A randomized phase II trial of adjuvant pembrolizumab versus observation following curative resection for stage I non-small cell lung cancer (NSCLC) with primary tumors between 1-4 cm: Big Ten Cancer Research Consortium BTCRC-LUN18-153.

TPS8118 Background: Each year, approximately 35,000 patients are diagnosed with stage I lung cancer in the United States. Despite early detection, the 5-year overall survival for this population remains disappointing, ranging between 73-86% with recurrence rates from 18-38%. The current standard of care for stage I NSCLC is surgery alone followed by observation as prior trials of adjuvant chemotherapy in this subgroup have failed to show benefit. More modern therapies such as programmed death-1 (PD-1) inhibitors have not been evaluated in the stage I setting but have demonstrated significant improvements in pathologic complete response, event free survival, and overall survival when added to chemotherapy for patients with fully resected stage II and III disease. The use of PD-(L)1 inhibition has also demonstrated clinically and statistically significant improvements in OS in both unresectable stage III NSCLC following chemoradiation and in the metastatic setting. Given the activity of PD-(L)1 inhibition in nearly every other subset of NSCLC patients, we aimed to evaluate this therapy following resection in stage I NSCLC patients. Methods: This study is a randomized phase II multicenter trial of adjuvant Pembrolizumab versus observation alone following complete resection of stage I NSCLC with tumors between 1-4cm. The trial randomizes patients 1:1 to either Pembrolizumab 400mg IV every 6 weeks for up to 9 cycles or observation alone. Patients are stratified by PD-L1 score (PD-L1 ≥50% vs. 2-4cm), and they undergo repeat CT imaging every 12 weeks. The study is being conducted through the Big Ten Cancer Research Consortium, and there are currently 11 sites open to accrual with one additional site pending activation. The primary endpoint is disease free survival with secondary endpoints including OS, DFS at multiple timepoints (1-, 2-, and 3-years), and safety. The trial initially opened to accrual at the lead site, Indiana University, in May 2020, and enrollment is currently at 95 patients with a planned enrollment of 244. (NCT04317534) Clinical trial information: NCT04317534 .