Checkpoint inhibition for consolidation after chemoradiotherapy (CRT) showed promising survival benefit in patients with unresectable stage III non–small cell lung cancer (NSCLC) in two recent studies, including one looking at the investigational agent sugemalimab and one assessing durvalumab in a real-world setting.
Statistically significant and clinically meaningful improvement in progression-free survival (PFS) was observed with sugemalimab versus placebo in the randomized, phase 3 GEMSTONE-301 study, and consolidation durvalumab showed effectiveness in a real-world cohort in the PACIFIC-R study.
Findings from both studies were presented at the 2021 European Society for Medical Oncology Congress.
GEMSTONE-301
Median progression-free survival among 381 patients randomized 2:1 to receive 1,200 mg of sugemalimab or placebo every 3 weeks after either concurrent or sequential chemoradiotherapy was 9.0 versus 5.8 months, in the treatment arms, respectively (hazard ratio, 0.64) (Abstract LBA43), reported Yi-Long Wu, MD, of Guangdong Lung Cancer Institute, Guangdong Provincial People’s Hospital, Guangzhou, China.
Patients were recruited from 50 sites, and one-third had received sequential CRT. Progression-free survival was assessed at median follow up of 14 months.
“The 12- and 18-month PFS rates were 45% vs. 26% and 39% vs. 23%, respectively,” Dr. Wu said.
Of note, the PFS benefit was observed both for patients who underwent sequential CRT (median PFS, 8.1 vs. 4.1 months with sugemalimab vs. placebo; hazard ratio, 0.59) and for those who received concurrent CRT (median PFS, 10.5 vs. 6.4 months; HR, 0.66).
Overall survival (OS) data were not mature at the time of the presentation, but a trend favoring sugemalimab was observed (HR, 0.44) he noted.
Sugemalimab, an investigational anti–programmed death-ligand 1 (PD-L1 )monoclonal antibody, was well tolerated; grade 3 or higher treatment-emergent adverse events (AEs) occurred in 24.3% of patients in the sugemalimab group and in 23.8% in the placebo group.
Concurrent chemoradiotherapy followed by immunotherapy is the standard of care for patients with unresectable stage III NSCLC, but nearly half undergo sequential CRT because they can’t tolerate concurrent treatment, Dr. Wu explained, describing the rationale for the study – the first phase 3 trial looking at both concurrent and sequential CRT in this patient population.
The results provide evidence for sugemalimab as a consolidation treatment for those who did not progress following either approach to CRT, he concluded.
PACIFIC-R study
The large, international, observational PACIFIC-R study also looked at consolidation in a real-world setting, and confirmed a PFS benefit with durvalumab in stage III NSCLC patients who had completed concurrent or sequential platinum-based CRT within the previous 12 weeks without evidence of disease progression (Abstract 1171MO).
“The median real-world PFS in this cohort was 21.7 months, which is higher than that in the durvalumab arm in the PACIFIC trial, which was 16.9 months,” reported Nicolas Girard, MD, a professor at Institut Curie, Paris.
The PACIFIC trial set the standard for durvalumab-based consolidation after CRT, and ongoing survival benefit was confirmed by 5-year follow-up data, he noted.
The PACIFIC-R trial included 1,399 patients from 11 countries who were treated as part of an expanded-access program following the PACIFIC trial.
Median time to durvalumab initiation after the end of radiotherapy in the cohort was 56 days. Overall median durvalumab treatment duration was 11 months, and the median number of infusions was 22, Dr. Girard said.
Pneumonitis was the most common adverse event leading to discontinuation: 214 (18.5%) patients experienced any-grade pneumonitis and/or interstitial lung disease, and 9.5 discontinued the study as a result. Most cases were mild or moderate, he said.
Subgroup analyses showed that real-world PFS was higher among patients with stage IIIa disease and those with PD-L1–positive tumors, those with nonsquamous disease histology, and those who received concurrent CRT.
“For example, in those with stage IIIa disease, the median real-world PFS was 23.7 months versus 19.2 months in patients with stage IIIb and c disease,” he said.
“PACIFIC-R demonstrated the efficacy of durvalumab consolidation in patients with unresectable stage III non–small cell lung cancer after completion of chemoradiotherapy,” said Dr. Girard. “The effectiveness of durvalumab was consistent among key subgroups, as was safety, when comparing the data with that of PACIFIC.
“The future read-outs of OS will further provide insight into the effectiveness of this regimen.”
Session chair Lizza E. Hendriks, MD, PhD, of Maastricht (the Netherlands) University, applauded the inclusion of patients undergoing sequential CRT in the GEMSTONE-301 and PACIFIC-R studies, noting that it is “very important to have data in sequential radiochemotherapy populations” given the substantial number of patients who require a sequential approach because of poor performance status, difficulty tolerating concurrent CRT, or logistical reasons, such as an inability to travel to receive concurrent CRT.
The GEMSTONE-301 study was funded by CStone Pharmaceuticals. Dr. Wu reported having no disclosures. The PACIFIC-R study was funded by AstraZeneca. Dr. Girard reported financial relationships with AstraZeneca, Bristol Myers Squibb, and Merck Sharp & Dohme. Dr. Hendriks reported financial relationships with numerous companies.