Description
Dose Escalation:
Population includes subjects with locally advanced or metastatic NSCLC with an EGFR exon 19 deletion or L858R mutation with tumor progression after treatment with osimertinib. The starting combination dose regimen is HER3-DXd 3.2 mg/kg IV every 21 days (Q3W) and osimertinib 80 mg orally (PO) once daily. At least 3 to 6 subjects will be enrolled in each cohort.
Dose Expansion: Two subject populations will be evaluated in the Dose Expansion Part:
* Second-Line: Subjects with locally advanced or metastatic NSCLC with an EGFR exon 19 deletion or L858R mutation with tumor progression after treatment with osimertinib
* First-Line: Subjects with locally advanced or metastatic NSCLC with an EGFR exon 19 deletion or L858R mutation, and without prior systemic therapy for advanced or metastatic disease. Note: The first line expansion will only be initiated if the RCD includes osimertinib 80 mg PO once daily.