Marquez J, Dong J, Dong C, Tian C, Serrero G (2021) Identification of Prostaglandin F2 Receptor Negative Regulator (PTGFRN) as an internalizable target in cancer cells for antibody-drug conjugate development. PLoS One 16(1):e0246197. doi: 10.1371/journal.pone.0246197
Summary: PTGFRN is a cell-surface protein that is upregulated in certain cancer types, including head and neck and, notably, pediatric medulloblastoma, an aggressive cancer with limited therapeutic options. With the selection of the mouse monoclonal antibody 33B7, the authors identified PTGFRN as a potential therapy target, and show that it is internalized by incubation with 33B7. Purified 33B7 antibody was sent to Advanced Targeting Systems where saporin was directly conjugated to the Fc region of 33B7 using their proprietary cleavable linker.
Dose: In a 96-well plate, 2000 cells/well were plated in triplicate in 100μL of DMEM/F12 medium supplemented with 2.5% FBS, 0.4 ug/ml 33B7 antibody, and 0.9ug/ml of Fab-ZAP mouse. As an isotype control, cells were incubated with mouse Fab IgG-SAP as control (instead of 33B7) and Fab-ZAP.
Masoumi KC, Huang X, Sime W, Mirkov A, Munksgaard Thorén M, Massoumi R, Lundgren-Åkerlund E (2021) Integrin α10-Antibodies Reduce Glioblastoma Tumor Growth and Cell Migration. Cancers (Basel) 13(5):1184. doi: 10.3390/cancers13051184
Summary: The authors investigated the treatment effect of two antibodies that have been developed to target the protein integrin 10, which is present on the surface of Glioblastoma (GB) cells. Function-blocking integrin alpha10, beta1-antibodies inhibit GB tumor growth as well as the migration of GB cells. This further validates integrin alpha10, beta1 as a promising target in GB and suggests a novel therapeutic strategy for the treatment of GB and other high-grade gliomas.
Dose: Infusions of anti-integrin α10β1-SAP or Anti-ctrl-SAP were made icv (1 µg/2 L per infusion). See Thorén et al. 2019.
Knuplez, E, Krier‐Burris, R, Cao, Y, Marsche, G, O’Sullivan, J, Bochner, BS. Superior mouse eosinophil depletion in vivo targeting transgenic Siglec‐8 instead of endogenous Siglec‐F: Mechanisms and pitfalls. (2020) J Leukoc Biol 108: 43– 58. doi: 10.1002/jlb.3hi0120-381r
Objective: To determine if targeting Siglec-8 with mouse IgG1 antibodies, rather than targeting Siglec-F with rat IgG antibodies, in mice transgenic for Siglec-8, will prove to be a more effective strategy for eliminating mouse eosinophils in vivo.
Summary: This study is the first to describe a novel mouse strain of Siglec-8+F− eosinophils—a useful tool for studying human Siglec biology in preclinical models.
Dose: Siglec-8+F− mouse eosinophils were pretreated with 10 μg/mL saporin-conjugated isotype controls (mouse IgG1 or rat IgG2), anti-Siglec-8 (2C4) or anti-Siglec-F (9C7) antibodies for 24 h.
Qian L, Kasas L, Milne MR, Rawashdeh O, Marks N, Sharma A, Bellingham MC, Coulson EJ. Cholinergic basal forebrain degeneration due to obstructive sleep apnoea increases Alzheimer’s pathology in mice. (2020) bioRxiv 2020.03.12.989848. doi: 10.1101/2020.03.12.989848
Dose: bilateral injections of urotensin II-saporin (UII- SAP; 0.07μg/μL per site – unless stated otherwise; generous gift from Advanced Targeting Systems)
Thal LB, Kovtun O, Rosenthal SJ. Labeling Neuronal Proteins with Quantum Dots for Single-Molecule Imaging (2020) Methods Mol Biol 2135:169-177. doi: 10.1007/978-1-0716-0463-2_9
Objective: The authors describe how nanometer-sized fluorescent semiconductors called quantum dots (QD) can be used to label neuronal proteins in a single QD imaging format.
Dose: Secondary antibody-conjugated QDs target membrane proteins pre-treated with SERT Mouse Monoclonal.
Munksgaard Thorén M, Chmielarska Masoumi K, Krona C, Huang X, Kundu S, Schmidt L, Forsberg-Nilsson K, Floyd Keep M, Englund E, Nelander S, Holmqvist B, Lundgren-Åkerlund E. Integrin α10, a Novel Therapeutic Target in Glioblastoma, Regulates Cell Migration, Proliferation, and Survival. (2019) Cancers (Basel) 11(4):587. doi: 10.3390/cancers11040587
Objective: To investigate the potential of integrin α10β1 as a therapeutic target in glioblastomas (GBMs).
Summary: integrin α10β1 has a crucial role in the migration, proliferation, and survival of GBM cells and that an integrin α10β1 antibody–drug conjugate induced cell death of GBM cells both in vitro and in vivo.
Dose: Infusions of anti-10-SAP or Anti-ctrl-SAP were made icv (1 µg/2 L per infusion).
Pang HW, Linares A, Couling L, Santollo J, Ancheta L, Daniels D, Speth RC. Novel high molecular weight albumin-conjugated angiotensin II activates β-arrestin and G-protein pathways. (2019) Endocrine 66(2):349-359. doi: 10.1007/s12020-019-01930-z
Objective: To study the ability of a novel bovine serum albumin-angiotensin II (BSA-Ang II) conjugate to effect responses of the AT1 angiotensin II receptor subtype mediated by the G-protein-coupled and the beta-arrestin pathways.
Summary: BSA-Ang II and Ang II stimulated water appetite equivalently but BSA-Ang II stimulated saline appetite more than Ang II. Both BSA-Ang II and Ang II were considerably more potent at causing calcium mobilization than β-arrestin binding.
Dose: Angiotensin II (Ang II) was conjugated with bovine serum albumin and compared with Ang II for competition binding to AT1 receptors, to stimulate aldosterone release from adrenocortical cells, to promote beta-arrestin binding to AT1 receptors, to promote calcium mobilization, and stimulate drinking of water and saline by rats.
Porter D, Moore A, Goodman R, Hileman S, Coolen L, Lehman M. SAT-421 Cell-Specific Ablation of GnRH Neurons Using Kisspeptin-Saporin in the Preoptic Area of Sheep, but Not Mice. (2019) J Endocrine Society, 3(1):April-May 2019, SAT–421. doi: 10.1210/js.2019-SAT-421
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.
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.
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.
Light-controlled endosomal escape of the novel CD133-targeting immunotoxin AC133-saporin by photochemical internalization – a minimally invasive cancer stem cell-targeting strategy. Bostad M, Olsen CE, Peng Q, Berg K, Hogset A, & Selbo PK. (2015). J Control Release, 206.
Summary: After only one systemic injection of AC133–Saporin and TPCS2a, a strong anti-tumor response was observed.
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.
Bacterial and plant toxins rely on various trafficking pathways to reach intracellular targets. Shiga and Shiga-like toxins have been found to be moved via vesicular transport through several subcellular structures on the way to the cytosol. Shiga toxin (STx) is the cause of hemolytic uremic syndrome, for which there is no effective treatment. In order to better understand the mechanisms of STx membrane translocation the authors used a custom conjugate of the receptor-binding B-subunit of STx (STxB) and saporin (Custom conjugation provided by Advanced Targeting Systems). In vitro assays demonstrated that STxB-SAP did not use retrograde transport to the Golgi complex in order to reach the cytosol. This information has relevance to antigen cross-presentation of antigen-presenting cells.