Switch Designed Ankyrin Repeat Protein (Switch DARPin) (Switch DARPin)

Switch Designed Ankyrin Repeat Proteins (Switch DARPins) are a specialized class of engineered scaffold proteins designed to provide conditional therapeutic activity (Molecular Partners, 2023). Unlike standard DARPins, which are small, highly stable proteins that bind targets with high affinity (Plückthun, 2015), Switch DARPins are engineered to undergo conformational changes or affinity shifts in response to specific environmental triggers, such as the acidic pH of the tumor microenvironment or the presence of a specific small molecule (Binz et al., 2004). This switch mechanism is intended to restrict the drug's activity to the site of disease, thereby improving the therapeutic index by reducing systemic off-target effects and toxicity. Developed primarily by Molecular Partners, this technology is being applied to create multispecific oncology treatments, such as tumor-localized immune cell engagers and agonists like MP0317 (Molecular Partners, 2023). These molecules offer advantages over traditional antibodies, including smaller size, higher stability, and the ability to be easily formatted into complex, multi-domain architectures for multi-target engagement. While not a biological target itself, the Switch DARPin platform represents a significant advancement in precision medicine by allowing for the localized modulation of disease-relevant pathways.

Other names

Switchable DARPinConditionally active DARPinpH-sensitive DARPinConformational switch DARPin

Switch DARPins function as conditionally active therapeutics that bind to their biological targets only under specific environmental conditions, such as low pH or in the presence of a specific co-target (Molecular Partners, 2023). This is achieved through engineered conformational changes or masking domains that are released or activated by the trigger, allowing for localized action and reduced systemic toxicity (Plückthun, 2015).