Liz Meszaros, MDLinx | July 15, 2019
In patients with stage III unresectable non-small cell lung cancer (NSCLC) with no disease progression following platinum-based chemoradiation therapy (CRT), durvalumab brought about superior long-term clinical benefits compared with placebo, with durable and sustained benefits in overall survival (OS), according to researchers. They presented their results from a 3-year OS update of the PACIFIC trial at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting, held May 31-June 3, in Chicago, IL.
Specifically, durvalumab conferred a 31% reduction in the risk of death in these patients compared with placebo. These results make durvalumab the only immunotherapy to date to demonstrate OS at 3 years in this patient population. Based on these results, the researchers recommend that the PACIFIC regimen become the standard of care for this specific patient population.
“In the past, patients with unresectable, stage III [NSCLC] faced 5-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 3 years, an important milestone that raises the bar for treatments in this curative-intent setting,” said lead author Jhanelle Gray, MD, director, Clinical Research, Thoracic Oncology Department, Moffitt Cancer Center, Tampa, FL.
The phase 3 PACIFIC trial is a multicenter, randomized, double-blind, placebo-controlled study that included 709 patients from 235 centers in 26 countries, who had unresectable, stage III NSCLC with no disease progression after platinum-based CRT.
Patients were randomized (2:1) to treatment with durvalumab (10 mg/kg IV every 2 weeks; n = 473) or placebo (n = 236) for up to 12 months.
Previously, Dr. Gray and colleagues had found significant improvements in patients treated with durvalumab compared with placebo in progression-free survival (HR: 0.52; 95% CI: 0.42–0.65; P < 0.0001) as well as in OS (HR: 0.68; 95% CI: 0.53–0.87; P = 0.00251). In addition, 12-month OS was 83.1% with durvalumab compared with 74.6% with placebo, and at 24 months, 66.3% vs 55.3%, respectively.
In this updated analysis of 3-year OS rates, Dr. Gray and colleagues found that additional results were consistent with previous findings (stratified HR: 0.69; 95% CI: 0.55-0.86). At 36 months, OS was 57.0% with durvalumab vs 43.5% with placebo. Median OS remained unreached because over 50% of patients treated with durvalumab were alive at the time of the analysis.
Upon treatment discontinuation, only 43.3% of patients treated with durvalumab went on to receive further anticancer treatment compared with 57.8% of placebo-treated patients. Immunotherapy comprised this additional treatment in 9.7% vs 26.6%, respectively.
“Updated OS data from PACIFIC, including 3-year survival rates, underscore the long-term clinical benefit with durvalumab following CRT and further establish the PACIFIC regimen as the standard of care in this population,” concluded Dr. Gray and fellow researchers.