Positive results from the POSEIDON Phase III trial showed AstraZeneca’s Imfinzi (durvalumab) and tremelimumab, when added to platinum-based chemotherapy, demonstrated a statistically significant and clinically meaningful improvement in overall survival (OS) and progression-free survival (PFS)...combinations that have the potential to improve efficacy in patients with lower PD-L1 expression and deliver the long-term survival benefits that have been observed with CTLA-4 inhibition.

In POSEIDON, the addition of T to D+CT extended clinical benefit to patients with PD-L1 TC <1% across both histologies, consistent with the role of CTLA-4 and PD-(L)1 checkpoints in the immune response. This has particular relevance for a subgroup with hard-to-treat disease and outcomes that can be suboptimal in clinical practice with currently available treatment options.

In this exploratory analysis, first-line durvalumab + tremelimumab showed a trend towards improved OS versus chemotherapy in Chinese patients with metastatic NSCLC, both in the PD-L1 TC <1% subset and in the ITT population. Both 24-month OS rates and 12-month PFS rates favoured durvalumab + tremelimumab, indicating benefit in the tails of the survival curves with this regimen. Durvalumab + tremelimumab was well tolerated in chinese patients with no new safety signals.