Tarceva (erlotinib) and Iressa (gefitnib) are both agents targeted against the EGFR pathway. This pathway is involved in cell growth and replication and when mutated or altered, excessive replication of cells can occur. These agents reduce the uncontrolled replication and growth of cancer cells by blocking mutated EGFR pathways.
According to an article published in the Journal of Clinical Oncology, the targeted agent Tarceva may provide anticancer responses for patients with non-small cell lung cancer (NSCLC) who stop responding to Iressa. These drugs are not associated with the side effects of chemotherapy, providing an effective alternative for patients who are not eligible for standard therapy.
A study was done to evaluate the effectiveness of Tarceva among patients who stopped responding to Iressa. The researchers concluded that -- Patients with NSCLC who demonstrate disease control with Iressa and do not have EGFR mutations appear to have benefit from treatment with Tarceva once their cancer progresses following their treatment with Iressa. Patients with recurrent NSCLC may wish to speak with their physician regarding their individual risks and benefits of treatment with Tarceva.
1. The epidermal growth factor receptor (EGFR) is a protein on the surface of a cell. EGFR inhibiting drugs certainly do target specific genes, but even knowing what genes the drugs target doesn't tell you the whole story. Both Iressa and Tarceva target EGFR protein-tyrosine kinases. But all the EGFR mutation or amplificaton studies can tell us is whether or not the cells are potentially susceptible to this mechanism of attack.
It doesn't tell you if Iressa is better or worse than Tarceva or other drugs which may target this. There are differences. The drugs have to get inside the cells in order to target anything. So, in different tumors, either Iressa or Tarceva might get in better or worse than the other. And the drugs may also be inactivated at different rates, also contributing to sensitivity versus resistance.
Improving cancer patient diagnosis and treatment through a combination of cellular and gene-based testing can offer predictive insight into the nature of an individual's particular cancer and enable oncologists to prescribe treatment more in keeping with the heterogeneity of the disease, and when it is beneficial to combine conventional anti-cancer drugs with "targeted" drugs. The biologies are very different and the response to given drugs is very different.
Posted at 8:46PM on Jun 30th 2007 by Gregory D. Pawelski