Osimertinib (Tagrisso)
Third-generation EGFR inhibitor for EGFR-mutated non-small cell lung cancer.
What is Osimertinib?
What it targets
Osimertinib irreversibly inhibits mutant EGFR — including exon 19 del, L858R, and T790M — blocking the proliferation signals that drive cancer growth.
Who it may help
Patients with NSCLC whose tumours carry EGFR exon 19 deletion, L858R, or T790M mutation confirmed by molecular testing.
Why testing matters
EGFR mutation testing is required before prescribing osimertinib. The drug has no benefit in EGFR-negative lung cancer.
Which cancers can Osimertinib treat?
Osimertinib is approved for five EGFR-mutated NSCLC indications — the applicable setting depends on mutation type, disease stage, and prior treatment history.
| First-line metastatic EGFR-mutated NSCLC | FDA and EMA approved as first-line therapy for metastatic NSCLC with EGFR exon 19 deletion or L858R mutation. The FLAURA trial demonstrated substantially longer progression-free survival and overall survival benefit over erlotinib or gefitinib. |
| First-line combination — FLAURA2 regimen | FDA approved (2024) for use with pemetrexed and platinum-based chemotherapy in first-line locally advanced or metastatic EGFR-mutated NSCLC with exon 19 deletion or L858R mutation. Adds chemotherapy-related toxicity but may offer deeper response. |
| Adjuvant NSCLC after complete resection | FDA and EMA approved as adjuvant therapy for up to 3 years after complete tumour removal in patients with EGFR exon 19 deletion or L858R. The ADAURA trial showed significantly reduced risk of disease recurrence or death. |
| Unresectable stage III NSCLC — post-chemoradiation | FDA approved (2024) for locally advanced unresectable stage III EGFR-mutated NSCLC that has not progressed after platinum-based chemoradiation. The LAURA trial demonstrated significantly prolonged progression-free survival over placebo. |
| T790M-positive metastatic NSCLC (second line) | FDA and EMA approved for metastatic NSCLC with confirmed EGFR T790M mutation after progression on an earlier EGFR TKI. The AURA3 trial showed superior outcomes over platinum-based chemotherapy in this resistance setting. |
Are you eligible for Osimertinib?
Eligibility depends on confirmed EGFR mutation status, lung cancer type and stage, prior treatment history, organ function, and cardiac safety.
- Confirmed NSCLC diagnosis — adenocarcinoma is most common but other histologies are also eligible if EGFR-mutated
- EGFR mutation confirmed by validated molecular test: exon 19 deletion, exon 21 L858R mutation
- EGFR T790M mutation confirmed if receiving osimertinib after progression on a prior EGFR TKI
- Adequate liver function — osimertinib is hepatically metabolised; dose adjustment may be needed in severe hepatic impairment
- Adequate kidney function and blood counts before treatment initiation
- No significant baseline QT interval prolongation or uncontrolled cardiac arrhythmia
- Not pregnant; effective contraception required during treatment and for 6 weeks after the final dose
- Suitable performance status as assessed by the treating thoracic oncologist
How does Osimertinib work?
- EGFR mutations drive lung cancer growth
- Irreversible blockade of mutant EGFR
- Cancer cells lose their growth signal
- Blood-brain barrier penetration
- Convenient oral, once-daily treatment
Osimertinib targets both common EGFR driver mutations and the T790M resistance mutation — a key advantage over earlier-generation EGFR TKIs.
