Choosing First-Line Therapy Among Four FDA-Approved HER2-Directed Options: Route, Efficacy, and Patient Fit

First-line treatment selection in HER2-mutant NSCLC balances route of administration, efficacy data by mutation subtype, and patient-specific logistics. Dr. Wu reviews the four FDA-approved HER2-directed therapies: two oral tyrosine kinase inhibitors (TKIs)—zongertinib (accelerated approval, first-line) and sevabertinib (accelerated approval, previously treated)—and two intravenous antibody-drug conjugates (ADCs)—fam-trastuzumab deruxtecan (T-DXd) and ado-trastuzumab emtansine (T-DM1), both approved for previously treated disease.

For William, geography and cost drive the conversation. Living 50 miles from the cancer center with $80–$120 rideshare trips, oral therapy is preferred. The only first-line oral option is zongertinib. NCCN does not express a preference between first-line zongertinib and standard chemo-immunotherapy for HER2-mutant adenocarcinoma, so both remain on the table.

A critical gating factor: zongertinib is approved specifically for HER2 tyrosine kinase domain (TKD) mutations. William's A775_G776insYVMA is a TKD mutation, so he is eligible. Non-TKD HER2 alterations would not qualify for zongertinib.

Efficacy data Dr. Wu highlights: In DESTINY-Lung01, T-DXd showed an overall response rate (ORR) of 55%, duration of response (DOR) 9 months, median PFS 8 months, and median overall survival (OS) 13.8 months. DESTINY-Lung02 randomized 5.4 mg/kg versus 6.4 mg/kg (2:1), with ORRs of 49% and 56%, respectively. In the Beamion LUNG-1 phase 1a/1b study at 120 mg, zongertinib produced an ORR of 71% in TKI-naïve TKD-mutant patients and 48% in those previously treated with a HER2-directed ADC. For sevabertinib, SOHO-01 (20 mg twice daily): Cohort D (HER2-naïve) ORR 64%; Cohort E (previously treated with a HER2-directed ADC) ORR 71%, DOR 8.5 months, median PFS 5.5 months; treatment-naïve cohort median DOR 11 months with immature PFS data.

In the next episode, “Zongertinib in the Context of Hepatic Impairment, Polypharmacy, and Hepatitis B Reactivation Risk,” Dr. Wu examines drug–drug interactions, liver monitoring, and practical logistics for a patient who lives 50 miles from clinic.