Long Term Imatinib Treatment for Chronic Myeloid Leukemia Safe and Effective

Long Term Imatinib Treatment for Chronic Myeloid Leukemia Safe and Effective

A study of the safety and effectiveness of imatinib treatment for chronic myeloid leukemia has shown that after almost 11 years following initial imatinib treatment, patients have not suffered unacceptable negative long term effects.

Imatinib – sold under the name Gleevac – is a selective BCR-ABL1 kinase inhibitor first approved for medical use in the United States in 2001. The drug is commonly used to treat chronic myelogenous leukemia and acute lymphocytic leukemia. The drug is already on the WHO list of essential medicines and is deemed to be both effective and safe to use.

The drug has been instrumental in improving survival rates of chronic myeloid leukemia. In 1993, the survival rate for chronic myeloid leukemia was just 31%. Since the introduction of imatinib, and subsequent development of the drug, survival rates increased to 59% between 2003 and 2009.

While the drug is believed to be both effective and safe, the long-term effects from continued treatment were not known. However, the results of a 2003 International Randomized study of Interferon and STI571 (IRIS) have shown that long term treatment of chronic myeloid leukemia with imatinib is safe. The majority of patients receiving imatinib treatment for chronic myeloid leukemia had a complete cytogenetic response and any adverse effects from the treatment were relatively uncommon.

The initial results from the trial showed imatinib treatment for chronic myeloid leukemia was safe and effective and that the drug was superior to interferon alfa and cytarabine. Consequently, many of the patients involved in the trial in the interferon alfa and cytarabine group switched treatments to imatinib during the trial.

Now that 10 years have elapsed since the treatment started, patient follow ups have been conducted. The results show that even after extended use of the drug, the efficacy of imatinib has persisted and patients do not have an increased risk of adverse events after extended use.

Unfortunately, the study could not show where there was an increased survival rate from using imatinib over interferon alfa and cytarabine as most patients had crossed over to treatment with imatinib during the study.

The randomized trial was initially conducted on 1,106 patients with two groups of 553 being administered each treatment. The median duration of treatment with imatinib was 8.9 years and the median follow up time was 10.9 years. The estimated overall survival rate at 10 years was 83.3%. 82.8% of the 48.3% of patients who were randomly assigned treatment with imatinib had a complete cytogenetic response.

Only 51 patients out of 551 (9.3%) had a serious adverse event while on the treatment, with the highest rate occurring during the first year of treatment. There were no new safety signals identified since the previous 5-year analysis.

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