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

Introduction: Patients with oligometastatic 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 found that patients with oligometastatic NSCLC treated with a year of pembrolizumab after LAT had superior progression-free survival (PFS) compared with a historical control cohort. Herein, we present long-term follow-up on PFS and overall survival (OS).

Methods: From February 1, 2015, to 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 end point was PFS from the start of pembrolizumab. Secondary end points included OS and safety. Median duration of follow-up was 66 months, and data cutoff was December 1, 2022.

Results: A total of 45 patients were enrolled and treated with pembrolizumab after LAT (median age, 64 y [range, 46-82]; 21 women [47%]; 31 with a solitary oligometastatic site [69%]). 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% confidence interval: 7.6-31.7 mo); median OS was not reached (95% confidence interval: 37.7 mo-not reached). OS at 5 years was 60.0% (SE, 7.4%). Metachronous oligometastatic disease was associated with improved OS and PFS through Cox proportional hazard models.

Conclusions: Pembrolizumab after LAT for oligometastatic NSCLC results in promising PFS and OS with a tolerable safety profile.