Cladribine is a drug commonly used to treat
hairy cell leukemia (leukemic reticuloendotheliosis). Its brand name is
Leustatin, and it is commonly referred to as 2CDA.

A purine analog, it is a synthetic antineoplastic agent with immunosuppressive
effects. Chemically, it mimics the nucleoside adenosine and thus inhibits
the enzyme adenosine deaminase, which interferes with the cell’s ability
to process DNA. It is easily destroyed by normal cells in the body except
for blood cells, with the result that it produces relatively few side
effects and results in very little non-target cell loss.
Pharmacology

Side Effects

About half of patients have no significant side effects from this treatment.

Most other patients have a high fever that is caused by cancerous and
non-cancerous white blood cells dying from the drug. This fever usually
starts on the second or third day of treatment (in a one-week/every-day
treatment program). As patients are at risk, from the disease as well
as from the drug, for infections, most physicians give antibiotics to
all patients with this fever just in case the fever is caused by a sudden
infection instead of from the drug. High fevers late in treatment are
much more likely to be caused by infection.

Patients are expected to experience a decline in blood cell counts during
treatment. Several weeks after successful treatment, cell counts will
begin to rebound, with platelet and neutrophil counts recovering before
red blood cells and T cells. T4 cell counts may never reach pre-disease
levels. Patients are usually advised to avoid sick people and large crowds
of people as well as to wash their hands and keep their hands away from
their eyes, nose, and mouth until their neutrophil counts have recovered.

Many patients experience fatigue, but since fatigue is a common feature
of the disease, this may be caused by the disease instead of by the drug.

This drug does not cause hair loss, vomiting, or other side effects that
are commonly associated with "old style" alkylating chemotherapy
drugs. However, peripheral neuropathy has been reported occasionally after
repeated doses of cladribine in the treatment of hairy cell leukemia.