Triggering FCα-Receptor I (CD89) Recruits Neutrophils as Effector Cells for CD20-Directed Antibody Therapy

Abstract

CD20 Abs induce clinical responses in lymphoma patients, but there are considerable differences between individual patients. In 51Cr release assays with whole blood as effector source, RAJI cells were effectively killed by a mouse/human chimeric IgG1 construct of CD20 Ab 1F5, whereas ARH-77 proved resistant to killing by this Ab. When whole blood was fractionated into plasma, mononuclear cells, or granulocytic effector cells, RAJI cells were effectively killed in the presence of complement-containing plasma, whereas the mature B cell line ARH-77 proved complement resistant. However, with a bispecific Ab (BsAb) against the myeloid receptor for IgA (CD89; FcαRI) and CD20, a broad range of B cell lines were effectively killed. FcαRI is expressed on monocytes/macrophages, neutrophils, and eosinophils. As the numbers of these effector cells and their functional activity can be enhanced by application of G-CSF or GM-CSF, lysis via (FcαRI × CD20) BsAb was significantly enhanced in blood from patients during therapy with these myeloid growth factors. Interestingly, the major effector cell population for this BsAb were polymorphonuclear neutrophils, which proved ineffective in killing malignant B cells with murine, chimeric IgG1, or FcγRI- or FcγRIII-directed BsAbs against CD20. Experiments with blood from human FcαRI/FcγRI double-transgenic mice showed corresponding results, allowing the establishment of relevant syngenic animal models in these mice. In conclusion, the combination of myeloid growth factors and an (FcαRI × CD20) BsAb may represent a promising approach to improve effector cell recruitment for CD20-directed lymphoma therapy.

The Multifaceted Roles Neutrophils Play in the Tumor Microenvironment

“…Neutrophils were also shown to contribute to the anti-tumor ADCC in Non-Hodgkin's Lymphoma using antibodies to CD20 (Rituximab) [341], in breast cancer using a Tn antigen-specific chimeric mAb [342], and in B-cell lymphoma using a bispecific singlechain fragment variable-specific for HLA class II and FcαRI (CD89) [343]. The bispecific antibody against the myeloid receptor for IgA (FcαR1; CD89) and the B-cell surface marker CD20 induced neutrophil-dependent ADCC toward broad range of B cell lines [344]. Lysis via FcαRI:CD20 bispecific antibodies was enhanced in blood from patients during therapy with G-CSF or GM-CSF [344].…”

“…The bispecific antibody against the myeloid receptor for IgA (FcαR1; CD89) and the B-cell surface marker CD20 induced neutrophil-dependent ADCC toward broad range of B cell lines [344]. Lysis via FcαRI:CD20 bispecific antibodies was enhanced in blood from patients during therapy with G-CSF or GM-CSF [344]. Interestingly, Otten et al [345] observed that immature neutrophils mobilized from the bone marrow upon G-CSF treatment, efficiently triggered tumor cell lysis via FcαRI (CD89), but were unable to initiate tumor cell killing via FcγR.…”

Rituximab Infusion Promotes Rapid Complement Depletion and Acute CD20 Loss in Chronic Lymphocytic Leukemia

“…Restoration of deposition of C3b(i) on target cells may increase the immunotherapeutic action of RTX, even when complement-mediated lysis does not occur. Several lines of evidence suggest that recognition of RTXopsonized cells by Fc␥ receptors on phagocytic cells promotes ADCC and contributes to RTX immunotherapeutic action (10,(15)(16)(17)(18). Opsonization of IgG-containing target cells with C3b activation products enhances Fc␥ receptor-mediated phagocytosis of cells by both neutrophils and monocytes (38,39).…”

“…The efficacy of this mAb in indolent or follicular NHL is well documented, and it is also being examined as an immunotherapeutic agent against chronic lymphocytic leukemia (CLL) (7)(8)(9)(10). The mechanism of antitumor activity of RTX in vivo remains a subject of some debate; preclinical studies, as well as more recent reports of animal models and clinical investigations have provided support for apoptosis (11)(12)(13)(14), Fc␥ receptor-mediated Ab-dependent cellular cytotoxicity (ADCC) (10,(15)(16)(17)(18), and complement-dependent cytotoxicity (CDC) (19 -28). In patients selected for treatment based on relatively low circulating lymphocyte counts (Ͻ5000/ l), infusion of RTX leads to rapid and prolonged depletion of normal and malignant B cells from the bloodstream (1,4).…”

A Recombinant Bispecific Single-Chain Fragment Variable Specific for HLA Class II and FcαRI (CD89) Recruits Polymorphonuclear Neutrophils for Efficient Lysis of Malignant B Lymphoid Cells

“…Surprisingly, PMNs were able to effectively kill a broad range of B cell lines mediated by a (FcaRI 3 CD20) bsAb (22). However, also with FcaRI as trigger molecule, PMNs were still not able to lyse malignant B cell lines via CD19 or CD37-directed chemically linked bsAbs.…”