How it is administered

Alemtuzumab is administered as an intravenous (IV) infusion. It is supplied as a clear, colorless solution in single-dose vials for IV use only. The medication is not given as a rapid IV push or bolus, but rather infused over a period of 2 hours (for blood cancer indications). The dose is gradually escalated to reduce the risk of infusion-related reactions. The typical regimen for blood cancer (B-cell chronic lymphocytic leukemia, B-CLL) is 30 mg/day, three times per week for up to 12 weeks, following a dose-escalation schedule.

Premedication with an oral antihistamine and acetaminophen is recommended before each infusion to help prevent infusion reactions. The medication must be diluted in saline or dextrose solution before administration.

How it works

Alemtuzumab is a type of targeted therapy called a monoclonal antibody. It works by binding to a protein called CD52, which is found on the surface of certain white blood cells, including B and T lymphocytes, most monocytes, macrophages, natural killer (NK) cells, and some granulocytes. Many leukemic (cancerous) cells in blood cancers such as B-CLL express CD52.

When alemtuzumab binds to CD52 on these cells, it triggers the immune system to destroy them through a process called antibody-dependent cellular-mediated lysis. This means the body’s own immune cells are recruited to attack and kill the targeted cancer cells. Alemtuzumab can also cause complement-mediated lysis, another immune process that destroys cells. By reducing the number of abnormal white blood cells, alemtuzumab helps control the progression of blood cancers like B-CLL.

Because CD52 is also present on normal immune cells, alemtuzumab can cause significant suppression of the immune system, leading to increased risk of infections and other complications.

Who Should take it

Alemtuzumab is indicated as a single agent for the treatment of B-cell chronic lymphocytic leukemia (B-CLL). It is generally used in patients who have not responded to other therapies or whose disease has progressed. The medication may be used in both previously untreated and previously treated B-CLL patients.

Patients who are candidates for alemtuzumab typically have evidence of progressive disease and require therapy to control their leukemia. It is important that patients are monitored closely during treatment, especially for blood counts and signs of infection, due to the risk of immunosuppression and cytopenias (low blood cell counts).

Who should not take it

There are no absolute contraindications listed for alemtuzumab in the treatment of B-CLL. However, it should not be used in patients with active, serious infections due to the risk of worsening immunosuppression. Caution should be exercised in patients with a history of autoimmune cytopenias, as alemtuzumab can cause or worsen these conditions.

Patients should not receive live viral vaccines during or shortly after alemtuzumab therapy, as their immune system will be suppressed and unable to respond appropriately. Women who are pregnant or breastfeeding should avoid alemtuzumab, as it may harm the fetus or infant. Patients with known hypersensitivity to alemtuzumab or any of its components should not receive the medication.

Commonly used with

Alemtuzumab is often used as a single agent in the treatment of B-CLL. However, supportive medications are commonly given alongside it to manage side effects and prevent infections. These include:

• Antihistamines and acetaminophen (to prevent infusion reactions)
• Prophylactic antibiotics (such as trimethoprim/sulfamethoxazole for Pneumocystis jirovecii pneumonia)
• Antiviral medications (such as famciclovir for herpes virus prevention)

These supportive medications are continued for at least 2 months after the last dose or until the immune system recovers.

Commonly tested with

In clinical studies, alemtuzumab has been compared to other chemotherapy agents such as chlorambucil in B-CLL. It is not typically combined with other chemotherapy agents in standard practice for B-CLL, but patients may have received prior therapies such as alkylating agents or fludarabine before starting alemtuzumab.

During treatment, patients are routinely tested with complete blood counts (CBC), CD4+ lymphocyte counts, and infection surveillance (such as CMV PCR testing) to monitor for side effects and complications.