Brief Report: Long-Term Follow-Up of Adjuvant Pembrolizumab After Locally Ablative Therapy for Oligometastatic NSCLC

Introduction: Patients with oligometastatic non-small cell lung cancer (NSCLC) benefit from locally ablative therapies (LAT); the role of adjuvant systemic therapies, however, remains less clear.In a single-arm Phase II clinical trial, we demonstrated that patients with oligometastatic NSCLC treated with a year of pembrolizumab following LAT had superior progression free survival (PFS) compared to a historical control cohort.Herein, we present long term follow-up on PFS and overall survival (OS).Methods: From February 1, 2015 through September 30, 2017, 45 patients with synchronous or metachronous oligometastatic ( 4 metastatic sites) NSCLC treated with LAT to all sites received adjuvant pembrolizumab every 21 days for up to 16 cycles.The primary efficacy endpoint was PFS from the start of pembrolizumab.Secondary endpoints included OS and safety.Median duration of follow-up was 66 months, and data cutoff was December 1, 2022.Results: 45 patients were enrolled and treated with pembrolizumab following LAT (median age, 64 years range, 46-82; 21 women 47%; 31 69% with a solitary oligometastatic site).At the data cutoff, 32 patients had progressive disease, 19 patients had died, and 13 patients had no evidence of relapse.Median PFS was 19.7 months (95% CI, 7.6-31.7 months); median OS was not reached (95% CI, 37.7 months-NR).OS at 5 years was 60.0% (SE, 7.4%).Metachronous oligometastatic disease was significantly associated with improved OS and PFS via Cox proportional-hazard models.Conclusions: Pembrolizumab following LAT for oligometastatic NSCLC results in promising PFS and OS with a tolerable safety profile.