Tests required before starting Osimertinib
These tests confirm EGFR mutation status, establish safety baselines, detect any contraindications, and enable response assessment once treatment begins.
| EGFR mutation testing (PCR or NGS) | Confirms EGFR exon 19 deletion, L858R, T790M, or other mutations. Essential before prescribing. Osimertinib should never be started without confirmed EGFR mutation status on a validated test. |
| Broad NGS panel | Recommended in advanced NSCLC to identify co-mutations such as MET amplification, HER2, TP53, and KRAS. Informs prognosis and helps plan next-line options. Also rules out exon 20 insertion, which is not targeted by osimertinib. |
| CT chest / PET-CT scan | Baseline staging, tumour measurement, and assessment of distant spread. Response will be compared to this baseline at follow-up imaging. |
| MRI brain | Recommended in metastatic NSCLC to detect asymptomatic brain metastases before treatment. Osimertinib has CNS activity; knowing brain involvement status guides treatment planning. |
| ECG (electrocardiogram) | Checks QT interval at baseline. Osimertinib can prolong QT interval; electrolyte abnormalities should be corrected before starting. Patients on other QT-prolonging medicines need extra care. |
| Liver and kidney function tests | Required for dosing safety. Osimertinib is hepatically metabolised; significant liver impairment may require dose adjustment. Kidney function guides fluid and electrolyte management. |
| Complete blood count (CBC) | Baseline blood counts before treatment. Cytopenias — anaemia, leukopenia, thrombocytopenia — can occur during treatment and are monitored with regular blood tests. |
| Echocardiogram (selected patients) | Recommended for patients with pre-existing heart conditions, prior cardiotoxic therapies, or significant cardiac risk factors due to osimertinib's potential cardiomyopathy risk. |
How is Osimertinib given?
Osimertinib is taken as a once-daily oral tablet at home. No hospital infusions are required, making it suitable for continuous outpatient management throughout the treatment period.
| Standard adult dose | 80mg once daily by mouth. This dose applies to most approved indications — first-line metastatic disease, adjuvant use after surgery, and post-chemoradiation use. |
| Combination regimen dose | 80mg once daily when combined with pemetrexed and platinum-based chemotherapy for eligible locally advanced or metastatic patients (FLAURA2 regimen). Chemotherapy is delivered by infusion on separate cycle days. |
| Dose reduction if needed | If significant side effects occur, the dose may be reduced to 40mg once daily at the oncologist's discretion. Do not adjust the dose independently without medical advice. |
| How to take | Swallow the tablet whole with water. Can be taken with or without food. If the patient cannot swallow whole, the tablet may be dispersed in water as directed — confirm with your oncologist or pharmacist before doing this. |
| Timing | Take at the same time each day to maintain consistent drug levels. Choosing a regular time — morning, evening, or with a meal — helps build the daily habit. |
| Missed dose | If a dose is missed, take it the same day when remembered. If the next scheduled dose is within 12 hours, skip the missed dose and resume the normal schedule. Never take two doses in one day. |
| Duration — adjuvant setting | In the adjuvant setting after complete surgical resection, osimertinib is typically taken for up to 3 years in disease-free patients, as established by the ADAURA trial. |
| Duration — metastatic setting | In metastatic disease, osimertinib is continued until cancer progression or unacceptable toxicity. Your oncologist will determine the appropriate treatment timeline based on scan results and tolerability. |
Clinical evidence and benefits
Osimertinib has been evaluated in multiple large randomised phase III trials across different NSCLC settings, establishing it as the standard targeted therapy for EGFR-mutated lung cancer.
| FLAURA trial — first-line metastatic NSCLC | Osimertinib demonstrated substantially longer progression-free survival and an overall survival benefit compared with erlotinib or gefitinib in patients with EGFR exon 19 deletion or L858R metastatic NSCLC. |
| ADAURA trial — adjuvant after surgery | Adjuvant osimertinib significantly reduced the risk of disease recurrence or death compared with placebo in patients with EGFR exon 19 deletion or L858R NSCLC following complete tumour resection. |
| LAURA trial — unresectable stage III NSCLC | Osimertinib after concurrent chemoradiation significantly prolonged progression-free survival over placebo in patients with unresectable stage III EGFR-mutated NSCLC (FDA approved 2024). |
| AURA3 trial — T790M-positive disease | Osimertinib significantly outperformed platinum-based chemotherapy in patients with EGFR T790M-positive metastatic NSCLC after progression on a prior EGFR TKI. |
| CNS activity | Osimertinib has demonstrated meaningful disease control against brain metastases — a clinical advantage of significant importance given how commonly EGFR-mutated NSCLC involves the CNS. |
| Oral daily convenience | As a once-daily oral tablet at home, osimertinib avoids the need for regular infusion visits, supporting a more normal daily routine while on treatment. |
Responses vary by patient. These are findings from published clinical trials — individual benefit depends on EGFR mutation type, stage, co-mutations, and overall health.
