Enhertu Beats Chemo-Immunotherapy in First-Line HER2-Mutant Lung Cancer

AstraZeneca (NASDAQ: AZN) and Daiichi Sankyo said Enhertu (trastuzumab deruxtecan) met its primary endpoint in DESTINY-Lung04, the Phase 3 trial testing the antibody-drug conjugate as a first-line treatment for HER2-mutant non-small cell lung cancer (NSCLC). AstraZeneca closed at $164.49 on August 20; Daiichi Sankyo’s ADR closed at $18.04.

In the August 17 readout, Enhertu showed a statistically significant and clinically meaningful improvement in progression-free survival (PFS) versus the global standard of care, platinum-pemetrexed chemotherapy plus pembrolizumab. The companies did not disclose the hazard ratio, and the trial will continue to evaluate overall survival and other secondary endpoints.

The result makes Enhertu the first and only HER2-directed medicine to improve PFS over standard of care in a Phase 3 trial in the first-line setting. HER2 mutations appear in about 2% to 4% of NSCLC cases, often in younger women with no smoking history, and the mutation is tied to poor prognosis and a higher rate of brain metastases.

Why It Matters

Enhertu is already approved for previously treated HER2-mutant NSCLC, an indication built on the DESTINY-Lung02 and DESTINY-Lung05 trials. DESTINY-Lung04 is the confirmatory study aimed at moving the drug into the first-line setting, where the current standard is chemo-immunotherapy and no HER2-targeted option exists.

Moving Enhertu earlier in treatment expands its addressable population and cements its position as the category leader in HER2-mutant lung cancer. The 454-patient trial is the largest head-to-head test of a HER2-directed ADC against first-line standard of care in this disease. For background on how Enhertu and its DXd payload technology work, see our guide to antibody-drug conjugates and our analysis of Daiichi Sankyo’s ADC franchise.

The safety profile in DESTINY-Lung04 was consistent with Enhertu’s known profile, with no new safety signals identified.

What Happens Next

The companies will present detailed DESTINY-Lung04 data at a forthcoming medical meeting and share results with global regulators. The headline PFS win sets up a potential first-line label expansion, but investors will watch the overall survival readout, which remains immature. The first-line HER2-mutant NSCLC setting is a multi-billion-dollar opportunity that has lacked a targeted therapy until now.