Consolidative stereotactic radiotherapy for oligo-residual non-small cell lung cancer after first-line chemoimmunotherapy: A single-arm, phase 2 trial from China

Background Retrospective evidence indicated potential survival benefit of consolidative stereotactic radiotherapy (SRT) in patients with metastatic driver mutation-negative non-small cell lung cancer (NSCLC) harboring oligo-residual disease (ORD) after effective immune checkpoint inhibitor treatment. However, prospective data about consolidative SRT in this disease population after first-line chemoimmunotherapy remains scarce. Methods and findings From March 2021 to March 2023, 59 patients (94.92% males) with metastatic driver mutation-negative NSCLC harboring ORD after effective first-line chemoimmunotherapy were enrolled in this single-arm, phase 2 trial (NCT04767009), which was conducted at Fudan University Shanghai Cancer Center, Shanghai, China. The median (interquartile range) age was 64 (57,71) years. All of the patients received extracranial and/or cranial SRT covering all of the oligo-residual lesions, without holding the maintenance systemic therapy during SRT. The most common sites targeted by consolidative SRT included the lung ( n = 30), lymph nodes ( n = 26), bone ( n = 22), and brain ( n = 22). All efficacy and safety analyses followed the intention-to-treat principle with all 59 enrolled patients included. No patient was lost to follow-up. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS) and treatment-related adverse events (TRAEs). With a median follow-up of 14.8 months, the median PFS was 29.0 (90% CI [13.97, Not Reach]) months, meeting the primary endpoint. The 2-year OS rate was 88.9% (95% CI [75.9%,100%]). TRAEs of any grade and grade ≥3 occurred in 58 (98.31%) and 13 (22.03%) patients, respectively. Moreover, a prespecified propensity score-matched comparison was conducted with a contemporary cohort of patients who developed ORD but received systematic therapy alone, which found that incorporating consolidative SRT was associated with prolonged PFS (adjusted HR 0.286, P < 0.001) and OS (adjusted HR 0.229, P = 0.023). The main methodological limitation of this single-arm trial is its inability to establish causal relationships and the findings require validation in randomized controlled trials. Conclusions Consolidative SRT was associated with prolonged PFS and generally acceptable toxicities in first-line chemoimmunotherapy-treated patients with metastatic NSCLC harboring ORD, supported by propensity-matched comparisons with a contemporary cohort.