What are cytokines?

Cancers treated:
Renal cell carcinoma, melanoma, lymphoma, Kaposi sarcoma, chronic myelogenous leukemia, hairy cell leukemia

Delivery route: Subcutaneous or intravenous (IV) injection

How these agents work: Cytokines are unique in that they bind to individual cell receptors. They can regulate several parts of the immune system by stimulating the production of cellular molecules that can attach themselves to the surface of tumor cells, where they have an antitumor effect. Other cytokines suppress the activity of cells and thus inhibit their action.

Cytokines have more than one mechanism of action, and many aspects of their cellular signaling are being actively researched. They are being investigated for their ability to kill tumor cells and for their potential to act as vaccines or adjuvant stimulants against the development of cancer cells by presensitizing the immune system to kill cancer cells if they develop.

Immunotherapy is still being aggressively studied for mechanisms of action, stimulation, and suppression, and it is believed that it will work in conjunction with other therapies rather than alone. The attractiveness of immunotherapy is the specificity of attacking only cancer cells and not harming normal cells, finding small numbers of cancer cells not identified though other treatment modalities, and using the existing immune system to treat cancer.

The main types of cytokines used to treat cancer are interferons and interleukins. Interferon alfa (IFN-alfa), which enhances immune response to cancerous cells and may also inhibit their growth or survival, has been approved by the US Food and Drug Administration (FDA) for treatment of melanoma, Kaposi sarcoma, hairy cell leukemia, and lymphoma. Interleukin 2 (IL-2), also known as T-cell growth factor, promotes the production of white blood cells and certain antibodies; the synthetic version, known as aldesleukin, has been approved to treat metastatic kidney cancer and metastatic melanoma. In addition, certain hematopoietic growth factors, including erythropoietin, interleukin 11, and granulocyte colony-stimulating factor, are sometimes used to alleviate side effects of some chemotherapies.

Side effects: Common side effects of cytokine treatment include nausea and vomiting, acute toxicity, capillary leak syndrome, low blood pressure, high cardiac output, liver toxicity, renal toxicity, pulmonary edema, fever, chills, gastric acidity, and infection. Most of the toxic side effects can be reversed. Fever and chills are treated with acetaminophen, and antibiotics are used for infection. Cytokine storm is a syndrome that can occur with the overstimulation of cytokines and can result in severe adverse effects, including death.

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