C-terminal linker of Fc: ADAPTIR-FLEX

ADAPTIR-FLEX platform technologies can be used to produce monospecific, bispecific, and multispecific immunotherapeutic proteins. These protein candidates bind to one or more targets found on tumor cells, immune cells, or other cells in the body or circulation to either amplify, suppress, or regulate the body’s defense mechanisms to treat cancer and autoimmune diseases. ADAPTIR-FLEX molecules are composed of two different polypeptides that form a dimer through modifying specific sequences in the Fc region of each polypeptide. Each end of the polypeptide may contain one or two different binding domains, enabling the ADAPTIR-FLEX molecules to bind up to four targets. In addition, the ADAPTIR-FLEX platform can be used to modify the valency of binding to each target, which means it can bind a target, through one binding domain or through multiple binding domains, to a specific target to enable modifying the strength of binding to a specific target.

Figure 1. A schematic illustration of the ADAPTIR-FLEX format. (Adopted from: https://www.annualreports.com/HostedData/AnnualReports/PDF/NASDAQ_APVO_2020.pdf)

Formats of bispecific antibodies (BsAbs)

Many formats have been developed for BsAb generation as listed in the following table.