Before reading any further, you'll want to know how chemotherapyKEY-MOW-THAIR-AH-PEE — Medication used to treat cancer, targeted therapyTAR-GET-TED THAIR-AH-PEE — Anticancer medication that attaches to a specific protein receptor and blocks the receptor’s normal function to stop cancer growth, and immunotherapyEM-MUN-O-THAIR-AH-PEE — Anticancer medication that alters the function of immune cells, triggering the immune work. (If you need to brush up your knowledge, you can review them in more depth here: targeted therapy, chemotherapy, and immunotherapy.) We’ll be building upon these concepts. Antibody-drug conjugatesAN-TEE-BOD-EE DRUG CON-JOO-GET — Anticancer medication that attaches to a specific protein receptor and delivers chemotherapy directly to the cell; antibody linked to chemotherapy are a combination therapy!
As you should now know, chemotherapy is the most common form of cancer treatmentTREET-MINT — Techniques to help eliminate or control a disease used today. It’s great at quickly controlling cancer, but it can also cause more side effects than other types of treatments. This is because chemotherapy works by attacking the parts of a cellSEL — One of the most basic components of all living things that together form the entire body and contains many smaller parts that guide its function that are common to many different cells, including normal cells. Chemotherapy just isn’t selective about the cells it affects.
But what if this wasn’t always true?
What if we could give more targeted chemotherapy? What if we could "release" the chemotherapy only where it's needed, and not throughout the whole body?
This is the whole idea behind antibody-drug conjugates (ADCs)! ADCs are the combination of targeted therapy, chemotherapy, and sometimes immunotherapy (depending on what you’re targeting).
Sounds pretty cool, right? Let’s get into how this is even possible.
An antibody-drug conjugate is an antibody linked to chemotherapy. Natural antibodiesAN-TEE-BOD-EE — A protein that is produced to fight foreign invaders in the body in the body are proteinsPRO-TEEN — A naturally occurring, large, complex substance made up of amino acids that is an essential part of living organisms that your immune systemEM-MUNE SIS-TEM — A network of proteins and cells that work together to stop invaders from taking over the body and causing many problems makes to search and fight infections (like the common cold or the fluIN-FLEW-EN-ZAH — A viral infection that causes a fever and severe aching). Similarly, ADCs are “man-made” antibodies designed only to find and attack specific proteins.
The antibody is targeted at a specific receptorREE-SEP-TOR — A protein in or on a cell that may control some functions of the cell or protein that is more commonly found on cancer cells than normal cells. Once the antibody finds the targeted protein receptor, it’s able to attach or link to the cancer cell.
Now it’s time for the magic!
The cancer cell absorbs the antibody, and only then is the chemotherapy "released." The antibody delivers chemotherapy directly inside the cancer cell to kill or control it.1 Sounds like "localLOW-COAL — Nearby" chemotherapy, right?
Just like with targeted therapy, if you’re able to identify proteins unique to the cancer cells (or only found on a few other normal cells), side effects are reduced. Additionally, because the chemotherapy is only being applied to certain cells, a higher “dose” of the chemotherapy medication can be delivered, making it more effective at killing the cancer. Right drug, in the right place, at the right time!
Let’s think about this a little differently.
Imagine your gardener has special bees that can carry a super-effective weed killer and have been programmed to land only on the leaves of dandelions. Your gardener releases the bees, and off they go, hunting for dandelion leaves.
When a bee finds the right leaf, it lands and releases the weed killer. The plant absorbs the weed killer and is killed (or at least it reduces in size). Once the bee delivers the weed killer, the bee dies so it cannot cause any issues. This process repeats over and over again as more bees land throughout the yard, delivering the weed killer.
Fortunately, these bees are good at targeting dandelion leaves, so almost all of the other flowers in the yard remain untouched.
The gardener continues to release these bees on a schedule to keep the dandelions under control. The main drawback of this approach is that there are over 250 different dandelions species, but the gardener can only program the bees to find a few specific types of dandelions (targets).
- Okeley NM, Miyamoto JB, Zhang X, et al. Intracellular Activation of SGN-35, a Potent Anti-CD30 Antibody-Drug Conjugate. Clinical Cancer Research. 2010;16(3):888-897. doi:10.1158/1078-0432.ccr-09-2069.