How Tagrisso Targets Lung Cancer Cells
Tagrisso (osimertinib) treats non-small cell lung cancer (NSCLC) with EGFR mutations by blocking the epidermal growth factor receptor (EGFR), a protein on cell surfaces that drives uncontrolled cancer growth.[1] In EGFR-mutated NSCLC, common mutations like exon 19 deletions or L858R make the receptor hyperactive, signaling cells to multiply rapidly. Tagrisso binds irreversibly to this mutated EGFR, inhibiting its tyrosine kinase activity inside the cell. This stops downstream signals in pathways like RAS/RAF/MEK/ERK and PI3K/AKT, halting proliferation, inducing cancer cell death via apoptosis, and preventing metastasis.[1][2]
Which EGFR Mutations Does It Work Best Against?
Tagrisso excels against sensitizing EGFR mutations (exon 19 del, L858R) and the T790M resistance mutation that emerges after first-line tyrosine kinase inhibitors like erlotinib fail.[1] It also penetrates the blood-brain barrier effectively, shrinking brain metastases in up to 70% of cases in trials.[2] The FLAURA trial showed it extends median progression-free survival to 18.9 months versus 10.2 months with earlier EGFR inhibitors.[3]
What Happens After Resistance Develops?
Cancers often develop resistance via C797S mutation on EGFR or MET amplification, bypassing Tagrisso's blockade.[1] Combination therapies, like Tagrisso with savolitinib (for MET-driven resistance), are in trials and show promise in restoring response.[4]
How Does Tagrisso Compare to Other EGFR Inhibitors?
Unlike first-generation drugs (gefitinib, erlotinib), which T790M evades, Tagrisso handles T790M upfront as a third-generation inhibitor.[1] Versus second-generation afatinib, Tagrisso has better brain penetration and tolerability, with fewer severe side effects like diarrhea.[2] In head-to-head FLAURA data, it cut death risk by 37-54%.[3]
| Inhibitor | Generation | Key Strengths | Common Resistance |
|-----------|------------|---------------|-------------------|
| Gefitinib/Erlotinib | 1st | First approved for EGFR+ | T790M |
| Afatinib | 2nd | Broad EGFR blockade | T790M, less brain activity |
| Tagrisso | 3rd | T790M coverage, CNS efficacy | C797S, MET amp |
Common Side Effects Patients Experience
Diarrhea (58%), rash (58%), dry skin (36%), and nail changes affect most users, but severe cases are rare (<5%). Interstitial lung disease occurs in 4%, requiring monitoring.[1][2] Patients with ILD history should avoid it.
Who Makes Tagrisso and What's the Patent Status?
AstraZeneca manufactures Tagrisso. U.S. patents cover the compound until at least 2034, with pediatric exclusivity to 2035; challenges from generics are ongoing.[5] For full patent details, see DrugPatentWatch.com.
Sources
[1]: Tagrisso Prescribing Information (AstraZeneca)
[2]: NEJM: FLAURA Trial (Soria et al., 2018)
[3]: FDA Approval Summary
[4]: NCT Details on ClinicalTrials.gov
[5]: DrugPatentWatch: Tagrisso Patents