3774 - Curative-Intent Chemoradiotherapy with Adjuvant Durvalumab plus SBRT to Metastatic Sites in Synchronous Oligometastatic NSCLC

K. N. McComas¹, and R. M. Whitaker²; ¹Vanderbilt University Medical Center, Nashville, TN, ²Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN

Purpose/Objective(s): The PACIFIC trial for locally advanced, unresectable, non-small cell lung cancer (NSCLC) demonstrated an improvement in 18-month progression free survival (PFS) of 17.2% in favor of consolidative durvalumab following definitive chemoradiotherapy (CRT). There continues to be a PFS benefit after 5 years, as well as an overall survival (OS) benefit of approximately 10%. Prior data has demonstrated improved survival with aggressive treatment of oligometastatic disease, including in stage IV NSCLC, which has a historically poor prognosis (median OS 8-11 months; PFS 3-5 months after chemotherapy alone). This study seeks to evaluate the utility of curative-intent CRT (to primary and metastatic sites) with adjuvant durvalumab for oligometastatic NSCLC. Materials/

Methods: A retrospective review of patients with oligometastatic NSCLC treated at our institution from 2018 to 2024 was performed. Ten patients with synchronous oligometastatic NSCLC were treated with definitive CRT to the primary tumor (60 Gy in 30 fractions with concurrent cisplatin and etoposide) and SBRT/SRS to oligometastatic sites, followed by adjuvant durvalumab per PACIFIC trial. Demographic, dosimetric, and clinical outcome measures were collected.
Results:

Median follow-up was 17.6 months. A majority of patients were males (60%) and most were non-Hispanic white (90%). 8 patients had brain metastases treated with surgery and adjuvant SRS or SRS alone, 1 patient had a solitary adrenal metastasis, and 1 patient had a solitary bony metastasis to L2. A majority of patients had confirmed adenocarcinoma histology (60%) with 2/10 pts with PD-L1 expression of 0%, 3/10 pts with PD-L1 expression of 1-49%, 2/10 pts with PD-L1 expression of at least 50%, and 3 with unknown PD-L1 expression. A single patient had a targetable mutation who received RET directed therapy at time of progression after PACIFIC regimen. Median PFS for the cohort was 11.1 months (6.3-68.7 months) and median OS has not been reached with 4/10 patients currently alive beyond 4 years.
Conclusion: Aggressive curative-intent treatment of oligometastatic NSCLC with definitive CRT, SBRT/SRS to metastases, and adjuvant durvalumab demonstrated an improvement in PFS and likely OS compared to historical data, with similar results to the PACIFIC trial cohort and subsequent real-world validation studies. Prospective randomized trials are needed to inform patient selection and for further evaluation of the efficacy and durability of combination definitive CRT and immunotherapy in the oligometastatic setting.