The time to initiate durvalumab treatment following chemoradiation was delayed in the real-world setting trial PACIFIC-R (NCT02125461) compared with the earlier phase 3 PACIFIC trial.
The time to initiate durvalumab (Imfinzi) treatment following chemoradiation (CRT) was delayed in the real-world setting trial PACIFIC-R (NCT02125461) compared with the earlier phase 3 PACIFIC trial. Results of the current study were presented during the European Lung Cancer Virtual Congress 2021 in March.1
Results showed that the median time from completing radiation (RT) to starting durvalumab therapy was 52 days in patients with non–small cell lung cancer (NSCLC); 35% of patients began durvalumab within 42 days. The shortest amount of time to durvalumab occurred in France (39 days), and the longest was in Israel (89 days).
“This is important because the exploratory analysis of the PACIFIC trial highlighted that those who started treatment with durvalumab within 14 days of radiotherapy had improved efficacy compared with those who started after 14 days following completion of radiotherapy,” said Fiona McDonald, MD, MA, MBBS, a consultant clinical oncologist at The Royal Marsden NHS Foundation Trust in London, England, in a virtual presentation during the meeting.
Additional findings showed that 76.8% of patients had received concurrent CRT whereas 14.6% received sequential CRT; 8.6% of patients received a regimen listed as “other.”
The most common adverse event (AE) of special interest in the first 3 months observed in patients on durvalumab was pneumonitis (10.6%), which led to treatment discontinuation in 4.8% of patients. Endocrinopathy also was observed (6.8%).
In February 2018, the FDA approved durvalumab as a treatment for patients with unresectable stage III NSCLC whose disease has not progressed following concurrent platinum-based chemotherapy and radiation therapy.
The decision was based on interim results of the PACIFIC trial in which the addition of durvalumab led to a median progression-free survival (PFS) of 16.8 vs 5.6 months with placebo (HR, 0.52; 95% CI, 0.42-0.65; P < .0001).2 The 12-month PFS rates were 55.9% and 35.3% with durvalumab and placebo, respectively, and the 18-month PFS rates were 44.2% and 27.0%, respectively.
In 4-year findings of the PACIFIC trial, the median overall survival (OS) was 47.5 months with durvalumab vs 29.1 months with placebo (HR, 0.71; 95% CI, 0.57-0.88).3 Additionally, the 4-year OS rates were 49.6% and 36.3% with durvalumab and placebo, respectively. The PFS rates were 35.3% and 19.5%, respectively. At the 2021 ASCO Annual Meeting, 5-year results showed that 43% of certain patients with nonsmall cell lung cancer (NSCLC) were alive after 5 years and 33% who received the immunotherapy had no advancing disease.
Post Hoc Analysis
In a post hoc analysis of PACIFIC, researchers looked at the impact of PFS on time from RT to randomization of treatment (< 14 days or ≥ 14 days). In the less-than-14-day cohort, the median PFS was not reached with durvalumab compared with 4.8 months with placebo (HR, 0.39; 95% CI, 0.26-0.58). For patients who were treated longer than 14 days after RT, the median PFS was 14.0 months and 5.6 months for durvalumab and placebo, respectively (HR, 0.63; 95% CI, 0.49-0.80).4
McDonald noted that insights on treatment and clinical outcomes for patients receiving immunotherapy in a real-world setting are needed.
Study In the international, observational PACIFIC-R study, investigators sought to explore the efficacy of durvalumab in a real-life study. The data presented at the European Lung Cancer Virtual Congress 2021 comprised baseline characteristics of the full cohort of patients enrolled on the trial and preliminary safety results.
Patients were eligible for enrollment, which occurred between September 2017 and September 2018, if they had unresectable stage III NSCLC, regardless of PD-L1 expression, and had no evidence of progression following definitive concurrent or sequential CRT.
“Following [European Medicines Agency] approval, the restriction in the last few months was to those who had a PD-L1 expression of at least 1%,” McDonald noted, adding that in France all patients had to have concurrent CRT.
Durvalumab was administered at 10 mg/kg intravenously every 2 weeks within 12 weeks of CRT, except in France, where the PD-L1 inhibitor had to be given within 6 weeks of treatment. Data were extracted from all patients’ medical records for retrospective data collection at varying time points.
The primary end point was investigator- assessed PFS and OS; secondary end points included demographics, disease characteristics, prior therapy, PFS/OS in subgroups, and AEs of special interest.
A total of 1193 patients were enrolled across 254 sites in 10 participating countries, 1155 of whom were eligible and included in the full analysis set (FAS). Patients were from France (n = 342), Australia (n = 165), the Netherlands (n = 155), Belgium (n = 118), Italy (n = 116), Israel (n = 92), Germany (n = 62), United Kingdom (n = 54), Norway (n = 36), and Switzerland (n = 5).
At baseline, notable comorbidities were hypertension (30.7%), chronic obstructive pulmonary disease (25.2%), diabetes (12.8%), and cardiovascular disease (12.6%).
In the total FAS population, the median age was 65.0 years (range, 26-88), most patients (64.9%) were male, and 65.0% of patients were former smokers. The majority (94.7%) of patients received a diagnosis of stage III NSCLC as their initial diagnosis, and more than half (57.5%) had adenocarcinoma histology. Patients had an ECOG performance status of 0 (50.7%), 1 (47.7%), 2 (1.5%), or 3 (0.1%).
McDonald noted that there were no significant differences in baseline characteristics between the concurrent and sequential CRT cohorts, except for those who were 70 years or older (28.4% on concurrent CRT vs 37.3% on sequential CRT) and longest dimension of primary tumor (15.8 mm vs 25.2 mm, respectively).
Additionally, 68.6% of patients were tested for PD-L1 expression. Most of those tested (72.5%) had PD-L1 expression of at least 1%, compared with 17.4% who had PD-L1 expression of less than 1%, and 10.1% of patients whose PD-L1 expression levels were not reported. No significant differences in baseline characteristics by PD-L1 expression level were noted, McDonald said.
The overall median total RT dose was 65 Gy; 85.0% of patients received a total median dose of 60 Gy to 66 Gy and 9.8% of patients received less than 60 Gy. The overall median RT duration was 6.4 weeks; this was found to be shortest in the Netherlands (5.1 weeks) and longest in France and Germany (7.0 weeks).
Platinum-based chemotherapy regimens also varied by country. Vinorelbine was preferred in France (43.6%), Germany (41.9%), and the United Kingdom (42.6%), whereas paclitaxel was used more frequently in Australia (49.1%) and Israel (54.3%). Etoposide was the most-used option in Norway (80.6%), Belgium (41.5%), and the Netherlands (29.7%).
The median duration of chemotherapy was 7.1 weeks overall; it was shortest in Norway at 3.4 weeks and longest in France at 10.1 weeks. McDonald explained that the proportions between concurrent and sequential CRT were similar in Italy, and all patients in Norway had received concurrent CRT.
Other AEs of special interest included rash/ dermatitis (4.8%). Diarrhea/colitis/intestinal perforation (2.9%) also were common but unlikely to lead to treatment interruption or discontinuation.
Future analyses of this real-world study will focus on PFS and OS outcomes, as well as duration of durvalumab treatment, McDonald concluded.