The active ingredient in Tagrix is osimertinib, a targeted EGFR tyrosine kinase inhibitor.
EGFR and lung cancer
EGFR is a receptor involved in signaling pathways that regulate cell growth and survival. Certain mutations can cause abnormal EGFR signaling that contributes to the growth of NSCLC.
Targeting mutant EGFR
Osimertinib binds irreversibly to selected mutant forms of EGFR. Beacon’s prescribing information specifically identifies activity against T790M, L858R and exon 19 deletion mutations.
EGFR exon 19 deletion
Exon 19 deletions are activating EGFR alterations associated with sensitivity to EGFR-targeted therapy.
EGFR L858R
L858R is another important activating EGFR mutation found in NSCLC.
EGFR T790M
T790M is an acquired resistance mutation that can emerge following earlier EGFR-targeted treatment. Osimertinib was developed with activity against this mutation.
Why testing matters
A diagnosis of NSCLC alone does not establish that Tagrix/osimertinib is appropriate. Molecular testing is needed to identify relevant EGFR alterations for the particular treatment setting.