by Dr. C.H. Weaver M.D. updated 3/2020
The United States Food and Drug Administration (FDA) has approved the targeted agent Tasigna® (nilotinib) for the treatment of chronic and accelerated-phase chronic myeloid leukemia (CML) for patients who are not able to tolerate or who have stopped responding to Gleevec® (imatinib).
CML is a cancer that originates in the immune cells. It affects approximately 4,600 people annually in the U.S. 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 myelogenous 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 also targets the same protein as Gleevec but through a different mechanism. Some trials have indicated that Tasigna is more potent than Gleevec. The clinical trial that prompted the FDA approval of Tasigna evaluated Tasigna in patients with CML who had received prior therapy with Gleevec. Patients treated with Tasigna had improvements in their blood cell levels while tolerating therapy well.(1)
In a randomized, prospective study of 846 patients comparing Tasigna with Gleevec, the rate of major molecular response at 24 months was 71% and 67% for two-dose schedules of nilotinib and 44% for imatinib. (2) Progression to accelerated-phase CML or blast crisis occurred in 17 patients on imatinib (14%), but this progression occurred in only two patients and in five patients respectively, on two-dose schedules of Tasigna. (2)
Tasigna in Gleevec Resistant Patients
Researchers from Europe conducted a study to further evaluate treatment with Tasigna in patients with CML who have stopped responding to Gleevec. Results of this study indicate that Tasigna was effective: blood cell levels were improved in 78% of patients in chronic-phase CML, 75% of patients in accelerated-phase CML, and 25% of patients in blast crisis.
The researchers concluded that these results provide additional evidence that Tasignaproduces significant anticancer activity among patients with CML who have stopped responding to Gleevec. Patients with CML that is resistant to Gleevec may wish to speak with their physician regarding their individual risks and benefits of participation in a clinical trial further evaluating nilotinib or other promising therapeutic approaches. (3)
- Novartis Pharmaceuticals. Tasigna® Receives US Approval Providing New Hope to Chronic Myeloid Leukemia Patients with Resistance or Intolerance to Existing Therapies. Available here. Accessed October 29, 2007.
- Kantarjian HM, Hochhaus A, Saglio G, et al.: Nilotinib versus imatinib for the treatment of patients with newly diagnosed chronic phase, Philadelphia chromosome-positive, chronic myeloid leukaemia: 24-month minimum follow-up of the phase 3 randomised ENESTnd trial. Lancet Oncol 12 (9): 841-51, 2011.
- Hochhaus A, et al. Hematologic and Cytogenetic Response Dynamics to Nilotinib (AMN107) Depend on the Type of BCR-ABL Mutations in Patients with Chronic Myelogeneous Leukemia (CML) after Imatinib Failure. Proceedings from the 2006 annual meeting of the American Society of Hematology. December 2006. Abstract #749.