The trial enrolled 563 patients whose disease had not progressed after initial treatment with Imfinzi and chemotherapy, including patients with brain metastases. At a planned interim analysis, median overall survival was 21.1 months with the combination versus 12.7 months with Imfinzi alone (HR 0.42). At one year, 79% of patients on the combination were alive, compared with 53%. The combination also cut the risk of progression or death by 66%, with median progression-free survival of 7.4 months versus 1.9 months.

Grade 3–4 treatment-related side effects occurred in 20.9% of patients on the combination and 10.8% on Imfinzi alone, with no treatment-related deaths. The results were presented in the Presidential Symposium at ESMO in Madrid and published simultaneously in The New England Journal of Medicine.

Small cell lung cancer makes up about 15% of lung cancers, and about two-thirds of patients are diagnosed at the extensive stage. Imdelltra is a bispecific T-cell engager targeting DLL3. The trial was sponsored by Amgen, with AstraZeneca partially funding it and supplying Imfinzi.

Leora Horn, Senior Vice President, Late Development Oncology at AstraZeneca, says the data “further reinforce Imfinzi as the backbone immunotherapy in this setting.”