Side effects of Osimertinib
Osimertinib's most common side effects arise from its activity on normal EGFR signalling in skin, nails, and gut. Most are manageable with supportive care. Certain rarer risks require immediate attention.
| Diarrhea | Common; usually mild to moderate. Manage with dietary adjustments, hydration, and antidiarrheal medication as directed by your oncology team. |
| Skin rash / acneiform rash | Common; typically affects face, chest, and upper back. Topical treatments and gentle moisturisers help. Rarely severe enough to require dose reduction. |
| Dry skin | Very common; use fragrance-free moisturisers regularly throughout treatment. Report persistent cracking or painful skin to your care team. |
| Nail changes / paronychia | Nail brittleness, thinning, or painful infection around the nails. Keep nails short and seek advice for paronychia early. |
| Mouth sores / stomatitis | Ulcers or soreness inside the mouth. Use alcohol-free mouthwash and maintain regular oral hygiene. |
| Fatigue | Common throughout treatment. Moderate activity when energy allows. Report significant new or worsening fatigue to your care team. |
| Nausea / reduced appetite | Generally mild. Small frequent meals and adequate hydration help. Report significant appetite loss or persistent nausea to the oncology team. |
| Low blood counts | Anaemia, low white blood cells, or low platelets can occur. Monitored with regular blood tests. Report unusual bruising, pallor, or signs of infection promptly. |
| Interstitial lung disease / pneumonitis | Rare but serious. Any new or worsening breathlessness, cough, or fever requires immediate medical evaluation. Treatment is usually interrupted or permanently stopped if ILD is confirmed. |
| QT interval prolongation | Can affect heart rhythm; monitored with ECG. Risk increases with certain other medicines and low electrolytes. Report palpitations, dizziness, or fainting. |
| Cardiomyopathy | Reduced heart pumping function reported in some patients. Closer monitoring is needed for patients with prior cardiac disease or cardiotoxic treatment history. |
| Keratitis / eye inflammation | Rare; presents as eye redness, pain, or blurred vision. Report any new eye symptoms promptly to your oncologist. |
Contact your doctor immediately if you develop:
- New or worsening breathlessness, dry cough, or fever — possible ILD or pneumonitis
- Fast, irregular, or pounding heartbeat, dizziness, or fainting — possible QT issue
- Eye pain, redness, tearing, or vision changes — possible keratitis
- Severe or persistent diarrhea with signs of dehydration
- Unusual bruising, extreme pallor, or infection signs — possible blood count issue
- Chest pain, chest pressure, or new breathlessness at rest — possible cardiac effect
Safety precautions and drug interactions
Tell your oncologist and pharmacist about all medicines, supplements, and herbal products before starting osimertinib.
- Rifampicin, carbamazepine, phenytoin, and St John's Wort significantly reduce osimertinib blood levels and may make treatment ineffective — avoid if possible
- Strong CYP3A4 inhibitors such as itraconazole and clarithromycin can increase osimertinib levels — discuss alternatives with your oncologist before starting
- Any medicine that prolongs the QT interval should be flagged — includes certain antibiotics, antifungals, and anti-arrhythmic drugs
- Warfarin and other anticoagulants — drug interaction risk; closer monitoring or switch to an alternative anticoagulant may be required
- Osimertinib is harmful to a developing baby; effective contraception is required during treatment and for 6 weeks after the final dose
- Breastfeeding should be stopped during treatment and for 2 weeks after the last dose
- Proton pump inhibitors and H2 blockers may reduce osimertinib absorption; discuss timing or alternatives with your pharmacist
Osimertinib combination treatments
Osimertinib can be used as monotherapy or as part of a combination regimen, depending on treatment setting, patient fitness, and the goals of treatment.
