapeutics: Employment, Equity Ownership. Weiss:TG Therapeutics, Inc.: Employment, Equity Ownership. Vakkalanka:Rhizen: Employment, Equity Ownership. Viswanadha:Incozen: Employment. O'Brien:Amgen, Celgene, GSK: Consultancy; CLL Global Research Foundation: Membership on an entity's Board of Directors or advisory committees; Emergent, Genentech, Gilead, Infinity, Pharmacyclics, Spectrum: Consultancy, Research Funding; MorphoSys, Acerta, TG Therapeutics: Research Funding.

Ublituximab (TG-1101), a Novel Glycoengineered Anti-CD20 Monoclonal Antibody, in Combination with Ibrutinib Is Highly Active in Patients with Relapsed and/or Refractory Mantle Cell Lymphoma; Results of a Phase II Trial

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3980-3980 ◽  
Author(s):  
Kathryn Kolibaba ◽  
John M. Burke ◽  
Heather D. Brooks ◽  
Daruka Mahadevan ◽  
Jason Melear ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Monoclonal Antibody ◽  
Mantle Cell Lymphoma ◽  
Research Funding ◽  
Cell Lymphoma ◽  
Employment Equity ◽  
Highly Active ◽  
Mantle Cell ◽  
Equity Ownership ◽  
Anti Cd20

Abstract Introduction: Ublituximab (UTX) is a novel, chimeric monoclonal antibody (mAb) which targets a unique epitope on the CD20 antigen and has been glycoengineered to enhance affinity for all variants of FcγRIIIa receptors, demonstrating greater ADCC than rituximab and ofatumumab. In patients (pts) with rel/ref CLL, the combination of UTX with ibrutinib was well-tolerated and highly active demonstrating an 88% ORR (95% ORR in high-risk CLL) with responses attained rapidly (median time to iwCLL response of 8 weeks). Ibrutinib has demonstrated single agent activity in Mantle Cell Lymphoma (MCL), achieving a 68% ORR (21% CR) in a single arm trial in relapsed or refractory patients (Wang et al, NEJM 2013). Herein we report on the first combination of ibrutinib with a glycoengineered anti-CD20 mAb, UTX, in patients with Mantle Cell Lymphoma (MCL). Methods: Eligible patients had rel/ref MCL with an ECOG PS < 3. Prior ibrutinib treatment was permitted. UTX (900 mg) was administered on Days 1, 8, and 15 in Cycle 1 followed by Day 1 of Cycles 2 - 6. Ibrutinib was started on Day 1 and continued daily at 560 mg. Following Cycle 6, patients came off study but could remain on ibrutinib. Primary endpoints were safety and ORR with an emphasis on early activity with response assessments by CT scan scheduled prior to cycles 3 and 6 only (criteria per Cheson 2007). Results: 15 patients were enrolled: 13 M/2 F, median age 71 yr (range 55-80), ECOG 0/1: 9/6, median prior Tx = 3 (range 1-8), 53% with ≥ 2 prior anti-CD20 therapies, 40% prior bortezomib. Gr 3/4 AE's occurring in at least 5% of patients and at least possibly related to UTX and/or ibrutinib included: neutropenia (13%), fatigue (7%), rash (7%) and atrial fibrillation (7%). Ibrutinib was dose reduced due to an AE in 1 patient (rash) and discontinued in 1 patient due to atrial fibrillation. No UTX dose reductions occurred. All 15 pts are evaluable for response with best response to treatment as follows: 87% (13/15) ORR with 33% (5/15) Complete Response. Three of the CR's occurred at week 8. Of the two patients not achieving an objective response, one patient was stable at first scan and came off treatment prior to second efficacy assessment (ibrutinib related A-Fib) and one patient progressed at first assessment. Responses generally improved from first to second assessment with median tumor reduction of 64% by week 8 and 82% by week 20. Conclusions: Ublituximab, a glycoengineered anti-CD20 mAb, in combination with ibrutinib is both well-tolerated and highly active in pts with rel/ref MCL. Response rate, depth of response, and time to response compare favorably to historical data with ibrutinib alone. A randomized phase 3 trial with ibrutinib +/- ublituximab is currently ongoing in high-risk CLL pts and future studies using this combination in MCL are being evaluated. Disclosures Kolibaba: Janssen: Research Funding; Novartis: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding; Gilead: Consultancy, Honoraria, Research Funding; TG Therapeutics: Research Funding; GSK: Research Funding; Genentech: Research Funding; Cell Therapeutics: Research Funding; Celgene: Research Funding; Amgen: Research Funding; Amgen: Research Funding; Acerta: Research Funding. Burke:Gilead: Consultancy; Millenium/Takeda: Consultancy; Seattle Genetics, Inc.: Research Funding; Incyte: Consultancy; Janssen: Consultancy; TG Therapeutics: Other: Travel expenses. Farber:TG Therapeutics, Inc.: Research Funding. Fanning:Celgene and Millennium/Takeda: Speakers Bureau. Schreeder:TG Therapeutics, Inc: Research Funding. Boccia:Incyte Corporation: Honoraria. Sportelli:TG Therapeutics, Inc.: Employment, Equity Ownership. Miskin:TG Therapeutics, Inc.: Employment, Equity Ownership. Weiss:TG Therapeutics, Inc.: Employment, Equity Ownership. Sharman:Roche: Research Funding; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics: Consultancy, Honoraria, Research Funding; Calistoga: Honoraria; Janssen: Research Funding; TG Therapeutics, Inc.: Research Funding; Celgene Corporation: Consultancy, Research Funding.

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