Ag-Tregs consist of antigen-specific Type 1 Treg cells, which are primed to specifically recognize an antigen that is present at the target site of inflammation.
The antigen specificity comes from the natural T cell receptor (TCR) as shown below.
The role of the chosen antigen is to trigger Ag-Treg activation locally in the inflamed tissue resulting in local immunosuppression. In this context, the chosen antigen is not necessarily associated with the pathological condition to treat.
The TxCell proprietary manufacturing process uses a single peripheral blood sample from a patient. The patient’s purified blood cells are educated ex-vivo to specifically recognize a chosen antigen. Ag-Tregs are mass produced and multiple doses covering several years of treatment are stored frozen. The product is administered to the patient by i.v. injection. The process is schematically outlined below.
In 2016, TxCell identified a new isolation method for its non-engineered Treg cells. This innovative procedure should enable a reduction of approximately 50% of both the production costs and the overall manufacturing leadtime, as well as a reduction of the risk of non-compliant manufacturing for future clinical trials and a potential commercial launch.
Combining these encouraging preliminary results and TxCell’s strict cost control policy, TxCell has decided to finalize and GMP-prove this new manufacturing process prior to the initiation of new clinical trials from the ASTrIA platform. Resulting from this decision, the clinical development of Ovasave® in refractory Crohn’s disease will not restart immediately.
When the patient’s own Ag-Treg cells are re-injected, they home to the site of inflammation where they are activated by the specific antigen.
The Ag-Tregs then act by release locally of immune suppressive factors, cell-cell contacts and cytotoxic activity to treat the inflammation.