Targeted Therapy (NCI, 2021)
Targeted therapies are substances developed to inhibit cancer by impeding certain molecules (“targets”) that help cancer grow and spread. Also known as “molecularly targeted drugs,” “molecularly targeted therapies,” and “precision medicine,” these drugs differ from chemotherapy in that they attack specific molecules or proteins while chemotherapies affect both rapidly dividing normal and cancer cells. The treatments are either small-molecule drugs or monoclonal antibodies (therapeutic antibodies) that work using a variety of mechanisms:
- Help the immune system destroy cancer cells
- Impede chemical signals that cause cancer cell growth
- Prevent the formation of new blood vessels that supply cancer cells
- Deliver toxic substances to kill cancer cells
- Alter proteins in cancer cells resulting in cell death
- Starve cancer of the hormones it needs to grow
Targeted treatments include hormone therapies, immunotherapies, signal transduction inhibitors, gene expression modulators, apoptosis inducers, angiogenesis inhibitors, and toxin molecules.
Biomarker Testing for Cancer Treatment (National Cancer Institute, 2021)
Biomarker testing helps clinicians determine what types of cancer treatments may be most effective, particularly in certain types of cancer such as non-small cell lung cancer, breast cancer, and colorectal cancer. Biomarker testing assesses for genes, proteins, and other substances within the tumor or blood that might be susceptible to specific therapies. Some cancer treatments, including targeted therapies and immunotherapies, may only work for people whose cancers have certain biomarkers. Biomarker testing is also known as tumor testing, tumor genetic testing, genomic testing or genomic profiling, molecular testing or molecular profiling, somatic testing, or tumor subtyping.
Hormone Therapy (NCI, 2021)
Hormone therapy is used primarily to treat cancers that depend on hormones to grow, such as prostate, breast, ovarian, and uterine cancers. Hormone therapy can be administered orally or by injection (subcutaneous or intramuscular) and may involve surgery to remove hormone-producing organs (i.e., ovaries in women or testicles in men).
There are two types of hormone therapy:
- Block hormone production
- Interfere with hormone effects
Like chemotherapy, hormone therapy is also often used in combination with other therapies as neoadjuvant treatment (to shrink tumors before surgery or radiation) or adjuvant treatment (to kill cancer cells that were not removed with surgery or radiation); and can also be used to treat cancer that returns or spreads to other parts of the body.
Common side effects of hormone therapy include hot flashes, loss of interest or inability to have intercourse, nausea, diarrhea, fatigue, and mood changes.
Immunotherapy (American Cancer Society, 2019c; NCI, 2021)
Immunotherapy employs an individual’s immune system to fight cancer either by stimulating the immune cells to work more effectively against cancer cells or by providing synthetic proteins that support the immune system. Also known as biologic therapy or biotherapy, these medications are administered by IV, oral, topical or intravesical (directly into the bladder) routes.
Types of immunotherapy include:
- Checkpoint inhibitors – allow the T cells (white blood cells) to kill cancer cells; prevent cancer cells from avoiding the immune system
- Adoptive cell transfer – improve the natural ability of T cells to fight cancer by growing T cells from the tumor itself
- Cancer-specific vaccines – boost the immune system’s response to cancer cells
Signal Transduction Inhibitors (NCI, 2021)
Signal transduction inhibitors impede molecules that help cells react to signals from the environment. Cancer cells are stimulated to divide unceasingly without signals from external growth factors. Signal transduction inhibitors prevent this inappropriate signaling.
Gene Expression Modulators (NCI, 2021)
Cancer may develop from a gene that does not normally express in a cell; rather it mutates causing uncontrolled cell growth. Gene expression modulators change the way proteins participate in gene expression.
Apoptosis Inducers
Apoptosis is a process the body uses to get rid of nonessential or abnormal cells through programmed cell death. Some cancer cells can evade this mechanism. Apoptosis inducers provoke cancer cells to self-destruct.
Angiogenesis Inhibitors
Angiogenesis inhibitors target molecules that stimulate new blood vessel formation to tumors thus preventing further growth.
Monoclonal Antibodies
Monoclonal antibodies, created in the lab, deliver toxic substances (radioactive or poisonous chemical) causing cancer cell death. The toxin will not impact normal cells (cells lacking the antibody target).
Stem Cell Transplant (American Cancer Society, 2020)
Stem cell transplants (peripheral blood, bone marrow, and cord blood transplants) are used to treat patients with leukemia, lymphoma, neuroblastoma and multiple myeloma. This therapy replaces the stem cell components (white blood cells, red blood cells, platelets) within the bone marrow that may have been destroyed by cancer, chemotherapy and radiation.
Transplants can be:
- Autologous – stem cells are donated by the patient
- Allogeneic – stem cells are donated from another person
- Syngeneic – stem cells come from an identical twin
In most cases, stem cell transplants do not fight cancer but instead help the body recover from the effects of chemotherapy and radiation. In some cases, allogeneic stem cell transplants may have a graft-versus-tumor effect causing white blood cells from the donor to attack cancer cells. However, allogeneic transplants may also cause graft-versus-host disease in which white blood cells from the donor attack the recipient’s normal cells. This may damage the skin, liver, intestines and other organs. Graft-versus-host disease can be treated with steroids or other immunosuppressant drugs. Additional side effects include bleeding and increased risk of infection.