CD markers in cancer diagnosis and treatment

CD markers, also known as CD antigens, are specific types of molecules found on the surface of cells that help distinguish one cell type from another. In fact, the initials “CD” stand for “differentiated clusters,” whose nomenclature was first established in 1982.

While some may be familiar with the terms CD4 and CD8 used to distinguish defensive immune cells called T cells, there are at least 371 known CD antigens that “mark” nearly every cell in the body, providing each own unique mark.

What CD Marks Tell Us

Among other things, CD markers are used to sort out the white blood cells that the body produces to help fight infection. These cells are core components of the immune system, working together to recognize, target and neutralize disease-causing pathogens. For example, CD4 T cells are called “helper cells” because their role is to signal “killer” CD8 T cells to attack and neutralize specific pathogens.

By understanding these dynamics, scientists can use CD markers not only to assess infection status (measured by increases or decreases in cell numbers), but also to measure the strength of the immune system itself.

Certain conditions, such as HIV and organ transplantation, are associated with immunosuppression, which means the body cannot build an immune defense, as evidenced by the absence of CD4 T cells. Before the introduction of CD nomenclature, assessing a person’s immune function was much more difficult and nonspecific.

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CD markers in cancer diagnosis and treatment

In addition to monitoring infection and immune status, CD antigens can be used to detect abnormal growth of cells called tumors. Tumors may be benign (noncancerous), malignant (cancerous), or precancerous, but like any other cell, they have CD markers that scientists can identify.

Not only are CD markers important in cancer diagnosis, but they can also help determine which types of treatments are likely to be most successful and measure the effectiveness of treatments by monitoring changes in relevant CD markers.

In addition, researchers were today able to create a defensive protein, called a monoclonal antibody (mAb), that matches a specific CD antigen. These cloned antibodies mimic those produced by the body and can be used to fight cancer in a form of treatment called targeted immunotherapy. When injected into the body, mAbs can function in unique ways depending on their design:

  • They may bind to CD markers on cancer cells and destroy them.
  • They may bind to CD markers on cancer cells and prevent their ability to replicate, stopping or slowing their growth.
  • They may enhance the body’s natural defenses against this cancer.
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In vitro, mAbs are commonly used diagnostically to detect specific CD antigens in blood, tissue or body fluid samples.

Targeted Immunotherapy for Cancer

Today, monoclonal antibodies are used to treat many different diseases, including some autoimmune diseases and certain types of cancer. Their effectiveness can vary, and some cancers respond better than others.

Another type of targeted immunotherapy is chimeric antigen receptor (CAR) T-cell therapy, a therapy that modifies a patient’s own T cells to help destroy cancer cells. In CAR T-cell therapy, immune cells are modified to fit the type of CD markers expressed by cancer cells, and then put back into the body to fight the cancer.

Advances in genetic technology have led to an increasing number of approved immunotherapy drugs. In contrast to older generations of chemotherapy, which target rapidly replicating cancer cells and healthy cells, these new-generation drugs target only those cells with a specific CD “signature.” Drugs currently approved by the U.S. Food and Drug Administration (FDA) for cancer immunotherapy include:

  • Adcetris (brentuximab vedotin) for the treatment of Hodgkin lymphoma and anaplastic large cell lymphoma
  • Arzerra (ofatumumab) for the treatment of small lymphocytic leukemia (SLL) and chronic lymphocytic leukemia (CLL)
  • Blincyto (blinatumomab) is used to treat certain types of acute lymphoblastic leukemia (ALL)
  • Breyanzi (lisocabtagene maraleucel) is used to treat certain types of large B-cell lymphoma
  • Campath (alemtuzumab) for the treatment of CLL
  • Carvykti (ciltacabtagene autoleucel) is used to treat certain types of multiple myeloma
  • Gazyva (obinutuzumab) for the treatment of SLL and CLL
  • Herceptin (trastuzumab) is used to treat certain breast and stomach cancers
  • Kadcyla (ado-trastuzumab emtansine) is used to treat certain types of breast cancer
  • Keytruda (pembrolizumab) for the treatment of certain head and neck cancers
  • Kymriah (tisagenlecleucel) is used to treat certain types of ALL and diffuse large B-cell lymphoma (DLBCL)
  • Ontak (denileukin diftitox) for the treatment of cutaneous lymphoma
  • Opdivo (nivolumab) for the treatment of metastatic lung cancer and certain head and neck cancers
  • Rituximab (rituximab) is used to treat certain types of non-Hodgkin lymphoma (NHL)
  • Zevalin (ibritumomab tiuxetan) is used to treat certain types of NHL
  • Yescarta (axicabtagene ciloleucel) is used to treat certain types of large B-cell lymphoma and follicular lymphoma (FL)