Interleukin-2 (IL-2), also known as aldesleukin or PROLEUKIN®, is a naturally occurring protein that serves as a cytokine within the immune system. Cytokines are signaling molecules that help regulate immune responses. While the term “chemo” often refers to traditional chemotherapy, which directly kills cancer cells, IL-2 operates differently. IL-2 is a form of immunotherapy, a biological therapy that leverages the body’s own immune system to fight cancer.
How IL-2 Fights Cancer
IL-2 works by stimulating and enhancing the activity of specific immune cells to recognize and destroy cancer cells. It primarily acts on T-lymphocytes, particularly cytotoxic T-cells, and natural killer (NK) cells. These specialized white blood cells identify and eliminate abnormal cells, including cancerous ones.
Upon administration, IL-2 promotes the proliferation and differentiation of these effector T cells, expanding their numbers to mount a stronger anti-tumor response. It also enhances the cytotoxic activity of NK cells, making them more effective at killing cancer cells without requiring prior sensitization.
Cancers Treated with IL-2
IL-2 has received approval for treating specific types of advanced cancers. It is commonly used for metastatic melanoma, a severe form of skin cancer that has spread to other parts of the body. Additionally, it is an established treatment for metastatic renal cell carcinoma, a type of kidney cancer that has spread beyond the kidney.
The effectiveness of IL-2 in these cancers stems from its ability to stimulate a systemic immune response. High-dose IL-2 therapy has demonstrated the potential to induce durable complete responses in a small percentage of patients with these advanced malignancies, with some remaining disease-free for years.
IL-2 Therapy in Practice
Receiving IL-2 therapy involves specific administration methods and monitoring protocols. It is administered intravenously through infusion. High-dose regimens require inpatient hospitalization, as patients need close monitoring by a specialized healthcare team.
A common high-dose schedule involves administering the drug three times per day for five days, followed by a rest period of seven to ten days, and then another five days of treatment. Low-dose regimens may also be given via subcutaneous injection, which can sometimes be managed in an outpatient setting. Throughout treatment, patients undergo continuous monitoring for potential side effects and overall response to the therapy.
Managing Side Effects
IL-2 therapy can lead to various side effects, which arise from the widespread activation of the immune system. Common side effects resemble flu-like symptoms, including fever, chills, weakness, muscle aches, and fatigue. These symptoms appear within hours to days after an infusion and may be managed with supportive medications like acetaminophen.
A more serious, though reversible, side effect is capillary leak syndrome. This condition involves fluid leaking from blood vessels, which can cause sudden drops in blood pressure, swelling in the limbs, and organ dysfunction affecting the kidneys or liver. Healthcare professionals closely monitor patients for these changes, and management involves supportive care, such as fluid management and medications to stabilize blood pressure. Other possible side effects include nausea, vomiting, diarrhea, skin rash, and changes in heart rhythm.