The targeted agent Tasigna® (nilotinib) appears to be an effective treatment for patients with newly diagnosed chronic myeloid leukemia (CML). These results were recently presented at the 2008 annual meeting of the American Society of Clinical Oncology.
CML is a cancer that originates in the immune cells. It affects approximately 4,600 people annually in the United States. In the case of CML, large numbers of young immune cells do not mature, resulting in an excess accumulation of these cells. These leukemia cells then crowd the bone marrow and blood, suppressing formation and function of other blood cells normally present in these areas. In addition, the leukemia cells cannot perform their function properly, leaving patients susceptible to infection.
Chronic myeloid leukemia begins with a chronic phase, during which few or no clinical problems occur. However, when left untreated, the chronic phase progresses into acute phases; these phases, called the accelerated and blastic phases, are characterized by fast-growing and aggressive cancer. Patients reaching these acute phases have a poor prognosis for long-term survival.
Philadelphia chromosome-positive (Ph-positive) CML refers to the majority of cases of CML in which a genetic abnormality, referred to as the Philadelphia chromosome, results in the constantly activated growth of cancer cells. Roughly 30% of adult patients with acute lymphocytic leukemia (ALL) also have this genetic abnormality.
Gleevec® (imatinib mesylate) is a biological agent that binds to and slows or stops the uncontrolled growth of cancer cells with the Philadelphia chromosome genetic mutation. Although Gleevec produces sustained anticancer responses in a significant portion of patients with Ph-positive CML, some patients stop responding to Gleevec or are not able to tolerate Gleevec. Unless these patients undergo a stem cell transplant, treatment options have remained limited.
Tasigna is an agent that targets the same protein as Gleevec but through a different mechanism. Some trials have indicated that Tasigna is more potent than Gleevec; however, further study into this issue is necessary. The U.S. Food and Drug Administration has approved the targeted agent Tasigna® for the treatment of chronic and accelerated-phase CML for patients who are not able to tolerate or who have stopped responding to Gleevec®.
Researchers from the M.D. Anderson Cancer Center in Houston, Texas, recently conducted a clinical trial to evaluate Tasigna as initial therapy for patients diagnosed with CML. The trial included 35 newly diagnosed patients who had been treated with Tasigna for a median of 6.5 months. Results from these patients were compared with data from patients with newly diagnosed CML who had been treated with Gleevec at two dose levels (400 milligrams per day and 800 milligrams per day). Complete cytogenetic responses (complete disappearances of the Philadelphia chromosome), a marker of disease responses, were compared between groups of patients.
The following table summarizes the main findings of this trial to date:
The authors concluded that Tasigna produced rapid and complete cytogenetic responses within three months in all patients treated. A clinical trial directly comparing Tasigna with Gleevec as initial therapy for patients with CML is necessary to truly understand the clinical benefits of Tasigna for patients with this disease. Patients diagnosed with CML may wish to speak with their physician regarding their individual risks and benefits of participation in a clinical trial further evaluating Tasigna or other promising therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (www.cancer.gov) and www.eCancerTrials.com.
Reference: Cortes JE, O’Brien SM, Ferrajoli A, et al. Efficacy of nilotinib (AMN107) in patients (pts) with newly diagnosed, previously untreated Philadelphia chromosome (Ph) + chronic myelogenous leukemia in early chronic phase (CML-CP). Journal of Clinical Oncology. 2008;26:abstract 7016.
Related News:Tasigna® Approved for Chronic Myeloid Leukemia (11/1/2007)
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