MADRID – For patients with locally advanced, unresectable non-small cell lung cancer, consolidation therapy with the anti-programmed death ligand 1 (PD-L1) inhibitor durvalumab after chemoradiation was associated with significantly better progression-free survival (PFS) than placebo, results of an interim analysis of the phase 3 PACIFIC trial showed.
Among 713 patients with stage III NSCLC treated with definitive chemoradiotherapy, the median PFS from randomization was 16.8 months for patients assigned to durvalumab compared with 5.6 months for patients assigned to placebo, reported Luis Paz-Ares, MD, from the University of Madrid, Spain.
“Overall, we think durvalumab is a promising option for patients with stage III non-small cell lung cancer treated with chemoradiation,” he said at a briefing at the European Society of Medical Oncology (ESMO) Congress.
Approximately 25% to 30% of patients with NSCLC have locally advanced disease at the time of presentation. Patients with unresectable disease and good performance status are treated with chemoradiotheraoy consisting of a platinum doublet with concurrent radiation, but median PFS in these patients is generally short, on the order of 8 months. The 5-year overall survival (OS) rate is 15%, he said.
Given the lack of major advances in the care of patients with stage 3 disease, investigators have been looking to newer therapies such as immune checkpoint inhibitors to see whether they could improve outcomes.
PACIFIC is a phase 3 trial in which patients with stage III NSCLC who did not have disease progression after a minimum of two cycles of platinum-based chemotherapy were assigned on a 2:1 basis to receive intravenous durvalumab 10 mg/kg or placebo every 2 weeks for up to 12 months. Patients were stratified by age, sex, and smoking history.
Dr. Paz-Ares presented PFS results from the interim analysis, planned when about 367 events had occurred. Data on the co-primary endpoint of OS were not mature at the time of the data cutoff.
Median PFS from randomization according to blinded independent central review for 476 patients treated with durvalumab was 16.8 months, compared with 5.6 months for 237 patients who received the placebo. This translated into a stratified hazard ratio (HR) of 0.52 (P less than .0001).
The respective PFS rates for durvalumab and placebo, were 59.9% vs. 35.3% at 12 months, and 44.2% vs. 27% at 18 months.
Among 443 patients on durvalumab and 213 on placebo who were evaluable for objective responses (OR), the respective OR rates were 28.4% vs. 16.
There were 6 complete responses (CR), 120 partial responses (PR), and 233 cases of stable disease in the durvalumab arm, compared with one CR, 33 PR, and 119 cases of stable disease in the placebo arm. In the durvalumab arm, 73 patients (16.5%) had progressive disease, compared with 59 patients (27.7%) in the placebo arm.
The median duration of response was not reached in the durvalumab arm, compared with 13.8 months in the placebo arm.
The PD-L1 inhibitor was also associated with a lower incidence of any new lesion among the intention-to-treat population (20.4% vs. 32.1%).
Grade 3 or 4 toxicities from any cause were slightly higher with durvalumab, at 29.9% vs. 26.1%. Events leading to discontinuation were also higher with the active drug, at 15.4% vs. 9.8% for placebo.
There were 21 deaths (4.4%) of patients treated with durvalumab, and 13 deaths (5.6%) of patients treated with placebo.
“In my opinion, this is a very well-designed study, and the results are very promising,” commented Enriqueta Felip, MD, who was not involved in the PACIFIC trial.
“We need to wait for the overall survival results, but in my opinion this is a very valuable trial in a group of patients [for whom] we need new strategies,” she said.
Dr. Felip was invited to the briefing as an independent commentator.
Results of the interim analysis of the PACIFIC trial were also published online in the New England Journal of Medicine.
The PACIFIC trial was funded by AstraZeneca. Dr. Paz-Ares has received consultancy fees from the company. Dr. Felip disclosed financial relationships with multiple companies not including AstraZeneca.