AstraZeneca and Amgen have reported positive high-level results from the planned interim analysis of the Phase 3 DeLLphi-305 trial, showing that Imfinzi (durvalumab) in combination with Amgen’s Imdelltra (tarlatamab) significantly improved Overall Survival (OS) compared with Imfinzi alone in patients with Extensive-Stage Small Cell Lung Cancer (ES-SCLC).

The trial evaluated patients whose disease had not progressed following first-line induction treatment with Imfinzi combined with platinum-based chemotherapy and etoposide. The combination also demonstrated statistically significant improvements in the secondary endpoints of Progression-Free Survival (PFS) and objective response rate.

The global, randomised, open-label Phase 3 trial enrolled 563 patients, who were assigned in a 1:1 ratio to receive either Imfinzi plus tarlatamab or Imfinzi alone until disease progression or unacceptable toxicity. Treatment was administered following Imfinzi-based induction therapy, with the study including patients with both treated and untreated asymptomatic brain metastases at baseline.

The safety and tolerability profile of the combination was consistent with the known profiles of the individual treatments, with no new safety signals identified. The companies said the detailed results will be presented at a forthcoming medical meeting and submitted to regulatory authorities globally.

Tarlatamab is an investigational targeted immunotherapy that binds to DLL3 on tumour cells and CD3 on T cells, activating T cells to attack DLL3-expressing small cell lung cancer cells. DLL3 is reported to be expressed on the surface of most SCLC cells while having limited expression in healthy tissue.

The DeLLphi-305 trial is sponsored by Amgen, with partial funding and Imfinzi provided by AstraZeneca. The primary endpoint is overall survival, while progression-free survival is a key secondary endpoint.

ES-SCLC is an aggressive form of lung cancer characterised by rapid tumour growth and metastatic spread. Although immune checkpoint inhibitors have improved outcomes and established new treatment standards, many patients continue to experience disease progression following initial therapy.

The positive interim results support further evaluation of the Imfinzi and tarlatamab combination as a potential first-line maintenance treatment for patients with ES-SCLC.