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Long-Term Benefit Seen With Imatinib, FDA Approves for Second-Line Treatment in Leukemia
Regular approval means that the FDA has determined that Gleevec has demonstrated a long-term clinical benefit for refractory CML patients. When Gleevec was originally approved under the accelerated approval program in May of 2001, available evidence indicated that a long-term clinical benefit was highly likely but further studies were necessary to confirm it.
“Our experience with Gleevec demonstrates the value of making promising drugs available early to patients with life threatening diseases based upon valid surrogate endpoints, such as short term tumor response rate, that are reasonably likely to predict that the drug can improve their lives,” said Mark B. McClellan, M.D., Ph.D., Commissioner of the Food and Drug Administration. “Our experience also demonstrates the importance of follow-up studies after approval to confirm the drug provides a clinical benefit, just as the sponsor has done in this case.”
The accelerated approval program helps make products for serious or life-threatening diseases available earlier in the development process by allowing approval to be based on a promising effect of the drug that can be observed in significantly sooner than a long-term clinical benefit. For Gleevec, these promising effects included a normalization of blood cell counts and a reduction in the percent of abnormal chromosomes in bone marrow white blood cells.
As part of the original approval, the sponsor, Novartis Pharmaceuticals, was required to continue to follow patients in their initial studies to confirm long-term benefit for this particular indication. Data presented to FDA showed that 95% of patients achieved normal blood cell counts. Further, favorable treatment responses were sustained. An estimated 88% of patients who achieved a reduction in the percent of abnormal chromosomes in bone marrow white blood cells maintained that response for at least two years. After two years of treatment, an estimated 85% of patients were free of disease worsening. The estimated overall survival was 91%. As a result of this additional data, FDA was presented with enough information to convert Gleevec, in this particular treatment setting, to regular approval.
Since May 2001, Gleevec has been approved for use in the first line treatment CML, for use in pediatric leukemia, and for a Gastrointestinal Stromal Cancer (GIST), a rare form of stomach/intestinal cancer.
The drug is manufactured by Novartis Pharma AG for Novartis Pharmaceuticals Corporation, East Hanover, N.J.
Source: The Food and Drug Administration