Macrophage-mediated Antibody-dependent Phagocytosis Research Articles

IgG antibodies mediated gold nanoparticles conjugated to methotrexate as targeted chemotherapy for lung cancer

Vincamine, a natural chemical, was used as a reducing agent in the synthesis of IgG antibodies mediated biogenic gold nanoparticles (IgGAuNPs). Eventually, the synthesised IgGAuNPs were bioconjugated with the chemotherapeutic drug methotrexate (MTX-IgGAuNPs). The IgG isotype can target cancer cells through polymorphic Fc gamma receptors (FcγRs) and have therapeutic effects. They can restrict cell division by inhibiting different intracellular signal transduction pathways and activating NK cells and macrophages through antibody-dependent cellular cytotoxicity and macrophage-mediated antibody-dependent phagocytosis, respectively. Further, IgGAuNPs and MTX-IgGAuNPs were characterised by physical techniques. Moreover, 3D conformational changes in the structure of IgG were analysed by fluorescence spectroscopy during and after the synthesis of IgGAuNPs. Furthermore, the IgGAuNPs and MTX-IgGAuNPs were effective against lung cancer (A549 cells), while they were found to be non-toxic against normal cells (NRK cells). The effectiveness of IgGAuNPs and MTX-IgGAuNPs was examined by MTT cytotoxicity assay, DCFDA method for the production of ROS, and release of Cyt-c from the mitochondria for caspase-3-mediated apoptosis. Moreover, the confirmation of internalisation of particles into the nucleus was examined under the DAPI assay, and it was found that particles caused nuclear fragmentation, which was also an indication of apoptosis.

Abstract 2957: CD127 is expressed by acute lymphoblastic leukemias and is efficiently targeted by the IL7R-antagonist OSE-127 through macrophage-mediated antibody dependent phagocytosis

Abstract Acute lymphoblastic leukemia (ALL) arises from the uncontrolled proliferation of precursor B or T cells (B- or T-ALL). Novel immunotherapies are urgently needed to reduce polychemotherapy-related toxicities and to target relapsed/refractory disease. The Interleukin 7 receptor (IL7R) plays a pivotal role in the development of ALL through mutations leading to constitutive activation of the oncogenic IL7R pathway or through overexpression of the receptor. The IL7Rα chain (CD127)-targeting antibody OSE-127 is a full antagonist of the IL7R pathway with an excellent safety profile (NCT03980080), currently evaluated in phase 2 trials in inflammatory and autoimmune diseases (NCT04882007, NCT04605978). We previously reported in vivo efficacy of OSE-127 in CD127+ ALL patient-derived xenografts (PDXs) and synergy with standard of care polychemotherapy, but we had not evaluated CD127 protein expression in ALL patient cells. Moreover, the mechanism of action underlying OSE-127’s anti-leukemic activity remained to be fully elucidated. Here we show that CD127 is expressed by >84% ALL patients and that OSE-127 efficiently targets CD127 not only via its IL7R antagonist activity but also through macrophage-mediated antibody dependent phagocytosis (ADCP). First, CD127 surface expression was prospectively measured by flow cytometry in 372 diagnostic ALL patient samples. We detected CD127-positivity (defined as ≥10% CD127+ blasts) in 84.4% (314/372) cases, of which 39.5% (147/372) were CD127hi (≥ 50% CD127+ blasts). CD127 expression was higher in T- than in B-ALL. Among B-ALL, highest expression was detected in E2A-PBX1+ and BCR-ABL-like ALLs. Mechanistically, OSE-127 blocked STAT5 phosphorylation in IL7-responsive ALL-PDX cells, leading to decreased cell survival and proliferation. Surprisingly, we detected high in vivo efficacy of OSE-127 therapy in IL7-unresponsive PDXs (e.g., unable to induce phosphorylation of STAT5 upon ex vivo IL7 stimulation or with IL7R mutation-induced constitutive phosphorylation of STAT5). We uncovered that OSE-127 induced macrophage-mediated ADCP of CD127+ ALL cells in vitro. Accordingly, treatment of IL7-unresponsive, but OSE-127-sensitive models with an OSE-127-LALAPG variant (conserving IL7R-antagonistic properties but lacking ADCP activity due to Fc-inactivating mutations) did not impact leukemia development, thereby substantiating that ADCP contributes to the anti-leukemic efficacy of OSE-127. In fact, ADCP levels induced by OSE-127 treatment in vitro correlated with its capacity to reduce ALL blasts in the blood of PDX mice in vivo. Altogether, through its dual mode of action, OSE-127 may represent a powerful novel immunotherapy option for ALL patients, including cases with dysregulated IL7R signaling, particularly in combination with standard of care polychemotherapy. Citation Format: Irene Baccelli, Lennart Lenk, Anna Laqua, Dorothee Winterberg, Anna Dietterle, Frederique Corallo, Julien Taurelle, Emma Narbeburu, Beat Bornhauser, Jean-Pierre Bourquin, Fotini Vogiatzi, Simon Raffel, Martin Schrappe, Gunnar Cario, Monika Brüggemann, Denis M Schewe, Nicolas Poirier. CD127 is expressed by acute lymphoblastic leukemias and is efficiently targeted by the IL7R-antagonist OSE-127 through macrophage-mediated antibody dependent phagocytosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2957.

Augmented antibody-based anticancer therapeutics boost neutrophil cytotoxicity.

Most clinically used anticancer mAbs are of the IgG isotype, which can eliminate tumor cells through NK cell-mediated antibody-dependent cellular cytotoxicity and macrophage-mediated antibody-dependent phagocytosis. IgG, however, ineffectively recruits neutrophils as effector cells. IgA mAbs induce migration and activation of neutrophils through the IgA Fc receptor (FcαRI) but are unable to activate NK cells and have poorer half-life. Here, we combined the agonistic activity of IgG mAbs and FcαRI targeting in a therapeutic bispecific antibody format. The resulting TrisomAb molecules recruited NK cells, macrophages, and neutrophils as effector cells for eradication of tumor cells in vitro and in vivo. Moreover, TrisomAb had long in vivo half-life and strongly decreased B16F10gp75 tumor outgrowth in mice. Importantly, neutrophils of colorectal cancer patients effectively eliminated tumor cells in the presence of anti-EGFR TrisomAb but were less efficient in mediating killing in the presence of IgG anti-EGFR mAb (cetuximab). The clinical application of TrisomAb may provide potential alternatives for cancer patients who do not benefit from current IgG mAb therapy.

Single-Arm Phase II Study of MOR208 Combined with Lenalidomide in Patients with Relapsed or Refractory Diffuse Large B-Cell Lymphoma: L-Mind

Single-Arm Phase II Study of MOR208 Combined with Lenalidomide in Patients with Relapsed or Refractory Diffuse Large B-Cell Lymphoma: L-Mind