The naive question: chemotherapy poisons cancer cells, but it also poisons healthy ones, which is why it's so brutal. What if you could deliver the poison only to the tumor? That is exactly the idea behind an antibody-drug conjugate.
Think of it like a guided missile. The antibody is the guidance system — engineered to lock onto a marker found mostly on cancer cells. The payload is the warhead, a toxin far too dangerous to inject on its own. And the linker is the tether that holds the warhead to the missile until it reaches the target.
That three-part structure is why ADCs are hard to build and why the patents cluster the way they do. Pierre Fabre's grant US11661457B2 covers an IGF-1R antibody-drug conjugate for cancer — naming the specific antibody target and its payload. Seagen's US11617798B2 covers anti-CD228 antibodies and the conjugates built from them.
The linker is the quiet hero. If it releases the payload too early, the toxin leaks into the bloodstream and you're back to chemotherapy's problem. If it never releases, the drug does nothing. Seattle Genetics' US11795229B2 is even about methods of reducing the side effects of an ADC therapy — proof that controlling where and when the warhead goes off is a patentable problem in its own right.
Here's the 'so what.' An ADC is not one invention; it is a system, and every part — target antibody, payload, linker, and dosing — can be separately engineered and separately patented. That is why a single ADC can be wrapped in a thick stack of claims, and why the field is so litigious.
The short version: when you read that a company has a promising ADC, picture a guided missile, and remember that the antibody is only the guidance. The toxin and the tether are where much of the 2023 patent fight actually lives.