In the recent past, HCL patients who were symptom-free typically did not receive any treatment for the disease. However, they did undergo routine follow-up exams every few months to monitor leukemia progression and identify any new symptoms. Now oncologists treat almost all newly diagnosed HCL cases with chemotherapeutic drugs known as purine analogs or nucleosides. In most cases, such treatment will produce a prolonged remission and perhaps a cure. Specifically, if the patient shows signs and symptoms such as low blood cell counts, frequent infections, bleeding/bruising, or fatigue, the oncologist may recommend chemotherapy with the purine analog cladribine (2-chlorodeoxyadenosine; 2-CDA). If the patient’s HCL becomes resistant to 2-CDA, chemotherapy with the purine analog pentostatin (2-deoxycoformycin; “DCF”) or immunotherapy with interferon-alpha (INF-a) may be used instead. In limited cases, the patient may benefit from splenectomy (removal of the spleen) or treatment with colony-stimulating factors (e.g., granulocyte colony-stimulating factor, a substance that helps to shorten the period of granulocytopenia resulting from chemotherapy). Unfortunately, some younger patients develop HCL that is unresponsive to treatment. Clinical trials are being conducted with high-dose chemotherapy followed by stem cell transplantation.