Osimertinib is an oral targeted medicine that blocks a specific growth-signal receptor found on certain lung cancer cells. It belongs to a class of medicines called EGFR tyrosine kinase inhibitors (TKIs), specifically designed to target EGFR mutations, including a resistance mutation (T790M) that makes cancer stop responding to earlier EGFR-targeted drugs. It is a prescription-only medicine.

• Therapeutic Class: Anti-cancer (oncology) targeted therapy.

• Pharmacological Class: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, third-generation.

• Drug Family: Small-molecule EGFR-targeted therapies.

• ATC Classification: L01EB04 (Osimertinib).

Approved: Adjuvant therapy after tumour resection in non-small cell lung cancer (NSCLC) with EGFR exon 19 deletions or exon 21 L858R mutations; locally advanced, unresectable (stage III) NSCLC with these mutations after chemoradiation; first-line treatment of metastatic NSCLC with these mutations, as monotherapy or combined with chemotherapy; and treatment of metastatic EGFR T790M mutation-positive NSCLC that has progressed on or after prior EGFR TKI therapy.

Commonly used for: Patients with NSCLC confirmed to carry specific EGFR mutations, identified through an FDA-approved companion diagnostic test, across early, locally advanced, and metastatic disease stages.

Off-label use (only under medical guidance): Being studied in other EGFR-mutation-positive cancers in clinical trials; use outside its approved settings is a specialist decision.

● Oral tablets: 40 mg and 80 mg.

Certain lung cancers have mutations in a growth-signal receptor called EGFR, causing cells to grow and divide uncontrollably. Osimertinib selectively and irreversibly blocks mutated forms of EGFR — including exon 19 deletion, exon 21 L858R, and the T790M resistance mutation — while having comparatively less effect on normal, non-mutated EGFR, which helps target the cancer cells more precisely.

• Standard dose: 80 mg taken orally once daily, with or without food.

• Condition-wise dose: For adjuvant therapy, treatment continues until disease recurrence, unacceptable toxicity, or for a total of 3 years; for other indications, treatment continues until disease progression or unacceptable toxicity.

• Route: Oral, once daily; for patients with difficulty swallowing solids, the tablet can be dispersed in water per specific administration instructions.

• Missed dose: If a dose is missed, it should not be taken if it is less than 12 hours until the next dose is due.

• Overdose: May increase the risk of known side effects such as heart or lung-related toxicity; requires medical attention.

• Common: Diarrhoea, rash, dry skin, nail toxicity, and stomatitis (mouth sores).

• Serious: Interstitial lung disease/pneumonitis (lung inflammation), QTc interval prolongation, cardiomyopathy (heart muscle weakening), keratitis (eye inflammation), and severe skin reactions including Stevens-Johnson syndrome.

• Emergency symptoms: New or worsening shortness of breath, cough, or fever (possible lung inflammation); chest pain or palpitations; severe eye pain or vision changes; or widespread blistering skin rash.

• Recovery advice: New respiratory symptoms should always be reported promptly, as interstitial lung disease, while uncommon, needs early identification and treatment interruption; routine heart function assessments help catch cardiac changes before they become symptomatic.

• Pregnancy: Can cause fetal harm; effective contraception is required during treatment and for a period after stopping.

• Breastfeeding: Not recommended during treatment and for a period after the last dose.

• Liver disease: No specific dose adjustment generally required in mild to moderate impairment; used with monitoring.

• Kidney disease: No specific dose adjustment generally required in mild to moderate impairment.

• Elderly: Commonly used in this age group, as lung cancer risk increases with age; monitored for cardiac and other side effects.

• Children: Not established for use in children; a medicine for adult NSCLC patients.

● Strong CYP3A4 inducers (e.g., rifampin, carbamazepine, phenytoin, St. John's Wort): can significantly decrease osimertinib exposure and reduce its effectiveness; co-administration is generally avoided.

● Other QT-prolonging medicines: combining with other drugs that affect heart rhythm increases the risk of QTc prolongation.

● BCRP substrate drugs (e.g., rosuvastatin): osimertinib may increase their levels, requiring monitoring.

● Other EGFR-targeted therapies: not combined with other EGFR TKIs.

● Baseline and periodic ECG and electrolyte monitoring, given the QTc prolongation risk.

● Cardiac function (e.g., left ventricular ejection fraction) assessment before starting and during treatment, particularly in patients with cardiac risk factors.

● Monitoring for new or worsening respiratory symptoms suggestive of interstitial lung disease.

● EGFR mutation testing before starting, using an FDA-approved companion diagnostic test.

Gefitinib, Erlotinib, Afatinib (earlier-generation EGFR TKIs, generally not effective against the T790M resistance mutation).

Used as monotherapy in most approved settings; also approved in combination with platinum-based chemotherapy (pemetrexed and cisplatin or carboplatin) for first-line treatment of certain EGFR-mutated metastatic NSCLC.

● Non-Small Cell Lung Cancer Medicines

● EGFR Tyrosine Kinase Inhibitors

● Targeted Oncology Therapies

1. Advanced Radiation Therapy Techniques for Lung Cancer

2. Exploring Surgical Options for Lung Cancer

1. https://www.guidelinecentral.com/drug/5e81b4a7-b971-45e1-9c31-29cea8c87ce7/

2. https://pmc.ncbi.nlm.nih.gov/articles/PMC8352275/

The information on this page is for educational purposes only and is not a substitute for medical advice. Please consult your oncologist to know if this treatment is appropriate for your condition.