An Introduction to Antibody-Drug-Conjugate Cancer Treatments

​The term "antibody-drug-conjugate" (ADCs) refers to a combination of chemotherapy and targeted therapy that medical professionals use to treat certain types of blood cancer and related malignant tumors. Cancer specialists do not typically begin treatment strategies based on ADCs; rather, they reserve the approach for recurrent cases of cancer, in situations when cancer begins to spread throughout the body, or when initial treatments prove ineffective.

A common form of cancer treatment, chemotherapy, involves the use of drugs to destroy cancer cells and prevent further tumor growth. Oncologists usually administer chemotherapy intravenously, but may opt for oral, topical, or injectable drugs. Targeted therapy, meanwhile, destroys cancer cells by honing in on the genetic mutations that occur when healthy cells become cancerous. By keying in on these changes, medical professionals can destroy cancer cells without harming the surrounding healthy cells.

As a combination of these two popular cancer treatments, ADC treatment consists of tracking cellular changes and then delivering a concentrated dose of chemotherapy drugs directly into the cells. ADCs cannot cure cancer, but research shows that ADC treatments can extend the lives of people living with the disease.

ADCs typically consist of three key components. The monoclonal antibody is an antibody created in a lab. Medical scientists create these antibodies specifically to attach to proteins and other molecules only associated with cancer cells, also known as tumor antigens. Antibodies and antigens essentially function as keys and locks, fitting perfectly together.

As the first step of ADC treatment, monoclonal antibodies open the door for chemotherapy drugs. Chemotherapy drugs come in many forms, which, like antibodies, oncologists tailor to a patient's specific cancer. Various tests demonstrate how each specific chemotherapy drug performs against different kinds of cancer.

Finally, ADCs rely on a special protein referred to as a "linker" protein, which provides two important functions during treatment. First, the linker protein binds the monoclonal antibody to the chemotherapy drugs as the treatment enters the tumor. Second, the protein times the release of the chemotherapy drug for the exact moment the drug enters the cancerous cell.

As mentioned, oncologists generally use ADCs to combat a wide range of blood-based cancers. In addition to Hodgkin lymphoma and multiple myeloma, ADCs can prove effective against acute lymphoblastic leukemia, acute myeloid leukemia, and anaplastic large cell lymphoma, among other blood cancers. Oncologists also implement ADCs against an array of cancerous tumors, ranging from cervical cancer tumors to tumors resulting from both triple-negative and HER2-positive breast cancer. Oncologists have also successfully curbed the growth of tumors associated with lung cancer, ovarian cancer, and urothelial cancer.

In the past, oncologists have not explored the possibilities of ADC treatments. In recent years, ADCs have become more common as a strategy for combating resistant and recurring cancers. A few commonly used ADCs include brentuximab vedotin (Adcetris), the first ADC to gain approval from the United States Food and Drug Administration. Oncologists use Adcetris against recurrent Hodgkin lymphoma and anaplastic large cell lymphoma, along with other blood cancers.

Trastuzumab emtansine (Kadcyla), meanwhile, is an increasingly popular choice for metastatic HER2-positive breast cancer. When medical professionals cannot pursue surgery as a treatment option for triple-negative breast cancer, or when the cancer begins to spread rapidly, oncologists may use sacituzumab govitean (Trodelvy), which has also proved effective against metastatic urothelial cancer.

Jason Sheasby

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