Three-year overall survival (OS) results from the Phase III PACIFIC trial of Imfinzi for Stage III non-small cell lung cancer.

AstraZeneca has presented three-year overall survival (OS) results from the Phase III PACIFIC trial of Imfinzi (durvalumab) in unresectable, Stage III non-small cell lung cancer (NSCLC) during the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. These latest results show a durable and sustained OS benefit in patients with unresectable, Stage III NSCLC who had not progressed following concurrent chemoradiation therapy (CRT), a previous standard-of-care (SoC) treatment.

The OS rate was 57% at three years for patients receiving Imfinzi vs. 43.5% for placebo following concurrent CRT. Median OS was not yet reached with the Imfinzi arm vs. 29.1 months for placebo. Results build on the primary two-year OS analysis that was published in The New England Journal of Medicine in September 2018 and demonstrated a significant OS benefit for treatment with Imfinzi vs. placebo after CRT, regardless of PD-L1 expression.

The primary analysis showed Imfinzi reduced the risk of death by 32% (HR 0.68, [99.73% CI, 0.47-0.997], p=0.0025). With the additional year of follow up, the latest results for Imfinzi showed consistent and durable efficacy, maintaining a 31% reduction in the risk of death vs. placebo after CRT (HR 0.69, [95% CI 0.55-0.86]).

Jhanelle Gray, MD, Director of Clinical Research in the Thoracic Oncology Department at Moffitt Cancer Center in Tampa, Florida, and an investigator in the PACIFIC trial, said: “In the past, patients with unresectable, Stage III non-small cell lung cancer faced five-year survival rates of only 15% to 30%. It is remarkable to see that more than half of patients treated with the PACIFIC regimen remain alive at three years, an important milestone that raises the bar for treatments in this curative-intent setting.”

The safety and tolerability profile for Imfinzi was consistent with the results reported at the time of the previous OS analysis. Among patients receiving Imfinzi, the most common adverse events (AE) (greater than or equal to 20% of patients) vs. placebo were cough (35.2% vs. 25.2%), fatigue (24.0% vs. 20.5%), dyspnoea (22.3% vs. 23.9%) and radiation pneumonitis (20.2% vs. 15.8%). 30.5% of patients experienced a grade 3 or 4 AE with Imfinzi vs. 26.1% with placebo, and 15.4% of patients discontinued treatment due to AEs with Imfinzi vs. 9.8% of patients on placebo.