Small-cell lung cancer is one of those diseases that tends to move fast and leave doctors with few good options. So when a Phase 3 readout shows a survival curve separating that sharply, people pay attention.
Amgen Inc. (AMGN) on Saturday released interim Phase 3 results showing that Imdelltra, tested in combination with AstraZeneca Plc's (AZN) Imfinzi, reduced the risk of death by 58% as a first-line maintenance therapy for extensive-stage small-cell lung cancer.
The DeLLphi-305 study looked at patients whose disease had not worsened after initial chemotherapy and immunotherapy. In other words, these were patients who had responded to the first punch and were waiting to see if the cancer would come back.
Researchers presented the findings during a Presidential Symposium at the European Society for Medical Oncology Congress 2026 and published them in The New England Journal of Medicine.
Significant Survival and Progression Benefits
The combination regimen extended median overall survival to 21.1 months compared to 12.7 months with Imfinzi alone. That is a survival advantage of more than eight months, which in this disease is not a rounding error.
Approximately 80% of patients who received the combination therapy remained alive at the one-year mark, compared to 53% of individuals treated with monotherapy.
The trial also demonstrated a 66% reduction in the risk of disease progression or death, with median progression-free survival reaching 7.4 months versus 1.9 months for the monotherapy group.
And the combination generated an objective response rate of 26.4%, more than six times higher than the 4.1% recorded for the control group.
These survival and progression benefits extended across prespecified patient subgroups, including individuals with brain or liver metastases. That matters because those are often the patients who have the hardest time.
Manageable Safety Profile and Broader Trial Evidence
The safety profile of the combination aligned with the known profiles of the individual drugs. Grade 3 or higher treatment-related adverse events occurred in 20.9% of combination patients compared to 10.8% on monotherapy.
Cytokine release syndrome occurred in 49.6% of patients, presenting predominantly as Grade 1 or 2 events, with zero Grade 4 or greater occurrences. That is the kind of side effect profile oncologists can work with.
The broader program has been building a case for a while. In the Phase 1b DeLLphi-303 study, first-line maintenance produced a median overall survival of 37.9 months.
In the Phase 3 DeLLphi-304 trial for previously treated patients, the therapy extended median survival by five months over chemotherapy, cutting death risk by 38%.
Price Action: AstraZeneca shares were up 0.10% at $171.67 and Amgen shares were up 0.79% at $442.72 during premarket trading on Monday, according to market data.
