How it is administered

Alemtuzumab is administered as an intravenous (IV) infusion. It is available as a sterile, clear, colorless solution in single-dose vials for IV use only. The medication should be infused over 2 hours (for blood cancers) or 4 hours (for multiple sclerosis), and not given as a rapid IV push or bolus. The dose is gradually escalated to a maximum of 30 mg per infusion, three times per week for up to 12 weeks in blood cancer treatment. Premedication with an antihistamine and acetaminophen is recommended before each dose to reduce infusion-related reactions.

How it works

Alemtuzumab is a monoclonal antibody that targets CD52, a protein found on the surface of B and T lymphocytes, as well as on most monocytes, macrophages, natural killer (NK) cells, and some granulocytes. By binding to CD52, alemtuzumab marks these cells for destruction by the immune system through processes called antibody-dependent cellular cytolysis and complement-mediated lysis. This action leads to a significant reduction in the number of circulating lymphocytes, which is beneficial in treating certain blood cancers, such as B-cell chronic lymphocytic leukemia (B-CLL), and may be considered in rare T-cell leukemias like T-Cell Prolymphocytic Leukemia (T-PLL) when other treatments are not effective.

The depletion of these immune cells helps control the abnormal growth of cancerous lymphocytes. However, this also results in immunosuppression, which increases the risk of infections and other immune-related complications. The effects on lymphocyte counts can be long-lasting, and immune recovery may take several months to over a year after treatment.

Who Should take it

Alemtuzumab is FDA-approved as a single agent for the treatment of B-cell chronic lymphocytic leukemia (B-CLL). In clinical practice, it may also be considered for certain other blood cancers, such as T-Cell Prolymphocytic Leukemia (T-PLL), especially when standard therapies have failed or are not suitable. It is typically used in adults who need treatment for progressive disease and have not responded adequately to other therapies.

Patients should undergo thorough evaluation before starting alemtuzumab, including blood counts and infection screening. The medication is generally reserved for patients who are able to tolerate its side effects and who do not have active, uncontrolled infections.

Who should not take it

Alemtuzumab should not be used in patients with known hypersensitivity to alemtuzumab or any of its components. It is contraindicated in patients with active infections, including HIV infection, due to the risk of prolonged and severe immunosuppression. Patients with severe, uncontrolled infections or those who are unable to comply with the required monitoring should not receive this medication.

It is not recommended for use in pediatric patients, as safety and effectiveness have not been established in children. Caution is also advised in pregnant or breastfeeding women, as alemtuzumab may cause harm to the fetus or infant. Patients with a history of autoimmune cytopenias or bone marrow aplasia should not be re-treated with alemtuzumab.

Commonly used with

Alemtuzumab is often used as a single agent in the treatment of blood cancers. However, it is standard practice to use premedications such as antihistamines (e.g., diphenhydramine) and acetaminophen to reduce the risk of infusion reactions. Prophylactic antibiotics (such as trimethoprim/sulfamethoxazole for Pneumocystis jirovecii pneumonia) and antiviral agents (such as famciclovir for herpes virus) are recommended during and after treatment to prevent infections.

In some cases, supportive medications like granulocyte colony-stimulating factors (G-CSF) may be used to help manage low white blood cell counts.

Commonly tested with

Alemtuzumab has been tested in combination with other chemotherapeutic agents, such as chlorambucil, in clinical trials for B-CLL. It has also been studied in patients previously treated with alkylating agents, fludarabine, or other chemotherapies. However, it is most commonly used as a single agent, especially in patients who have not responded to other treatments.

Routine monitoring with blood tests, including complete blood counts and CD4+ lymphocyte counts, is essential during and after treatment to assess for cytopenias and immune recovery.