| Osimertinib + Pemetrexed + Platinum (FLAURA2) | FDA-approved combination for first-line locally advanced or metastatic EGFR-mutated NSCLC with exon 19 deletion or L858R. The FLAURA2 trial showed improved response depth in selected patients. Adds chemotherapy-related toxicity and infusion visits compared to monotherapy. |
| Sequential use after chemoradiation (LAURA) | Osimertinib is given as maintenance after concurrent platinum-based chemoradiation completes in unresectable stage III EGFR-mutated NSCLC. This is sequential, not simultaneous — osimertinib begins after radiation ends. |
| Local treatment for oligoprogression | When only one or a few sites of cancer grow during osimertinib, local treatment such as stereotactic radiosurgery or radiation may be added to those sites while systemic osimertinib continues. |
| Adjuvant monotherapy after surgery | Following complete surgical resection of EGFR-mutated NSCLC, osimertinib is used as adjuvant monotherapy for up to 3 years. No additional systemic treatment is added in this setting. |
| After earlier EGFR TKI failure (T790M+) | When cancer has acquired T790M resistance after a first- or second-generation EGFR TKI, osimertinib is given as second-line monotherapy. No combination is standard in this resistance setting. |
If Osimertinib stops working
Acquired resistance to osimertinib develops in most patients over time. Identifying the specific resistance mechanism is essential for planning effective next-line treatment.
| EGFR C797S mutation | The most commonly reported on-target resistance mechanism after osimertinib. C797S prevents irreversible binding to EGFR. It cannot be overcome by other approved EGFR TKIs alone; investigational combinations and next-generation agents are being evaluated. |
| MET amplification | A bypass resistance pathway where MET amplification restores cell growth signalling independent of EGFR. Clinically actionable — MET inhibitors and osimertinib-plus-MET inhibitor combinations are being studied in this resistance setting. |
| HER2 amplification and KRAS mutation | Additional bypass mechanisms detectable at osimertinib progression. Broad NGS or liquid biopsy at disease progression is required to identify these and guide targeted treatment decisions. |
| Small cell histological transformation | A subset of EGFR-mutated NSCLC can undergo small cell transformation at progression. A new biopsy is required to detect this change; it is then treated with small cell lung cancer regimens. |
| Platinum-based chemotherapy | Remains a standard systemic option after osimertinib failure, particularly when no actionable resistance mutation is identified. Combination regimens with pemetrexed are commonly used. |
| Amivantamab-based regimens | Amivantamab — an EGFR-MET bispecific antibody — combined with chemotherapy has been approved in some settings following osimertinib failure. Eligibility and access vary by country and current approval status; verify with your oncologist. |
Cost of Osimertinib by country
The cost of branded Tagrisso varies significantly by country. Generic osimertinib is available in India and some other markets, providing more affordable access for eligible patients.
| India | Branded Tagrisso is expensive in India without insurance. Generic osimertinib is now available from Indian manufacturers at substantially lower cost. AstraZeneca patient assistance programmes may be available for eligible patients. CancerFax can help identify legitimate sourcing options. |
| USA | Tagrisso is expensive in the USA and typically requires private or federal insurance. AstraZeneca's AZ&ME programme provides assistance for eligible uninsured or underinsured patients. Generic osimertinib is not yet widely available in the USA as of 2026. |
| UK / Europe | NICE-approved in the UK; funded by the NHS for approved EGFR-mutated NSCLC indications. EMA-approved across the EU. National reimbursement terms vary by country; most major EU health systems cover it for first-line metastatic and adjuvant settings. |
| China | Tagrisso is included in China's National Reimbursement Drug List (NRDL), significantly reducing patient cost within the national insurance system. Widely available at major cancer hospitals in tier-1 cities. |
| Singapore / Southeast Asia | Available at major oncology hospitals across the region. Costs and insurance coverage vary significantly by country. AstraZeneca patient access programmes may apply in some markets. |
Availability of Osimertinib globally
Osimertinib is available in many countries as branded Tagrisso and, increasingly, as generic formulations. Access depends on national regulatory approval, hospital supply, and insurance coverage.
