Imfinzi Still Improving Survival Rates in Advanced NSCLC Patients, PACIFIC Update Shows

AstraZeneca‘s Imfinzi (durvalumab) continues to demonstrate superior overall survival compared to placebo when given to patients with stage III, inoperable non-small-cell lung cancer (NSCLC) whose disease did not progress after platinum-based chemotherapy and radiation therapy.

That finding comes from the three-year data update of the company’s  randomized, blinded PACIFIC Phase 3 trial (NCT02125461). The results were shared during a poster presentation, “Three-year overall survival update from the PACIFIC trial,” at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting, May 31–June 4 in Chicago, Illinois.

Imfinzi is a human antibody that binds the PD-L1 protein on cancer cells and blocks its interaction with two other proteins PD-1 and CD80, preventing tumors from evading immune attacks.

The treatment is already approved in more than 45 countries — including those of the European Union, the United States, Canada, Japan, India, and Brazil — for inoperable stage III NSCLC patients whose disease has not progressed following concurrent platinum-based chemotherapy and radiation therapy, based on data from PACIFIC.

PACIFIC was designed to test Imfinzi versus placebo in this patient population, regardless of their PD-L1 status — a marker of responses to immune checkpoint inhibitors like Imfinzi. It included 713 patients across 26 countries, randomized to receive Imfinzi or placebo every two weeks for up to one year.

Previous data from the PACIFIC trial had demonstrated that Imfinzi significantly extended the time to disease progression or death and prolonged overall survival compared with placebo, meeting both of its primary goals.

In December 2018, researchers reported that 66.3% of patients on Imfinzi lived past the two-year mark in the PACIFIC trial, compared to 55.6% of those on placebo. This meant that Imfinzi reduced the risk of death by 32%.

The update presented at the meeting included data collected after a median follow-up of 33 months, and showed that its survival benefits remained consistent, maintaining a 31% reduction in the risk of death compared to the placebo.

After three years of follow-up, researchers reported that 57% of patients on Imfinzi were alive, compared to 43.5% of those on placebo. Also, patients on placebo lived a median of 29.2 months, but the median overall survival for those on Imfinzi could not be estimated because more than half the patients were alive at the time of the analysis.

Among those who discontinued treatment for some reason, fewer patients on Imfinzi received a subsequent anti-cancer treatment (9.7% versus 26.6%).

”These findings for Imfinzi are another example of our focus on bringing long-term survival benefits to patients who still have a chance of being cured. These three-year survival results further establish the PACIFIC regimen as the standard of care for these patients, and we are optimistic that this survival trend will continue as we move towards the five-year landmark in this curative-intent setting,” Dave Fredrickson, said in a press release. Fredrickson is the executive vice president of Oncology Business at AstraZeneca.

“In the past, patients with unresectable [inoperable], Stage III non-small cell lung cancer faced five-year survival rates of only 15 to 30%. It is remarkable to see more than half of the patients treated with the PACIFIC regimen alive after three years, an important milestone in this curative-intent setting,” said PACIFIC trial researcher Jhanelle Gray. Gray is director of Clinical Research in the Thoracic Oncology Department at Moffitt Cancer Center in Tampa, Florida.