Dacomitinib for EGFR-Mutant NSCLC: Dosing, Switching, and Safety Profile

　　1.Overview and Key Points

　　Dacomitinib(brand name VIZIMPRO)is a second-generation irreversible EGFR tyrosine kinase inhibitor(TKI),indicated for first-line treatment of metastatic non-small cell lung cancer(NSCLC)with EGFR exon 19 deletions or L858R substitution mutations confirmed by testing.

　　Contraindications include hypersensitivity to any component and pregnancy;severe hepatic impairment requires caution.Warnings cover interstitial lung disease(rare but fatal),severe diarrhea,skin toxicity,and QT prolongation.Drug interactions:caution with strong CYP2D6 inhibitors(e.g.,paroxetine);reduced absorption with proton pump inhibitors(recommend 6-hour separation or switch to H2 antagonist).

　　2.Standard Dosing and Administration

　　Recommended dose is 45 mg orally once daily until disease progression or unacceptable toxicity.Dose reduction steps:45 mg→30 mg→15 mg;if 15 mg is intolerable,permanently discontinue.May be taken with or without food.

　　3.Switching Considerations

　　From first-generation TKIs(gefitinib,erlotinib)to dacomitinib:Confirm mutation remains 19del/L858R(exclude T790M),assess adverse profile and lung function.First-gen TKIs have half-life~24-48 hours;allow 3-5 days washout before starting dacomitinib.

　　From dacomitinib to osimertinib(if T790M emerges):Observe 1-2 days after stopping dacomitinib due to irreversible binding.Imaging evaluation in 6-8 weeks post-switch;if ineffective,consider re-biopsy for resistance mechanisms.

　　4.Comparison with Osimertinib

　　Both are first-line options for EGFR-mutant NSCLC:

　　Efficacy:Osimertinib has superior median PFS(18.9 vs 14.7 months)and OS(38.6 vs 34.1 months).

　　Intracranial:Osimertinib penetrates CNS better,higher intracranial response.

　　Safety:Osimertinib grade≥3 adverse events(~20-30%)lower than dacomitinib(~40-50%),especially diarrhea and rash.

　　Resistance:~50-60%of dacomitinib resistance is T790M,allowing sequential osimertinib;osimertinib resistance is more complex(e.g.,C797S).

　　Indications:Osimertinib also approved for adjuvant and T790M-positive settings,broader scope.

　　Osimertinib is the standard first-line preference;dacomitinib serves as an alternative when osimertinib is unavailable.

　　5.Adverse Event Management

　　Skin toxicity:initiate moisturizing and sun protection from day one.Diarrhea:early use of loperamide and hydration.For grade≥3 adverse reactions,hold dosing until recovery to≤grade 1,then resume at reduced dose.