India
Tagrisso available at licensed oncology hospitals. Generic osimertinib available from Indian manufacturers. Prescription from a qualified oncologist required. CancerFax can assist with access guidance, cost comparison, and report review.
USA
FDA-approved for all major EGFR-mutated NSCLC indications. Available at oncology centres and specialty pharmacies. AZ&ME patient assistance programme available for eligible patients without adequate insurance.
UK
NICE-approved; funded by the NHS for approved EGFR-mutated NSCLC indications. Dispensed via hospital oncology pharmacy following specialist prescription.
China
NMPA-approved. Included in the National Reimbursement Drug List (NRDL), significantly reducing cost under national insurance. Widely available at tier-1 cancer hospitals. CancerFax supports patients navigating China-based treatment pathways.
Germany / EU
EMA-approved; available across EU member states through national health insurance or hospital formularies. Reimbursement terms and approved indications vary by country.
Osimertinib in current clinical trials
Osimertinib continues to be investigated in active research programmes focused on earlier-stage disease, combination strategies, resistance mechanisms, and CNS disease.
| Neoadjuvant use before surgery | Trials studying osimertinib given before surgery in resectable EGFR-mutated NSCLC to evaluate pathological response and long-term outcomes. Results may expand its role into earlier-stage disease management. |
| Resistance and next-line strategies | Multiple trials investigating options after osimertinib failure, including amivantamab-based combinations, novel fourth-generation EGFR TKIs designed to overcome C797S, and bispecific antibody approaches. |
| FLAURA2 subgroup analyses | Ongoing analyses from the FLAURA2 trial identifying which patient populations benefit most from osimertinib plus chemotherapy versus osimertinib monotherapy as first-line treatment. |
| Combination with immunotherapy | Trials exploring whether checkpoint inhibitors added to osimertinib improve outcomes in selected EGFR-mutated NSCLC patients, while managing the added toxicity observed in earlier combination attempts. |
| CNS-focused studies | Studies evaluating depth and durability of CNS control with osimertinib, the timing of brain-directed radiotherapy, and prophylactic approaches in EGFR-mutated NSCLC with high brain metastasis risk. |
Your treatment journey with Osimertinib
Initial lung cancer diagnosis
Biopsy and pathology confirmation
EGFR mutation testing
Oncology consultation and treatment planning
Baseline safety tests and prescription
Starting osimertinib
First response assessment
Long-term monitoring and follow-up
Questions to ask your oncologist about Osimertinib
- Which EGFR mutation do I have, and what does it mean for my treatment?
- What stage is my lung cancer, and which treatment setting applies to me?
- Should I take osimertinib alone or with chemotherapy?
- Do I need an ECG and heart monitoring before and during treatment?
- What side effects need urgent reporting?
- How often will I need CT scans to check for response?
- What happens if the cancer becomes resistant to osimertinib?
- Is generic osimertinib safe and appropriate for me?
- Should I have a broad NGS test even if my EGFR mutation is already known?
