Immunotherapy Screening – OX40:OX40L pathway

The treatment of diseases by inducing, enhancing, or surpressing an immune response is referred to as Immunotherapy. T-cell activation and inactivation requires the coordination of various co-inhibitory and co-stimulatory signals and most immunotherapies modulate these signals.

Therapeutic manipulation of immunopathways has lead to promising clinical results for the treatment of a number of diseases such as cancer, autoimmune diseases and inflammatory diseases. Research in this field is rapidly evolving as scientists seek to identify the next generation of therapies.

Over the past 12 months I have introduced a number of pathways and proteins involved, which represent potential targets for drug discovery campaigns and I’ve presented assays to measure inhibitor effects on these pathways (B7-1 / CD28 and B7-1 / CTLA4; PD-1/PD-L1/PD-L2; BLTA:HVEM, CD47:SIRPα; GITR:GITRL; CD40:CD40L; CD137:CD137L; IDO).

Ox40:Ox40L pathway

Receptor-ligand pathwayd involved in T-cell immunoregulation.

Fig. 1: T-cell immunoregulation.

Today I’ll be concentrating on OX40 (CD134) which is a co-stimulatory receptor not constitutively expressed on resting naïve T cells. It serves as a secondary co-stimulatory immune checkpoint molecule. OX40L, the ligand binding to OX40 is not expressed on resting antigen presenting cells as well, but is following their activation. Binding of OX40 to its ligand, OX40L (CD252), present on dendritic cells, modulates T cell activation and T cell effector function (Fig.1). Studies have shown that OX40 agonists can increase anti-tumor immunity and improve tumor-free survival in pre-clinical studies. Alternatively, OX40 antagonists offer potential as therapeutics for inflammatory diseases (for a review see 1). Recently, phase I studies have been conducted with an OX40 agonist (monoclonal anti Ox40 antibody) in patients with solid tumors with promising results (2).

OX40 : OX40L Screening tools

Fig. 2: Inhibition of OX40 [Biotinylated]: OX40L binding measured using the OX40 [Biotinylated]:OX40L Inhibitor Screening Assay Kit (cat. nr 14972045). 

Fig. 2: Inhibition of OX40 [Biotinylated]: OX40L binding measured using the OX40 [Biotinylated]:OX40L Inhibitor Screening Assay Kit (cat. nr 14972045).

As the OX40:OX40L pathway is a “hot topic” in drug discovery, BPS Bioscience have developed the OX40[Biotinylated]:OX40L Inhibitor Screening Assay Kit. The key to this kit is the high sensitivity of detection of biotin-labeled OX40 by streptavidin-HRP. Only a few simple steps on a microtiter plate are required for the assay. First, OX40L is coated on a 96-well plate. Next, OX40-biotin is incubated with OX40L on the plate. Finally, the plate is treated with streptavidin-HRP followed by addition of an HRP substrate to produce chemilumines-cence, which can then be measured using a chemiluminescence reader. Typical results of an experiment with this kit using unlabeled OX40 to block out the binding and measurement of OX40-biotin are shown in Fig. 2. For scientists who want to set up their own binding assay or conduct other functional studies we also offer rec. OX4o and OX40-biotin as well as OX40L.

If you would like more information about the OX4o:OX40L product line or any other Immunotherapy related kits and proteins, get in touch by leaving your questions or comments below.


  1. Linch S. N. et al., OX40 agonists and combination immunotherapy: putting the pedal to the metal, Frontiers in Oncology 5 (2015)
  2. Curti B. D. et al., OX40 is a potent immune stimulating target in late stage cancer patients, Cancer Res.  73 (24): 7189–7198 (2013)
Written by Ali El Baya, PhD
Ali el Bayâ is the Sales Manager at tebu-bio for the North of Europe.