Amgen's Imdelltra Cuts Lung Cancer Death Risk by 40% in Phase III

Amgen (AMGN) announced positive interim results from its Phase III DeLLphi-304 study of Imdelltra (tarlatamab-dlle) in small cell lung cancer (SCLC), demonstrating a 40% reduction in death risk and extending median overall survival by 5.3 months to 13.6 months compared to standard chemotherapy. The drug, already FDA-approved under accelerated approval, also showed improved progression-free survival and symptom relief, with a manageable safety profile; continued approval is contingent on the DeLLphi-304 study's success.

Analysis

Amgen's (AMGN) Imdelltra (tarlatamab-dlle) has demonstrated significant clinical benefits in treating Small Cell Lung Cancer (SCLC) patients who have progressed after platinum-based chemotherapy, according to new interim data from the Phase III DeLLphi-304 study. The drug achieved a 40% reduction in the risk of death and extended median overall survival (OS) by 5.3 months to 13.6 months, compared to 8.3 months for standard-of-care chemotherapy. Furthermore, Imdelltra showed statistically significant improvement in median progression-free survival (PFS) and patient-reported outcomes, including relief from dyspnea and cough, while maintaining a generally well-tolerated safety profile with mostly mild to moderate adverse events. This positive data is crucial as the DeLLphi-304 study serves as the confirmatory trial for Imdelltra's 2024 FDA accelerated approval for pre-treated extensive-stage SCLC (ES-SCLC), potentially transforming the treatment paradigm for this aggressive cancer which has a low five-year survival rate of 5-10%. Commercially, Imdelltra, Amgen's second FDA-approved BiTE molecule, recorded $81 million in sales in Q1 2025, a 21% sequential increase driven by volume growth, indicating early market traction. Amgen's stock has reflected this positive momentum, gaining 10.7% year-to-date, outperforming the industry's 3.9% decline. The success of Imdelltra, alongside strong performance from Blincyto (another BiTE therapy which generated $370 million in Q1 2025, up 52% YoY), underscores Amgen's strength in its BiTE platform and oncology franchise. However, Imdelltra's label includes a Boxed Warning for serious or life-threatening cytokine release syndrome and neurologic toxicity, which remains a factor for consideration.

Key Decisions for Investors

• Investors should view the positive interim Phase III data for Imdelltra as a significant de-risking event for Amgen's oncology pipeline, supporting a favorable outlook for the drug's full approval and market expansion in SCLC.
• Monitor the final results from the DeLLphi-304 study and subsequent regulatory decisions, as these will be key catalysts for Imdelltra's long-term commercial success and impact on Amgen's revenue.
• Track Imdelltra's sales ramp-up and market share capture in the ES-SCLC segment, considering its potential to address a high unmet medical need, while also remaining cognizant of the Boxed Warning and its potential impact on physician adoption.
• Evaluate Amgen's stock performance in the context of its growing BiTE therapy franchise, including both Imdelltra and Blincyto, as these innovative treatments are becoming increasingly important revenue drivers for the company.