Heterodimeric Bispecific Single-Chain Variable-Fragment Antibodies Against EpCAM and CD16 Induce Effective Antibody-Dependent Cellular Cytotoxicity Against Human Carcinoma Cells

Abstract

A heterodimeric bispecific biological recombinant drug was synthesized by splicing DNA fragments from two fully humanized single-chain variable-fragment (scFV) antibody fragments forming a novel drug simultaneously recognizing the CD16 natural killer (NK) cell marker and the cancer marker epithelial cell adhesion molecule (EpCAM). The drug precipitously enhanced the killing of human carcinomas of the prostate, breast, colon, head, and neck even at very low effector:target ratios. The drug EpCAM16 rendered even nonactivated NK cellproficient killers and activated them to kill via degranulation and cytokine production. Studies show that bispecific antibodies can be used to induce proficient killing of the carcinoma targets that ordinarily are resistant to NK-mediated killing. Apparently, the innate immune system can be effectively recruited to kill cancer cells using the bispecific antibody platform and EpCAM targeting.

NK cells and cancer: you can teach innate cells new tricks

“…Different tumour types have been targeted by linking these anti-CD16 Fv domains to Fv domains against CD19 (REF. 177) and HLA class II for B cell malignancies 178 , CD30 for Hodgkin's lymphoma 176,179 , epidermal growth factor receptor (EGFR), which is overexpressed in several epithelial cancer types 175 , HER2 (REFS 180,181) for breast cancer, CD33 for AML 182,183 and EPCAM 184 for carcinomas. The in vitro and in vivo efficacy of these optimized proteins in eliciting specific antitumour activity is encouraging and should be further developed in clinical settings.…”

CD16xCD33 bispecific killer cell engager (BiKE) activates NK cells against primary MDS and MDSC CD33+ targets

“…12,13 Currently, novel single-chain variable fragment (scFv) recombinant reagents termed bispecific and trispecific killer cell engagers (BiKE and TriKE), which specifically target CD16 expressed on effector NK cells and antigens of interest on tumor cells, are being developed and tested for clinical use. [14][15][16][17][18] We recently developed a novel BiKE that targets CD16 along with the myeloid differentiation antigen CD33 (CD16xCD33) and demonstrated its ability to facilitate effective NK cell elimination of primary CD33…”

Trispecific killer engager CD16xIL15xCD33 potently induces NK cell activation and cytotoxicity against neoplastic mast cells

“…CD107a, TNF-a, and IFN-g were determined as previously described. 8 ROSA KIT D816V MCs were labeled with CellTrace Violet Cell Proliferation Dye (Invitrogen), incubated with NK cells for 4 hours, and counted with flow cytometer for the killing assay. NK cell-mediated cytotoxicity of ROSA KIT D816V cells was also assessed in real time over a 24-hour period using an IncuCyte Live Cell Analysis System (Essen BioScience) as previously described.…”