Oncology · Medical Literature
Sequential chemo-immunotherapy followed by standard versus reduced thoracic radiotherapy for older and/or frail stage III non-small-cell lung cancer: A randomized open-label cohort trial.
Abstract
The appropriateness of concurrent chemoradiotherapy (cCRT) for older or clinically vulnerable stage III unresectable non-small-cell lung cancer (NSCLC) patients remains contentious. Furthermore, the survival implications of de-escalating thoracic radiotherapy (RT) intensity in this population have not been conclusively elucidated. We conducted a phase II randomized, open-label, two-cohort (non-comparative) trial at a tertiary hospital in China (NCT05557552). Between September 30, 2022 and April 30, 2024, we enrolled 56 older and/or frail patients with stage III NSCLC who were ineligible for cCRT. The primary endpoint was the 1-year progression-free survival (PFS) rate estimated using the Kaplan-Meier method. Secondary endpoints included objective response rate (ORR), overall survival (OS), and safety. In the intention-to-treat (ITT) set, which included all 56 randomized patients who received at least one dose of study treatment, the 1-year PFS was 84.3% (95% confidence interval [CI] [70.3%, 98.3%]) in the standard RT group and 70.7% (95% CI [54.3%, 87.1%]) in the reduced RT group. In the per-protocol set (53 patients), the 1-year PFS was 82.9% (95% CI [68.9%, 98.8%]) in the standard RT group and 73.4% (95% CI [58.3%, 92.4%]), with a median follow-up of 24 months. Among 56 patients in the safety analysis set, 71.4% of patients experienced grade 3/4 adverse events (AEs) in the standard RT group and 53.6% in the reduced RT group. One patient (3.6%) in the reduced RT and three patients (10.7%) in the standardized RT experienced grade 5 AEs. The main limitations are the non-comparative design, small sample size, and lack of power to establish non-inferiority or superiority. The current study suggested that reduced RT combined with sequential chemo-immunotherapy might be feasible for older/frail patients intolerant to cCRT, showing numerically similar survival outcomes. These exploratory findings warrant confirmation in larger, adequately powered randomized trials. The trial had been registered on ClinicalTrials.gov on Sep 30, 2022. ClinicalTrials.gov NCT05557552.
Clinical relevance
In older and/or frail patients with unresectable stage III NSCLC who are ineligible for concurrent chemoradiotherapy, does sequential induction chemo-immunotherapy followed by reduced-dose thoracic radiotherapy (50 Gy/25 fractions) plus immune checkpoint inhibitor (ICI) maintenance provide comparable 1-year progression-free survival to the same regimen using standard-dose radiotherapy (60 Gy/30 fractions)? __SNAPSHOT__ {"studyDesign":"Phase II randomized, open-label, two-cohort non-comparative trial (Simon's two-stage design; cohorts assessed independently against a historical control threshold, not head-to-head)","setting":"Single tertiary hospital, China (NCT05557552)","sampleSize":"n=56 (standard RT [Cohort A]: n=28; reduced RT [Cohort B]: n=28); per-protocol set: n=53","population":"Older and/or frail patients with unresectable stage III NSCLC deemed ineligible for concurrent chemoradiotherapy (cCRT); excluded prior chemo-, immuno-, or radiotherapy for NSCLC; excluded autoimmune disease, immunodeficiency, active malignancy, leptomeningeal carcinomatosis, and immunosuppressive medication use. Only patients with confirmed CR, PR, or SD after 4–6 induction cycles were eligible for secondary registration (radiotherapy phase).","intervention":"4–6 cycles of induction platinum-doublet chemotherapy plus an immune checkpoint inhibitor (ICI), followed by thoracic radiotherapy at 50 Gy in 25 fractions (reduced dose, Cohort B) with concurrent ICI, then ICI maintenance for at least 6 months (8 cycles) or until progression/unacceptable toxicity/death","comparator":"Same induction regimen followed by standard thoracic radiotherapy at 60 Gy in 30 fractions (Cohort A) with concurrent ICI, then ICI maintenance","primaryOutcome":"1-year progression-free survival (PFS) rate estimated by Kaplan–Meier method","followUp":"Median 24 months (per-protocol set)","fundingSource":"Not reported in the available abstract and publicly available study record"}
Key findings
This was a non-comparative (two-cohort) phase II trial; no formal head-to-head statistical comparison between groups was pre-specified or reported. The trial was powered to detect an improvement in 1-year PFS from a historical control rate of 20% (derived from the JCOG0301 trial of RT ± low-dose chemotherapy in older NSCLC patients) to 40% in each cohort independently. In the intention-to-treat (ITT) set (n=56), the 1-year PFS was 84.3% (95% CI: 70.3%–98.3%) in the standard RT group and 70.7% (95% CI: 54.3%–87.1%) in the reduced RT group—both substantially exceeding the pre-specified 40% historical threshold. In the per-protocol set (n=53), 1-year PFS was 82.9% (95% CI: 68.9%–98.8%) in the standard RT group and 73.4% (95% CI: 58.3%–92.4%) in the reduced RT group. Median OS was not reached in either group at the time of analysis; 9 of 27 patients (33.3%) in the reduced RT group and 3 of 26 patients (11.5%) in the standard RT group had died by end of follow-up (no formal between-group OS comparison reported; HR not reported). Objective response rate (ORR, best response in per-protocol set) was 92.6% (25/27) in the reduced RT group (14.8% complete response, 77.8% partial response) and 92.3% (24/26) in the standard RT group (7.7% complete response, 84.6% partial response). All 56 patients completed induction chemo-immunotherapy and planned thoracic radiotherapy. The median ICI maintenance duration was 6 months (95% CI: 4–12 months); 57.1% of patients completed more than 6 months of maintenance and 37.5% completed 1 year of ICI maintenance. Approximately 50% of patients in each group experienced interruptions in ICI maintenance, primarily due to pneumonitis (including radiation pneumonitis). Grade ≥3 pneumonitis (including radiation pneumonitis) occurred in 7.6% of the reduced RT group and 10.7% of the standard RT group—higher than the PACIFIC trial rate (3.4%) but comparable to the DOLPHIN trial (11.8%). Common non-hematologic grade 3/4 adverse events included pneumonitis and lung infection; specific rates and NNT/NNH for other endpoints were not reported in the available sources.
