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Oncotarget. 2017 Dec 9;8(69):113895-113909. doi: 10.18632/oncotarget.23040. eCollection 2017 Dec 26.

A comparative global phosphoproteomics analysis of obinutuzumab (GA101) versus rituximab (RTX) against RTX sensitive and resistant Burkitt lymphoma (BL) demonstrates differential phosphorylation of signaling pathway proteins after treatment.

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Department of Pediatrics, New York Medical College, Valhalla, NY, USA.
Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA.
Department of Medicine, Roswell Park Cancer Institute, Buffalo, NY, USA.
Roche Pharmaceutical Research & Early Development, Roche Innovation Center Zurich, Schlieren, Switzerland.
Department of Medicine, New York Medical College, Valhalla, NY, USA.
Department of Pathology, New York Medical College, Valhalla, NY, USA.
Department of Microbiology & Immunology, New York Medical College, Valhalla, NY, USA.
Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA.


We recently demonstrated that obinutuzumab (GA101), a novel glycoengineered type II CD20 Ab compared to rituximab (RTX) mediates significantly enhanced antibody-dependent cell cytotoxicity (ADCC) in vitro and increased overall survival in a Burkitt lymphoma (BL) xenograft non-obese diabetic severe combined immunodeficiency gamma (NSG) model. In this study we compared the phosphoproteomic changes by pathway analysis following obinutuzumab vs RTX against RTX-sensitive (Raji) and -resistant BL (Raji4RH). Phosphoproteomic analyses were performed by mass-spectrometry (MS)-based label-free quantitative phosphoproteomic profiling. We demonstrated that 418 proteins in Raji and 377 proteins in Raji 4RH, were differentially phosphorylated (>1.5-fold) after obinutuzumab vs. RTX. Proteins that were significantly differentially phosphorylated included the B cell antigen receptor (BCR) (PLCG2, BTK and GSK3B), Fc gamma phagocytosis (FCRG2B, MAPK1, PLCG2 and RAF1), and natural killer cell-mediated cytotoxicity (MAPK1, RAF1, PLCG2 and MAPK3) signaling pathways. Differential phosphorylation of BCR or cytotoxicity pathway proteins revealed significant up-regulation of BTK, PLCY2 and ERK1/RAF1 after obinutuzumab compared to RTX. Silencing of PLCG2 in the BCR and MAPK1 in the cytotoxicity pathway significantly increased BL proliferation and decreased BL cytotoxicity after obinutuzumab compared to RTX. These results in combination with our previous results demonstrating a significant improvement in in vitro BL cytotoxicity and in vivo BL survival by obinutuzumab compared to RTX may in part be due to differential effects on selected BL protein signaling pathways.


Burkitt lymphoma; obinutuzumab; proteomics; resistant; rituximab

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