- Long-term data from PACIFIC Phase III trial at ASCO showed 33% of patients remained progression-free at five years
- Longest-ever survival reported in a Phase III immunotherapy trial in this setting
Updated results from the positive PACIFIC Phase III trial showed AstraZeneca’s Imfinzi (durvalumab) demonstrated a sustained, clinically meaningful overall survival (OS) and progression-free survival (PFS) benefit at five years in patients with unresectable, Stage III non-small cell lung cancer (NSCLC) who had not progressed following concurrent chemoradiation therapy (CRT).
Lung cancer is the leading cause of cancer death accounting for about one-fifth of all cancer deaths, and 80-85% of patients with lung cancer have NSCLC. One in four patients with NSCLC are diagnosed at Stage III, where the majority of tumours are unresectable (cannot be removed with surgery).4,5 The approval of Imfinzi in this setting based on the results of this trial was the first new treatment to be available to these patients in decades.
Results from the updated post-hoc analyses showed an estimated five-year OS rate of 42.9% for patients treated with Imfinzi versus 33.4% for those on placebo after CRT. Median OS was 47.5 months for Imfinzi versus 29.1 for placebo. Following a maximum treatment course of one year, an estimated 33.1% of patients treated with Imfinzi had not progressed five years after enrolment versus 19% for placebo. These results build on the primary PFS and OS analyses published in The New England Journal of Medicine in 2017 and 2018, which demonstrated a sustained, significant benefit with Imfinzi for these primary endpoints.
David Spigel, MD, Chief Scientific Officer at the Sarah Cannon Research Institute, and investigator in the PACIFIC trial, said: “This trial has once again set a new precedent in the treatment of patients with unresectable, Stage III non-small cell lung cancer. Historically, only 15-30% of these patients survived five years but these results show that with up to one year of treatment with Imfinzi, an estimated 43% of patients are still alive at five years. Moreover, three quarters of these patients had also not progressed in that time. This is a momentous achievement at the five-year landmark in this curative-intent setting.”
Dave Fredrickson, Executive Vice President, Oncology Business Unit, said: “Five-year survival is a clinically significant and emotionally meaningful milestone for people with cancer and their families, and it’s incredible to see the majority of patients surviving that long have not progressed four years after completing treatment. These results – the first of their kind in Stage III unresectable lung cancer – reinforce the long-term benefit of Imfinzi as the established standard of care in this curative-intent setting. With trials like PACIFIC and our comprehensive development programme in early-stage disease across cancer settings, our strategy is to improve cancer outcomes by treating patients as early as possible, aiming to deliver life-changing treatments that increase the potential for cure.”
In the primary OS analysis of the PACIFIC Phase III trial, the most common adverse events (AEs) (greater than or equal to 20%) among patients treated with Imfinzi versus placebo were cough (35.2% versus 25.2%), fatigue (24.0% versus 20.5%), dyspnoea (22.3% versus 23.9%) and radiation pneumonitis (20.2% versus 15.8%). A grade 3 or 4 AE was experienced by 30.5% of patients treated with Imfinzi versus 26.1% for placebo, and 15.4% of patients discontinued treatment due to AEs with Imfinzi versus 9.8% for placebo.
These results were presented on 4 June during the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting.
Imfinzi is approved in the curative-intent setting of unresectable, Stage III NSCLC after CRT in the US, Japan, China, across the EU and in many other countries. Since the first approval in February 2018, more than 80,000 patients in this setting have been treated with Imfinzi.
AstraZeneca has several ongoing registrational trials focused on testing Imfinzi in earlier stages of lung cancer, including in potentially curative settings (PACIFIC-2, 4 and 5, MERMAID-1 and 2, AEGEAN, ADJUVANT BR.31, and ADRIATIC Phase III trials). The Company is also testing novel combinations with Imfinzi in two Phase II platform trials in the Stage III unresectable setting (COAST) and neoadjuvant early-stage setting (NeoCOAST).