Practice implications
This phase II non-comparative trial established feasibility and preliminary efficacy of sequential chemo-immunotherapy followed by thoracic radiotherapy (either 60 Gy or 50 Gy) with concurrent and maintenance ICI in older and/or frail patients with stage III NSCLC who cannot receive standard cCRT. Both cohorts far exceeded the pre-specified 40% 1-year PFS threshold derived from historical controls, suggesting meaningful activity compared to RT alone or RT with low-dose chemotherapy in this population. Importantly, the trial was explicitly designed as non-comparative between the two RT dose groups; no definitive conclusion about the superiority or non-inferiority of reduced-dose RT (50 Gy) versus standard-dose RT (60 Gy) can be drawn. The numerically lower death count in the standard RT arm (11.5% vs. 33.3%) at final follow-up is hypothesis-generating but must be interpreted with extreme caution given the small sample size, non-comparative design, and immature OS data. The comparably high ORR (>92% in both arms) and the higher-than-anticipated 1-year PFS across both cohorts are noteworthy in this historically undertreated population. The grade ≥3 pneumonitis rates (7.6%–10.7%) are clinically meaningful in frail patients with limited respiratory reserve and exceed rates seen in the PACIFIC trial's younger, fitter cohort. Findings may not generalize beyond the single Chinese tertiary center setting; the performance status thresholds, comorbidity profiles, and specific ICI agents used may differ from practice in other health systems. Patients with active autoimmune disease, prior lung cancer therapy, or EGFR/ALK-driven NSCLC were excluded, and results do not apply to these subgroups. Only the abstract and supplementary web sources were available for this summary; additional data from the full publication may modify these interpretations. Practice should not change based on this trial alone; prospective confirmation in larger, ideally multi-center trials with pre-specified OS endpoints and formal dose-comparison arms is required. __LIMITATIONS__ Small sample size (n=56 total, 28 per cohort), limiting statistical power for any between-group comparison and for detecting rare but clinically important adverse events.,Non-comparative two-cohort design: the trial was not powered or pre-specified to test superiority or non-inferiority of 50 Gy versus 60 Gy; any between-arm comparisons are exploratory at best.,Single-center study at a tertiary hospital in China, limiting generalizability to other healthcare settings, ethnic populations, and practice environments.,Open-label design introduces performance bias, particularly in symptom-based and quality-of-life assessments.,Surrogate primary endpoint (1-year PFS rate) without a pre-specified OS co-primary endpoint; OS data are immature (median OS not reached at 24 months).,Historical control benchmark (20% 1-year PFS from JCOG0301) reflects an era predating ICI therapy and may underestimate the contemporary comparator, inflating the apparent treatment benefit.,Induction phase allowed 4–6 cycles, introducing heterogeneity in treatment intensity based on individual tolerance; specific ICI agents and chemotherapy doublets used are not detailed in the available abstract.,The numerically higher death count in the reduced RT arm (33.3% vs. 11.5%) at analysis cutoff is confounded by immature follow-up and small numbers and should not be used to infer OS inferiority of 50 Gy.,ICI maintenance interruptions in ~50% of patients may have diluted the immunotherapy benefit, and reasons for interruptions (primarily pneumonitis) indicate real-world tolerability challenges.,Funding source not reported; potential conflicts of interest cannot be assessed. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ In older and/or frail patients with unresectable stage III NSCLC ineligible for concurrent chemoradiotherapy, sequential chemo-immunotherapy followed by either standard (60 Gy) or reduced-dose (50 Gy) thoracic radiotherapy with concurrent and maintenance ICI appears feasible and yielded 1-year PFS rates (71%–84%) far exceeding historical benchmarks for this population. However, this was a small, single-center, non-comparative phase II trial that cannot establish the equivalence of 50 Gy to 60 Gy, and OS data remain immature. Larger, multi-center, confirmatory trials with formal dose-comparison arms and OS co-primary endpoints are needed before this regimen or dose de-escalation strategy can be adopted into routine clinical practice.