Tagrisso (osimertinib)

Tagrisso® is a targeted therapy that is used to treat some non-small cell lung cancers (NSCLC) that have a certain EGFR (epidermal growth factor receptor) mutation, specifically the exon 19 deletions or exon 21 L858R mutation, or T790M mutation. EGFR mutation is determined by biomarker tests (molecular testing) conducted on a biopsy sample of the tumor. Osimertinib is an EGFR inhibitor and is also classified as a kinase inhibitor. It is designed to block the activating sites (kinases) of several proteins within the cancer cell. These proteins can stimulate cancer growth when the tumor has an EGFR mutation. By blocking the action of the proteins, osimertinib may shrink the cancer or slow the cancer’s progression.1,2

Osimertinib is used to treat patients with NSCLC that are positive for EGFR mutation T790M that is metastatic (spread to distant parts of the body) after other EGFR tyrosine kinase inhibitor (TKI) therapies have already been tried and the cancer got worse. Osimertinib is also used to treat NSCLC that is positive for EGFR mutation (exon 19 deletions or exon 21 L858R mutation) that are metastatic (spread to distant parts of the body) prior to other treatment.2

About EGFR mutations

It is estimated that approximately 10-20 percent of patients with non-small cell lung cancer (NSCLC) in the United States have a tumor mutation associated with EGFR. EGFR mutations are most often found in tumors in patients who have never smoked (patients may be considered “never smokers” if they have smoked less than 100 cigarettes in their lifetime). The tumors are likely to be adenocarcinoma. However, EGFR mutations are not exclusive to this type of NSCLC or non-smokers – mutations have also been found in smokers and in other tumor types.3,4

Receiving osimertinib

Osimertinib is a pill that is taken by mouth. The dosage of osimertinib is determined by several factors, including the patient’s general health and ongoing response to treatment. Patients should take their medication as prescribed by their doctor. Patients should talk to their doctor if they have any questions, or if they have questions regarding their osimertinib regimen.2

Side effects of osimertinib

Osimertinib may cause side effects, and in some cases, these side effects can be severe. Any side effects should be reported to a health care professional. Side effects experienced in greater than approximately 30 percent of patients taking osimertinib include lowered white blood cells (increasing the risk of infection), lowered platelets (increasing the risk of bleeding or bruising), low red blood cells (anemia), diarrhea, skin rash, neutropenia (decrease in a specific type of white blood cell), and dry skin. Less common side effects experienced in approximately 10-29 percent of patients receiving osimertinib include nail changes, low sodium levels in the blood, high magnesium levels in the blood, eye disorders (including dry eyes, blurred vision, keratitis, cataract, eye irritation, floaters, or eye pain), nausea, decreased appetite, constipation, fatigue, cough, itching, back pain, mouth sores, and headache. Less commonly, osimertinib can cause severe side effects, including serious heart and lung events. Patients taking osimertinib should seek medical care immediately if they experience any of the following symptoms: trouble breathing, shortness of breath, cough, fever, heart pounding or racing, swelling of the ankles and feet, or feeling lightheaded.1,2

This is not an exhaustive list of all potential side effects of osimertinib. Talk to your healthcare provider or pharmacist for further information.


Patients receiving osimertinib should talk to their doctor about any other medications (prescription and over-the-counter), herbal remedies, and any supplements they are taking, as well as any other health conditions. Patients who are pregnant or planning to become pregnant should discuss their condition with their doctor prior to starting treatment with osimertinib, as it may be hazardous to the fetus. Females who can become pregnant should utilize effective birth control (patients should discuss appropriate birth control methods with their doctor) throughout osimertinib treatment and for six weeks following the last dose of osimertinib. Males with female partners who can become pregnant should utilize effective birth control (patients should discuss appropriate birth control methods with their doctor) throughout osimertinib treatment and for four months following the last dose of osimertinib. It is not known whether osimertinib passes into breast milk, and patients should not breastfeed while taking osimertinib and for two weeks following the last dose of osimertinib.2

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Written by: Emily Downward | Last reviewed: January 2021.