Treatment of Chronic Myelogenous Leukemia

Experimental Treatments for Chronic Myelogenous Leukemia

Various experimental approaches to treatment are being investigated worldwide in an attempt to improve the effectiveness of currently available treatments and prolong survival. Some of these newer experimental treatments include:

• Pegylated interferon
• Decitabine
• Homoharringtonine
• Farnesyl transferase inhibitors

Pegylated Interferon

Pegylated interferon (PEG-IFN; Pegasys) is standard interferon that has been modified by attaching interferon to polyethylene glycol. Polyethylene glycol is a chemical that can significantly extend the "half-life" of interferon (the time required for the body to eliminate one-half of the original drug dose). The half-life of standard (unpegylated) interferon is about 4 to 9 hours, whereas, the half-life of pegylated interferon is about 75 hours. In practical terms this means that pegylated interferon can be given once a week as compared to daily dosing that is required for the standard interferon. Pegylated interferon is administered once a week by injection under the skin (subcutaneous injection).

In a recent clinical trial involving 144 patients with early chronic phase chronic myelogenous leukemia, pegylated interferon was found to be more effective than standard interferon in terms of achieving both higher rates of complete hematological responses as well as major cytogenetic responses.

Decitabine

Decitabine (5-aza-2-deoxycytidine) belongs to a family of drugs called hypomethylating agents that are useful for the treatment of certain types of cancers because they inhibit DNA synthesis and, therefore, prevent cancer cells from replicating. Decitabine is currently being investigated in patients with chronic myelogenous leukemia who have failed to respond to treatment with imatinib mesylate.

Homoharringtonine

Homoharringtonine (HHT) is a plant alkaloid that has been shown to be effective in the treatment of chronic phase chronic myelogenous leukemia. Currently, HHT is being investigated in combination with other drugs for the treatment of chronic phase chronic myelogenous leukemia.

Farnesyl Transferase Inhibitors

This novel class of anticancer drugs inhibits an enzyme called farnesyl transferase that plays an important role in the molecular events leading to the development of leukemia. The potential efficacy of farnesyl transferase inhibitors for the treatment of chronic myelogenous leukemia has been demonstrated in laboratory studies as well as animal models of chronic myelogenous leukemia. Human studies of this drug are currently in progress.