Understanding Antibody-Drug Conjugate (ADC) Medicines for Cancer

Christin Melton, ELS Disclosures Published on Jul 31, 2023

This article is for people who are living with cancer and their caregivers and anyone who wants to learn more about how ADC medicines are used to treat cancer. The goal of this education activity is to help you work with your doctor and healthcare team to decide if ADC medicines should be part of your treatment plan.

You will learn about:

What ADCs are and how they work
What types of cancers ADCs are used to treat
Talking to your doctor and your healthcare team about ADCs and your treatment plan
Questions to ask your doctor and your healthcare team

Medicines listed in this activity may not be approved by the US Food and Drug Administration (FDA) for cancer but are recommended by the National Comprehensive Cancer Network (NCCN).

Test Your Knowledge

What Is an Antibody-Drug Conjugate (ADC)?

An antibody-drug conjugate, or ADC, is a type of medicine used to treat many different cancers, including some blood cancers and solid tumor cancers of the cervix, ovary, bladder or urinary tract, breast, stomach, and lung. Depending on the ADC, it may be given alone or with another anti-cancer medicine.

ADCs for solid tumors are mainly used for advanced cancer or for cancer that has spread to other parts of your body (called metastatic cancer). ADCs don't usually cure cancer, but they may help you live longer or slow your cancer's growth.

Some ADCs require that you get a test of your blood or cancer tissue first to see if it could work for your cancer. Other ADCs don't require a test.

Parts of an ADC

An ADC has 3 main parts: an antibody, a payload, and a linker.

The antibody is known as a monoclonal antibody (a MAB). It's made to find a specific protein -- sometimes called the target protein -- that's much more common in cancer cells than in normal cells.

The payload is a cancer-killing medicine that the ADC delivers to your tumor. It's usually a cytotoxic medicine like chemotherapy. Cytotoxic means "toxic to cells."

The linker is a chemical that connects the MAB and its payload. The linker's job is to hold them together as the MAB directs the ADC to the cancer cells.

How an ADC Works

An ADC is infused into your vein through a needle. Once the ADC is in your bloodstream, its MAB begins searching for cells that have the target protein.

Most of your cancer cells have a lot of the target protein, which makes it easy for the MAB to find them. Some normal cells also have the target protein, but the amount is usually too low for the MAB to notice.

The MAB drives the ADC to the cancer cell and attaches to the target protein on the cell's surface. The cancer cell then brings the ADC inside. The cytotoxic payload is freed from the ADC and gets to work killing the cancer cell.

The Bystander Effect

Some ADCs have a bystander effect, which is when the ADC accidentally kills some cells that happen to be next to the targeted cancer cells. This happens if some of the cytotoxic payload escapes the target cancer cell or remains active after the cancer cell breaks apart and causes damage to nearby cells.

The bystander effect is good when it allows the ADC to kill cancer cells that the MAB couldn't find. It's not so good when it harms normal cells that are nearby.

Possible Side Effects of ADCs

All cancer medicines can damage some normal cells, which is often the main cause of side effects. ADCs damage normal cells if the linker drops the payload before the ADC gets inside the cancer cell, if the MAB attaches to a normal cell that has the target protein, or because of the bystander effect.

Possible side effects of each ADC depend on which MAB, linker, and payload it contains. The type of cancer you have, your age, other health issues you may have, and other medicines you take may also affect your risk of side effects during treatment with an ADC.

Mild or serious side effects can happen with every ADC. Before starting any treatment, it's important to ask your doctor and healthcare team about side effects that can happen and ways to help manage them.

Making a Treatment Plan

Your doctor and healthcare team will work with you to make a treatment plan. They can tell you more about how ADCs help fight cancer, their possible side effects and how they're managed, and any follow-up you'll need during treatment.

If more than one ADC can be used to treat your cancer, they can tell you about differences between the ADCs.

If you try an ADC and it doesn't work or you have side effects that can't be managed, or it stops working after a while, your doctor and healthcare team can work with you to change your treatment plan.