How it is administered

Pentostatin is administered as an intravenous (IV) infusion. It is supplied as a sterile, lyophilized powder that must be reconstituted and diluted before use. The recommended dosage is 4 mg/m² every other week. The medication can be given by bolus injection or as an infusion over 20 to 30 minutes. Patients usually receive hydration before and after the infusion to help protect the kidneys.

How it works

Pentostatin works by inhibiting an enzyme called adenosine deaminase (ADA), which is found in high levels in lymphoid cells, including those involved in certain blood cancers. By blocking ADA, pentostatin causes a buildup of toxic substances inside cancer cells, especially when adenosine or deoxyadenosine is present. This buildup leads to increased levels of dATP, which interferes with DNA synthesis and can also affect RNA synthesis and increase DNA damage. These combined effects result in the death of cancerous cells.

Pentostatin is particularly effective in diseases where lymphoid cells are involved, such as hairy cell leukemia. While the exact way it works in all blood cancers is not fully understood, its ability to disrupt the growth and survival of abnormal lymphocytes is key to its therapeutic effect.

Who Should take it

Pentostatin is indicated for patients with hairy cell leukemia, including those who have not been treated before and those whose disease has not responded to alpha-interferon therapy. It is used in patients with active disease, which means they have symptoms or blood count abnormalities such as anemia, neutropenia, or thrombocytopenia.

While its primary FDA-approved use is for hairy cell leukemia, pentostatin may sometimes be considered in other lymphoid blood cancers in clinical settings, but this would be at the discretion of the treating physician.

Who should not take it

Pentostatin should not be used in patients who have had a hypersensitivity (allergic) reaction to the drug. It should also be used with great caution in patients with active infections, as treatment can worsen infections and lead to serious complications. If there is evidence of nervous system toxicity or severe rash, treatment should be withheld or discontinued.

Pentostatin is not recommended for use during pregnancy due to the risk of harm to the unborn baby. Its safety and effectiveness in children have not been established. Patients with significant kidney impairment should only receive pentostatin if the potential benefit outweighs the risk, as the drug is cleared by the kidneys and may accumulate in those with poor kidney function.

Commonly used with

Pentostatin is most often used as a single agent for the treatment of hairy cell leukemia. It is not commonly combined with other chemotherapy drugs for this indication. However, in some settings, it may be part of a conditioning regimen for bone marrow transplantation, but this is less common and carries additional risks.

Commonly tested with

Pentostatin has been tested in combination with other agents such as carmustine, etoposide, and high-dose cyclophosphamide as part of conditioning regimens for bone marrow transplantation. However, these combinations have been associated with serious side effects, including acute pulmonary edema and hypotension. It has also been studied with interferon and allopurinol, but combination with fludarabine phosphate is not recommended due to increased risk of fatal pulmonary toxicity.