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How it is administered
Ofatumumab is administered as an intravenous (IV) infusion. It is supplied as a clear, colorless liquid concentrate in single-use vials. The medication is diluted in saline and given through a vein, typically in a hospital or clinic setting where you can be closely monitored.
The dosing schedule depends on the specific treatment plan for chronic lymphocytic leukemia (CLL):
- For previously untreated CLL (with chlorambucil): 300 mg on Day 1, 1,000 mg on Day 8, then 1,000 mg on Day 1 of each 28-day cycle for at least 3 cycles (up to 12 cycles).
- For relapsed CLL (with fludarabine and cyclophosphamide): 300 mg on Day 1, 1,000 mg on Day 8, then 1,000 mg on Day 1 of each 28-day cycle for up to 6 cycles.
- For extended treatment: 300 mg on Day 1, 1,000 mg on Day 8, then 1,000 mg every 8 weeks for up to 2 years.
- For refractory CLL: 300 mg on Day 1, 2,000 mg weekly for 7 doses, then 2,000 mg every 4 weeks for 4 doses.
Premedication with acetaminophen, antihistamines, and corticosteroids is recommended before each infusion to help prevent reactions.
How it works
Ofatumumab is a monoclonal antibody that targets the CD20 molecule found on the surface of B-cells, including the cancerous B-cells in CLL. By binding to CD20, ofatumumab triggers the immune system to attack and destroy these cells.
The medication works through two main mechanisms:
- Complement-dependent cytotoxicity: Ofatumumab activates a part of the immune system called the complement system, which helps to break down and kill the targeted B-cells.
- Antibody-dependent cell-mediated cytotoxicity: The drug also helps recruit other immune cells to attack and destroy the B-cells.
By depleting abnormal B-cells, ofatumumab helps control the progression of CLL. The depletion of B-cells can last for months after treatment, and recovery of normal B-cell levels may take some time. This targeted approach helps reduce the number of cancerous cells in the blood and lymph nodes, improving symptoms and disease outcomes.
Common side effects
- Infusion reactions (such as chills, fever, rash, breathing problems, flushing, or low blood pressure), especially with the first two infusions
- Neutropenia (low white blood cell counts)
- Leukopenia (low total white blood cell counts)
- Febrile neutropenia (low white blood cells with fever)
- Anemia (low red blood cell counts)
- Thrombocytopenia (low platelets)
- Infections (including pneumonia, upper and lower respiratory tract infections, herpes simplex, and herpes zoster)
- Fatigue
- Cough
- Diarrhea
- Nausea
- Headache
- Rash
Serious side effects can include severe infusion reactions, infections, hepatitis B reactivation, progressive multifocal leukoencephalopathy (a rare brain infection), tumor lysis syndrome, and severe cytopenias (low blood counts).
Who Should take it
Ofatumumab is indicated for adults with chronic lymphocytic leukemia (CLL) in several situations:
- In combination with chlorambucil for patients who have not been treated before and for whom fludarabine-based therapy is not suitable.
- In combination with fludarabine and cyclophosphamide for patients with relapsed CLL.
- As extended treatment for patients who have achieved a complete or partial response after at least two lines of prior therapy for recurrent or progressive CLL.
- For patients whose CLL is refractory (not responding) to fludarabine and alemtuzumab.
Your doctor will determine if ofatumumab is appropriate based on your treatment history, current health, and specific characteristics of your CLL.
Who should not take it
Ofatumumab should not be used in patients who have had a severe allergic reaction (anaphylaxis) to ofatumumab or any of its ingredients.
Caution is also needed in patients with active infections, especially hepatitis B, as the medication can cause reactivation of hepatitis B virus, which can be life-threatening. All patients should be screened for hepatitis B before starting treatment. If you have a history of hepatitis B or are a carrier, your doctor will monitor you closely and may recommend antiviral therapy.
Live viral vaccines should not be given during or soon after treatment with ofatumumab, as your immune response may be weakened. Ofatumumab is not recommended for use in children, as safety and effectiveness have not been established in pediatric patients.
Commonly used with
Ofatumumab is often used in combination with other chemotherapy medications, depending on your treatment plan:
- Chlorambucil (for previously untreated CLL)
- Fludarabine and cyclophosphamide (for relapsed CLL)
Your doctor may also prescribe medications to help prevent infusion reactions (such as acetaminophen, antihistamines, and corticosteroids) and to prevent infections or manage side effects.
Commonly tested with
Ofatumumab has been tested in clinical trials in combination with:
- Chlorambucil (for first-line therapy)
- Fludarabine and cyclophosphamide (for relapsed CLL)
It has also been studied as a single agent for patients with refractory CLL and as extended treatment for patients who have responded to previous therapies. These combinations have been shown to improve outcomes in various stages of CLL.