How it is administered

Ofatumumab is administered as an intravenous (IV) infusion for blood cancer indications, specifically chronic lymphocytic leukemia (CLL). It is supplied as a clear, colorless liquid concentrate in single-use vials at a concentration of 20 mg/mL. The medication must be diluted and given through an IV line in a healthcare setting, where patients can be closely monitored for infusion reactions.

The dosing schedule and amount depend on the specific CLL indication (untreated, relapsed, refractory, or extended treatment). Pre-medication with acetaminophen, antihistamine, and corticosteroid is recommended before each infusion to reduce the risk of infusion reactions.

How it works

Ofatumumab is a monoclonal antibody that targets the CD20 protein found on the surface of B lymphocytes (a type of white blood cell involved in blood cancers like CLL). By binding to CD20, ofatumumab triggers the immune system to destroy these B cells through two main mechanisms: complement-dependent cytotoxicity and antibody-dependent cell-mediated cytotoxicity. This means it helps the body’s immune system recognize and eliminate the cancerous B cells.

The CD20 protein is not shed from the cell surface and is not internalized after antibody binding, making it a stable target. Ofatumumab’s action leads to a significant reduction in the number of B cells in the blood, which is associated with control of the leukemia. However, the exact relationship between B-cell depletion and clinical response can vary between patients.

Who Should take it

Ofatumumab is indicated for adults with chronic lymphocytic leukemia (CLL) in several situations:

• In combination with chlorambucil for previously untreated patients with CLL for whom fludarabine-based therapy is considered inappropriate (such as older adults or those with other health problems).
• In combination with fludarabine and cyclophosphamide for patients with relapsed CLL.
• As extended treatment for patients who are in complete or partial response after at least two lines of therapy for recurrent or progressive CLL.
• For patients with CLL that is refractory (not responding) to fludarabine and alemtuzumab.

Your doctor will determine if ofatumumab is suitable for you based on your treatment history, current health, and specific type of CLL.

Who should not take it

Ofatumumab should not be used in patients with a known hypersensitivity to the drug or any of its components. While there are no absolute contraindications listed, caution is necessary in patients with active infections, especially hepatitis B, as ofatumumab can cause reactivation of hepatitis B virus (HBV), which may lead to severe or fatal liver problems.

Patients with a history of severe infusion reactions or anaphylaxis to monoclonal antibodies should not receive ofatumumab. It is also not recommended to administer live viral vaccines during or after treatment with ofatumumab until B-cell recovery occurs. Pregnant women should be aware that ofatumumab may cause fetal B-cell depletion, and its safety in children has not been established.

Commonly used with

Ofatumumab is commonly used in combination with other chemotherapy agents for CLL, such as:

• Chlorambucil (for previously untreated patients)
• Fludarabine and cyclophosphamide (for relapsed patients)

It may also be used as a single agent for extended treatment in patients who have responded to prior therapies.

Commonly tested with

In clinical trials, ofatumumab has been tested with:

• Chlorambucil (for first-line treatment of CLL)
• Fludarabine and cyclophosphamide (for relapsed CLL)

It has also been studied as a single agent for patients with refractory CLL and for extended maintenance treatment after response to prior therapies.