Respiratory and thoracic cancers:
Indications for IRESSA:
First-line treatment of metastatic non-small cell lung cancer (NSCLC) with EGFR exon 19 deletions or exon 21 (L858R) substitution mutations as detected by an FDA-approved test.
Limitations of Use:
Not established in metastatic NSCLC with EGFR mutations other than exon 19 deletions or exon 21 substitution mutations.
May disperse tabs in water; drink immediately or give via NG tube. Give 250mg once daily until disease progression or unacceptable toxicity occurs. Dose modifications for adverse reactions: see full labeling. Concomitant strong CYP3A4 inducers: increase to 500mg daily; resume at 250mg seven days after discontinuation of the CYP3A4 inducer.
Permanently discontinue if confirmed interstitial lung disease (ILD), severe hepatic impairment, GI perforation, or persistent ulcerative keratitis occurs. Withhold for up to 14 days if acute onset or worsening pulmonary symptoms, NCI CTCAE Grade ≥2 ALT and/or AST elevations, Grade ≥3 diarrhea or skin reactions, or severe or worsening ocular disorders (including keratitis) occurs. Interrupt or discontinue therapy if severe bullous and exfoliative skin disorders develop. Obtain periodic LFTs. Moderate and severe hepatic impairment; monitor. Use effective contraception during treatment and for at least 2 weeks after completion. Pregnancy, nursing mothers: not recommended.
Tyrosine kinase inhibitor.
Potentiated by strong CYP3A4 inhibitors (eg, ketoconazole, itraconazole); monitor. Antagonized by strong CYP3A4 inducers (eg, rifampicin, phenytoin, tricyclics); see Adults. May be antagonized by drugs that increase gastric pH (eg, H2-blockers, antacids); take gefitinib 6 hours after or 6 hours before an H2-blocker or antacid. Avoid concomitant PPIs; if necessary, take gefitinib 12 hours after last dose or 12 hours before next PPI dose. May potentiate warfarin; monitor INR.
Skin reactions, diarrhea, vomiting, decreased appetite, stomatitis; ILD, hepatotoxicity, GI perforation, ocular disorders.
Testing considerations: EGFR mutation analysis.