A Crushing Blow: Promising Lung Cancer Drug Withdrawn After Failing to Extend Lives

Major Setback: Daiichi Sankyo and Merck have voluntarily withdrawn their application for patritumab deruxtecan in advanced EGFR-mutated lung cancer.
Survival Hopes Dashed: The decision follows a pivotal Phase 3 trial where the drug failed to show a statistically significant improvement in overall survival for patients.
Future Uncertain: Despite this, further analyses are planned to identify patients who might still benefit, as the fight against this challenging cancer continues.

In a stunning turn of events for patients battling relentlessly aggressive EGFR-mutated non-small cell lung cancer (NSCLC), Daiichi Sankyo and Merck have pulled their Biologics License Application (BLA) for the highly anticipated drug, patritumab deruxtecan (HER3-DXd). The decision, announced from Basking Ridge and Rahway, N.J., casts a shadow over the treatment landscape for those who have exhausted other therapies.

The withdrawal stems from the topline overall survival (OS) results of the confirmatory HERTHENA-Lung02 Phase 3 trial. While the drug, a HER3-directed antibody-drug conjugate (ADC), had previously shown statistically significant progression-free survival (PFS), this benefit was deemed clinically marginal—a mere 0.4 months improvement over chemotherapy^{4, 6}. Crucially, it did not translate into patients living longer, failing to meet the trial's critical OS endpoint. This was the decisive factor, following discussions with the U.S. Food and Drug Administration, and is notably unrelated to a previous manufacturing facility inspection issue^{4, 6}.

The HER3 protein, a key target for patritumab deruxtecan, is commonly expressed in EGFR-mutated NSCLC^{4, 6}, with estimates from broader research suggesting up to 90% of advanced tumors show expression after prior TKI treatment. This prevalence had fueled significant hope.

"While we are disappointed with the overall survival results," stated Ken Takeshita, MD, Global Head, R&D at Daiichi Sankyo, signaling the company's intent to conduct "further biomarker analyses to better identify patients that may benefit." Eliav Barr, MD, from Merck Research Laboratories, acknowledged the immense challenge, calling the results "a reminder of how challenging it can be to treat patients with EGFR-mutated non-small cell lung cancer in the second and later line settings."

Full results from HERTHENA-Lung02, which enrolled 586 patients, are slated for presentation at the ASCO 2025 Annual Meeting. Despite this blow, both companies remain committed to their broader ADC programs, underscoring the arduous path of cancer drug development.

A Crushing Blow: Promising Lung Cancer Drug Withdrawn After Failing to Extend Lives

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