Tarceva vs Iressa
Both are EGFR inhibitors. Here is how Tarceva and Iressa compare on class, mechanism, dosing, approval and supply.
At a glance
Key differences
- Same class. Both Tarceva and Iressa are EGFR inhibitors, so they work through the same broad mechanism. Differences between them tend to be about dosing, route, how selective they are, and side effects rather than what they target.
- Time on the market. Tarceva was first approved by the FDA in 2004, Iressa in 2003.
- Who markets them. Tarceva is marketed by OSI Pharmaceuticals; Iressa by AstraZeneca.
What each one treats
An oral targeted therapy used to treat non-small cell lung cancer and pancreatic cancer.
IRESSA is indicated for the first-line treatment of patients with metastatic non-small cell lung cancer (NSCLC) whose tumors have epidermal growth factor receptor (EGFR) exon 19 deletions or exon 21 (L858R) substitution mutations as detected by an FDA-approved test [see Clinical Studies (14) ] . Limitation of Use: Safety and efficacy of IRESSA have not been established in patients with metastatic NSCLC whose tumors have EGFR mutations other than exon 19 deletions or exon 21 (L858R) substitution mutations [see Clinical Studies (14) ] . IRESSA is a tyrosine kinase inhibitor indicated for the first-line treatment of patients with metastatic non-small cell lung cancer (NSCLC) whose tumors have epidermal growth factor receptor (EGFR) exon 19 deletions or exon 21 (L858R) substitution mutations as detected by an FDA-approved test. (1) Limitation of Use: Safety and efficacy of IRESSA have not b…
How each one works
An oral targeted therapy used to treat non-small cell lung cancer and pancreatic cancer.
12.1 Mechanism of Action The epidermal growth factor receptor (EGFR) is expressed on the cell surface of both normal and cancer cells and plays a role in the processes of cell growth and proliferation. Some EGFR activating mutations (exon 19 deletion or exon 21 point mutation L858R) within NSCLC cells have been identified as contributing to the promotion of tumor cell growth, blocking of apoptosis, increasing the production of angiogenic factors and facilitating the processes of metastasis. Gefitinib reversibly inhibits the kinase activity of wild-type and certain activating mutations of EGFR, preventing autophosphorylation of tyrosine residues associated with the receptor, thereby inhibiti…
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How this page is built
The facts on this page are pulled directly from official U.S. FDA datasets — they are not written from memory. Each field below names the dataset it came from, so you can check it yourself.
- FDA Drug Label (openFDA) ↗ Indications, mechanism of action and pharmacologic class
- Drugs@FDA ↗ First FDA approval date and the company holding the application
- FDA Drug Shortage Database ↗ Current US supply / shortage status
Plain-English summaries and drug-class explainers are written and reviewed by Sreepriya Prasannan (MSc Digital Transformation of Life Sciences (Innopharma Education / Griffith College); MSc & BSc Botany). Data is retrieved automatically from the sources above and cross-checked with AI-assisted verification (Anthropic's Claude) — brand and generic names are matched against the exact FDA product record so that a combination product or a different formulation cannot be mistaken for the drug on this page. An editor reviews the result before publication. We describe this in full in our editorial standards and corrections policy. The FDA data on this page was last retrieved on 6 Oct 2026. How every register is built: methodology · fixes we have made: corrections log.