O’Sullivan JA, Carroll DJ, Cao Y, Salicru AN, & Bochner BS. Leveraging Siglec-8 Endocytic Mechanisms to Kill Human Eosinophils and Malignant Mast Cells. (2018). J Allergy Clin Immunol, 141 (5):1774-1785.e1777.
Objective: to determine whether Siglec-8 is endocytosed in human eosinophils and malignant mast cells, identify mechanisms underlying its endocytosis, and demonstrate whether a toxin can be targeted to Siglec-8–bearing cells to kill these cells.
Summary: Targeting saporin to Siglec-8 consistently caused extensive cell death in eosinophils and the human mast cell leukemia cell line HMC-1.2. Therapeutic payloads can be targeted selectively to eosinophils and malignant mast cells by exploiting this Siglec-8 endocytic pathway.
Dose: Eosinophil cell death was assessed after 18 to 24 hours of incubation with 2C4 mAb or isotype control (MOPC-21; both at 2.5 μg/mL) or equimolar concentrations of saporin-conjugated 2C4 or MOPC-2.
Cua S, Tan HL, Fong WJ, Chin A, Lau A, Ding V, Song Z, Yang Y, & Choo A. Targeting of Embryonic Annexin A2 Expressed on Ovarian and Breast Cancer by the Novel Monoclonal Antibody 2448. (2018). Oncotarget, 9 (17):13206-13221. 2018/03/24. 5862572.
Dose: Cells were seeded in 96-well plates at 1000 or 2000 cells/well. Primary antibody, 2448 or ch2448 (10 μg/mL) was pre-mixed with appropriate secondary saporin conjugate, Mab-ZAP or Hum-ZAP. The most significant decreases in cell viability (20% to 60%) were observed against the epithelial IGROV1 and MCF7 cell lines. A Custom ADC was created by direct conjugation of saporin to ch2448 (ch2448-SAP). As a control, an isotype chimeric IgG was also conjugated to saporin (IgG-SAP). Compared to using secondary saporin conjugates, ch2448-SAP induced and increase of 20–30% cytotoxicity.
Objective: To develop mAbs to potentially target oncofetal antigens and be repurposed for antibody or antibody drug conjugate (ADC) therapy.
Summary: The novel IgG1, 2448, was shown to target a unique glycosylated surface epitope on ANXA2. As a possible therapeutic candidate for ovarian and breast cancer, 2448 demonstrated anti-tumor activity via two independent mechanisms of action.
Effective antitumor therapy based on a novel antibody-drug conjugate targeting the Tn carbohydrate antigen. Sedlik C, Heitzmann A, Viel S, Ait Sarkouh R, Batisse C, Schmidt F, De La Rochere P, Amzallag N, Osinaga E, Oppezzo P, Pritsch O, Sastre-Garau X, Hubert P, Amigorena S, Piaggio E. Oncoimmunology 5(7):e1171434, 2016. PMID: 27622021
Scientists wanted to study the potential of Chi-Tn, a monoclonal antibody against a glycol-peptidic tumor-associated antigen, as an anticancer antibody-drug conjugate. They demonstrated that Chi-Tn specifically targeted tumor cells in vivo, using flow cytometry and deconvolution microscopy to show that Chi-Tn is rapidly internalized. Chi-Tn-SAP (ATS Custom Services) effectively killed Tn-positive cells, but had no effect on Tn-negative cells. Saporin (Cat. #PR-01) was used as control. The cytotoxicity of the Chi-Tn-SAP correlated with the level of tumoral Tn expression.
Retrograde transport is not required for cytosolic translocation of the B-subunit of Shiga toxin. Garcia-Castillo MD, Tran T, Bobard A, Renard HF, Rathjen SJ, Dransart E, Stechmann B, Lamaze C, Lord M, Cintrat JC, Enninga J, Tartour E, Johannes L. J Cell Sci 128(13):2373-2387, 2015.