KEY TAKEAWAYS
- The POSEIDON phase III trial aimed to characterize the clinical characteristics and outcomes of patients achieving PFS.
- Patient characteristics and outcomes, including ORR, DoR, OS, and safety, were compared between PFS ≥12 months and PFS <12 months subgroups.
- T+D+CT showed significantly better long-term benefit (PFS ≥12 months) vs. CT alone, with improved ORR, DoR, and OS.
The POSEIDON study found that adding a limited course of tremelimumab to durvalumab and chemotherapy significantly improved both progression-free survival (PFS) and overall survival (OS) in patients with first-line EGFR/ALK wild-type metastatic non-small cell lung cancer(NSCLC). Researchers aimed to characterize the clinical characteristics and outcomes of patients achieving PFS.
Patients were randomly assigned in a 1:1:1 ratio to receive first-line treatment with T+D+CT, D+CT, or CT. Exploratory subgroup analyses employed a preliminary threshold of PFS ≥12 months to identify the long-term clinical benefits. The study evaluated patient demographics, clinical characteristics, ORR, duration of response (DoR), OS, and safety in subgroups based on PFS duration (≥12 months vs. <12 months).
Among the patients randomized to T+D+CT, D+CT, and CT (338, 338, and 337, respectively), 16.6%, 15.7%, and 6.8% had PFS ≥12 months. Across all arms, the PFS <12 months subgroup exhibited higher percentages of squamous histology and liver metastases compared to the PFS ≥12 months subgroup.
In the PFS ≥12 months subgroup of the T+D+CT arm, there was a lower percentage of patients with PD-L1 tumor cell expression <1% compared to other arms. Patients in the T+D+CT arm with PFS ≥12 months demonstrated improved ORR (80.4% vs. 30.5%), median DoR (not reached vs. 5.7 months), and 2-year OS rates (89.1% vs. 21.6%) compared to the PFS <12 months subgroup.
Researchers highlighted that cross-arm comparisons should be approached cautiously due to possible bias post-randomization. Safety data for the PFS ≥12 and <12 months subgroups are yet to be presented.
The study found that long-term clinical benefit (PFS ≥12 months) was significantly higher with T+D+CT compared to CT alone in POSEIDON, with favorable ORR, DoR, and OS outcomes.
Source: https://cattendee.abstractsonline.com/meeting/10925/presentation/2256
Clinical Trial: https://clinicaltrials.gov/study/NCT03164616
Cho BC, Diaz Perez I, Lowery C, Szadkowski L, Peters S, Garon EB, Mok T, Johnson ML; on behalf of the POSEIDON investigators. Durvalumab ± Tremelimumab + Chemotherapy in 1L Metastatic NSCLC: Characterization of patients with PFS ≥12 months in POSEIDON.
