How it is administered

Cladribine is most commonly administered as an intravenous (IV) infusion. For blood cancers, such as Hairy Cell Leukemia, it is typically given as a continuous infusion over 7 consecutive days at a dose of 0.09 mg/kg/day. The medication is diluted in a saline solution and infused through a vein, either in a hospital or clinic setting.

There is also an oral tablet form of cladribine, but this is primarily used for multiple sclerosis and not for blood cancers.

How it works

Cladribine is a type of chemotherapy known as a purine nucleoside analog. It works by interfering with the growth and survival of certain white blood cells, particularly lymphocytes and monocytes, which are involved in many blood cancers.

Once inside the cell, cladribine is converted into an active form that gets incorporated into the cell's DNA. This damages the DNA and prevents the cell from repairing itself or dividing properly. As a result, both actively dividing and resting (quiescent) cancerous lymphocytes are destroyed. This unique action makes cladribine effective against blood cancers where abnormal lymphocytes are present, such as in Hairy Cell Leukemia and, in some cases, other rare leukemias like T-Cell Prolymphocytic Leukemia.

By reducing the number of abnormal blood cells, cladribine helps restore normal blood cell production and improves symptoms related to the disease.

Who Should take it

Cladribine is FDA-approved for the treatment of active Hairy Cell Leukemia, a rare type of blood cancer. It may also be used off-label for other blood cancers, such as T-Cell Prolymphocytic Leukemia, especially when other treatments have not worked or are not suitable.

Patients who have significant symptoms from their blood cancer—such as anemia, low white blood cell counts, low platelets, or disease-related symptoms—may be considered for cladribine therapy. The decision to use cladribine should be made by a doctor experienced in treating blood cancers, who will consider the patient’s overall health, type of leukemia, and previous treatments.

Who should not take it

Cladribine should not be used in patients who are allergic to cladribine or any of its components. It is also not recommended for people with active, severe infections, or those who are significantly immunocompromised, as it can further suppress the immune system.

Pregnant women should not take cladribine, as it can harm the developing baby. Women and men of reproductive potential should use effective contraception during treatment and for at least 6 months after the last dose. Cladribine is also not recommended for breastfeeding mothers, as it is unknown if it passes into breast milk and may cause harm to the baby.

Commonly used with

Cladribine is often used as a single-agent therapy for blood cancers like Hairy Cell Leukemia. In some cases, it may be used with other supportive treatments, such as antibiotics to prevent or treat infections, blood transfusions for anemia or low platelets, and medications to manage side effects (like anti-nausea drugs).

It is not commonly combined with other chemotherapy drugs at the same time due to the risk of increased toxicity, but your doctor may consider other treatments before or after cladribine depending on your response.

Commonly tested with

Cladribine has been tested in combination with other chemotherapy agents in clinical trials, especially in the context of bone marrow transplant conditioning regimens (with drugs like cyclophosphamide and total body irradiation).

It has also been studied in patients who have previously received other treatments, such as interferon or deoxycoformycin. In these cases, cladribine may be considered when other therapies have not worked.