Anti-CTLA4 (Ipilimumab biosimilar - IgG1 isotype)

Human IgG1 monoclonal antibody (mAb) against human CTLA4

Anti-hCTLA4-hIgG1 is the biosimilar of the clinical antibody ipilimumab. Anti-hCTLA4-hIgG1 features the constant region of the human IgG1 isotype and the variable region of ipilimumab. Ipilimumab is a fully human IgG1 monoclonal antibody that targets CTLA-4 (also known as CD152), a negative regulator of T cell activation.

By binding CTLA-4, ipilimumab inhibits negative signals that physiologically downregulate T cell activation and exerts its therapeutic activity by upregulating the antitumor activity of T lymphocytes [1, 2]. In addition, Ipilimumab induces antibody-dependent cell-mediated cytotoxicity (ADCC) and TNF-α production [3]. Ipilimumab has been approved by the FDA for the treatment of unresectable or metastatic melanoma. Ipilimumab is undergoing clinical trials for other types of cancers, including lung cancer [4]. Human IgG1 is the most abundant immunoglobin present in serum and binds with high affinity to the Fc receptor on phagocytic cells. The human IgG1 isotype displays high ADCC and complement-dependent cytotoxicity (CDC).

Anti-hCTLA4-hIgG1 was generated by recombinant DNA technology. It has been produced in  Chinese hamster ovary (CHO) cells and purified by affinity chromatography with protein G.  More isotypes of this antibody are available and can be used for comparison of biological activities such as ADCC (see below or in the 'upon request' section). 

References:

Grosso JF. & Jure-Kunkel MN., 2013. CTLA-4 blockade in tumor models: an overview of preclinical and translational research. Cancer Immun. 13:5.
Maio M. et al., 2013. Update on the role of ipilimumab in melanoma and first data on new combination therapies. Curr Opin Oncol. 25:166-72.
Laurent S.. et al., 2013. The engagement of CTLA-4 on primary melanoma cell lines induces antibody-dependent cellular cytotoxicity and TNF-α production. J Transl Med. 11:108.
Tomasini P., 2012. Ipilimumab: its potential in non-small cell lung cancer. Ther Adv Med Oncol. 4: 43–50.

Figures

Comparison of ADCC potency for native and engineered anti-human CTLA-4 antibody isotypes: Raji-hCTLA4 cells were incubated with gradient concentrations of Anti-hCTLA4 or Anti-β-galactosidase (β-gal) mAbs for 1 hour. Jurkat-Lucia™ NFAT-CD16 effector cells were then co-incubated with targets cells for 6 hours. NFAT activation, reflecting the induced ADCC response, was assessed by determining Lucia luciferase activity in the supernatant using QUANTI-Luc™. Percentages of the maximal response normalized to the IgG1 isotype are shown.

Specifications

Specificity: Targets cells expressing human CTLA-4

Clonality: Monoclonal antibody

Clone: Ipilimumab (Anti-hCTLA4-hIgG1, kappa)

Isotype: Human IgG1, kappa

Control: Human IgG1

Source: CHO cells

Formulation: 0.2 µm filtered solution in 68 mM sodium phosphate buffer (pH 7.4) with 91 mM glycine, 5% w/v saccharose, and stabilizing agents

Purity: Purified by affinity chromatography with protein G

Tested applications: Flow cytometry and ADCC

Quality control:

• Binding of Anti-hCTLA4-hIgG1 to human CTLA-4 has been tested using flow cytometry.
• The complete sequence of this antibody has been verified.
• The absence of bacterial contamination (e.g. lipoproteins and endotoxins) has been confirmed using HEK-Blue™ TLR2 and HEK-Blue™ TLR4 cells.

Contents

Anti-hCTLA4-hIgG1 purified monoclonal antibody is provided azide-free and lyophilized. It is available in two quantities:

• hctla4-mab1: 100 µg
• hctla4-mab1-1: 10 x 100 µg (1 mg)

 The product is shipped at room temperature.

Upon receipt, store at -20°C.

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