Enhertu Improves Progression-Free Survival Over Pembrolizumab Plus Chemotherapy in First-Line HER2-Mutant NSCLC in DESTINY-Lung04

What was disclosed and what was not

The release calls the PFS gain "statistically significant and clinically meaningful" and says the safety profile was consistent with what is known for Enhertu, with no new concerns, and that is the whole of the efficacy information. The magnitude of benefit, the response-rate comparison and any subgroup reading by smoking status or brain metastasis will wait for a meeting presentation. Both companies said the results will be shared with global regulatory authorities.

Susan Galbraith, executive vice president for oncology hematology R&D at AstraZeneca, described the trial as "the first Phase III trial to demonstrate a progression-free survival benefit versus the global standard of care in this first-line setting, supporting the potential for Enhertu to move earlier in the treatment of HER2-mutant non-small cell lung cancer." John Tsai, global head of R&D at Daiichi Sankyo, said Enhertu "is already established as the first and only antibody drug conjugate for the second-line treatment of HER2-mutant metastatic non-small cell lung cancer."

Where Enhertu already stands in lung cancer

Enhertu at 5.4 mg/kg is approved in more than 80 countries for previously treated metastatic NSCLC with activating HER2 (ERBB2) mutations, on the DESTINY-Lung02 and DESTINY-Lung05 trials, with the label language specifying mutations "as detected by a locally or regionally approved test." The U.S. and Chinese approvals in that setting remain contingent on confirmatory data. The drug also carries a tumor-agnostic approval for HER2-positive (IHC 3+) solid tumors after prior treatment, which the companies note covers HER2-overexpressing NSCLC. DESTINY-Lung04 would be the basis for moving the mutation indication to first line. A separate Phase 3, DESTINY-Lung06, is testing Enhertu first line in HER2-overexpressing non-squamous disease.

The readout landed in the same week as two other AstraZeneca lung results, as Fierce Pharma's Asia roundup on Aug. 21 noted: a positive Phase 3 for the Hutchmed-partnered Orpathys with Tagrisso in EGFR-mutant disease after Tagrisso, and a failed Phase 3 for the bispecific volrustomig against Keytruda plus chemotherapy in first-line NSCLC with PD-L1 below 50%.

Why This Matters to the APO|APE Reader

A first-line HER2-mutant indication would make ERBB2 exon 19 and 20 mutation status something that has to be on the report before the first cycle, alongside EGFR, ALK, ROS1, KRAS G12C and the rest, in a 2% to 4% population that skews toward younger never-smokers with a higher rate of brain metastases. DESTINY-Lung04 stratified on brain metastasis history, so the eventual data set should say how the ADC performed in patients whose CNS disease often keeps them out of trials. And pembrolizumab plus platinum-pemetrexed, the regimen most HER2-mutant patients receive today, has now been beaten on the primary endpoint.