Adding tarlatamab to durvalumab extended median overall survival to 21.1 months from 12.7 months in a phase 3 trial of extensive-stage small cell lung cancer, according to results released on October 24. Dana-Farber Cancer Institute said Jacob Sands presented the DeLLphi-305 findings at the ESMO Congress in Madrid. The analysis was a planned interim assessment.
The randomized, open-label trial enrolled 563 patients whose disease had not progressed after initial durvalumab, platinum chemotherapy and etoposide. They received either the two-drug combination or durvalumab alone as maintenance treatment. Dana-Farber explained that tarlatamab brings immune T cells close to cancer cells by targeting CD3 and DLL3 proteins, helping the immune system attack the tumour.
AstraZeneca reported a 58% relative reduction in the hazard of death after approximately 16 months of median follow-up, with a hazard ratio of 0.42 and a 95% confidence interval of 0.32–0.54. Estimated one-year survival was 79% with the combination and 53% with durvalumab alone. Those figures describe outcomes in the trial population, rather than a guaranteed benefit for an individual patient.
Disease control also improved. According to AstraZeneca, median progression-free survival was 7.4 months with the combination versus 1.9 months with durvalumab alone. This measures time without cancer worsening or death. The findings support investigating earlier use of tarlatamab in an aggressive disease, but remain results from a specific maintenance-treatment population.
The benefit came with additional toxicity. Amgen reported treatment-related adverse events of grade 3 or higher in 20.9% of combination recipients versus 10.8% of the comparison group. Cytokine release syndrome occurred in 49.6% of combination recipients, predominantly at grade 1 or 2. Monitoring and management of these effects are therefore part of assessing the regimen's practical use.
Amgen sponsors the study, with partial funding and durvalumab supplied by AstraZeneca. Dana-Farber said tarlatamab already has US approval for a later treatment line; these new results concern earlier maintenance use. Amgen said it plans to share the data with regulators worldwide. The announcement reports trial evidence and does not itself establish a new regulatory approval.
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