2018 Research & Innovation Day Program

A one day showcase of applied research, social innovation, scholarship projects and activities.https://first.fanshawec.ca/cri_cripublications/1005/thumbnail.jp

Therapeutic efficacy of FcgammaRI/CD64-directed bispecific antibodies in B-cell lymphoma

CD64 (Fc?RI) receptors represent highly potent trigger molecules for activated polymorphonuclear cells (PMN) and mediate lysis of a range of tumors in the presence of appropriate monoclonal antibodies. An huCD64 transgenic mouse model designed to analyze the therapeutic activity of a panel of bispecific F(ab')2(BsAb) in retargeting granulocyte–colony-stimulating factor (G-CSF)–activated PMN against syngeneic B-cell lymphomas is reported. This model allows careful analysis of the individual elements of the therapeutic process. BsAb were directed against immunoglobulin-idiotype (Id), major histocompatibility class II (MHC II), or CD19 on the tumors and huCD64 on the effectors. In vitro cytotoxicity assays and in vivo tumor tracking showed that, provided effectors were activated with G-CSF, all 3 derivatives destroyed and cleared lymphoma cells, with (huCD64?×?MHC II) proving by far the most cytotoxic in vitro. However, though all derivatives delivered some survival advantage, only the [huCD64?×?Id] BsAb provided long-term protection to tumor-bearing animals. These results demonstrate that CD64-recruited cytotoxic effectors operate in vivo but that the (huCD64?×?Id) conferred an additional anti-tumor function essential for long-term protection. T-cell depletion studies demonstrated that this extra therapeutic activity with [huCD64?×?Id] was totally dependent on CD4 and CD8 T cells and that mice, once “cured” with BsAb, were resistant to tumor rechallenge. These findings indicate that CD64 is an effective trigger molecule for delivering cytokine-activated PMN against tumor in vivo and that, provided tumor targets are selected appropriately, CD64-based BsAb can establish long-term T-cell immunity. <br/

Novel type II anti-CD20 monoclonal antibody (GA101) evokes homotypic adhesion and actin-dependent, lysosome-mediated cell death in B-cell malignancies

The anti-CD20 mAb rituximab has substantially improved the clinical outcome of patients with a wide range of B-cell malignancies. However, many patients relapse or fail to respond to rituximab, and thus there is intense investigation into the development of novel anti-CD20 mAbs with improved therapeutic efficacy. Although Fc-FcγR interactions appear to underlie much of the therapeutic success with rituximab, certain type II anti-CD20 mAbs efficiently induce programmed cell death (PCD), whereas rituximab-like type I anti-CD20 mAbs do not. Here, we show that the humanized, glycoengineered anti-CD20 mAb GA101 and derivatives harboring non-glycoengineered Fc regions are type II mAb that trigger nonapoptotic PCD in a range of B-lymphoma cell lines and primary B-cell malignancies. We demonstrate that GA101-induced cell death is dependent on actin reorganization, can be abrogated by inhibitors of actin polymerization, and is independent of BCL-2 overexpression and caspase activation. GA101-induced PCD is executed by lysosomes which disperse their contents into the cytoplasm and surrounding environment. Taken together, these findings reveal that GA101 is able to potently elicit actin-dependent, lysosomal cell death, which may potentially lead to improved clearance of B-cell malignancies in vivo.</p

Novel type II anti-CD20 monoclonal antibody (GA101) evokes homotypic adhesion and actin-dependent, lysosome-mediated cell death in B-cell malignancies

The anti-CD20 monoclonal antibody (mAb) rituximab has substantially improved the clinical outcome of patients with a wide range of B-cell malignancies. However, many patients relapse or fail to respond to rituximab, and thus there is intense investigation into the development of novel anti-CD20 mAbs with improved therapeutic efficacy. Although Fc-Fc?R interactions appear to underlie much of the therapeutic success with rituximab, certain type II anti-CD20 mAbs efficiently induce programmed cell death (PCD), whereas rituximab-like type I anti-CD20 mAbs do not. Here we show that the humanized, glycoengineered anti-CD20 mAb GA101 and derivatives harboring non-glycoengineered Fc regions are type II mAb that trigger non-apoptotic PCD in a range of B-lymphoma cell lines and primary B-cell malignancies. We demonstrate that GA101-induced cell death is dependent on actin reorganization, can be abrogated by inhibitors of actin polymerization and is independent of BCL-2 over-expression and caspase activation. GA101-induced PCD is executed by lysosomes which disperse their contents into the cytoplasm and surrounding environment. Taken together, these findings reveal that GA101 is able to potently elicit actin-dependent, lysosomal cell death, which may potentially lead to improved clearance of B-cell malignancies in vivo