Antibody Drug Conjugates: How A New Drug Class Treats Cancer

Antibody drug conjugates (ADCs) are a type of targeted therapy. They deliver medicine directly to cancer cells. They are used to treat both blood cancers and solid tumors, with ongoing research expanding their role.

This article will help you understand what an ADC is, how it works to treat cancer, and what types of cancer can be treated with an ADC. 

How do ADCs Work

ADC’s recognize specific markers on the surface of cancer cells. They have three main parts:

• an antibody 
• a chemotherapy drug 
• and a linker  

Each part plays an important role. The antibody guides the treatment to the right place. The linker keeps the drug stable as it travels. Once the ADC enters the cancer cell, the linker binds to the target and releases the chemotherapy. This design allows ADCs to deliver treatment in a more targeted way. Some healthy cells may still be affected, but the goal is to limit how much of the drug reaches healthy cells. 

What makes ADCs different from traditional chemotherapy

ADCs work differently from traditional chemotherapy. Chemotherapy affects both cancer cells and healthy cells. This can lead to more side effects. 

ADCs are more targeted. They focus on cells with specific markers, which may reduce some of the impact on healthy tissue and result in fewer side effects. ADCs may be used along with other treatments, depending on the cancer type and response.

How are ADCs used to treat cancer?

ADCs are used to treat several blood cancers, including leukemia, lymphoma, and multiple myeloma. ADCs are also used to treat solid tumor cancers. Like with blood cancers, these therapies target specific markers found on tumor cells. By delivering medicine directly to cancer cells, ADCs can improve how treatment works. 

ADCs are often used when cancer has come back or has not responded to other treatments.  Sometimes they are used sooner, depending on the type of cancer and available treatment options. 

ADCs may be used alone or as part of a combination approach.  Treatment plans will be adjusted over time based on how the cancer responds. 

The FDA has approved the following ADCs

ADCs approved for leukemia

• Gemtuzumab ozogamicin (Mylotarg)
• Inotuzumab ozogamicin (Besponsa)
• Moxetumomab pasudotox (Lumoxiti)

ADCs approved for lymphoma

• Brentuximab vedotin (Adcetris)
• Polatuzumab vedotin (Polivy)
• Loncastuximab tesirine (Zynlota)

ADCs approved for multiple myeloma

• Belantamab mafodotin (Blenrep)

What makes someone a good candidate for an ADC

Choosing an ADC is a shared decision between you and your care team. Not everyone will be a good candidate for an ADC. In determining whether an ADC is the right treatment, your care team will consider:

• Specific markers on cancer cells
• The type of cancer
• How advanced the cancer is
• What treatments have already been tried 
• Overall health

What to expect during treatment

ADCs are usually given through an IV infusion, which is a tube placed into a vein. Treatment is given in cycles, with time between doses to allow the body to recover. Even though ADCs help spare healthy cells, they are not without side effects.  Some common side effects reported are: 

• Fatigue
• Nausea
• Low blood counts 
• Infection risk

Managing side effects during treatment

Not everyone experiences the same side effects. Many of these symptoms can be managed with supportive treatments or dosage adjustments of the ADCs. If you experience new or worsening symptoms, it is important to let your care team know right away.  You do not need to wait until symptoms become severe.  Keeping your care team informed helps them support you throughout treatment. 

Questions to ask your care team

Your care team will help you determine if an ADC is right for you.  You may want to ask your doctor questions to better understand how this type of treatment will affect your day-to-day life. 

Some questions you may want to ask are: 

• Whether the treatment will affect your ability to work, travel, or exercise 
• If there are any medications or supplements that could cause an adverse interaction 
• How much the treatment will cost and whether it is covered by your insurance 

The decision about which treatment is best is not one-size-fits-all. Some people may prioritize treatments that allow them to stay active or continue working. Others may focus on treatments with the strongest response

It is also helpful for people who can become pregnant to discuss with their doctor how this treatment could affect pregnancy and fertility. These conversations can help you plan ahead and feel more prepared for the next steps in treatment.  

Research and future directions for ADCs

Research on ADCs is expanding, and new therapies are being studied in clinical trials. These studies look at how safe treatments are and how well they work in different groups of patients. Researchers are studying how to improve each part of the drug, including stronger linkers and more precise antibodies. 

Some studies also collect real-world data, which comes from everyday care settings outside of clinical trials. This type of data helps researchers understand how treatments perform in real life.

People living with cancer can take part in real-world data research through simple surveys. Sharing your experience can help improve outcomes and guide future treatment development.

Sources: 

• https://pmc.ncbi.nlm.nih.gov/articles/PMC8628511/ 
• https://www.thermofisher.com/blog/behindthebench/antibody-drug-conjugates-101-smart-bombs-for-cancer-and-beyond/ 
• https://www.youtube.com/watch?v=HMP0gof25M0 
• https://pmc.ncbi.nlm.nih.gov/articles/PMC12044742/