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Chronic Phase CML Treatment

In the chronic phase of chronic myeloid leukemia (CML) the treatment goals are to:

  • return the levels of blood cells to normal
  • kill all CML cells

The drug imatinib mesylate (Gleevec®) is the first treatment choice and standard of care for many newly diagnosed CML patients in the chronic phase. Health Canada approved two other drugs, nilotnib (Tasigna®) and dasatinib (Sprycel®).

Gleevec was the first of several targeted drug therapies approved by Health Canada  to control CML. Targeted drugs are designed to interfere with functions or growth of specific cancer cells. Gleevec targets and blocks Bcr-Abl tyrosine kinase, the abnormal protein in cells that leads to CML. Gleevec falls into a class of drugs known as Bcr-Abl tyrosine kinase inhibitors (TKIs).

Gleevec, Tasigna and Sprycel control CML for most people as long as they continue to take the drugs as prescribed. Patients who don?t respond to usual doses may respond to a higher dose, but that may cause more severe side effects.

Gleevec, Tasigna and Sprycel offer benefits to CML patients that weren't available to them in the past:

  • The drugs come in tablet form and can easily be swallowed.
  • They have decreased side effects when compared with former CML therapies, and any side effects are manageable.
  • They do little damage to healthy tissues.
  • Older patients tolerate them well.
  • They have a very high response rate.

If First-Line Therapy Doesn't Work

Depending on the drug you take as a newly diagnosed patient - Gleevec, Tasigna or Sprycel - your doctor may prescribe another TKI option if:

  • the drug can't control your CML (called drug resistance)
  • you have strong side effects (called drug intolerance)
  • the drug no longer works for you (called a loss of response)

If you're intolerant of or resistant to Gleevec, your doctor may prescribe Sprycel, which may work better for you. Sprycel blocks Bcr-Abl tyrosine kinase but binds to the abnormal protein differently than the other approved TKIs do. If you used Sprycel when you were newly diagnosed, and you became intolerant of or resistant to it, your doctor may prescribe Tasigna. Both Sprycel and Tasigna are Health Canada approved to treat CML patients in chronic or accelerated phases of CML.

Other CML Drug Therapies

Before the approval of Gleevec, other drugs such as interferon were the first line of treatment for CML. If you're unable to tolerate or are resistant to TKIs, your doctor may suggest one of the following drugs instead; however, their side effects may be severe:

  • interferon-alpha (Intron® A)
  • hydroxyurea (Hydrea®)
  • cytarabine (Cytosar-U®)
  • busulfan (Myleran®)

These drugs, or new treatment approaches in clinical trials, may be used to treat CML patients with a specific mutation (change) called T3151. This mutation changes the Bcr-Abl gene to make current TKIs ineffective.

Measuring Your Treatment Response

TKI drug therapy doesn't cure chronic phase CML, but it brings about a stable remission (no signs or symptoms of the disease). Most patients being treated for CML can go about their day-to-day activities. Treatment usually returns blood cell levels to normal and the spleen to its normal size. Studies show that patients who've been treated with Gleevec since the drug has been on the market (2001) have been able to keep their chronic phase CML under control.

During the period you undergo treatment, which can be indefinite, your doctor will continue to carefully check you for any signs that CML is returning (called a relapse). You'll need regular health checkups, including blood tests. From time to time, you'll need a bone marrow test.

Treatment in Older Adults

The first treatment choice for older adults who have chronic myeloid leukemia (CML) is the standard of care for all CML patients: targeted drug therapy with Gleevec. Because of their relatively mild side effects, both drugs are usually well tolerated by older adults. However, if you're not responding well to drug therapy, your doctor may suggest that you undergo a stem cell transplantation.

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last updated on Thursday, March 24, 2011