Seldom has a clinical trial in oncology yielded such striking results. Amgen announced that its immunotherapy Imdelltra, combined with AstraZeneca's Imfinzi, reduced the risk of death by 58% in patients with extensive-stage small cell lung cancer. The data were presented at the European Society for Medical Oncology Congress 2026 and simultaneously published in The New England Journal of Medicine. This aggressive form of cancer spreads rapidly beyond the lung and has long been considered exceptionally difficult to treat.
The Phase 3 DeLLphi-305 trial demonstrated that the drug combination extended median overall survival to 21.1 months. By contrast, patients receiving Imfinzi alone survived a median of 12.7 months. The combination also lowered the risk of disease progression or death by 66%, with median progression-free survival reaching 7.4 months versus 1.9 months. Furthermore, nearly 80% of patients on the combination were alive at one year, compared with only 53% on Imfinzi alone.
What distinguishes this therapeutic approach is its innovative mechanism. Imdelltra is a first-in-class targeted immunotherapy that binds to a protein called DLL3 on tumour cells and CD3 on immune cells. This dual binding activates the body's own immune system to attack cancer cells directly. The trial tested the combination as maintenance therapy after patients completed initial chemotherapy and immunotherapy. Crucially, benefits were observed across all patient subgroups, including those with brain or liver metastases.
Small cell lung cancer constitutes approximately 15% of the 2.4 million annual lung cancer diagnoses worldwide. Its five-year survival rate stands at a mere 7%, underscoring the severity of this malignancy. For decades, treatment options remained largely stagnant, with minimal therapeutic advancements. The unprecedented magnitude of these trial results has therefore been characterised as a watershed moment in oncology.
Amgen intends to submit the findings to regulatory authorities globally, though no specific timeline has been disclosed. Imdelltra already holds approval in more than 15 markets for later-stage small cell lung cancer. Should regulators grant expanded approval, the combination could become the new standard of care. The implications extend beyond individual patient outcomes, potentially altering the broader paradigm of how clinicians approach this formidable disease.
