Drug Overview

Gefitinib is a pioneering medication used to treat specific types of lung cancer. It belongs to a group of medicines known as Targeted Therapy. In the medical field, it is frequently called a “Smart Drug” because it is designed to find and block specific signals that cancer cells use to grow and multiply, rather than attacking all cells in the body like traditional chemotherapy.

This medication has revolutionized treatment for patients whose tumors have a specific genetic “signature.” By focusing on the root cause of the cancer’s growth, gefitinib helps patients live longer with a better quality of life.

Generic Name: Gefitinib
US Brand Names: Iressa
Drug Class: Tyrosine Kinase Inhibitor (TKI); EGFR Inhibitor
Route of Administration: Oral (Tablet taken by mouth)
FDA Approval Status: FDA Approved

What Is It and How Does It Work? (Mechanism of Action)

To understand how this Smart Drug works, imagine a cancer cell has a “master switch” on its surface called the Epidermal Growth Factor Receptor (EGFR). In certain lung cancers, this switch is broken and stuck in the “ON” position, telling the cell to grow and divide non-stop.

At the molecular level, gefitinib works as a precise “switch blocker”:

Finding the Target: Gefitinib travels through the blood and enters the cancer cells. It heads straight for the internal part of the EGFR switch.
Blocking the Energy: For the switch to send a growth signal, it needs energy from a molecule called ATP. Gefitinib mimics the shape of ATP and sits in its “parking spot” (the ATP-binding pocket).
Cutting the Signal: Because gefitinib is blocking the spot, the energy molecule cannot plug in. This prevents the enzyme (tyrosine kinase) from activating the internal “wiring” (signaling pathways like PI3K/Akt and MAPK/ERK).
Stopping the Growth: Without these signals, the cancer cell becomes “confused” and stops multiplying. Over time, the cell may shrink or die, a process known as apoptosis.

FDA Approved Clinical Indications

Gefitinib is specifically approved for patients whose lung cancer has specific mutations (changes) in the EGFR gene.

Oncological Uses

Metastatic Non-Small Cell Lung Cancer (NSCLC): First-line treatment for patients whose tumors have specific EGFR mutations (Exon 19 deletions or Exon 21 L858R substitution mutations), as detected by an FDA-approved test.

Non-Oncological Uses

None. This medication is strictly used for the treatment of cancer.

Dosage and Administration Protocols

Gefitinib is a convenient daily pill that is taken at home. It does not require a hospital stay or an IV drip.

Protocol Detail	Standard Recommendation
Standard Dose	250 mg once daily.
Frequency	Taken at the same time every day.
Administration	Swallow whole with or without food. Can be dispersed in water if swallowing is difficult.
Hepatic Insufficiency	Use with caution in patients with moderate to severe liver impairment.
Renal Insufficiency	No dose adjustment is usually needed for mild to moderate kidney issues.

Clinical Efficacy and Research Results

Clinical data from 2020 to 2025 continues to support gefitinib as a cornerstone of lung cancer care, especially in global markets.

Progression-Free Survival (PFS): In major clinical trials (such as the IPASS study), patients with EGFR mutations taking gefitinib lived significantly longer without their cancer getting worse compared to those on standard chemotherapy.
Response Rates: Numerical data shows that approximately 70% to 75% of patients with the correct mutation see their tumors shrink when taking gefitinib.
Survival Trends: Recent real-world data indicates that while newer “third-generation” drugs exist, gefitinib remains a highly effective option that provides a median survival of over 20 months for many metastatic patients.

Safety Profile and Side Effects

Gefitinib is generally better tolerated than chemotherapy, but it has specific side effects because EGFR is also found in healthy skin and the lining of the gut.

Black Box Warning:

Gefitinib does not currently have an FDA Black Box Warning. However, it carries serious warnings for lung inflammation and liver damage.

Common Side Effects (>10%)

Skin Rash: An acne-like rash on the face and chest.
Diarrhea: Frequent or loose stools.
Dry Skin: Itchy or cracked skin.
Nausea: Mild upset stomach.
Loss of Appetite: Feeling less hungry than usual.

Serious Adverse Events

Interstitial Lung Disease (ILD): A rare but very serious inflammation of the lungs that can cause trouble breathing.
Hepatotoxicity: High levels of liver enzymes indicating liver stress.
Gastrointestinal Perforation: A rare hole in the wall of the stomach or intestines.

Management Strategies

For Rash: Use fragrance-free moisturizers and avoid harsh soaps. Your doctor may prescribe a steroid cream.
For Diarrhea: Stay hydrated and use over-the-counter medicine like loperamide if approved by your doctor.

Research Areas

Gefitinib is a major focus in Combination Therapy research. Scientists are currently testing if gefitinib works better when combined with Immunotherapy or other targeted drugs to prevent the cancer from becoming resistant. There is also early research into using gefitinib in “liquid biopsies”—using simple blood tests to monitor how well the drug is working in real-time.

Patient Management and Practical Recommendations

Pre-treatment Tests to be Performed

EGFR Mutation Test: This is mandatory. The drug will not work effectively if the tumor does not have the specific EGFR mutation.
Liver Function Tests (LFTs): To check your baseline liver health.
Chest X-ray/CT Scan: To have a clear image of the tumor before starting.

Precautions During Treatment

Sun Protection: Gefitinib makes your skin more sensitive to the sun. Wear sunscreen and protective clothing.
Drug Interactions: Avoid taking “Proton Pump Inhibitors” (like omeprazole) at the same time, as they can stop the drug from being absorbed.

“Do’s and Don’ts” List

Do take your pill at the same time every day to keep the medicine level steady.
Do tell your doctor immediately if you have a sudden cough or trouble breathing.
Don’t use acne medications on the gefitinib rash; it looks like acne but is different and requires special care.
Don’t stop taking the drug without talking to your oncologist, even if you feel better.

Legal Disclaimer

Standard Medical Information Disclaimer: This guide is for informational purposes only and does not constitute medical advice. Gefitinib (Iressa) is a prescription medication with potential risks. Always consult with a licensed oncologist or healthcare professional to discuss treatment options, risks, and benefits specific to your medical history. This content is based on medical data available as of 2026.