A new class of drugs, antibody-drug conjugates (ADCs), combines the specificity of targeted therapy with the cytotoxicity of chemotherapy for a powerhouse effect against certain types of cancer variants. Here’s what you need to know about this novel treatment modality.
What Are ADCs?
The U.S. Food and Drug Administration has approved seven ADCs as of June 2020, and at least 70 more are currently in clinical trials:
- Ado-trastuzumab emtansine
- Brentuximab vedotin
- Enfortumab vedotin
- Fam-trastuzumab deruxtecan-nxki
- Gemtuzumab ozogamicin
- Inotuzumab ozogamicin
- Polatuzumab vedotin-piiq
The drugs chemically link tumor-targeting monoclonal antibodies (mAbs) to chemotherapies. They are targeted directly to the cancer and begin their cytotoxic effects when they reach the tumor site, sparing healthy tissue, reducing the extent of adverse events, and combatting multidrug treatment resistance.
Action and Adverse Effects
Drug delivery to the tumor is a three-step process: First, the antibody binds to antigen or receptors on the cancer cell. Then, the entire ADC is absorbed into the cell and the link between the antibody and chemotherapy degrades. Finally, the now-active chemotherapy agent goes to work against the cancer.
The mAb is the biggest part of the ADC package, so the treatment shares many of mAbs’ considerations, including a low volume of distribution, slow clearance, and a long half-life. In contrast, most of the side effects stem from the chemotherapy agent and vary depending on the specific drug used. The more commonly seen adverse events are peripheral neuropathy, neutropenia, thrombocytopenia, elevated liver enzymes, infusion reactions, or transient shortness of breath. Immunologic rejection can also occur.
Oncology nurses should assess for and manage adverse events and monitor patients for infusion reactions during treatment. Premedication with a corticosteroid, antihistamine, and acetaminophen is recommended one hour prior to ADC infusion. Signs or symptoms of anaphylaxis, including severe respiratory symptoms or clinically significant hypotension, indicate a need to discontinue treatment. Drug-drug interactions are also possible and vary depending on the agent. Refer to the package insert for each treatment.
Patient education should include signs and symptoms to watch for, how to report them, and any specific considerations to the ADC each patient is receiving. Refer to the package insert for the agent for a full overview of patient education considerations.