An Extracellular Drug Conjugate (EDC) is comprised of three parts: an antibody, a drug and a linker that connects them. This is similar to the Antibody Drug Conjugate (ADC) system, except with the EDC system the drug and antibody remain extracellular (outside of the cell) and are permanently linked.  EDCs do not require cell internalization or release of the drug from the antibody. These characteristics allow EDCs to avoid the disadvantages of the ADC system, while also making them safer, higher-potency and more precise medicines. 

In the EDC system, the antibody and drug, while linked, bind to their respective cell surface targets at the same time and in synergy.  The incredible precision of the EDC system arises from the requirement that both targets (antibody target and drug target) must be present and in close proximity for the EDC to act. Centrose can now show that this close proximity is only present on the surface of rapidly-growing diseased cells like cancer cells. After EDC binding, the drug sends signals into the cell, inducing strong programmed cell death responses. Since the EDC acts outside of the membrane, internalization and degradation are not required. In fact, degradation leads to drug neutralization, a major safety mechanism that prevents off-target side effects.