FDA Public Health Advisory
The Food and Drug Administration (FDA) has approved new labeling for gefitinib (Iressa) that limits the indication to cancer patients, who, in the opinion of their treating physician, are currently benefiting, or have previously benefited, from gefitinib treatment. The FDA has agreed to AstraZeneca's proposal to limit distribution of this drug under a risk management plan called the Iressa Access Program, to the following patient populations:
patients currently receiving and benefiting from Iressa;
patients who have previously received and benefited from Iressa; and
previously enrolled patients or new patients in non-Investigational New Drug (IND) clinical trials approved by an IRB prior to June 17, 2005.
New patients may also be able to obtain Iressa if AstraZeneca decides to make it available under IND and the patients meet the criteria for enrollment under the IND.
Gefitinib, an orally administered epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, was approved for marketing in May 2003 for patients with non-small cell lung cancer under Subpart H accelerated approval regulations that allow products to be approved on the basis of a surrogate endpoint for clinical efficacy. For gefitinib the surrogate end-point was tumor response rate. The response rate in patients taking the drug was approximately 10%. The approved indication was for the treatment of patients who were refractory to established cancer treatments (both a platinum drug and docetaxel). However, since the initial approval of Iressa, Tarceva (erlotinib) has been approved for treatment of this same group. Tarceva was approved based on improved overall survival.
FDA has carefully reviewed data from two failed clinical studies of Iressa, one of which was required by the agency as part of the drug’s accelerated approval. This trial enrolled patients with regionally advanced or metastatic NSCLC who had failed one or two prior treatment regimens. In this large study, 1,692 patients were given either gefitinib or placebo. There was no significant survival benefit in the overall study population nor in patients who had high levels of a surface marker called “EGFR.” In contrast, the presence of EGFR at high levels appears to predict a good response to Tarceva.
In the second trial in patients with stage III NSCLC, after completion of induction and consolidation chemotherapy and radiation therapy, patients were given either gefitinib or placebo maintenance therapy. No gefitinib survival benefit could be demonstrated.
The Food and Drug Administration is not considering market withdrawal of gefitinib at this time. New clinical trials are being developed, other ongoing trials are being completed, and there will be further analysis of the completed trials described above. These will determine the future role of gefitinib treatment.