WILMINGTON, DE — AstraZeneca’s IMFINZI combined with Amgen’s tarlatamab-dlle extended median survival to 21.1 months in patients with extensive-stage small cell lung cancer, compared with 12.7 months for IMFINZI alone, according to Phase III trial results that could alter first-line maintenance treatment for one of the most aggressive forms of lung cancer.
The DeLLphi-305 study found that the combination reduced the risk of death by 58% and the risk of disease progression or death by 66%, meeting its primary and key secondary endpoints with statistically significant improvements.
The findings were presented at the European Society for Medical Oncology Congress 2026 in Madrid, Spain, and simultaneously published in The New England Journal of Medicine.
The trial evaluated patients whose cancer had not progressed following initial treatment with IMFINZI, also known as durvalumab, plus platinum-based chemotherapy and etoposide. Patients subsequently received maintenance treatment with either IMFINZI and tarlatamab-dlle or IMFINZI alone.
At a median follow-up of approximately 16 months, the combination produced a median overall survival of 21.1 months, compared with 12.7 months for the control group, an improvement of 8.4 months.
The overall survival hazard ratio was 0.42, with a 95% confidence interval of 0.32 to 0.54 and a p-value below 0.001.
An estimated 79% of patients receiving the combination were alive after one year, compared with 53% of those treated with IMFINZI alone.
The results represent the longest median overall survival reported in a Phase III trial involving extensive-stage small cell lung cancer, according to AstraZeneca.
Progression-free survival also improved substantially.
Patients receiving the combination experienced a median of 7.4 months without disease progression or death, compared with 1.9 months for patients receiving IMFINZI alone.
The progression-free survival hazard ratio was 0.34, with a 95% confidence interval of 0.28 to 0.42 and a p-value below 0.001.
At one year, an estimated 38% of patients in the combination group remained alive without disease progression, compared with 10% in the IMFINZI-only group.
The survival and disease-control benefits were consistent across all prespecified patient subgroups, including those with brain or liver metastases.
The combination also produced a confirmed objective response rate of 26.4%, compared with 4.1% for IMFINZI alone.
Among patients whose tumors responded to treatment, the median duration of response reached 12.7 months with the combination, compared with 5.6 months in the control group.
Small cell lung cancer is an aggressive disease characterized by rapid growth and a high likelihood of spreading beyond the lungs. Extensive-stage disease presents particular treatment challenges because durable responses and long-term survival have historically been difficult to achieve.
The DeLLphi-305 findings suggest that adding tarlatamab-dlle during maintenance treatment could extend the benefit of initial chemotherapy and immunotherapy in patients whose disease has not progressed.
Jacob Sands, associate chief of the Lowe Center for Thoracic Oncology at Dana-Farber Cancer Institute and international coordinating investigator for the trial, emphasized the consistency of the results across patient groups.
“For a disease where durable survival has remained extremely difficult to achieve, the magnitude and consistency of benefit in DeLLphi-305 are striking,” Sands stated.
“Importantly, the benefit was seen across clinically relevant groups, including patients with brain metastases.”
IMFINZI is AstraZeneca’s immunotherapy, while tarlatamab-dlle is a T-cell-engaging therapy developed by Amgen.
The combination represents an approach that pairs established immunotherapy with a treatment designed to engage the immune system against cancer cells.
Leora Horn, AstraZeneca’s senior vice president of late development oncology, indicated that the company sees the regimen as a potential new treatment standard for extensive-stage disease.
The findings strengthen AstraZeneca’s clinical evidence for IMFINZI-based treatment in small cell lung cancer while supporting further development of combination immunotherapy strategies.
The survival improvements establish the clinical significance of the DeLLphi-305 results, while regulatory review would determine whether the combination becomes an approved first-line maintenance treatment option.
Support the local news that supports Chester County. MyChesCo delivers reliable, fact-based reporting and essential community resources—free for everyone. If you value that, click here to become a patron today.