Extensive-stage small-cell lung cancer: tarlatamab plus durvalumab maintenance cut deaths by more than half

Design

Phase 3, international, open-label randomised trial, interim analysis (DeLLphi-305)

Population

563 patients with extensive-stage SCLC without progression after chemoimmunotherapy

Primary outcome

Overall survival from start of maintenance

Effect

Median OS 21.1 vs 12.7 months; HR 0.42 (95% CI 0.32 to 0.54)

DeLLphi-305 was an international, open-label phase 3 trial in 563 patients with extensive-stage small-cell lung cancer whose disease had not progressed after first-line chemoimmunotherapy. They were randomised to maintenance durvalumab plus tarlatamab, a bispecific T-cell engager targeting DLL3, or durvalumab alone. This is the prespecified interim analysis.

Median overall survival was 21.1 months with the combination and 12.7 months with durvalumab alone (hazard ratio 0.42, 95% CI 0.32 to 0.54). Median progression-free survival was 7.4 against 1.9 months (0.34, 0.28 to 0.42). Grade 3 or higher adverse events occurred in 46.8% against 40.6%. Cytokine release syndrome occurred in nearly half of those receiving tarlatamab, mostly grade 1–2.

An eight-month gain in median survival in a disease where survival gains have been modest is large. Tarlatamab needs monitoring for cytokine release and neurotoxicity, which shapes where it can safely be given. Access and cost in India are likely to be the main barriers, and longer follow-up will confirm the size of the benefit.

• Discuss tarlatamab plus durvalumab maintenance for eligible patients without progression after first-line chemoimmunotherapy.
• Plan monitoring for cytokine release syndrome, especially around early doses.
• Watch for neurological toxicity during tarlatamab treatment.
• Confirm local approval and access before offering it.

Why it matters

Maintenance in small-cell lung cancer has offered little until now; this changes the conversation after first-line therapy.

Don't overread it

An interim analysis of an open-label, industry-funded trial; longer follow-up may narrow the gain.

The statistics, in plain English

A hazard ratio of 0.42 means less than half the rate of death at any point. Median survival rose from 12.7 to 21.1 months. Interim analyses can overstate effects if stopped early, so final results may be somewhat smaller.

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