Daiichi Sankyo and Merck Achieve Phase III Success with HER3-Targeted ADC in Lung Cancer

Phase III Success:
Daiichi Sankyo and Merck & Co. have announced that their investigational antibody-drug conjugate (ADC), patritumab deruxtecan, has met the primary endpoint in the Phase III HERTHENA-Lung02 study in non-small cell lung cancer (NSCLC).

HER3 Targeting:
Patritumab deruxtecan is a HER3-targeted ADC, designed to target the HER3 protein on cancer cells and deliver a topoisomerase I inhibitor payload to induce cell death.

Clinical Trial Details:
The HERTHENA-Lung02 study is an open-label, late-stage trial that enrolled patients with locally advanced or metastatic NSCLC with EGFR mutations who had undergone prior treatment with an EGFR tyrosine kinase inhibitor.

Efficacy:
The trial demonstrated a statistically significant improvement in progression-free survival compared with platinum plus pemetrexed induction chemotherapy followed by maintenance with pemetrexed.

Safety Profile:
The safety profile of patritumab deruxtecan in the trial was consistent with what had been established in prior studies, with no new signals. However, two deaths due to grade 5 interstitial lung disease (ILD) events were reported, though no causal link to patritumab deruxtecan treatment was established.

Regulatory Path:
The companies plan to present full findings and analyses from the study at an upcoming medical meeting and will share the results with regulatory authorities to discuss next steps.

Previous Setbacks:
In June 2024, the FDA denied approval for patritumab deruxtecan due to issues with a third-party manufacturing facility, not related to the drug's safety or efficacy.

Collaboration:
Daiichi Sankyo and Merck & Co. entered into a global collaboration in October 2023 to jointly develop and commercialize patritumab deruxtecan, among other ADCs.