The durvalumab plus chemotherapy arm demonstrated a statistically significant improvement in PFS versus chemotherapy in the previous analysis, but the OS trend observed in this analysis did not achieve statistical significance.
Positive high-level results from the final analysis of the phase 3 POSEIDON trial showed the combination of durvalumab (Imfinzi, AstraZeneca), tremelimumab, and chemotherapy demonstrated a statistically significant and clinically meaningful overall survival (OS) benefit versus chemotherapy alone, according to a press release.
This immunotherapy combination also demonstrated a statistically significant improvement in progression-free survival (PFS) versus chemotherapy alone, as previously reported in October 2019. Patients in this arm were treated with a short course of tremelimumab, an anti-CTLA4 antibody, over a 16-week period in addition to durvalumab and standard chemotherapy.
The durvalumab plus chemotherapy arm demonstrated a statistically significant improvement in PFS versus chemotherapy in the previous analysis, but the OS trend observed in this analysis did not achieve statistical significance. Patients in the control arm were treated with up to 6 cycles of chemotherapy, while those in the experimental arms were treated with up to 4 cycles.
Each combination demonstrated an acceptable safety profile and no new safety signals were identified. Further, the combination with tremelimumab delivered a broadly similar safety profile to the durvalumab and chemotherapy combination and did not lead to an increased discontinuation of treatment.
“We are pleased to see the POSEIDON Phase III trial demonstrate, for the first time, a significant and clinically meaningful overall survival benefit for Imfinzi plus tremelimumab with chemotherapy in metastatic non-small cell lung cancer,” said Dave Fredrickson, executive vice president, AstraZeneca Oncology Business Unit, in the press release. “We were particularly pleased by the safety profile. We’ve seen encouraging uptake of novel combinations in this setting and believe this new approach will add a further option for patients with high unmet medical need. We look forward to discussing next steps with regulatory authorities.”
Durvalumab is the only approved immunotherapy in the curative-intent setting of unresectable, stage 3 NSCLC after chemoradiation therapy and is approved in the United States, EU, Japan, and other countries for the treatment of extensive-stage small cell lung cancer based on the CASPIAN phase 3 trial.
The combination of durvalumab and tremelimumab is being tested in lung cancer, bladder cancer, and liver cancer settings, according to the press release.
Imfinzi and tremelimumab with chemotherapy demonstrated overall survival benefit in POSEIDON trial for 1st-line Stage IV non-small cell lung cancer. AstraZeneca. Published May 7, 2021. Accessed May 14, 2021. https://www.astrazeneca.com/media-centre/press-releases/2021/imfinzi-and-tremelimumab-showed-survival-in-poseidon.html