How CancerFax supports Osimertinib patients
CancerFax helps patients and families navigate EGFR mutation testing, lung cancer treatment planning, and access to osimertinib in India, China, and other countries.
| EGFR report review | Upload your EGFR mutation test, NGS panel, or lung biopsy pathology report — our team reviews the findings and explains their implications for osimertinib eligibility and treatment planning |
| Second opinion | If you want an independent review of your lung cancer diagnosis, EGFR test result, or treatment plan, CancerFax arranges a second opinion with an experienced thoracic oncologist |
| India and China access | We help patients in India, Southeast Asia, and other regions understand practical access options for osimertinib — including generic sourcing guidance and hospital treatment pathways in China |
| Clinical trial matching | For patients progressing on osimertinib or seeking advanced options, CancerFax identifies relevant clinical trials in India, China, and internationally based on the patient's mutation profile and resistance findings |
| Cost and access guidance | We help patients understand the cost landscape for branded Tagrisso and generic alternatives, and identify patient assistance programmes or affordable access channels by country |
| Hospital and specialist coordination | CancerFax connects lung cancer patients with thoracic oncologists and EGFR specialists at leading hospitals in India, China, Singapore, and other international oncology centres |
Frequently asked questions about Osimertinib
Common questions from patients and caregivers
Osimertinib (Tagrisso) is a third-generation EGFR tyrosine kinase inhibitor designed to block both the common activating EGFR mutations — exon 19 deletion and L858R — and the T790M resistance mutation that causes failure with older EGFR TKIs. First-generation agents like gefitinib and erlotinib often became ineffective once T790M developed, but osimertinib was designed to overcome this. It is now the preferred first-line targeted therapy for EGFR-mutated metastatic NSCLC in NCCN, ESMO, and other major oncology guidelines.
Yes. EGFR mutation testing is essential before starting osimertinib. The drug is only effective in patients whose lung cancer carries specific EGFR mutations — exon 19 deletion, exon 21 L858R, or EGFR T790M. Testing is done on a biopsy sample or liquid biopsy using PCR, next-generation sequencing (NGS), or another validated molecular test. Starting osimertinib without confirmed EGFR mutation status is not recommended and may expose patients to side effects without clinical benefit.
Osimertinib is approved for EGFR exon 19 deletion and exon 21 L858R mutations in the first-line metastatic setting, as adjuvant therapy after surgery, and after chemoradiation for unresectable stage III disease. It is also approved for EGFR T790M-positive metastatic NSCLC that has progressed on an earlier EGFR TKI. Uncommon mutations such as exon 20 insertions are generally not targeted by osimertinib — your oncologist will confirm based on your specific molecular test result.
Most patients with EGFR-mutated NSCLC who respond to osimertinib see early signs of improvement within the first 6 to 12 weeks, usually confirmed by a CT scan response assessment. Some patients notice reduced breathlessness or cough sooner. Responses vary — the oncologist will track progress with regular imaging. Taking the drug consistently at the same time each day gives the best chance of maintaining response.
Generic osimertinib has become available in some markets, including India, as the drug's patent landscape evolves. Generic formulations contain the same active ingredient at the same dose and should have equivalent bioavailability. Patients should only use generics from manufacturers verified by a qualified oncologist or pharmacist. CancerFax can assist with identifying legitimate access channels for osimertinib in India and other countries.
Contact your oncologist immediately. New or worsening breathlessness, dry cough, or fever while on osimertinib may be signs of interstitial lung disease (ILD) or pneumonitis — a serious but recognised side effect. Treatment is usually paused or permanently stopped if ILD is confirmed. Do not dismiss these symptoms as a minor infection. Reporting them early gives your medical team the best chance to manage the problem safely.
Yes. Osimertinib has demonstrated meaningful activity against brain metastases in EGFR-mutated NSCLC, which is one of its key clinical advantages over first- and second-generation EGFR TKIs. It crosses the blood-brain barrier more effectively than earlier agents. In patients with EGFR-mutated NSCLC and brain metastases, osimertinib is generally the preferred targeted therapy, though additional local treatment such as stereotactic radiosurgery may still be recommended in some cases.
If scans or symptoms suggest the cancer is progressing, your oncologist will typically order a repeat biopsy or blood-based liquid biopsy to look for resistance mechanisms such as MET amplification or the C797S mutation. Depending on what is found, options include adding or switching to chemotherapy, joining a clinical trial of a newer targeted combination, or other therapies matched to the specific resistance pattern.